ttinterp.h revision 049d6fea481044fcc000e7782e5bc7046fc70844 
1/***************************************************************************/
2/*                                                                         */
3/*  ttinterp.h                                                             */
4/*                                                                         */
5/*    TrueType bytecode interpreter (specification).                       */
6/*                                                                         */
7/*  Copyright 1996-2001, 2002, 2003, 2004, 2005, 2006, 2007 by             */
8/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
9/*                                                                         */
10/*  This file is part of the FreeType project, and may only be used,       */
11/*  modified, and distributed under the terms of the FreeType project      */
12/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
13/*  this file you indicate that you have read the license and              */
14/*  understand and accept it fully.                                        */
15/*                                                                         */
16/***************************************************************************/
17
18
19#ifndef __TTINTERP_H__
20#define __TTINTERP_H__
21
22#include <ft2build.h>
23#include "ttobjs.h"
24
25
26FT_BEGIN_HEADER
27
28
29#ifndef TT_CONFIG_OPTION_STATIC_INTERPRETER /* indirect implementation */
30
31#define EXEC_OP_   TT_ExecContext  exc,
32#define EXEC_OP    TT_ExecContext  exc
33#define EXEC_ARG_  exc,
34#define EXEC_ARG   exc
35
36#else                                       /* static implementation */
37
38#define EXEC_OP_   /* void */
39#define EXEC_OP    /* void */
40#define EXEC_ARG_  /* void */
41#define EXEC_ARG   /* void */
42
43#endif /* TT_CONFIG_OPTION_STATIC_INTERPRETER */
44
45
46  /*************************************************************************/
47  /*                                                                       */
48  /* Rounding mode constants.                                              */
49  /*                                                                       */
50#define TT_Round_Off             5
51#define TT_Round_To_Half_Grid    0
52#define TT_Round_To_Grid         1
53#define TT_Round_To_Double_Grid  2
54#define TT_Round_Up_To_Grid      4
55#define TT_Round_Down_To_Grid    3
56#define TT_Round_Super           6
57#define TT_Round_Super_45        7
58
59
60  /*************************************************************************/
61  /*                                                                       */
62  /* Function types used by the interpreter, depending on various modes    */
63  /* (e.g. the rounding mode, whether to render a vertical or horizontal   */
64  /* line etc).                                                            */
65  /*                                                                       */
66  /*************************************************************************/
67
68  /* Rounding function */
69  typedef FT_F26Dot6
70  (*TT_Round_Func)( EXEC_OP_ FT_F26Dot6  distance,
71                             FT_F26Dot6  compensation );
72
73  /* Point displacement along the freedom vector routine */
74  typedef void
75  (*TT_Move_Func)( EXEC_OP_ TT_GlyphZone  zone,
76                            FT_UShort     point,
77                            FT_F26Dot6    distance );
78
79  /* Distance projection along one of the projection vectors */
80  typedef FT_F26Dot6
81  (*TT_Project_Func)( EXEC_OP_ FT_Pos   dx,
82                               FT_Pos   dy );
83
84  /* reading a cvt value.  Take care of non-square pixels if necessary */
85  typedef FT_F26Dot6
86  (*TT_Get_CVT_Func)( EXEC_OP_ FT_ULong  idx );
87
88  /* setting or moving a cvt value.  Take care of non-square pixels  */
89  /* if necessary                                                    */
90  typedef void
91  (*TT_Set_CVT_Func)( EXEC_OP_ FT_ULong    idx,
92                               FT_F26Dot6  value );
93
94
95  /*************************************************************************/
96  /*                                                                       */
97  /* This structure defines a call record, used to manage function calls.  */
98  /*                                                                       */
99  typedef struct  TT_CallRec_
100  {
101    FT_Int   Caller_Range;
102    FT_Long  Caller_IP;
103    FT_Long  Cur_Count;
104    FT_Long  Cur_Restart;
105
106  } TT_CallRec, *TT_CallStack;
107
108
109  /*************************************************************************/
110  /*                                                                       */
