shear.c revision 262953221f081eb2454b7155b027ffa1f93bbdf3
1/*
2%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3%                                                                             %
4%                                                                             %
5%                                                                             %
6%                      SSSSS  H   H  EEEEE   AAA    RRRR                      %
7%                      SS     H   H  E      A   A   R   R                     %
8%                       SSS   HHHHH  EEE    AAAAA   RRRR                      %
9%                         SS  H   H  E      A   A   R R                       %
10%                      SSSSS  H   H  EEEEE  A   A   R  R                      %
11%                                                                             %
12%                                                                             %
13%    MagickCore Methods to Shear or Rotate an Image by an Arbitrary Angle     %
14%                                                                             %
15%                               Software Design                               %
16%                                 John Cristy                                 %
17%                                  July 1992                                  %
18%                                                                             %
19%                                                                             %
20%  Copyright 1999-2011 ImageMagick Studio LLC, a non-profit organization      %
21%  dedicated to making software imaging solutions freely available.           %
22%                                                                             %
23%  You may not use this file except in compliance with the License.  You may  %
24%  obtain a copy of the License at                                            %
25%                                                                             %
26%    http://www.imagemagick.org/script/license.php                            %
27%                                                                             %
28%  Unless required by applicable law or agreed to in writing, software        %
29%  distributed under the License is distributed on an "AS IS" BASIS,          %
30%  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   %
31%  See the License for the specific language governing permissions and        %
32%  limitations under the License.                                             %
33%                                                                             %
34%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
35%
36%  The RotateImage, XShearImage, and YShearImage methods are based on the
37%  paper "A Fast Algorithm for General Raster Rotatation" by Alan W. Paeth,
38%  Graphics Interface '86 (Vancouver).  RotateImage is adapted from a similar
39%  method based on the Paeth paper written by Michael Halle of the Spatial
40%  Imaging Group, MIT Media Lab.
41%
42%
43*/
44
45/*
46  Include declarations.
47*/
48#include "MagickCore/studio.h"
49#include "MagickCore/artifact.h"
50#include "MagickCore/attribute.h"
51#include "MagickCore/blob-private.h"
52#include "MagickCore/cache-private.h"
53#include "MagickCore/color-private.h"
54#include "MagickCore/colorspace-private.h"
55#include "MagickCore/composite.h"
56#include "MagickCore/composite-private.h"
57#include "MagickCore/decorate.h"
58#include "MagickCore/distort.h"
59#include "MagickCore/draw.h"
60#include "MagickCore/exception.h"
61#include "MagickCore/exception-private.h"
62#include "MagickCore/gem.h"
63#include "MagickCore/geometry.h"
64#include "MagickCore/image.h"
65#include "MagickCore/image-private.h"
66#include "MagickCore/memory_.h"
67#include "MagickCore/list.h"
68#include "MagickCore/monitor.h"
69#include "MagickCore/monitor-private.h"
70#include "MagickCore/pixel-accessor.h"
71#include "MagickCore/quantum.h"
72#include "MagickCore/resource_.h"
73#include "MagickCore/shear.h"
74#include "MagickCore/statistic.h"
75#include "MagickCore/string_.h"
76#include "MagickCore/string-private.h"
77#include "MagickCore/thread-private.h"
78#include "MagickCore/threshold.h"
79#include "MagickCore/transform.h"
80
81/*
82%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
83%                                                                             %
84%                                                                             %
85%                                                                             %
86%     A f f i n e T r a n s f o r m I m a g e                                 %
87%                                                                             %
88%                                                                             %
89%                                                                             %
90%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
91%
92%  AffineTransformImage() transforms an image as dictated by the affine matrix.
93%  It allocates the memory necessary for the new Image structure and returns
94%  a pointer to the new image.
95%
96%  The format of the AffineTransformImage method is:
97%
98%      Image *AffineTransformImage(const Image *image,
99%        AffineMatrix *affine_matrix,ExceptionInfo *exception)
100%
101%  A description of each parameter follows:
102%
103%    o image: the image.
104%
105%    o affine_matrix: the affine matrix.
106%
107%    o exception: return any errors or warnings in this structure.
108%
109*/
110MagickExport Image *AffineTransformImage(const Image *image,
111  const AffineMatrix *affine_matrix,ExceptionInfo *exception)
112{
113  double
114    distort[6];
115
116  Image
117    *deskew_image;
118
119  /*
120    Affine transform image.
121  */
122  assert(image->signature == MagickSignature);
123  if (image->debug != MagickFalse)
124    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
125  assert(affine_matrix != (AffineMatrix *) NULL);
126  assert(exception != (ExceptionInfo *) NULL);
127  assert(exception->signature == MagickSignature);
128  distort[0]=affine_matrix->sx;
129  distort[1]=affine_matrix->rx;
130  distort[2]=affine_matrix->ry;
131  distort[3]=affine_matrix->sy;
132  distort[4]=affine_matrix->tx;
133  distort[5]=affine_matrix->ty;
134  deskew_image=DistortImage(image,AffineProjectionDistortion,6,distort,
135    MagickTrue,exception);
136  return(deskew_image);
137}
138
139/*
140%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
141%                                                                             %
142%                                                                             %
143%                                                                             %
144+   C r o p T o F i t I m a g e                                               %
145%                                                                             %
146%                                                                             %
147%                                                                             %
148%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
149%
150%  CropToFitImage() crops the sheared image as determined by the bounding box
151%  as defined by width and height and shearing angles.
152%
153%  The format of the CropToFitImage method is:
154%
155%      MagickBooleanType CropToFitImage(Image **image,
156%        const MagickRealType x_shear,const MagickRealType x_shear,
157%        const MagickRealType width,const MagickRealType height,
158%        const MagickBooleanType rotate,ExceptionInfo *exception)
159%
160%  A description of each parameter follows.
161%
162%    o image: the image.
163%
164%    o x_shear, y_shear, width, height: Defines a region of the image to crop.
165%
166%    o exception: return any errors or warnings in this structure.
167%
168*/
169static MagickBooleanType CropToFitImage(Image **image,
170  const MagickRealType x_shear,const MagickRealType y_shear,
171  const MagickRealType width,const MagickRealType height,
172  const MagickBooleanType rotate,ExceptionInfo *exception)
173{
174  Image
175    *crop_image;
176
177  PointInfo
178    extent[4],
179    min,
180    max;
181
182  RectangleInfo
183    geometry,
184    page;
185
186  register ssize_t
187    i;
188
189  /*
190    Calculate the rotated image size.
191  */
192  extent[0].x=(double) (-width/2.0);
193  extent[0].y=(double) (-height/2.0);
194  extent[1].x=(double) width/2.0;
195  extent[1].y=(double) (-height/2.0);
196  extent[2].x=(double) (-width/2.0);
197  extent[2].y=(double) height/2.0;
198  extent[3].x=(double) width/2.0;
199  extent[3].y=(double) height/2.0;
200  for (i=0; i < 4; i++)
201  {
202    extent[i].x+=x_shear*extent[i].y;
203    extent[i].y+=y_shear*extent[i].x;
204    if (rotate != MagickFalse)
205      extent[i].x+=x_shear*extent[i].y;
206    extent[i].x+=(double) (*image)->columns/2.0;
207    extent[i].y+=(double) (*image)->rows/2.0;
208  }
209  min=extent[0];
210  max=extent[0];
211  for (i=1; i < 4; i++)
212  {
213    if (min.x > extent[i].x)
214      min.x=extent[i].x;
215    if (min.y > extent[i].y)
216      min.y=extent[i].y;
217    if (max.x < extent[i].x)
218      max.x=extent[i].x;
219    if (max.y < extent[i].y)
220      max.y=extent[i].y;
221  }
222  geometry.x=(ssize_t) ceil(min.x-0.5);
223  geometry.y=(ssize_t) ceil(min.y-0.5);
224  geometry.width=(size_t) floor(max.x-min.x+0.5);
225  geometry.height=(size_t) floor(max.y-min.y+0.5);
226  page=(*image)->page;
227  (void) ParseAbsoluteGeometry("0x0+0+0",&(*image)->page);
228  crop_image=CropImage(*image,&geometry,exception);
229  if (crop_image == (Image *) NULL)
230    return(MagickFalse);
231  crop_image->page=page;
232  *image=DestroyImage(*image);
233  *image=crop_image;
234  return(MagickTrue);
235}
236
237/*
238%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
239%                                                                             %
240%                                                                             %
241%                                                                             %
242%     D e s k e w I m a g e                                                   %
243%                                                                             %
244%                                                                             %
245%                                                                             %
246%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
247%
248%  DeskewImage() removes skew from the image.  Skew is an artifact that
249%  occurs in scanned images because of the camera being misaligned,
250%  imperfections in the scanning or surface, or simply because the paper was
251%  not placed completely flat when scanned.
252%
253%  The format of the DeskewImage method is:
254%
255%      Image *DeskewImage(const Image *image,const double threshold,
256%        ExceptionInfo *exception)
257%
258%  A description of each parameter follows:
259%
260%    o image: the image.
