SkScalerContext.cpp revision 309485b7b51f4cae4c0361ab4da00fe9cc89515c 
1/* libs/graphics/sgl/SkScalerContext.cpp
2**
3** Copyright 2006, The Android Open Source Project
4**
5** Licensed under the Apache License, Version 2.0 (the "License");
6** you may not use this file except in compliance with the License.
7** You may obtain a copy of the License at
8**
9**     http://www.apache.org/licenses/LICENSE-2.0
10**
11** Unless required by applicable law or agreed to in writing, software
12** distributed under the License is distributed on an "AS IS" BASIS,
13** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14** See the License for the specific language governing permissions and
15** limitations under the License.
16*/
17
18#include "SkScalerContext.h"
19#include "SkColorPriv.h"
20#include "SkDescriptor.h"
21#include "SkDraw.h"
22#include "SkFontHost.h"
23#include "SkMaskFilter.h"
24#include "SkPathEffect.h"
25#include "SkRasterizer.h"
26#include "SkRegion.h"
27#include "SkStroke.h"
28#include "SkThread.h"
29
30#ifdef SK_DEBUG
31//    #define TRACK_MISSING_CHARS
32#endif
33
34#define ComputeBWRowBytes(width)        (((unsigned)(width) + 7) >> 3)
35
36static const uint8_t* gBlackGammaTable;
37static const uint8_t* gWhiteGammaTable;
38
39void SkGlyph::toMask(SkMask* mask) const {
40    SkASSERT(mask);
41
42    mask->fImage = (uint8_t*)fImage;
43    mask->fBounds.set(fLeft, fTop, fLeft + fWidth, fTop + fHeight);
44    mask->fRowBytes = this->rowBytes();
45    mask->fFormat = static_cast<SkMask::Format>(fMaskFormat);
46}
47
48size_t SkGlyph::computeImageSize() const {
49    const size_t size = this->rowBytes() * fHeight;
50
51    switch (fMaskFormat) {
52    case SkMask::kHorizontalLCD_Format:
53        return SkAlign4(size) + sizeof(uint32_t) * ((fWidth + 2) * fHeight);
54    case SkMask::kVerticalLCD_Format:
55        return SkAlign4(size) + sizeof(uint32_t) * (fWidth * (fHeight + 2));
56    case SkMask::k3D_Format:
57        return 3 * size;
58    default:
59        return size;
60    }
61}
62
63void SkGlyph::zeroMetrics() {
64    fAdvanceX = 0;
65    fAdvanceY = 0;
66    fWidth    = 0;
67    fHeight   = 0;
68    fTop      = 0;
69    fLeft     = 0;
70    fRsbDelta = 0;
71    fLsbDelta = 0;
72}
73
74void SkGlyph::expandA8ToLCD() const {
75    SkASSERT(fMaskFormat == SkMask::kHorizontalLCD_Format ||
76             fMaskFormat == SkMask::kVerticalLCD_Format);
77
78#if defined(SK_BUILD_SUBPIXEL)
79    uint8_t* input = reinterpret_cast<uint8_t*>(fImage);
80    uint32_t* output = reinterpret_cast<uint32_t*>(input + SkAlign4(rowBytes() * fHeight));
81
82    if (fMaskFormat == SkMask::kHorizontalLCD_Format) {
83        for (unsigned y = 0; y < fHeight; ++y) {
84            const uint8_t* inputRow = input;
85            *output++ = 0;  // make the extra column on the left clear
86            for (unsigned x = 0; x < fWidth; ++x) {
87                const uint8_t alpha = *inputRow++;
88                *output++ = SkPackARGB32(alpha, alpha, alpha, alpha);
89            }
90            *output++ = 0;
91
92            input += rowBytes();
93        }
94    } else {
95        const unsigned outputRowBytes = sizeof(uint32_t) * fWidth;
96        memset(output, 0, outputRowBytes);
97        output += fWidth;
98
99        for (unsigned y = 0; y < fHeight; ++y) {
100            const uint8_t* inputRow = input;
101            for (unsigned x = 0; x < fWidth; ++x) {
102                const uint8_t alpha = *inputRow++;
103                *output++ = SkPackARGB32(alpha, alpha, alpha, alpha);
104            }
