| /***************************************************************************/ |
| /* */ |
| /* ttinterp.h */ |
| /* */ |
| /* TrueType bytecode interpreter (specification). */ |
| /* */ |
| /* Copyright 1996-2016 by */ |
| /* David Turner, Robert Wilhelm, and Werner Lemberg. */ |
| /* */ |
| /* This file is part of the FreeType project, and may only be used, */ |
| /* modified, and distributed under the terms of the FreeType project */ |
| /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
| /* this file you indicate that you have read the license and */ |
| /* understand and accept it fully. */ |
| /* */ |
| /***************************************************************************/ |
| |
| |
| #ifndef TTINTERP_H_ |
| #define TTINTERP_H_ |
| |
| #include <ft2build.h> |
| #include "ttobjs.h" |
| |
| |
| FT_BEGIN_HEADER |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* Rounding mode constants. */ |
| /* */ |
| #define TT_Round_Off 5 |
| #define TT_Round_To_Half_Grid 0 |
| #define TT_Round_To_Grid 1 |
| #define TT_Round_To_Double_Grid 2 |
| #define TT_Round_Up_To_Grid 4 |
| #define TT_Round_Down_To_Grid 3 |
| #define TT_Round_Super 6 |
| #define TT_Round_Super_45 7 |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* Function types used by the interpreter, depending on various modes */ |
| /* (e.g. the rounding mode, whether to render a vertical or horizontal */ |
| /* line etc). */ |
| /* */ |
| /*************************************************************************/ |
| |
| /* Rounding function */ |
| typedef FT_F26Dot6 |
| (*TT_Round_Func)( TT_ExecContext exc, |
| FT_F26Dot6 distance, |
| FT_F26Dot6 compensation ); |
| |
| /* Point displacement along the freedom vector routine */ |
| typedef void |
| (*TT_Move_Func)( TT_ExecContext exc, |
| TT_GlyphZone zone, |
| FT_UShort point, |
| FT_F26Dot6 distance ); |
| |
| /* Distance projection along one of the projection vectors */ |
| typedef FT_F26Dot6 |
| (*TT_Project_Func)( TT_ExecContext exc, |
| FT_Pos dx, |
| FT_Pos dy ); |
| |
| /* getting current ppem. Take care of non-square pixels if necessary */ |
| typedef FT_Long |
| (*TT_Cur_Ppem_Func)( TT_ExecContext exc ); |
| |
| /* reading a cvt value. Take care of non-square pixels if necessary */ |
| typedef FT_F26Dot6 |
| (*TT_Get_CVT_Func)( TT_ExecContext exc, |
| FT_ULong idx ); |
| |
| /* setting or moving a cvt value. Take care of non-square pixels */ |
| /* if necessary */ |
| typedef void |
| (*TT_Set_CVT_Func)( TT_ExecContext exc, |
| FT_ULong idx, |
| FT_F26Dot6 value ); |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* This structure defines a call record, used to manage function calls. */ |
| /* */ |
| typedef struct TT_CallRec_ |
| { |
| FT_Int Caller_Range; |
| FT_Long Caller_IP; |
| FT_Long Cur_Count; |
| |
| TT_DefRecord *Def; /* either FDEF or IDEF */ |
| |
| } TT_CallRec, *TT_CallStack; |
| |
| |
| #ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY |
| |
| /*************************************************************************/ |
| /* */ |
| /* These structures define rules used to tweak subpixel hinting for */ |
| /* various fonts. "", 0, "", NULL value indicates to match any value. */ |
| /* */ |
| |
| #define SPH_MAX_NAME_SIZE 32 |
| #define SPH_MAX_CLASS_MEMBERS 100 |
| |
| typedef struct SPH_TweakRule_ |
| { |
| const char family[SPH_MAX_NAME_SIZE]; |
| const FT_UInt ppem; |
| const char style[SPH_MAX_NAME_SIZE]; |
| const FT_ULong glyph; |
| |
| } SPH_TweakRule; |
| |
| |
| typedef struct SPH_ScaleRule_ |
| { |
| const char family[SPH_MAX_NAME_SIZE]; |
| const FT_UInt ppem; |
| const char style[SPH_MAX_NAME_SIZE]; |
| const FT_ULong glyph; |
| const FT_ULong scale; |
| |
| } SPH_ScaleRule; |
| |
| |
| typedef struct SPH_Font_Class_ |
| { |
| const char name[SPH_MAX_NAME_SIZE]; |
| const char member[SPH_MAX_CLASS_MEMBERS][SPH_MAX_NAME_SIZE]; |
| |
| } SPH_Font_Class; |
| |
| #endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* The main structure for the interpreter which collects all necessary */ |
| /* variables and states. */ |
| /* */ |
| typedef struct TT_ExecContextRec_ |
| { |
| TT_Face face; |
| TT_Size size; |
| FT_Memory memory; |
| |
| /* instructions state */ |
| |