261%
262%    o threshold: separate background from foreground.
263%
264%    o exception: return any errors or warnings in this structure.
265%
266*/
267
268typedef struct _RadonInfo
269{
270  CacheType
271    type;
272
273  size_t
274    width,
275    height;
276
277  MagickSizeType
278    length;
279
280  MagickBooleanType
281    mapped;
282
283  char
284    path[MaxTextExtent];
285
286  int
287    file;
288
289  unsigned short
290    *cells;
291} RadonInfo;
292
293static RadonInfo *DestroyRadonInfo(RadonInfo *radon_info)
294{
295  assert(radon_info != (RadonInfo *) NULL);
296  switch (radon_info->type)
297  {
298    case MemoryCache:
299    {
300      if (radon_info->mapped == MagickFalse)
301        radon_info->cells=(unsigned short *) RelinquishMagickMemory(
302          radon_info->cells);
303      else
304        radon_info->cells=(unsigned short *) UnmapBlob(radon_info->cells,
305          (size_t) radon_info->length);
306      RelinquishMagickResource(MemoryResource,radon_info->length);
307      break;
308    }
309    case MapCache:
310    {
311      radon_info->cells=(unsigned short *) UnmapBlob(radon_info->cells,(size_t)
312        radon_info->length);
313      RelinquishMagickResource(MapResource,radon_info->length);
314    }
315    case DiskCache:
316    {
317      if (radon_info->file != -1)
318        (void) close(radon_info->file);
319      (void) RelinquishUniqueFileResource(radon_info->path);
320      RelinquishMagickResource(DiskResource,radon_info->length);
321      break;
322    }
323    default:
324      break;
325  }
326  return((RadonInfo *) RelinquishMagickMemory(radon_info));
327}
328
329static MagickBooleanType ResetRadonCells(RadonInfo *radon_info)
330{
331  register ssize_t
332    x;
333
334  ssize_t
335    count,
336    y;
337
338  unsigned short
339    value;
340
341  if (radon_info->type != DiskCache)
342    {
343      (void) ResetMagickMemory(radon_info->cells,0,(size_t) radon_info->length);
344      return(MagickTrue);
345    }
346  value=0;
347  (void) lseek(radon_info->file,0,SEEK_SET);
348  for (y=0; y < (ssize_t) radon_info->height; y++)
349  {
350    for (x=0; x < (ssize_t) radon_info->width; x++)
351    {
352      count=write(radon_info->file,&value,sizeof(*radon_info->cells));
353      if (count != (ssize_t) sizeof(*radon_info->cells))
354        break;
355    }
356    if (x < (ssize_t) radon_info->width)
357      break;
358  }
359  return(y < (ssize_t) radon_info->height ? MagickFalse : MagickTrue);
360}
361
362static RadonInfo *AcquireRadonInfo(const Image *image,const size_t width,
363  const size_t height,ExceptionInfo *exception)
364{
365  MagickBooleanType
366    status;
367
368  RadonInfo
369    *radon_info;
370
371  radon_info=(RadonInfo *) AcquireMagickMemory(sizeof(*radon_info));
372  if (radon_info == (RadonInfo *) NULL)
373    return((RadonInfo *) NULL);
374  (void) ResetMagickMemory(radon_info,0,sizeof(*radon_info));
375  radon_info->width=width;
376  radon_info->height=height;
377  radon_info->length=(MagickSizeType) width*height*sizeof(*radon_info->cells);
378  radon_info->type=MemoryCache;
379  status=AcquireMagickResource(AreaResource,radon_info->length);
380  if ((status != MagickFalse) &&
381      (radon_info->length == (MagickSizeType) ((size_t) radon_info->length)))
382    {
383      status=AcquireMagickResource(MemoryResource,radon_info->length);
384      if (status != MagickFalse)
385        {
386          radon_info->mapped=MagickFalse;
387          radon_info->cells=(unsigned short *) AcquireMagickMemory((size_t)
388            radon_info->length);
389          if (radon_info->cells == (unsigned short *) NULL)
390            {
391              radon_info->mapped=MagickTrue;
392              radon_info->cells=(unsigned short *) MapBlob(-1,IOMode,0,(size_t)
393                radon_info->length);
394            }
395          if (radon_info->cells == (unsigned short *) NULL)
396            RelinquishMagickResource(MemoryResource,radon_info->length);
397        }
398    }
399  radon_info->file=(-1);
400  if (radon_info->cells == (unsigned short *) NULL)
401    {
402      status=AcquireMagickResource(DiskResource,radon_info->length);
403      if (status == MagickFalse)
404        {
405          (void) ThrowMagickException(exception,GetMagickModule(),CacheError,
406            "CacheResourcesExhausted","`%s'",image->filename);
407          return(DestroyRadonInfo(radon_info));
408        }
409      radon_info->type=DiskCache;
410      (void) AcquireMagickResource(MemoryResource,radon_info->length);
411      radon_info->file=AcquireUniqueFileResource(radon_info->path);
412      if (radon_info->file == -1)
413        return(DestroyRadonInfo(radon_info));
414      status=AcquireMagickResource(MapResource,radon_info->length);
415      if (status != MagickFalse)
416        {
417          status=ResetRadonCells(radon_info);
418          if (status != MagickFalse)
419            {
420              radon_info->cells=(unsigned short *) MapBlob(radon_info->file,
421                IOMode,0,(size_t) radon_info->length);
422              if (radon_info->cells != (unsigned short *) NULL)
423                radon_info->type=MapCache;
424              else
425                RelinquishMagickResource(MapResource,radon_info->length);
426            }
427        }
428    }
429  return(radon_info);
430}
431
432static inline size_t MagickMin(const size_t x,const size_t y)
433{
434  if (x < y)
435    return(x);
436  return(y);
437}
438
439static inline ssize_t ReadRadonCell(const RadonInfo *radon_info,
440  const MagickOffsetType offset,const size_t length,unsigned char *buffer)
441{
442  register ssize_t
443    i;
444
445  ssize_t
446    count;
447
448#if !defined(MAGICKCORE_HAVE_PPREAD)
449#if defined(MAGICKCORE_OPENMP_SUPPORT)
450  #pragma omp critical (MagickCore_ReadRadonCell)
451#endif
452  {
453    i=(-1);
454    if (lseek(radon_info->file,offset,SEEK_SET) >= 0)
455      {
456#endif
457        count=0;
458        for (i=0; i < (ssize_t) length; i+=count)
459        {
460#if !defined(MAGICKCORE_HAVE_PPREAD)
461          count=read(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
462            SSIZE_MAX));
463#else
464          count=pread(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
465            SSIZE_MAX),offset+i);
466#endif
467          if (count > 0)
468            continue;
469          count=0;
470          if (errno != EINTR)
471            {
472              i=(-1);
473              break;
474            }
475        }
476#if !defined(MAGICKCORE_HAVE_PPREAD)
477      }
478  }
479#endif
480  return(i);
481}
482
483static inline ssize_t WriteRadonCell(const RadonInfo *radon_info,
484  const MagickOffsetType offset,const size_t length,const unsigned char *buffer)
485{
486  register ssize_t
487    i;
488
489  ssize_t
490    count;
491
492#if !defined(MAGICKCORE_HAVE_PWRITE)
493#if defined(MAGICKCORE_OPENMP_SUPPORT)
494  #pragma omp critical (MagickCore_WriteRadonCell)
495#endif
496  {
497    if (lseek(radon_info->file,offset,SEEK_SET) >= 0)
498      {
499#endif
500        count=0;
501        for (i=0; i < (ssize_t) length; i+=count)
502        {
503#if !defined(MAGICKCORE_HAVE_PWRITE)
504          count=write(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
505            SSIZE_MAX));
506#else
507          count=pwrite(radon_info->file,buffer+i,MagickMin(length-i,(size_t)
508            SSIZE_MAX),offset+i);
509#endif
510          if (count > 0)
511            continue;
512          count=0;
513          if (errno != EINTR)
514            {
515              i=(-1);
516              break;
517            }
518        }
519#if !defined(MAGICKCORE_HAVE_PWRITE)
520      }
521  }
522#endif
523  return(i);
524}
525