111  /* The main structure for the interpreter which collects all necessary   */
112  /* variables and states.                                                 */
113  /*                                                                       */
114  typedef struct  TT_ExecContextRec_
115  {
116    TT_Face            face;
117    TT_Size            size;
118    FT_Memory          memory;
119
120    /* instructions state */
121
122    FT_Error           error;      /* last execution error */
123
124    FT_Long            top;        /* top of exec. stack   */
125
126    FT_UInt            stackSize;  /* size of exec. stack  */
127    FT_Long*           stack;      /* current exec. stack  */
128
129    FT_Long            args;
130    FT_UInt            new_top;    /* new top after exec.  */
131
132    TT_GlyphZoneRec    zp0,        /* zone records */
133                       zp1,
134                       zp2,
135                       pts,
136                       twilight;
137
138    FT_Size_Metrics    metrics;
139    TT_Size_Metrics    tt_metrics; /* size metrics */
140
141    TT_GraphicsState   GS;         /* current graphics state */
142
143    FT_Int             curRange;  /* current code range number   */
144    FT_Byte*           code;      /* current code range          */
145    FT_Long            IP;        /* current instruction pointer */
146    FT_Long            codeSize;  /* size of current range       */
147
148    FT_Byte            opcode;    /* current opcode              */
149    FT_Int             length;    /* length of current opcode    */
150
151    FT_Bool            step_ins;  /* true if the interpreter must */
152                                  /* increment IP after ins. exec */
153    FT_Long            cvtSize;
154    FT_Long*           cvt;
155
156    FT_UInt            glyphSize; /* glyph instructions buffer size */
157    FT_Byte*           glyphIns;  /* glyph instructions buffer */
158
159    FT_UInt            numFDefs;  /* number of function defs         */
160    FT_UInt            maxFDefs;  /* maximum number of function defs */
161    TT_DefArray        FDefs;     /* table of FDefs entries          */
162
163    FT_UInt            numIDefs;  /* number of instruction defs */
164    FT_UInt            maxIDefs;  /* maximum number of ins defs */
165    TT_DefArray        IDefs;     /* table of IDefs entries     */
166
167    FT_UInt            maxFunc;   /* maximum function index     */
168    FT_UInt            maxIns;    /* maximum instruction index  */
169
170    FT_Int             callTop,    /* top of call stack during execution */
171                       callSize;   /* size of call stack */
172    TT_CallStack       callStack;  /* call stack */
173
174    FT_UShort          maxPoints;    /* capacity of this context's `pts' */
175    FT_Short           maxContours;  /* record, expressed in points and  */
176                                     /* contours.                        */
177
178    TT_CodeRangeTable  codeRangeTable;  /* table of valid code ranges */
179                                        /* useful for the debugger   */
180
181    FT_UShort          storeSize;  /* size of current storage */
182    FT_Long*           storage;    /* storage area            */
183
184    FT_F26Dot6         period;     /* values used for the */
185    FT_F26Dot6         phase;      /* `SuperRounding'     */
186    FT_F26Dot6         threshold;
187
188#if 0
189    /* this seems to be unused */
190    FT_Int             cur_ppem;   /* ppem along the current proj vector */
191#endif
192
193    FT_Bool            instruction_trap; /* If `True', the interpreter will */
194                                         /* exit after each instruction     */
195
196    TT_GraphicsState   default_GS;       /* graphics state resulting from   */
197                                         /* the prep program                */
198    FT_Bool            is_composite;     /* true if the glyph is composite  */
199    FT_Bool            pedantic_hinting; /* true if pedantic interpretation */
200
201    /* latest interpreter additions */
202
203    FT_Long            F_dot_P;    /* dot product of freedom and projection */
204                                   /* vectors                               */
205    TT_Round_Func      func_round; /* current rounding function             */
206
207    TT_Project_Func    func_project,   /* current projection function */
208                       func_dualproj,  /* current dual proj. function */
209                       func_freeProj;  /* current freedom proj. func  */
210
211    TT_Move_Func       func_move;      /* current point move function */
212    TT_Move_Func       func_move_orig; /* move original position function */
213
214    TT_Get_CVT_Func    func_read_cvt;  /* read a cvt entry              */