| FT_Error error; /* last execution error */ |
| |
| FT_Long top; /* top of exec. stack */ |
| |
| FT_Long stackSize; /* size of exec. stack */ |
| FT_Long* stack; /* current exec. stack */ |
| |
| FT_Long args; |
| FT_Long new_top; /* new top after exec. */ |
| |
| TT_GlyphZoneRec zp0, /* zone records */ |
| zp1, |
| zp2, |
| pts, |
| twilight; |
| |
| FT_Long pointSize; /* in 26.6 format */ |
| FT_Size_Metrics metrics; |
| TT_Size_Metrics tt_metrics; /* size metrics */ |
| |
| TT_GraphicsState GS; /* current graphics state */ |
| |
| FT_Int curRange; /* current code range number */ |
| FT_Byte* code; /* current code range */ |
| FT_Long IP; /* current instruction pointer */ |
| FT_Long codeSize; /* size of current range */ |
| |
| FT_Byte opcode; /* current opcode */ |
| FT_Int length; /* length of current opcode */ |
| |
| FT_Bool step_ins; /* true if the interpreter must */ |
| /* increment IP after ins. exec */ |
| FT_ULong cvtSize; |
| FT_Long* cvt; |
| |
| FT_UInt glyphSize; /* glyph instructions buffer size */ |
| FT_Byte* glyphIns; /* glyph instructions buffer */ |
| |
| FT_UInt numFDefs; /* number of function defs */ |
| FT_UInt maxFDefs; /* maximum number of function defs */ |
| TT_DefArray FDefs; /* table of FDefs entries */ |
| |
| FT_UInt numIDefs; /* number of instruction defs */ |
| FT_UInt maxIDefs; /* maximum number of ins defs */ |
| TT_DefArray IDefs; /* table of IDefs entries */ |
| |
| FT_UInt maxFunc; /* maximum function index */ |
| FT_UInt maxIns; /* maximum instruction index */ |
| |
| FT_Int callTop, /* top of call stack during execution */ |
| callSize; /* size of call stack */ |
| TT_CallStack callStack; /* call stack */ |
| |
| FT_UShort maxPoints; /* capacity of this context's `pts' */ |
| FT_Short maxContours; /* record, expressed in points and */ |
| /* contours. */ |
| |
| TT_CodeRangeTable codeRangeTable; /* table of valid code ranges */ |
| /* useful for the debugger */ |
| |
| FT_UShort storeSize; /* size of current storage */ |
| FT_Long* storage; /* storage area */ |
| |
| FT_F26Dot6 period; /* values used for the */ |
| FT_F26Dot6 phase; /* `SuperRounding' */ |
| FT_F26Dot6 threshold; |
| |
| FT_Bool instruction_trap; /* If `True', the interpreter will */ |
| /* exit after each instruction */ |
| |
| TT_GraphicsState default_GS; /* graphics state resulting from */ |
| /* the prep program */ |
| FT_Bool is_composite; /* true if the glyph is composite */ |
| FT_Bool pedantic_hinting; /* true if pedantic interpretation */ |
| |
| /* latest interpreter additions */ |
| |
| FT_Long F_dot_P; /* dot product of freedom and projection */ |
| /* vectors */ |
| TT_Round_Func func_round; /* current rounding function */ |
| |
| TT_Project_Func func_project, /* current projection function */ |
| func_dualproj, /* current dual proj. function */ |
| func_freeProj; /* current freedom proj. func */ |
| |
| TT_Move_Func func_move; /* current point move function */ |
| TT_Move_Func func_move_orig; /* move original position function */ |
| |
| TT_Cur_Ppem_Func func_cur_ppem; /* get current proj. ppem value */ |
| |
| TT_Get_CVT_Func func_read_cvt; /* read a cvt entry */ |
| TT_Set_CVT_Func func_write_cvt; /* write a cvt entry (in pixels) */ |
| TT_Set_CVT_Func func_move_cvt; /* incr a cvt entry (in pixels) */ |
| |
| FT_Bool grayscale; /* bi-level hinting and */ |
| /* grayscale rendering */ |
| |
| #ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL |
| /* |
| * Modern TrueType fonts are usually rendered through Microsoft's |
| * collection of rendering techniques called ClearType (e.g., subpixel |
| * rendering and subpixel hinting). When ClearType was introduced, most |
| * fonts were not ready. Microsoft decided to implement a backwards |
| * compatibility mode that employed several simple to complicated |
| * assumptions and tricks that modified the interpretation of the |
| * bytecode contained in these fonts to make them look ClearType-y |
| * somehow. Most (web)fonts that were released since then have come to |
| * rely on these hacks to render correctly, even some of Microsoft's |
| * flagship ClearType fonts (Calibri, Cambria, Segoe UI). |
| * |
| * The minimal subpixel hinting code (interpreter version 40) employs a |