526static inline unsigned short GetRadonCell(const RadonInfo *radon_info,
527  const ssize_t x,const ssize_t y)
528{
529  MagickOffsetType
530    i;
531
532  unsigned short
533    value;
534
535  i=(MagickOffsetType) radon_info->height*x+y;
536  if ((i < 0) ||
537      ((MagickSizeType) (i*sizeof(*radon_info->cells)) >= radon_info->length))
538    return(0);
539  if (radon_info->type != DiskCache)
540    return(radon_info->cells[i]);
541  value=0;
542  (void) ReadRadonCell(radon_info,i*sizeof(*radon_info->cells),
543    sizeof(*radon_info->cells),(unsigned char *) &value);
544  return(value);
545}
546
547static inline MagickBooleanType SetRadonCell(const RadonInfo *radon_info,
548  const ssize_t x,const ssize_t y,const unsigned short value)
549{
550  MagickOffsetType
551    i;
552
553  ssize_t
554    count;
555
556  i=(MagickOffsetType) radon_info->height*x+y;
557  if ((i < 0) ||
558      ((MagickSizeType) (i*sizeof(*radon_info->cells)) >= radon_info->length))
559    return(MagickFalse);
560  if (radon_info->type != DiskCache)
561    {
562      radon_info->cells[i]=value;
563      return(MagickTrue);
564    }
565  count=WriteRadonCell(radon_info,i*sizeof(*radon_info->cells),
566    sizeof(*radon_info->cells),(const unsigned char *) &value);
567  if (count != (ssize_t) sizeof(*radon_info->cells))
568    return(MagickFalse);
569  return(MagickTrue);
570}
571
572static void RadonProjection(RadonInfo *source_cells,
573  RadonInfo *destination_cells,const ssize_t sign,size_t *projection)
574{
575  RadonInfo
576    *swap;
577
578  register ssize_t
579    x;
580
581  register RadonInfo
582    *p,
583    *q;
584
585  size_t
586    step;
587
588  p=source_cells;
589  q=destination_cells;
590  for (step=1; step < p->width; step*=2)
591  {
592    for (x=0; x < (ssize_t) p->width; x+=2*(ssize_t) step)
593    {
594      register ssize_t
595        i;
596
597      ssize_t
598        y;
599
600      unsigned short
601        cell;
602
603      for (i=0; i < (ssize_t) step; i++)
604      {
605        for (y=0; y < (ssize_t) (p->height-i-1); y++)
606        {
607          cell=GetRadonCell(p,x+i,y);
608          (void) SetRadonCell(q,x+2*i,y,cell+GetRadonCell(p,x+i+(ssize_t)
609            step,y+i));
610          (void) SetRadonCell(q,x+2*i+1,y,cell+GetRadonCell(p,x+i+(ssize_t)
611            step,y+i+1));
612        }
613        for ( ; y < (ssize_t) (p->height-i); y++)
614        {
615          cell=GetRadonCell(p,x+i,y);
616          (void) SetRadonCell(q,x+2*i,y,cell+GetRadonCell(p,x+i+(ssize_t) step,
617            y+i));
618          (void) SetRadonCell(q,x+2*i+1,y,cell);
619        }
620        for ( ; y < (ssize_t) p->height; y++)
621        {
622          cell=GetRadonCell(p,x+i,y);
623          (void) SetRadonCell(q,x+2*i,y,cell);
624          (void) SetRadonCell(q,x+2*i+1,y,cell);
625        }
626      }
627    }
628    swap=p;
629    p=q;
630    q=swap;
631  }
632#if defined(MAGICKCORE_OPENMP_SUPPORT)
633  #pragma omp parallel for schedule(dynamic,4)
634#endif
635  for (x=0; x < (ssize_t) p->width; x++)
636  {
637    register ssize_t
638      y;
639
640    size_t
641      sum;
642
643    sum=0;
644    for (y=0; y < (ssize_t) (p->height-1); y++)
645    {
646      ssize_t
647        delta;
648
649      delta=GetRadonCell(p,x,y)-(ssize_t) GetRadonCell(p,x,y+1);
650      sum+=delta*delta;
651    }
652    projection[p->width+sign*x-1]=sum;
653  }
654}
655
656static MagickBooleanType RadonTransform(const Image *image,
657  const double threshold,size_t *projection,ExceptionInfo *exception)
658{
659  CacheView
660    *image_view;
661
662  MagickBooleanType
663    status;
664
665  RadonInfo
666    *destination_cells,
667    *source_cells;
668
669  register ssize_t
670    i;
671
672  size_t
673    count,
674    width;
675
676  ssize_t
677    y;
678
679  unsigned char
680    byte;
681
682  unsigned short
683    bits[256];
684
685  for (width=1; width < ((image->columns+7)/8); width<<=1) ;
686  source_cells=AcquireRadonInfo(image,width,image->rows,exception);
687  destination_cells=AcquireRadonInfo(image,width,image->rows,exception);
688  if ((source_cells == (RadonInfo *) NULL) ||
689      (destination_cells == (RadonInfo *) NULL))
690    {
691      if (destination_cells != (RadonInfo *) NULL)
692        destination_cells=DestroyRadonInfo(destination_cells);
693      if (source_cells != (RadonInfo *) NULL)
694        source_cells=DestroyRadonInfo(source_cells);
695      return(MagickFalse);
696    }
697  if (ResetRadonCells(source_cells) == MagickFalse)
698    {
699      destination_cells=DestroyRadonInfo(destination_cells);
700      source_cells=DestroyRadonInfo(source_cells);
701      return(MagickFalse);
702    }
703  for (i=0; i < 256; i++)
704  {
705    byte=(unsigned char) i;
706    for (count=0; byte != 0; byte>>=1)
707      count+=byte & 0x01;
708    bits[i]=(unsigned short) count;
709  }
710  status=MagickTrue;
711  image_view=AcquireCacheView(image);
712#if defined(MAGICKCORE_OPENMP_SUPPORT)
713  #pragma omp parallel for schedule(dynamic,4) shared(status)
714#endif
715  for (y=0; y < (ssize_t) image->rows; y++)
716  {
717    register const Quantum
718      *restrict p;
719
720    register ssize_t
721      i,
722      x;
723
724    size_t
725      bit,
726      byte;
727
728    if (status == MagickFalse)
729      continue;
730    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
731    if (p == (const Quantum *) NULL)
732      {
733        status=MagickFalse;
734        continue;
735      }
736    bit=0;
737    byte=0;
738    i=(ssize_t) (image->columns+7)/8;
739    for (x=0; x < (ssize_t) image->columns; x++)
740    {
741      byte<<=1;
742      if (GetPixelIntensity(image,p) < threshold)
743        byte|=0x01;
744      bit++;
745      if (bit == 8)
746        {
747          (void) SetRadonCell(source_cells,--i,y,bits[byte]);
748          bit=0;
749          byte=0;
750        }
751      p+=GetPixelChannels(image);
752    }
753    if (bit != 0)
754      {
755        byte<<=(8-bit);
756        (void) SetRadonCell(source_cells,--i,y,bits[byte]);
757      }
758  }
759  RadonProjection(source_cells,destination_cells,-1,projection);
760  (void) ResetRadonCells(source_cells);
761#if defined(MAGICKCORE_OPENMP_SUPPORT)
762  #pragma omp parallel for schedule(dynamic,4) shared(status)
763#endif
764  for (y=0; y < (ssize_t) image->rows; y++)
765  {
766    register const Quantum
767      *restrict p;
768
769    register ssize_t
770      i,
771      x;
772
773    size_t
774      bit,
775      byte;
776
777    if (status == MagickFalse)
778      continue;
779    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
780    if (p == (const Quantum *) NULL)
781      {
782        status=MagickFalse;
783        continue;
784      }
785    bit=0;
786    byte=0;
787    i=0;
788    for (x=0; x < (ssize_t) image->columns; x++)
789    {
790      byte<<=1;
791      if (GetPixelIntensity(image,p) < threshold)
792        byte|=0x01;
793      bit++;
794      if (bit == 8)
795        {
796          (void) SetRadonCell(source_cells,i++,y,bits[byte]);
797          bit=0;
798          byte=0;
799        }
800      p+=GetPixelChannels(image);
801    }
802    if (bit != 0)
803      {
804        byte<<=(8-bit);
805        (void) SetRadonCell(source_cells,i++,y,bits[byte]);
806      }
807  }
808  RadonProjection(source_cells,destination_cells,1,projection);
809  image_view=DestroyCacheView(image_view);
810  destination_cells=DestroyRadonInfo(destination_cells);
811  source_cells=DestroyRadonInfo(source_cells);
812  return(MagickTrue);
813}
814
815static void GetImageBackgroundColor(Image *image,const ssize_t offset,
816  ExceptionInfo *exception)
817{
818  CacheView
819    *image_view;
820
821  PixelInfo
822    background;
823
824  MagickRealType
825    count;
826
827  ssize_t
828    y;