105
106            input += rowBytes();
107        }
108
109        memset(output, 0, outputRowBytes);
110        output += fWidth;
111    }
112#else
113#endif
114}
115
116///////////////////////////////////////////////////////////////////////////////
117
118#ifdef SK_DEBUG
119    #define DUMP_RECx
120#endif
121
122static SkFlattenable* load_flattenable(const SkDescriptor* desc, uint32_t tag) {
123    SkFlattenable*  obj = NULL;
124    uint32_t        len;
125    const void*     data = desc->findEntry(tag, &len);
126
127    if (data) {
128        SkFlattenableReadBuffer   buffer(data, len);
129        obj = buffer.readFlattenable();
130        SkASSERT(buffer.offset() == buffer.size());
131    }
132    return obj;
133}
134
135SkScalerContext::SkScalerContext(const SkDescriptor* desc)
136    : fPathEffect(NULL), fMaskFilter(NULL)
137{
138    static bool gHaveGammaTables;
139    if (!gHaveGammaTables) {
140        const uint8_t* tables[2];
141        SkFontHost::GetGammaTables(tables);
142        gBlackGammaTable = tables[0];
143        gWhiteGammaTable = tables[1];
144        gHaveGammaTables = true;
145    }
146
147    fBaseGlyphCount = 0;
148    fNextContext = NULL;
149
150    const Rec* rec = (const Rec*)desc->findEntry(kRec_SkDescriptorTag, NULL);
151    SkASSERT(rec);
152
153    fRec = *rec;
154
155#ifdef DUMP_REC
156    desc->assertChecksum();
157    SkDebugf("SkScalarContext checksum %x count %d length %d\n", desc->getChecksum(), desc->getCount(), desc->getLength());
158    SkDebugf(" textsize %g prescale %g preskew %g post [%g %g %g %g]\n",
159        rec->fTextSize, rec->fPreScaleX, rec->fPreSkewX, rec->fPost2x2[0][0],
160        rec->fPost2x2[0][1], rec->fPost2x2[1][0], rec->fPost2x2[1][1]);
161    SkDebugf("  frame %g miter %g hints %d framefill %d format %d join %d\n",
162        rec->fFrameWidth, rec->fMiterLimit, rec->fHints, rec->fFrameAndFill,
163        rec->fMaskFormat, rec->fStrokeJoin);
164    SkDebugf("  pathEffect %x maskFilter %x\n", desc->findEntry(kPathEffect_SkDescriptorTag, NULL),
165        desc->findEntry(kMaskFilter_SkDescriptorTag, NULL));
166#endif
167
168    fPathEffect = (SkPathEffect*)load_flattenable(desc, kPathEffect_SkDescriptorTag);
169    fMaskFilter = (SkMaskFilter*)load_flattenable(desc, kMaskFilter_SkDescriptorTag);
170    fRasterizer = (SkRasterizer*)load_flattenable(desc, kRasterizer_SkDescriptorTag);
171}
172
173SkScalerContext::~SkScalerContext() {
174    SkDELETE(fNextContext);
175
176    fPathEffect->safeUnref();
177    fMaskFilter->safeUnref();
178    fRasterizer->safeUnref();
179}
180
181static SkScalerContext* allocNextContext(const SkScalerContext::Rec& rec) {
182    // fonthost will determine the next possible font to search, based
183    // on the current font in fRec. It will return NULL if ctx is our
184    // last font that can be searched (i.e. ultimate fallback font)
185    uint32_t newFontID = SkFontHost::NextLogicalFont(rec.fFontID);
186    if (0 == newFontID) {
187        return NULL;
188    }
189
190    SkAutoDescriptor    ad(sizeof(rec) + SkDescriptor::ComputeOverhead(1));
191    SkDescriptor*       desc = ad.getDesc();
192
193    desc->init();
194    SkScalerContext::Rec* newRec =
195    (SkScalerContext::Rec*)desc->addEntry(kRec_SkDescriptorTag,
196                                          sizeof(rec), &rec);
197    newRec->fFontID = newFontID;
198    desc->computeChecksum();
199
200    return SkFontHost::CreateScalerContext(desc);
201}
202
203/*  Return the next context, creating it if its not already created, but return