| * small list of font-agnostic hacks to bludgeon non-native-ClearType |
| * fonts (except tricky ones[1]) into submission. It will not try to |
| * toggle hacks for specific fonts for performance and complexity |
| * reasons. The focus is on modern (web)fonts rather than legacy fonts |
| * that were made for black-and-white rendering. |
| * |
| * Major hacks |
| * |
| * - Any point movement on the x axis is ignored (cf. `Direct_Move' and |
| * `Direct_Move_X'). This has the smallest code footprint and single |
| * biggest effect. The ClearType way to increase resolution is |
| * supersampling the x axis, the FreeType way is ignoring instructions |
| * on the x axis, which gives the same result in the majority of |
| * cases. |
| * |
| * - Points are not moved post-IUP (neither on the x nor on the y axis), |
| * except the x component of diagonal moves post-IUP (cf. |
| * `Direct_Move', `Direct_Move_Y', `Move_Zp2_Point'). Post-IUP |
| * changes are commonly used to `fix' pixel patterns which has little |
| * use outside monochrome rendering. |
| * |
| * - SHPIX and DELTAP don't execute unless moving a composite on the |
| * y axis or moving a previously y touched point. SHPIX additionally |
| * denies movement on the x axis (cf. `Ins_SHPIX' and `Ins_DELTAP'). |
| * Both instructions are commonly used to `fix' pixel patterns for |
| * monochrome or Windows's GDI rendering but make little sense for |
| * FreeType rendering. Both can distort the outline. See [2] for |
| * details. |
| * |
| * - The hdmx table and modifications to phantom points are ignored. |
| * Bearings and advance widths remain unchanged (except rounding them |
| * outside the interpreter!), cf. `compute_glyph_metrics' and |
| * `TT_Hint_Glyph'. Letting non-native-ClearType fonts modify spacing |
| * might mess up spacing. |
| * |
| * Minor hacks |
| * |
| * - FLIPRGON, FLIPRGOFF, and FLIPPT don't execute post-IUP. This |
| * prevents dents in e.g. Arial-Regular's `D' and `G' glyphs at |
| * various sizes. |
| * |
| * (Post-IUP is the state after both IUP[x] and IUP[y] have been |
| * executed.) |
| * |
| * The best results are achieved for fonts that were from the outset |
| * designed with ClearType in mind, meaning they leave the x axis mostly |
| * alone and don't mess with the `final' outline to produce more |
| * pleasing pixel patterns. The harder the designer tried to produce |
| * very specific patterns (`superhinting') for pre-ClearType-displays, |
| * the worse the results. |
| * |
| * Microsoft defines a way to turn off backwards compatibility and |
| * interpret instructions as before (called `native ClearType')[2][3]. |
| * The font designer then regains full control and is responsible for |
| * making the font work correctly with ClearType without any |
| * hand-holding by the interpreter or rasterizer[4]. The v40 |
| * interpreter assumes backwards compatibility by default, which can be |
| * turned off the same way by executing the following in the control |
| * program (cf. `Ins_INSTCTRL'). |
| * |
| * #PUSH 4,3 |
| * INSTCTRL[] |
| * |
| * [1] Tricky fonts as FreeType defines them rely on the bytecode |
| * interpreter to display correctly. Hacks can interfere with them, |
| * so they get treated like native ClearType fonts (v40 with |
| * backwards compatibility turned off). Cf. `TT_RunIns'. |
| * |
| * [2] Proposed by Microsoft's Greg Hitchcock in |
| * https://www.microsoft.com/typography/cleartype/truetypecleartype.aspx |
| * |
| * [3] Beat Stamm describes it in more detail: |
| * http://www.beatstamm.com/typography/RTRCh4.htm#Sec12 |
| * |
| * [4] The list of `native ClearType' fonts is small at the time of this |
| * writing; I found the following on a Windows 10 Update 1511 |
| * installation: Constantia, Corbel, Sitka, Malgun Gothic, Microsoft |
| * JhengHei (Bold and UI Bold), Microsoft YaHei (Bold and UI Bold), |
| * SimSun, NSimSun, and Yu Gothic. |
| * |
| */ |
| |
| /* Using v40 implies subpixel hinting. Used to detect interpreter */ |
| /* version switches. `_lean' to differentiate from the Infinality */ |
| /* `subpixel_hinting', which is managed differently. */ |
| FT_Bool subpixel_hinting_lean; |
| |
| /* Long side of a LCD subpixel is vertical (e.g., screen is rotated). */ |