829
830  /*
831    Compute average background color.
832  */
833  if (offset <= 0)
834    return;
835  GetPixelInfo(image,&background);
836  count=0.0;
837  image_view=AcquireCacheView(image);
838  for (y=0; y < (ssize_t) image->rows; y++)
839  {
840    register const Quantum
841      *restrict p;
842
843    register ssize_t
844      x;
845
846    if ((y >= offset) && (y < ((ssize_t) image->rows-offset)))
847      continue;
848    p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
849    if (p == (const Quantum *) NULL)
850      continue;
851    for (x=0; x < (ssize_t) image->columns; x++)
852    {
853      if ((x >= offset) && (x < ((ssize_t) image->columns-offset)))
854        continue;
855      background.red+=QuantumScale*GetPixelRed(image,p);
856      background.green+=QuantumScale*GetPixelGreen(image,p);
857      background.blue+=QuantumScale*GetPixelBlue(image,p);
858      if ((GetPixelAlphaTraits(image) & UpdatePixelTrait) != 0)
859        background.alpha+=QuantumScale*GetPixelAlpha(image,p);
860      count++;
861      p+=GetPixelChannels(image);
862    }
863  }
864  image_view=DestroyCacheView(image_view);
865  image->background_color.red=ClampToQuantum((MagickRealType) QuantumRange*
866    background.red/count);
867  image->background_color.green=ClampToQuantum((MagickRealType) QuantumRange*
868    background.green/count);
869  image->background_color.blue=ClampToQuantum((MagickRealType) QuantumRange*
870    background.blue/count);
871  if ((GetPixelAlphaTraits(image) & UpdatePixelTrait) != 0)
872    image->background_color.alpha=ClampToQuantum((MagickRealType) QuantumRange*
873      background.alpha/count);
874}
875
876MagickExport Image *DeskewImage(const Image *image,const double threshold,
877  ExceptionInfo *exception)
878{
879  AffineMatrix
880    affine_matrix;
881
882  const char
883    *artifact;
884
885  double
886    degrees;
887
888  Image
889    *clone_image,
890    *crop_image,
891    *deskew_image,
892    *median_image;
893
894  MagickBooleanType
895    status;
896
897  RectangleInfo
898    geometry;
899
900  register ssize_t
901    i;
902
903  size_t
904    max_projection,
905    *projection,
906    width;
907
908  ssize_t
909    skew;
910
911  /*
912    Compute deskew angle.
913  */
914  for (width=1; width < ((image->columns+7)/8); width<<=1) ;
915  projection=(size_t *) AcquireQuantumMemory((size_t) (2*width-1),
916    sizeof(*projection));
917  if (projection == (size_t *) NULL)
918    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
919  status=RadonTransform(image,threshold,projection,exception);
920  if (status == MagickFalse)
921    {
922      projection=(size_t *) RelinquishMagickMemory(projection);
923      ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
924    }
925  max_projection=0;
926  skew=0;
927  for (i=0; i < (ssize_t) (2*width-1); i++)
928  {
929    if (projection[i] > max_projection)
930      {
931        skew=i-(ssize_t) width+1;
932        max_projection=projection[i];
933      }
934  }
935  projection=(size_t *) RelinquishMagickMemory(projection);
936  /*
937    Deskew image.
938  */
939  clone_image=CloneImage(image,0,0,MagickTrue,exception);
940  if (clone_image == (Image *) NULL)
941    return((Image *) NULL);
942  (void) SetImageVirtualPixelMethod(clone_image,BackgroundVirtualPixelMethod);
943  degrees=RadiansToDegrees(-atan((double) skew/width/8));
944  if (image->debug != MagickFalse)
945    (void) LogMagickEvent(TransformEvent,GetMagickModule(),
946      "  Deskew angle: %g",degrees);
947  affine_matrix.sx=cos(DegreesToRadians(fmod((double) degrees,360.0)));
948  affine_matrix.rx=sin(DegreesToRadians(fmod((double) degrees,360.0)));
949  affine_matrix.ry=(-sin(DegreesToRadians(fmod((double) degrees,360.0))));
950  affine_matrix.sy=cos(DegreesToRadians(fmod((double) degrees,360.0)));
951  affine_matrix.tx=0.0;
952  affine_matrix.ty=0.0;
953  artifact=GetImageArtifact(image,"deskew:auto-crop");
954  if (artifact == (const char *) NULL)
955    {
956      deskew_image=AffineTransformImage(clone_image,&affine_matrix,exception);
957      clone_image=DestroyImage(clone_image);
958      return(deskew_image);
959    }
960  /*
961    Auto-crop image.
962  */
963  GetImageBackgroundColor(clone_image,(ssize_t) StringToLong(artifact),
964    exception);
965  deskew_image=AffineTransformImage(clone_image,&affine_matrix,exception);
966  clone_image=DestroyImage(clone_image);
967  if (deskew_image == (Image *) NULL)
968    return((Image *) NULL);
969  median_image=StatisticImage(deskew_image,MedianStatistic,3,3,exception);
970  if (median_image == (Image *) NULL)
971    {
972      deskew_image=DestroyImage(deskew_image);
973      return((Image *) NULL);
974    }
975  geometry=GetImageBoundingBox(median_image,exception);
976  median_image=DestroyImage(median_image);
977  if (image->debug != MagickFalse)
978    (void) LogMagickEvent(TransformEvent,GetMagickModule(),"  Deskew geometry: "
979      "%.20gx%.20g%+.20g%+.20g",(double) geometry.width,(double)
980      geometry.height,(double) geometry.x,(double) geometry.y);
981  crop_image=CropImage(deskew_image,&geometry,exception);
982  deskew_image=DestroyImage(deskew_image);
983  return(crop_image);
984}
985
986/*
987%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
988%                                                                             %
989%                                                                             %
990%                                                                             %
991+   I n t e g r a l R o t a t e I m a g e                                     %
992%                                                                             %
993%                                                                             %
994%                                                                             %
995%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
996%
997%  IntegralRotateImage() rotates the image an integral of 90 degrees.  It
998%  allocates the memory necessary for the new Image structure and returns a
999%  pointer to the rotated image.
1000%
1001%  The format of the IntegralRotateImage method is:
1002%
1003%      Image *IntegralRotateImage(const Image *image,size_t rotations,
1004%        ExceptionInfo *exception)
1005%
1006%  A description of each parameter follows.
1007%
1008%    o image: the image.
1009%
1010%    o rotations: Specifies the number of 90 degree rotations.
1011%
1012*/
1013static Image *IntegralRotateImage(const Image *image,size_t rotations,
1014  ExceptionInfo *exception)
1015{
1016#define RotateImageTag  "Rotate/Image"
1017
1018  CacheView
1019    *image_view,
1020    *rotate_view;
1021
1022  Image
1023    *rotate_image;
1024
1025  MagickBooleanType
1026    status;
1027
1028  MagickOffsetType
1029    progress;
1030
1031  RectangleInfo
1032    page;
1033
1034  ssize_t
1035    y;
1036
1037  /*
1038    Initialize rotated image attributes.
1039  */
1040  assert(image != (Image *) NULL);
1041  page=image->page;
1042  rotations%=4;
1043  if (rotations == 0)
1044    return(CloneImage(image,0,0,MagickTrue,exception));
1045  if ((rotations == 1) || (rotations == 3))
1046    rotate_image=CloneImage(image,image->rows,image->columns,MagickTrue,
1047      exception);
1048  else
1049    rotate_image=CloneImage(image,image->columns,image->rows,MagickTrue,
1050      exception);
1051  if (rotate_image == (Image *) NULL)
1052    return((Image *) NULL);
1053  /*
1054    Integral rotate the image.
1055  */
1056  status=MagickTrue;
1057  progress=0;
1058  image_view=AcquireCacheView(image);
1059  rotate_view=AcquireCacheView(rotate_image);
1060  switch (rotations)
1061  {
1062    case 0:
1063    {
1064      /*
1065        Rotate 0 degrees.
1066      */
1067      break;
1068    }
1069    case 1:
1070    {
1071      size_t
1072        tile_height,
1073        tile_width;
1074
1075      ssize_t
1076        tile_y;