215    TT_Set_CVT_Func    func_write_cvt; /* write a cvt entry (in pixels) */
216    TT_Set_CVT_Func    func_move_cvt;  /* incr a cvt entry (in pixels)  */
217
218    FT_Bool            grayscale;      /* are we hinting for grayscale? */
219
220  } TT_ExecContextRec;
221
222
223  extern const TT_GraphicsState  tt_default_graphics_state;
224
225
226  FT_LOCAL( FT_Error )
227  TT_Goto_CodeRange( TT_ExecContext  exec,
228                     FT_Int          range,
229                     FT_Long         IP );
230
231  FT_LOCAL( FT_Error )
232  TT_Set_CodeRange( TT_ExecContext  exec,
233                    FT_Int          range,
234                    void*           base,
235                    FT_Long         length );
236
237  FT_LOCAL( FT_Error )
238  TT_Clear_CodeRange( TT_ExecContext  exec,
239                      FT_Int          range );
240
241
242  /*************************************************************************/
243  /*                                                                       */
244  /* <Function>                                                            */
245  /*    TT_New_Context                                                     */
246  /*                                                                       */
247  /* <Description>                                                         */
248  /*    Queries the face context for a given font.  Note that there is     */
249  /*    now a _single_ execution context in the TrueType driver which is   */
250  /*    shared among faces.                                                */
251  /*                                                                       */
252  /* <Input>                                                               */
253  /*    face :: A handle to the source face object.                        */
254  /*                                                                       */
255  /* <Return>                                                              */
256  /*    A handle to the execution context.  Initialized for `face'.        */
257  /*                                                                       */
258  /* <Note>                                                                */
259  /*    Only the glyph loader and debugger should call this function.      */
260  /*                                                                       */
261  FT_EXPORT( TT_ExecContext )
262  TT_New_Context( TT_Driver  driver );
263
264  FT_LOCAL( FT_Error )
265  TT_Done_Context( TT_ExecContext  exec );
266
267  FT_LOCAL( FT_Error )
268  TT_Load_Context( TT_ExecContext  exec,
269                   TT_Face         face,
270                   TT_Size         size );
271
272  FT_LOCAL( FT_Error )
273  TT_Save_Context( TT_ExecContext  exec,
274                   TT_Size         ins );
275
276  FT_LOCAL( FT_Error )
277  TT_Run_Context( TT_ExecContext  exec,
278                  FT_Bool         debug );
279
280
281  /*************************************************************************/
282  /*                                                                       */
283  /* <Function>                                                            */
284  /*    TT_RunIns                                                          */
285  /*                                                                       */
286  /* <Description>                                                         */
287  /*    Executes one or more instruction in the execution context.  This   */
288  /*    is the main function of the TrueType opcode interpreter.           */
289  /*                                                                       */
290  /* <Input>                                                               */
291  /*    exec :: A handle to the target execution context.                  */
292  /*                                                                       */
293  /* <Return>                                                              */
294  /*    FreeType error code.  0 means success.                             */
295  /*                                                                       */
296  /* <Note>                                                                */
297  /*    Only the object manager and debugger should call this function.    */
298  /*                                                                       */
299  /*    This function is publicly exported because it is directly          */
300  /*    invoked by the TrueType debugger.                                  */
301  /*                                                                       */
302  FT_EXPORT( FT_Error )
303  TT_RunIns( TT_ExecContext  exec );
304
305
306FT_END_HEADER
307
308#endif /* __TTINTERP_H__ */
309
310
311/* END */
312