204    NULL if the fonthost says there are no more fonts to fallback to.
205 */
206SkScalerContext* SkScalerContext::getNextContext() {
207    SkScalerContext* next = fNextContext;
208    // if next is null, then either it isn't cached yet, or we're at the
209    // end of our possible chain
210    if (NULL == next) {
211        next = allocNextContext(fRec);
212        if (NULL == next) {
213            return NULL;
214        }
215        // next's base is our base + our local count
216        next->setBaseGlyphCount(fBaseGlyphCount + this->getGlyphCount());
217        // cache the answer
218        fNextContext = next;
219    }
220    return next;
221}
222
223SkScalerContext* SkScalerContext::getGlyphContext(const SkGlyph& glyph) {
224    unsigned glyphID = glyph.getGlyphID();
225    SkScalerContext* ctx = this;
226    for (;;) {
227        unsigned count = ctx->getGlyphCount();
228        if (glyphID < count) {
229            break;
230        }
231        glyphID -= count;
232        ctx = ctx->getNextContext();
233        if (NULL == ctx) {
234            SkDebugf("--- no context for glyph %x\n", glyph.getGlyphID());
235            // just return the original context (this)
236            return this;
237        }
238    }
239    return ctx;
240}
241
242/*  This loops through all available fallback contexts (if needed) until it
243    finds some context that can handle the unichar. If all fail, returns 0
244 */
245uint16_t SkScalerContext::charToGlyphID(SkUnichar uni) {
246    SkScalerContext* ctx = this;
247    unsigned glyphID;
248    for (;;) {
249        glyphID = ctx->generateCharToGlyph(uni);
250        if (glyphID) {
251            break;  // found it
252        }
253        ctx = ctx->getNextContext();
254        if (NULL == ctx) {
255            return 0;   // no more contexts, return missing glyph
256        }
257    }
258    // add the ctx's base, making glyphID unique for chain of contexts
259    glyphID += ctx->fBaseGlyphCount;
260    // check for overflow of 16bits, since our glyphID cannot exceed that
261    if (glyphID > 0xFFFF) {
262        glyphID = 0;
263    }
264    return SkToU16(glyphID);
265}
266
267void SkScalerContext::getAdvance(SkGlyph* glyph) {
268    // mark us as just having a valid advance
269    glyph->fMaskFormat = MASK_FORMAT_JUST_ADVANCE;
270    // we mark the format before making the call, in case the impl
271    // internally ends up calling its generateMetrics, which is OK
272    // albeit slower than strictly necessary
273    this->getGlyphContext(*glyph)->generateAdvance(glyph);
274}
275
276void SkScalerContext::getMetrics(SkGlyph* glyph) {
277    this->getGlyphContext(*glyph)->generateMetrics(glyph);
278
279    // for now we have separate cache entries for devkerning on and off
280    // in the future we might share caches, but make our measure/draw
281    // code make the distinction. Thus we zap the values if the caller
282    // has not asked for them.