1077
1078      /*
1079        Rotate 90 degrees.
1080      */
1081      GetPixelCacheTileSize(image,&tile_width,&tile_height);
1082      tile_y=0;
1083      for ( ; tile_y < (ssize_t) image->rows; tile_y+=(ssize_t) tile_height)
1084      {
1085        register ssize_t
1086          tile_x;
1087
1088        if (status == MagickFalse)
1089          continue;
1090        tile_x=0;
1091        for ( ; tile_x < (ssize_t) image->columns; tile_x+=(ssize_t) tile_width)
1092        {
1093          MagickBooleanType
1094            sync;
1095
1096          register const Quantum
1097            *restrict p;
1098
1099          register ssize_t
1100            y;
1101
1102          register Quantum
1103            *restrict q;
1104
1105          size_t
1106            height,
1107            width;
1108
1109          width=tile_width;
1110          if ((tile_x+(ssize_t) tile_width) > (ssize_t) image->columns)
1111            width=(size_t) (tile_width-(tile_x+tile_width-image->columns));
1112          height=tile_height;
1113          if ((tile_y+(ssize_t) tile_height) > (ssize_t) image->rows)
1114            height=(size_t) (tile_height-(tile_y+tile_height-image->rows));
1115          p=GetCacheViewVirtualPixels(image_view,tile_x,tile_y,width,height,
1116            exception);
1117          if (p == (const Quantum *) NULL)
1118            {
1119              status=MagickFalse;
1120              break;
1121            }
1122#if defined(MAGICKCORE_OPENMP_SUPPORT)
1123          #pragma omp parallel for schedule(static,1) shared(progress, status)
1124#endif
1125          for (y=0; y < (ssize_t) width; y++)
1126          {
1127            register const Quantum
1128              *restrict tile_pixels;
1129
1130            register ssize_t
1131              x;
1132
1133            if (status == MagickFalse)
1134              continue;
1135            q=QueueCacheViewAuthenticPixels(rotate_view,(ssize_t)
1136              (rotate_image->columns-(tile_y+height)),y+tile_x,height,1,
1137              exception);
1138            if (q == (Quantum *) NULL)
1139              {
1140                status=MagickFalse;
1141                continue;
1142              }
1143            tile_pixels=p+((height-1)*width+y)*GetPixelChannels(image);
1144            for (x=0; x < (ssize_t) height; x++)
1145            {
1146              register ssize_t
1147                i;
1148
1149              for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
1150              {
1151                PixelChannel
1152                  channel;
1153
1154                PixelTrait
1155                  rotate_traits,
1156                  traits;
1157
1158                traits=GetPixelChannelMapTraits(image,(PixelChannel) i);
1159                channel=GetPixelChannelMapChannel(image,(PixelChannel) i);
1160                rotate_traits=GetPixelChannelMapTraits(rotate_image,channel);
1161                if ((traits == UndefinedPixelTrait) ||
1162                    (rotate_traits == UndefinedPixelTrait))
1163                  continue;
1164                if ((rotate_traits & CopyPixelTrait) != 0)
1165                  {
1166                    q[channel]=tile_pixels[i];
1167                    continue;
1168                  }
1169                q[channel]=tile_pixels[i];
1170              }
1171              tile_pixels-=width*GetPixelChannels(image);
1172              q+=GetPixelChannels(rotate_image);
1173            }
1174            sync=SyncCacheViewAuthenticPixels(rotate_view,exception);
1175            if (sync == MagickFalse)
1176              status=MagickFalse;
1177          }
1178        }
1179        if (image->progress_monitor != (MagickProgressMonitor) NULL)
1180          {
1181            MagickBooleanType
1182              proceed;
1183
1184            proceed=SetImageProgress(image,RotateImageTag,progress+=tile_height,
1185              image->rows);
1186            if (proceed == MagickFalse)
1187              status=MagickFalse;
1188          }
1189      }
1190      (void) SetImageProgress(image,RotateImageTag,(MagickOffsetType)
1191        image->rows-1,image->rows);
1192      Swap(page.width,page.height);
1193      Swap(page.x,page.y);
1194      if (page.width != 0)
1195        page.x=(ssize_t) (page.width-rotate_image->columns-page.x);
1196      break;
1197    }
1198    case 2:
1199    {
1200      /*
1201        Rotate 180 degrees.
1202      */
1203#if defined(MAGICKCORE_OPENMP_SUPPORT)
1204  #pragma omp parallel for schedule(static,8) shared(progress,status)
1205#endif
1206      for (y=0; y < (ssize_t) image->rows; y++)
1207      {
1208        MagickBooleanType
1209          sync;
1210
1211        register const Quantum
1212          *restrict p;
1213
1214        register ssize_t
1215          x;
1216
1217        register Quantum
1218          *restrict q;
1219
1220        if (status == MagickFalse)
1221          continue;
1222        p=GetCacheViewVirtualPixels(image_view,0,y,image->columns,1,exception);
1223        q=QueueCacheViewAuthenticPixels(rotate_view,0,(ssize_t) (image->rows-y-
1224          1),image->columns,1,exception);
1225        if ((p == (const Quantum *) NULL) || (q == (Quantum *) NULL))
1226          {
1227            status=MagickFalse;
1228            continue;
1229          }
1230        q+=GetPixelChannels(rotate_image)*image->columns;
1231        for (x=0; x < (ssize_t) image->columns; x++)
1232        {
1233          register ssize_t
1234            i;
1235
1236          q-=GetPixelChannels(rotate_image);
1237          for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
1238          {
1239            PixelChannel
1240              channel;
1241
1242            PixelTrait
1243              rotate_traits,
1244              traits;
1245
1246            traits=GetPixelChannelMapTraits(image,(PixelChannel) i);
1247            channel=GetPixelChannelMapChannel(image,(PixelChannel) i);
1248            rotate_traits=GetPixelChannelMapTraits(rotate_image,channel);
1249            if ((traits == UndefinedPixelTrait) ||
1250                (rotate_traits == UndefinedPixelTrait))
1251              continue;
1252            if ((rotate_traits & CopyPixelTrait) != 0)
1253              {
1254                q[channel]=p[i];
1255                continue;
1256              }
1257            q[channel]=p[i];
1258          }
1259          p+=GetPixelChannels(image);
1260        }
1261        sync=SyncCacheViewAuthenticPixels(rotate_view,exception);
1262        if (sync == MagickFalse)
1263          status=MagickFalse;
1264        if (image->progress_monitor != (MagickProgressMonitor) NULL)
1265          {
1266            MagickBooleanType
1267              proceed;
1268
1269            proceed=SetImageProgress(image,RotateImageTag,progress++,
1270              image->rows);
1271            if (proceed == MagickFalse)
1272              status=MagickFalse;
1273          }
1274      }
1275      if (page.width != 0)
1276        page.x=(ssize_t) (page.width-rotate_image->columns-page.x);
1277      if (page.height != 0)
1278        page.y=(ssize_t) (page.height-rotate_image->rows-page.y);
1279      break;
1280    }
1281    case 3:
1282    {
1283      size_t
1284        tile_height,
1285        tile_width;
1286
1287      ssize_t
1288        tile_y;
1289
1290      /*
1291        Rotate 270 degrees.
1292      */
1293      GetPixelCacheTileSize(image,&tile_width,&tile_height);
1294      tile_y=0;
1295      for ( ; tile_y < (ssize_t) image->rows; tile_y+=(ssize_t) tile_height)
1296      {
1297        register ssize_t
1298          tile_x;
1299
1300        if (status == MagickFalse)
1301          continue;
1302        tile_x=0;
1303        for ( ; tile_x < (ssize_t) image->columns; tile_x+=(ssize_t) tile_width)
1304        {
1305          MagickBooleanType
1306            sync;
1307
1308          register const Quantum
1309            *restrict p;
1310
1311          register ssize_t
1312            y;
1313
1314          register Quantum
1315            *restrict q;
1316
1317          size_t
1318            height,
1319            width;
1320
1321          width=tile_width;
1322          if ((tile_x+(ssize_t) tile_width) > (ssize_t) image->columns)
1323            width=(size_t) (tile_width-(tile_x+tile_width-image->columns));
1324          height=tile_height;
1325          if ((tile_y+(ssize_t) tile_height) > (ssize_t) image->rows)
1326            height=(size_t) (tile_height-(tile_y+tile_height-image->rows));
1327          p=GetCacheViewVirtualPixels(image_view,tile_x,tile_y,width,height,
1328            exception);
1329          if (p == (const Quantum *) NULL)
1330            {
1331              status=MagickFalse;
1332              break;
1333            }
1334#if defined(MAGICKCORE_OPENMP_SUPPORT)
1335          #pragma omp parallel for schedule(static,1) shared(progress,status)
1336#endif
1337          for (y=0; y < (ssize_t) width; y++)
1338          {
1339            register const Quantum
1340              *restrict tile_pixels;
1341
1342            register ssize_t
1343              x;
1344
1345            if (status == MagickFalse)
1346              continue;
1347            q=QueueCacheViewAuthenticPixels(rotate_view,tile_y,(ssize_t) (y+
1348              rotate_image->rows-(tile_x+width)),height,1,exception);
1349            if (q == (Quantum *) NULL)
1350              {
1351                status=MagickFalse;
1352                continue;
1353              }
1354            tile_pixels=p+((width-1)-y)*GetPixelChannels(image);
1355            for (x=0; x < (ssize_t) height; x++)
1356            {
1357              register ssize_t
1358                i;
1359
1360              for (i=0; i < (ssize_t) GetPixelChannels(image); i++)
1361              {
1362                PixelChannel
1363                  channel;
1364
1365                PixelTrait
1366                  rotate_traits,
1367                  traits;
1368
1369                traits=GetPixelChannelMapTraits(image,(PixelChannel) i);
1370                channel=GetPixelChannelMapChannel(image,(PixelChannel) i);
1371                rotate_traits=GetPixelChannelMapTraits(rotate_image,channel);
1372                if ((traits == UndefinedPixelTrait) ||
1373                    (rotate_traits == UndefinedPixelTrait))
1374                  continue;
1375                if ((rotate_traits & CopyPixelTrait) != 0)
1376                  {
1377                    q[channel]=tile_pixels[i];
1378                    continue;
1379                  }
1380                q[channel]=tile_pixels[i];
1381              }
1382              tile_pixels+=width*GetPixelChannels(image);
1383              q+=GetPixelChannels(rotate_image);
1384            }
1385            sync=SyncCacheViewAuthenticPixels(rotate_view,exception);
1386            if (sync == MagickFalse)
1387              status=MagickFalse;
1388          }
1389        }
1390        if (image->progress_monitor != (MagickProgressMonitor) NULL)
1391          {
1392            MagickBooleanType
1393              proceed;
1394
1395            proceed=SetImageProgress(image,RotateImageTag,progress+=tile_height,
1396              image->rows);
1397            if (proceed == MagickFalse)
1398              status=MagickFalse;
1399          }
1400      }
1401      (void) SetImageProgress(image,RotateImageTag,(MagickOffsetType)
1402        image->rows-1,image->rows);
1403      Swap(page.width,page.height);
1404      Swap(page.x,page.y);
1405      if (page.height != 0)
1406        page.y=(ssize_t) (page.height-rotate_image->rows-page.y);
1407      break;
1408    }
1409  }
1410  rotate_view=DestroyCacheView(rotate_view);
1411  image_view=DestroyCacheView(image_view);
1412  rotate_image->type=image->type;
1413  rotate_image->page=page;
1414  if (status == MagickFalse)
1415    rotate_image=DestroyImage(rotate_image);
1416  return(rotate_image);
1417}
1418
1419/*
1420%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1421%                                                                             %
1422%                                                                             %
1423%                                                                             %
1424+   X S h e a r I m a g e                                                     %
1425%                                                                             %
1426%                                                                             %
1427%                                                                             %
1428%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1429%
1430%  XShearImage() shears the image in the X direction with a shear angle of
1431%  'degrees'.  Positive angles shear counter-clockwise (right-hand rule), and
1432%  negative angles shear clockwise.  Angles are measured relative to a vertical
1433%  Y-axis.  X shears will widen an image creating 'empty' triangles on the left
1434%  and right sides of the source image.
1435%
1436%  The format of the XShearImage method is:
1437%
1438%      MagickBooleanType XShearImage(Image *image,const MagickRealType degrees,
1439%        const size_t width,const size_t height,
1440%        const ssize_t x_offset,const ssize_t y_offset,ExceptionInfo *exception)
1441%
1442%  A description of each parameter follows.
1443%
1444%    o image: the image.
1445%
1446%    o degrees: A MagickRealType representing the shearing angle along the X
1447%      axis.
1448%
1449%    o width, height, x_offset, y_offset: Defines a region of the image
1450%      to shear.
1451%
1452%    o exception: return any errors or warnings in this structure.
1453%
1454*/
1455static MagickBooleanType XShearImage(Image *image,const MagickRealType degrees,
1456  const size_t width,const size_t height,const ssize_t x_offset,
1457  const ssize_t y_offset,ExceptionInfo *exception)
1458{
1459#define XShearImageTag  "XShear/Image"
1460
1461  typedef enum
1462  {
1463    LEFT,
1464    RIGHT
1465  } ShearDirection;
1466
1467  CacheView
1468    *image_view;
1469
1470  MagickBooleanType
1471    status;
1472
1473  MagickOffsetType
1474    progress;
1475
1476  PixelInfo
1477    background;
1478
1479  ssize_t
1480    y;
1481
1482  assert(image != (Image *) NULL);
1483  assert(image->signature == MagickSignature);
1484  if (image->debug != MagickFalse)
1485    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1486  GetPixelInfo(image,&background);
1487  SetPixelInfoPacket(image,&image->background_color,&background);
1488  if (image->colorspace == CMYKColorspace)
1489    ConvertRGBToCMYK(&background);
1490  /*
1491    X shear image.
1492  */
1493  status=MagickTrue;
1494  progress=0;
1495  image_view=AcquireCacheView(image);
1496#if defined(MAGICKCORE_OPENMP_SUPPORT)
1497  #pragma omp parallel for schedule(dynamic,4) shared(progress, status)
1498#endif
1499  for (y=0; y < (ssize_t) height; y++)
1500  {
1501    PixelInfo
1502      pixel,
1503      source,
1504      destination;
1505
1506    MagickRealType
1507      area,
1508      displacement;
1509
1510    register Quantum
1511      *restrict p,
1512      *restrict q;
1513
1514    register ssize_t
1515      i;
1516
1517    ShearDirection
1518      direction;
1519
1520    ssize_t
1521      step;
1522
1523    if (status == MagickFalse)
1524      continue;
1525    p=GetCacheViewAuthenticPixels(image_view,0,y_offset+y,image->columns,1,
1526      exception);
1527    if (p == (Quantum *) NULL)
1528      {
1529        status=MagickFalse;
1530        continue;
1531      }
1532    p+=x_offset*GetPixelChannels(image);
1533    displacement=degrees*(MagickRealType) (y-height/2.0);
1534    if (displacement == 0.0)
1535      continue;
1536    if (displacement > 0.0)
1537      direction=RIGHT;
1538    else
1539      {
1540        displacement*=(-1.0);
1541        direction=LEFT;
1542      }
1543    step=(ssize_t) floor((double) displacement);
1544    area=(MagickRealType) (displacement-step);
1545    step++;
1546    pixel=background;
1547    GetPixelInfo(image,&source);
1548    GetPixelInfo(image,&destination);
1549    switch (direction)
1550    {
1551      case LEFT:
1552      {
1553        /*
1554          Transfer pixels left-to-right.
1555        */
1556        if (step > x_offset)
1557          break;
1558        q=p-step*GetPixelChannels(image);
1559        for (i=0; i < (ssize_t) width; i++)
1560        {
1561          if ((x_offset+i) < step)
1562            {
1563              p+=GetPixelChannels(image);
1564              SetPixelInfo(image,p,&pixel);
1565              q+=GetPixelChannels(image);
1566              continue;
1567            }
1568          SetPixelInfo(image,p,&source);
1569          CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1570            &source,(MagickRealType) GetPixelAlpha(image,p),area,
1571            &destination);
1572          SetPixelPixelInfo(image,&destination,q);
1573          SetPixelInfo(image,p,&pixel);
1574          p+=GetPixelChannels(image);
1575          q+=GetPixelChannels(image);
1576        }
1577        CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1578          &background,(MagickRealType) background.alpha,area,&destination);
1579        SetPixelPixelInfo(image,&destination,q);
1580        q+=GetPixelChannels(image);
1581        for (i=0; i < (step-1); i++)
1582        {
1583          SetPixelPixelInfo(image,&background,q);
1584          q+=GetPixelChannels(image);
1585        }
1586        break;
1587      }
1588      case RIGHT:
1589      {
1590        /*
1591          Transfer pixels right-to-left.
1592        */
1593        p+=width*GetPixelChannels(image);
1594        q=p+step*GetPixelChannels(image);
1595        for (i=0; i < (ssize_t) width; i++)
1596        {
1597          p-=GetPixelChannels(image);
1598          q-=GetPixelChannels(image);
1599          if ((size_t) (x_offset+width+step-i) >= image->columns)
1600            continue;
1601          SetPixelInfo(image,p,&source);
1602          CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1603            &source,(MagickRealType) GetPixelAlpha(image,p),area,
1604            &destination);
1605          SetPixelPixelInfo(image,&destination,q);
1606          SetPixelInfo(image,p,&pixel);
1607        }
1608        CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1609          &background,(MagickRealType) background.alpha,area,&destination);
1610        q-=GetPixelChannels(image);
1611        SetPixelPixelInfo(image,&destination,q);
1612        for (i=0; i < (step-1); i++)
1613        {
1614          q-=GetPixelChannels(image);
1615          SetPixelPixelInfo(image,&background,q);
1616        }
1617        break;
1618      }
1619    }
1620    if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
1621      status=MagickFalse;
1622    if (image->progress_monitor != (MagickProgressMonitor) NULL)
1623      {
1624        MagickBooleanType
1625          proceed;
1626
1627#if defined(MAGICKCORE_OPENMP_SUPPORT)
1628  #pragma omp critical (MagickCore_XShearImage)
1629#endif
1630        proceed=SetImageProgress(image,XShearImageTag,progress++,height);
1631        if (proceed == MagickFalse)
1632          status=MagickFalse;
1633      }
1634  }
1635  image_view=DestroyCacheView(image_view);
1636  return(status);
1637}
1638
1639/*
1640%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1641%                                                                             %
1642%                                                                             %
1643%                                                                             %
1644+   Y S h e a r I m a g e                                                     %
1645%                                                                             %
1646%                                                                             %
1647%                                                                             %
1648%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1649%
1650%  YShearImage shears the image in the Y direction with a shear angle of
1651%  'degrees'.  Positive angles shear counter-clockwise (right-hand rule), and
1652%  negative angles shear clockwise.  Angles are measured relative to a
1653%  horizontal X-axis.  Y shears will increase the height of an image creating
1654%  'empty' triangles on the top and bottom of the source image.
1655%
1656%  The format of the YShearImage method is:
1657%
1658%      MagickBooleanType YShearImage(Image *image,const MagickRealType degrees,
1659%        const size_t width,const size_t height,
1660%        const ssize_t x_offset,const ssize_t y_offset,ExceptionInfo *exception)
1661%
1662%  A description of each parameter follows.