283    if ((fRec.fFlags & SkScalerContext::kDevKernText_Flag) == 0) {
284        // no devkern, so zap the fields
285        glyph->fLsbDelta = glyph->fRsbDelta = 0;
286    }
287
288    // if either dimension is empty, zap the image bounds of the glyph
289    if (0 == glyph->fWidth || 0 == glyph->fHeight) {
290        glyph->fWidth   = 0;
291        glyph->fHeight  = 0;
292        glyph->fTop     = 0;
293        glyph->fLeft    = 0;
294        glyph->fMaskFormat = 0;
295        return;
296    }
297
298    if (fRec.fFrameWidth > 0 || fPathEffect != NULL || fRasterizer != NULL) {
299        SkPath      devPath, fillPath;
300        SkMatrix    fillToDevMatrix;
301
302        this->internalGetPath(*glyph, &fillPath, &devPath, &fillToDevMatrix);
303
304        if (fRasterizer) {
305            SkMask  mask;
306
307            if (fRasterizer->rasterize(fillPath, fillToDevMatrix, NULL,
308                                       fMaskFilter, &mask,
309                                       SkMask::kJustComputeBounds_CreateMode)) {
310                glyph->fLeft    = mask.fBounds.fLeft;
311                glyph->fTop     = mask.fBounds.fTop;
312                glyph->fWidth   = SkToU16(mask.fBounds.width());
313                glyph->fHeight  = SkToU16(mask.fBounds.height());
314            } else {
315                // draw nothing 'cause we failed
316                glyph->fLeft    = 0;
317                glyph->fTop     = 0;
318                glyph->fWidth   = 0;
319                glyph->fHeight  = 0;
320                return;
321            }
322        } else {
323            // just use devPath
324            SkIRect ir;
325            devPath.getBounds().roundOut(&ir);
326
327            glyph->fLeft    = ir.fLeft;
328            glyph->fTop     = ir.fTop;
329            glyph->fWidth   = SkToU16(ir.width());
330            glyph->fHeight  = SkToU16(ir.height());
331        }
332    }
333
334    glyph->fMaskFormat = fRec.fMaskFormat;
335
336    if (fMaskFilter) {
337        SkMask      src, dst;
338        SkMatrix    matrix;
339
340        glyph->toMask(&src);
341        fRec.getMatrixFrom2x2(&matrix);
342
343        src.fImage = NULL;  // only want the bounds from the filter
344        if (fMaskFilter->filterMask(&dst, src, matrix, NULL)) {
345            SkASSERT(dst.fImage == NULL);
346            glyph->fLeft    = dst.fBounds.fLeft;
347            glyph->fTop     = dst.fBounds.fTop;
348            glyph->fWidth   = SkToU16(dst.fBounds.width());
349            glyph->fHeight  = SkToU16(dst.fBounds.height());
350            glyph->fMaskFormat = dst.fFormat;
351        }
352    }
353}
354
355void SkScalerContext::getImage(const SkGlyph& origGlyph) {
356    const SkGlyph*  glyph = &origGlyph;
357    SkGlyph         tmpGlyph;
358
359    if (fMaskFilter) {   // restore the prefilter bounds
360        tmpGlyph.fID = origGlyph.fID;
361
362        // need the original bounds, sans our maskfilter
363        SkMaskFilter* mf = fMaskFilter;
364        fMaskFilter = NULL;             // temp disable
365        this->getMetrics(&tmpGlyph);
366        fMaskFilter = mf;               // restore
367
368        tmpGlyph.fImage = origGlyph.fImage;
369
370        // we need the prefilter bounds to be <= filter bounds
371        SkASSERT(tmpGlyph.fWidth <= origGlyph.fWidth);
372        SkASSERT(tmpGlyph.fHeight <= origGlyph.fHeight);
373        glyph = &tmpGlyph;
374    }
375
376    if (fRec.fFrameWidth > 0 || fPathEffect != NULL || fRasterizer != NULL) {
377        SkPath      devPath, fillPath;
378        SkMatrix    fillToDevMatrix;
379
380        this->internalGetPath(*glyph, &fillPath, &devPath, &fillToDevMatrix);
381
382        const bool lcdMode = fRec.fMaskFormat == SkMask::kHorizontalLCD_Format ||
383                             fRec.fMaskFormat == SkMask::kVerticalLCD_Format;
384
385        if (fRasterizer) {
386            SkMask  mask;
387
388            glyph->toMask(&mask);
389            mask.fFormat = SkMask::kA8_Format;
390            sk_bzero(glyph->fImage, mask.computeImageSize());
391
392            if (!fRasterizer->rasterize(fillPath, fillToDevMatrix, NULL,
393                                        fMaskFilter, &mask,
394                                        SkMask::kJustRenderImage_CreateMode)) {
395                return;
396            }
397        } else {
398            SkBitmap    bm;
399            SkBitmap::Config config;
400            SkMatrix    matrix;
401            SkRegion    clip;
402            SkPaint     paint;
403            SkDraw      draw;
404
405            if (SkMask::kA8_Format == fRec.fMaskFormat || lcdMode) {
406                config = SkBitmap::kA8_Config;
407                paint.setAntiAlias(true);
408            } else {
409                SkASSERT(SkMask::kBW_Format == fRec.fMaskFormat);
410                config = SkBitmap::kA1_Config;
411                paint.setAntiAlias(false);
412            }
413
414            clip.setRect(0, 0, glyph->fWidth, glyph->fHeight);
415            matrix.setTranslate(-SkIntToScalar(glyph->fLeft),
416                                -SkIntToScalar(glyph->fTop));
417            bm.setConfig(config, glyph->fWidth, glyph->fHeight,
418                         glyph->rowBytes());
419            bm.setPixels(glyph->fImage);
420            sk_bzero(glyph->fImage, bm.height() * bm.rowBytes());
421
422            draw.fClip  = &clip;
423            draw.fMatrix = &matrix;
424            draw.fBitmap = &bm;
425            draw.fBounder = NULL;
426            draw.drawPath(devPath, paint);
427        }
428
429        if (lcdMode)
430            glyph->expandA8ToLCD();
431    } else {
432        this->getGlyphContext(*glyph)->generateImage(*glyph);
433    }
434
435    if (fMaskFilter) {
436        SkMask      srcM, dstM;
437        SkMatrix    matrix;
438
439        // the src glyph image shouldn't be 3D
440        SkASSERT(SkMask::k3D_Format != glyph->fMaskFormat);
441        glyph->toMask(&srcM);
442        fRec.getMatrixFrom2x2(&matrix);
443
444        if (fMaskFilter->filterMask(&dstM, srcM, matrix, NULL)) {
445            int width = SkFastMin32(origGlyph.fWidth, dstM.fBounds.width());
446            int height = SkFastMin32(origGlyph.fHeight, dstM.fBounds.height());
447            int dstRB = origGlyph.rowBytes();
448            int srcRB = dstM.fRowBytes;
449
450            const uint8_t* src = (const uint8_t*)dstM.fImage;
451            uint8_t* dst = (uint8_t*)origGlyph.fImage;
452
453            if (SkMask::k3D_Format == dstM.fFormat) {
454                // we have to copy 3 times as much
455                height *= 3;
456            }
457
458            // clean out our glyph, since it may be larger than dstM
459            //sk_bzero(dst, height * dstRB);
460
461            while (--height >= 0) {
462                memcpy(dst, src, width);
463                src += srcRB;
464                dst += dstRB;
465            }
466            SkMask::FreeImage(dstM.fImage);
467        }
468    }
469
470    // check to see if we should filter the alpha channel
471
472    if (NULL == fMaskFilter &&
473        fRec.fMaskFormat != SkMask::kBW_Format &&
474        (fRec.fFlags & (kGammaForBlack_Flag | kGammaForWhite_Flag)) != 0)
475    {
476        const uint8_t* table = (fRec.fFlags & kGammaForBlack_Flag) ? gBlackGammaTable : gWhiteGammaTable;
477        if (NULL != table)
478        {
479            uint8_t* dst = (uint8_t*)origGlyph.fImage;
480            unsigned rowBytes = origGlyph.rowBytes();
481
482            for (int y = origGlyph.fHeight - 1; y >= 0; --y)
483            {
484                for (int x = origGlyph.fWidth - 1; x >= 0; --x)
485                    dst[x] = table[dst[x]];
486                dst += rowBytes;
487            }
488        }
489    }
490}
491
492void SkScalerContext::getPath(const SkGlyph& glyph, SkPath* path)
493{
494    this->internalGetPath(glyph, NULL, path, NULL);
495}
496
497void SkScalerContext::getFontMetrics(SkPaint::FontMetrics* mx, SkPaint::FontMetrics* my)
498{
499    this->generateFontMetrics(mx, my);
500}
501
502///////////////////////////////////////////////////////////////////////
503
504void SkScalerContext::internalGetPath(const SkGlyph& glyph, SkPath* fillPath, SkPath* devPath, SkMatrix* fillToDevMatrix)
505{
506    SkPath  path;
507
508    this->getGlyphContext(glyph)->generatePath(glyph, &path);
509
510    if (fRec.fFrameWidth > 0 || fPathEffect != NULL)