1663%
1664%    o image: the image.
1665%
1666%    o degrees: A MagickRealType representing the shearing angle along the Y
1667%      axis.
1668%
1669%    o width, height, x_offset, y_offset: Defines a region of the image
1670%      to shear.
1671%
1672%    o exception: return any errors or warnings in this structure.
1673%
1674*/
1675static MagickBooleanType YShearImage(Image *image,const MagickRealType degrees,
1676  const size_t width,const size_t height,const ssize_t x_offset,
1677  const ssize_t y_offset,ExceptionInfo *exception)
1678{
1679#define YShearImageTag  "YShear/Image"
1680
1681  typedef enum
1682  {
1683    UP,
1684    DOWN
1685  } ShearDirection;
1686
1687  CacheView
1688    *image_view;
1689
1690  MagickBooleanType
1691    status;
1692
1693  MagickOffsetType
1694    progress;
1695
1696  PixelInfo
1697    background;
1698
1699  ssize_t
1700    x;
1701
1702  assert(image != (Image *) NULL);
1703  assert(image->signature == MagickSignature);
1704  if (image->debug != MagickFalse)
1705    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1706  GetPixelInfo(image,&background);
1707  SetPixelInfoPacket(image,&image->background_color,&background);
1708  if (image->colorspace == CMYKColorspace)
1709    ConvertRGBToCMYK(&background);
1710  /*
1711    Y Shear image.
1712  */
1713  status=MagickTrue;
1714  progress=0;
1715  image_view=AcquireCacheView(image);
1716#if defined(MAGICKCORE_OPENMP_SUPPORT)
1717  #pragma omp parallel for schedule(dynamic,4) shared(progress, status)
1718#endif
1719  for (x=0; x < (ssize_t) width; x++)
1720  {
1721    ssize_t
1722      step;
1723
1724    MagickRealType
1725      area,
1726      displacement;
1727
1728    PixelInfo
1729      pixel,
1730      source,
1731      destination;
1732
1733    register Quantum
1734      *restrict p,
1735      *restrict q;
1736
1737    register ssize_t
1738      i;
1739
1740    ShearDirection
1741      direction;
1742
1743    if (status == MagickFalse)
1744      continue;
1745    p=GetCacheViewAuthenticPixels(image_view,x_offset+x,0,1,image->rows,
1746      exception);
1747    if (p == (Quantum *) NULL)
1748      {
1749        status=MagickFalse;
1750        continue;
1751      }
1752    p+=y_offset*GetPixelChannels(image);
1753    displacement=degrees*(MagickRealType) (x-width/2.0);
1754    if (displacement == 0.0)
1755      continue;
1756    if (displacement > 0.0)
1757      direction=DOWN;
1758    else
1759      {
1760        displacement*=(-1.0);
1761        direction=UP;
1762      }
1763    step=(ssize_t) floor((double) displacement);
1764    area=(MagickRealType) (displacement-step);
1765    step++;
1766    pixel=background;
1767    GetPixelInfo(image,&source);
1768    GetPixelInfo(image,&destination);
1769    switch (direction)
1770    {
1771      case UP:
1772      {
1773        /*
1774          Transfer pixels top-to-bottom.
1775        */
1776        if (step > y_offset)
1777          break;
1778        q=p-step*GetPixelChannels(image);
1779        for (i=0; i < (ssize_t) height; i++)
1780        {
1781          if ((y_offset+i) < step)
1782            {
1783              p+=GetPixelChannels(image);
1784              SetPixelInfo(image,p,&pixel);
1785              q+=GetPixelChannels(image);
1786              continue;
1787            }
1788          SetPixelInfo(image,p,&source);
1789          CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1790            &source,(MagickRealType) GetPixelAlpha(image,p),area,
1791            &destination);
1792          SetPixelPixelInfo(image,&destination,q);
1793          SetPixelInfo(image,p,&pixel);
1794          p+=GetPixelChannels(image);
1795          q+=GetPixelChannels(image);
1796        }
1797        CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1798          &background,(MagickRealType) background.alpha,area,&destination);
1799        SetPixelPixelInfo(image,&destination,q);
1800        q+=GetPixelChannels(image);
1801        for (i=0; i < (step-1); i++)
1802        {
1803          SetPixelPixelInfo(image,&background,q);
1804          q+=GetPixelChannels(image);
1805        }
1806        break;
1807      }
1808      case DOWN:
1809      {
1810        /*
1811          Transfer pixels bottom-to-top.
1812        */
1813        p+=height*GetPixelChannels(image);
1814        q=p+step*GetPixelChannels(image);
1815        for (i=0; i < (ssize_t) height; i++)
1816        {
1817          p-=GetPixelChannels(image);
1818          q-=GetPixelChannels(image);
1819          if ((size_t) (y_offset+height+step-i) >= image->rows)
1820            continue;
1821          SetPixelInfo(image,p,&source);
1822          CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1823            &source,(MagickRealType) GetPixelAlpha(image,p),area,
1824            &destination);
1825          SetPixelPixelInfo(image,&destination,q);
1826          SetPixelInfo(image,p,&pixel);
1827        }
1828        CompositePixelInfoAreaBlend(&pixel,(MagickRealType) pixel.alpha,
1829          &background,(MagickRealType) background.alpha,area,&destination);
1830        q-=GetPixelChannels(image);
1831        SetPixelPixelInfo(image,&destination,q);
1832        for (i=0; i < (step-1); i++)
1833        {
1834          q-=GetPixelChannels(image);
1835          SetPixelPixelInfo(image,&background,q);
1836        }
1837        break;
1838      }
1839    }
1840    if (SyncCacheViewAuthenticPixels(image_view,exception) == MagickFalse)
1841      status=MagickFalse;
1842    if (image->progress_monitor != (MagickProgressMonitor) NULL)
1843      {
1844        MagickBooleanType
1845          proceed;
1846
1847#if defined(MAGICKCORE_OPENMP_SUPPORT)
1848  #pragma omp critical (MagickCore_YShearImage)
1849#endif
1850        proceed=SetImageProgress(image,YShearImageTag,progress++,image->rows);
1851        if (proceed == MagickFalse)
1852          status=MagickFalse;
1853      }
1854  }
1855  image_view=DestroyCacheView(image_view);
1856  return(status);
1857}
1858
1859/*
1860%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1861%                                                                             %
1862%                                                                             %
1863%                                                                             %
1864%   R o t a t e I m a g e                                                     %
1865%                                                                             %
1866%                                                                             %
1867%                                                                             %
1868%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
1869%
1870%  RotateImage() creates a new image that is a rotated copy of an existing
1871%  one.  Positive angles rotate counter-clockwise (right-hand rule), while
1872%  negative angles rotate clockwise.  Rotated images are usually larger than
1873%  the originals and have 'empty' triangular corners.  X axis.  Empty
1874%  triangles left over from shearing the image are filled with the background
1875%  color defined by member 'background_color' of the image.  RotateImage
1876%  allocates the memory necessary for the new Image structure and returns a
1877%  pointer to the new image.
1878%
1879%  RotateImage() is based on the paper "A Fast Algorithm for General
1880%  Raster Rotatation" by Alan W. Paeth.  RotateImage is adapted from a similar
1881%  method based on the Paeth paper written by Michael Halle of the Spatial
1882%  Imaging Group, MIT Media Lab.
1883%
1884%  The format of the RotateImage method is:
1885%
1886%      Image *RotateImage(const Image *image,const double degrees,
1887%        ExceptionInfo *exception)
1888%
1889%  A description of each parameter follows.
1890%
1891%    o image: the image.
1892%
1893%    o degrees: Specifies the number of degrees to rotate the image.
1894%
1895%    o exception: return any errors or warnings in this structure.