511    {
512        // need the path in user-space, with only the point-size applied
513        // so that our stroking and effects will operate the same way they
514        // would if the user had extracted the path themself, and then
515        // called drawPath
516        SkPath      localPath;
517        SkMatrix    matrix, inverse;
518
519        fRec.getMatrixFrom2x2(&matrix);
520        matrix.invert(&inverse);
521        path.transform(inverse, &localPath);
522        // now localPath is only affected by the paint settings, and not the canvas matrix
523
524        SkScalar width = fRec.fFrameWidth;
525
526        if (fPathEffect)
527        {
528            SkPath effectPath;
529
530            if (fPathEffect->filterPath(&effectPath, localPath, &width))
531                localPath.swap(effectPath);
532        }
533
534        if (width > 0)
535        {
536            SkStroke    stroker;
537            SkPath      outline;
538
539            stroker.setWidth(width);
540            stroker.setMiterLimit(fRec.fMiterLimit);
541            stroker.setJoin((SkPaint::Join)fRec.fStrokeJoin);
542            stroker.setDoFill(SkToBool(fRec.fFlags & kFrameAndFill_Flag));
543            stroker.strokePath(localPath, &outline);
544            localPath.swap(outline);
545        }
546
547        // now return stuff to the caller
548        if (fillToDevMatrix)
549            *fillToDevMatrix = matrix;
550
551        if (devPath)
552            localPath.transform(matrix, devPath);
553
554        if (fillPath)
555            fillPath->swap(localPath);
556    }
557    else    // nothing tricky to do
558    {
559        if (fillToDevMatrix)
560            fillToDevMatrix->reset();
561
562        if (devPath)
563        {
564            if (fillPath == NULL)
565                devPath->swap(path);
566            else
567                *devPath = path;
568        }
569
570        if (fillPath)
571            fillPath->swap(path);
572    }
573
574    if (devPath)
575        devPath->updateBoundsCache();
576    if (fillPath)
577        fillPath->updateBoundsCache();
578}
579
580
581void SkScalerContext::Rec::getMatrixFrom2x2(SkMatrix* dst) const
582{
583    dst->reset();
584    dst->setScaleX(fPost2x2[0][0]);
585    dst->setSkewX( fPost2x2[0][1]);
586    dst->setSkewY( fPost2x2[1][0]);
587    dst->setScaleY(fPost2x2[1][1]);
588}
589
590void SkScalerContext::Rec::getLocalMatrix(SkMatrix* m) const
591{
592    m->setScale(SkScalarMul(fTextSize, fPreScaleX), fTextSize);
593    if (fPreSkewX)
594        m->postSkew(fPreSkewX, 0);
595}
596
597void SkScalerContext::Rec::getSingleMatrix(SkMatrix* m) const
598{
599    this->getLocalMatrix(m);
600
601    //  now concat the device matrix
602    {
603        SkMatrix    deviceMatrix;
604        this->getMatrixFrom2x2(&deviceMatrix);
605        m->postConcat(deviceMatrix);
606    }
607}
608
609///////////////////////////////////////////////////////////////////////////////
610
611#include "SkFontHost.h"
612
613class SkScalerContext_Empty : public SkScalerContext {
614public:
615    SkScalerContext_Empty(const SkDescriptor* desc) : SkScalerContext(desc) {}
616
617protected:
618    virtual unsigned generateGlyphCount() const {
619        return 0;
620    }
621    virtual uint16_t generateCharToGlyph(SkUnichar uni) {
622        return 0;
623    }
624    virtual void generateAdvance(SkGlyph* glyph) {
625        glyph->zeroMetrics();
626    }
627    virtual void generateMetrics(SkGlyph* glyph) {
628        glyph->zeroMetrics();
629    }
630    virtual void generateImage(const SkGlyph& glyph) {}
631    virtual void generatePath(const SkGlyph& glyph, SkPath* path) {}
632    virtual void generateFontMetrics(SkPaint::FontMetrics* mx,
633                                     SkPaint::FontMetrics* my) {
634        if (mx) {
635            sk_bzero(mx, sizeof(*mx));
636        }
637        if (my) {
638            sk_bzero(my, sizeof(*my));
639        }
640    }
641};
642
643SkScalerContext* SkScalerContext::Create(const SkDescriptor* desc)
644{
645    SkScalerContext* c = SkFontHost::CreateScalerContext(desc);
646    if (NULL == c) {
647        c = SkNEW_ARGS(SkScalerContext_Empty, (desc));
648    }
649    return c;
650}
651
652