1896%
1897*/
1898MagickExport Image *RotateImage(const Image *image,const double degrees,
1899  ExceptionInfo *exception)
1900{
1901  Image
1902    *integral_image,
1903    *rotate_image;
1904
1905  MagickBooleanType
1906    status;
1907
1908  MagickRealType
1909    angle;
1910
1911  PointInfo
1912    shear;
1913
1914  RectangleInfo
1915    border_info;
1916
1917  size_t
1918    height,
1919    rotations,
1920    width,
1921    y_width;
1922
1923  ssize_t
1924    x_offset,
1925    y_offset;
1926
1927  /*
1928    Adjust rotation angle.
1929  */
1930  assert(image != (Image *) NULL);
1931  assert(image->signature == MagickSignature);
1932  if (image->debug != MagickFalse)
1933    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
1934  assert(exception != (ExceptionInfo *) NULL);
1935  assert(exception->signature == MagickSignature);
1936  angle=degrees;
1937  while (angle < -45.0)
1938    angle+=360.0;
1939  for (rotations=0; angle > 45.0; rotations++)
1940    angle-=90.0;
1941  rotations%=4;
1942  /*
1943    Calculate shear equations.
1944  */
1945  integral_image=IntegralRotateImage(image,rotations,exception);
1946  if (integral_image == (Image *) NULL)
1947    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
1948  shear.x=(-tan((double) DegreesToRadians(angle)/2.0));
1949  shear.y=sin((double) DegreesToRadians(angle));
1950  if ((shear.x == 0.0) && (shear.y == 0.0))
1951    return(integral_image);
1952  if (SetImageStorageClass(integral_image,DirectClass,exception) == MagickFalse)
1953    {
1954      integral_image=DestroyImage(integral_image);
1955      return(integral_image);
1956    }
1957  if (integral_image->matte == MagickFalse)
1958    (void) SetImageAlphaChannel(integral_image,OpaqueAlphaChannel,exception);
1959  /*
1960    Compute image size.
1961  */
1962  width=image->columns;
1963  height=image->rows;
1964  if ((rotations == 1) || (rotations == 3))
1965    {
1966      width=image->rows;
1967      height=image->columns;
1968    }
1969  y_width=width+(ssize_t) floor(fabs(shear.x)*height+0.5);
1970  x_offset=(ssize_t) ceil((double) width+((fabs(shear.y)*height)-width)/2.0-
1971    0.5);
1972  y_offset=(ssize_t) ceil((double) height+((fabs(shear.y)*y_width)-height)/2.0-
1973    0.5);
1974  /*
1975    Surround image with a border.
1976  */
1977  integral_image->border_color=integral_image->background_color;
1978  integral_image->compose=CopyCompositeOp;
1979  border_info.width=(size_t) x_offset;
1980  border_info.height=(size_t) y_offset;
1981  rotate_image=BorderImage(integral_image,&border_info,image->compose,
1982    exception);
1983  integral_image=DestroyImage(integral_image);
1984  if (rotate_image == (Image *) NULL)
1985    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
1986  /*
1987    Rotate the image.
1988  */
1989  status=XShearImage(rotate_image,shear.x,width,height,x_offset,(ssize_t)
1990    (rotate_image->rows-height)/2,exception);
1991  if (status == MagickFalse)
1992    {
1993      rotate_image=DestroyImage(rotate_image);
1994      return((Image *) NULL);
1995    }
1996  status=YShearImage(rotate_image,shear.y,y_width,height,(ssize_t)
1997    (rotate_image->columns-y_width)/2,y_offset,exception);
1998  if (status == MagickFalse)
1999    {
2000      rotate_image=DestroyImage(rotate_image);
2001      return((Image *) NULL);
2002    }
2003  status=XShearImage(rotate_image,shear.x,y_width,rotate_image->rows,(ssize_t)
2004    (rotate_image->columns-y_width)/2,0,exception);
2005  if (status == MagickFalse)
2006    {
2007      rotate_image=DestroyImage(rotate_image);
2008      return((Image *) NULL);
2009    }
2010  status=CropToFitImage(&rotate_image,shear.x,shear.y,(MagickRealType) width,
2011    (MagickRealType) height,MagickTrue,exception);
2012  if (status == MagickFalse)
2013    {
2014      rotate_image=DestroyImage(rotate_image);
2015      return((Image *) NULL);
2016    }
2017  rotate_image->compose=image->compose;
2018  rotate_image->page.width=0;
2019  rotate_image->page.height=0;
2020  return(rotate_image);
2021}
2022
2023/*
2024%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2025%                                                                             %
2026%                                                                             %
2027%                                                                             %
2028%   S h e a r I m a g e                                                       %
2029%                                                                             %
2030%                                                                             %
2031%                                                                             %
2032%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2033%
2034%  ShearImage() creates a new image that is a shear_image copy of an existing
2035%  one.  Shearing slides one edge of an image along the X or Y axis, creating
2036%  a parallelogram.  An X direction shear slides an edge along the X axis,
2037%  while a Y direction shear slides an edge along the Y axis.  The amount of
2038%  the shear is controlled by a shear angle.  For X direction shears, x_shear
2039%  is measured relative to the Y axis, and similarly, for Y direction shears
2040%  y_shear is measured relative to the X axis.  Empty triangles left over from
2041%  shearing the image are filled with the background color defined by member
2042%  'background_color' of the image..  ShearImage() allocates the memory
2043%  necessary for the new Image structure and returns a pointer to the new image.
2044%
2045%  ShearImage() is based on the paper "A Fast Algorithm for General Raster
2046%  Rotatation" by Alan W. Paeth.
2047%
2048%  The format of the ShearImage method is:
2049%
2050%      Image *ShearImage(const Image *image,const double x_shear,
2051%        const double y_shear,ExceptionInfo *exception)
2052%
2053%  A description of each parameter follows.
2054%
2055%    o image: the image.
2056%
2057%    o x_shear, y_shear: Specifies the number of degrees to shear the image.
2058%
2059%    o exception: return any errors or warnings in this structure.
2060%
2061*/
2062MagickExport Image *ShearImage(const Image *image,const double x_shear,
2063  const double y_shear,ExceptionInfo *exception)
2064{
2065  Image
2066    *integral_image,
2067    *shear_image;
2068
2069  ssize_t
2070    x_offset,
2071    y_offset;
2072
2073  MagickBooleanType
2074    status;
2075
2076  PointInfo
2077    shear;
2078
2079  RectangleInfo
2080    border_info;
2081
2082  size_t
2083    y_width;
2084
2085  assert(image != (Image *) NULL);
2086  assert(image->signature == MagickSignature);
2087  if (image->debug != MagickFalse)
2088    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
2089  assert(exception != (ExceptionInfo *) NULL);
2090  assert(exception->signature == MagickSignature);
2091  if ((x_shear != 0.0) && (fmod(x_shear,90.0) == 0.0))
2092    ThrowImageException(ImageError,"AngleIsDiscontinuous");
2093  if ((y_shear != 0.0) && (fmod(y_shear,90.0) == 0.0))
2094    ThrowImageException(ImageError,"AngleIsDiscontinuous");
2095  /*
2096    Initialize shear angle.
2097  */
2098  integral_image=CloneImage(image,0,0,MagickTrue,exception);
2099  if (integral_image == (Image *) NULL)
2100    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
2101  shear.x=(-tan(DegreesToRadians(fmod(x_shear,360.0))));
2102  shear.y=tan(DegreesToRadians(fmod(y_shear,360.0)));
2103  if ((shear.x == 0.0) && (shear.y == 0.0))
2104    return(integral_image);
2105  if (SetImageStorageClass(integral_image,DirectClass,exception) == MagickFalse)
2106    {
2107      integral_image=DestroyImage(integral_image);
2108      return(integral_image);
2109    }
2110  if (integral_image->matte == MagickFalse)
2111    (void) SetImageAlphaChannel(integral_image,OpaqueAlphaChannel,exception);
2112  /*
2113    Compute image size.
2114  */
2115  y_width=image->columns+(ssize_t) floor(fabs(shear.x)*image->rows+0.5);
2116  x_offset=(ssize_t) ceil((double) image->columns+((fabs(shear.x)*image->rows)-
2117    image->columns)/2.0-0.5);
2118  y_offset=(ssize_t) ceil((double) image->rows+((fabs(shear.y)*y_width)-
2119    image->rows)/2.0-0.5);
2120  /*
2121    Surround image with border.
2122  */
2123  integral_image->border_color=integral_image->background_color;
2124  integral_image->compose=CopyCompositeOp;
2125  border_info.width=(size_t) x_offset;
2126  border_info.height=(size_t) y_offset;
2127  shear_image=BorderImage(integral_image,&border_info,image->compose,exception);
2128  integral_image=DestroyImage(integral_image);
2129  if (shear_image == (Image *) NULL)
2130    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
2131  /*
2132    Shear the image.
2133  */
2134  if (shear_image->matte == MagickFalse)
2135    (void) SetImageAlphaChannel(shear_image,OpaqueAlphaChannel,exception);
2136  status=XShearImage(shear_image,shear.x,image->columns,image->rows,x_offset,
2137    (ssize_t) (shear_image->rows-image->rows)/2,exception);
2138  if (status == MagickFalse)
2139    {
2140      shear_image=DestroyImage(shear_image);
2141      return((Image *) NULL);
2142    }
2143  status=YShearImage(shear_image,shear.y,y_width,image->rows,(ssize_t)
2144    (shear_image->columns-y_width)/2,y_offset,exception);
2145  if (status == MagickFalse)
2146    {
2147      shear_image=DestroyImage(shear_image);
2148      return((Image *) NULL);
2149    }
2150  status=CropToFitImage(&shear_image,shear.x,shear.y,(MagickRealType)
2151    image->columns,(MagickRealType) image->rows,MagickFalse,exception);
2152  if (status == MagickFalse)
2153    {
2154      shear_image=DestroyImage(shear_image);
2155      return((Image *) NULL);
2156    }
2157  shear_image->compose=image->compose;
2158  shear_image->page.width=0;
2159  shear_image->page.height=0;
2160  return(shear_image);
2161}
2162