| /* `_lean' to differentiate from the Infinality `vertical_lcd', which */ |
| /* is managed differently. */ |
| FT_Bool vertical_lcd_lean; |
| |
| /* Default to backwards compatibility mode in v40 interpreter. If */ |
| /* this is false, it implies the interpreter is in v35 or in native */ |
| /* ClearType mode. */ |
| FT_Bool backwards_compatibility; |
| |
| /* Useful for detecting and denying post-IUP trickery that is usually */ |
| /* used to fix pixel patterns (`superhinting'). */ |
| FT_Bool iupx_called; |
| FT_Bool iupy_called; |
| |
| /* ClearType hinting and grayscale rendering, as used by Universal */ |
| /* Windows Platform apps (Windows 8 and above). Like the standard */ |
| /* colorful ClearType mode, it utilizes a vastly increased virtual */ |
| /* resolution on the x axis. Different from bi-level hinting and */ |
| /* grayscale rendering, the old mode from Win9x days that roughly */ |
| /* adheres to the physical pixel grid on both axes. */ |
| FT_Bool grayscale_cleartype; |
| #endif /* TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL */ |
| |
| #ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY |
| TT_Round_Func func_round_sphn; /* subpixel rounding function */ |
| |
| FT_Bool subpixel_hinting; /* Using subpixel hinting? */ |
| FT_Bool ignore_x_mode; /* Standard rendering mode for */ |
| /* subpixel hinting. On if gray */ |
| /* or subpixel hinting is on. */ |
| |
| /* The following 6 aren't fully implemented but here for MS rasterizer */ |
| /* compatibility. */ |
| FT_Bool compatible_widths; /* compatible widths? */ |
| FT_Bool symmetrical_smoothing; /* symmetrical_smoothing? */ |
| FT_Bool bgr; /* bgr instead of rgb? */ |
| FT_Bool vertical_lcd; /* long side of LCD subpixel */ |
| /* rectangles is horizontal */ |
| FT_Bool subpixel_positioned; /* subpixel positioned */ |
| /* (DirectWrite ClearType)? */ |
| FT_Bool gray_cleartype; /* ClearType hinting but */ |
| /* grayscale rendering */ |
| |
| FT_Int rasterizer_version; /* MS rasterizer version */ |
| |
| FT_Bool iup_called; /* IUP called for glyph? */ |
| |
| FT_ULong sph_tweak_flags; /* flags to control */ |
| /* hint tweaks */ |
| |
| FT_ULong sph_in_func_flags; /* flags to indicate if in */ |
| /* special functions */ |
| |
| #endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ |
| |
| } TT_ExecContextRec; |
| |
| |
| extern const TT_GraphicsState tt_default_graphics_state; |
| |
| |
| #ifdef TT_USE_BYTECODE_INTERPRETER |
| FT_LOCAL( void ) |
| TT_Goto_CodeRange( TT_ExecContext exec, |
| FT_Int range, |
| FT_Long IP ); |
| |
| FT_LOCAL( void ) |
| TT_Set_CodeRange( TT_ExecContext exec, |
| FT_Int range, |
| void* base, |
| FT_Long length ); |
| |
| FT_LOCAL( void ) |
| TT_Clear_CodeRange( TT_ExecContext exec, |
| FT_Int range ); |
| |
| |
| FT_LOCAL( FT_Error ) |
| Update_Max( FT_Memory memory, |
| FT_ULong* size, |
| FT_ULong multiplier, |
| void* _pbuff, |
| FT_ULong new_max ); |
| #endif /* TT_USE_BYTECODE_INTERPRETER */ |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* TT_New_Context */ |
| /* */ |
| /* <Description> */ |
| /* Queries the face context for a given font. Note that there is */ |
| /* now a _single_ execution context in the TrueType driver which is */ |
| /* shared among faces. */ |
| /* */ |
| /* <Input> */ |
| /* face :: A handle to the source face object. */ |
| /* */ |
| /* <Return> */ |
| /* A handle to the execution context. Initialized for `face'. */ |
| /* */ |
| /* <Note> */ |
| /* Only the glyph loader and debugger should call this function. */ |
| /* (And right now only the glyph loader uses it.) */ |
| /* */ |
| FT_EXPORT( TT_ExecContext ) |
| TT_New_Context( TT_Driver driver ); |
| |
| |
| #ifdef TT_USE_BYTECODE_INTERPRETER |
| FT_LOCAL( void ) |
| TT_Done_Context( TT_ExecContext exec ); |
| |
| FT_LOCAL( FT_Error ) |
| TT_Load_Context( TT_ExecContext exec, |
| TT_Face face, |
| TT_Size size ); |
| |
| FT_LOCAL( void ) |
| TT_Save_Context( TT_ExecContext exec, |
| TT_Size ins ); |
| |
| FT_LOCAL( FT_Error ) |
| TT_Run_Context( TT_ExecContext exec ); |
| #endif /* TT_USE_BYTECODE_INTERPRETER */ |
| |
| |
| /*************************************************************************/ |
| /* */ |
| /* <Function> */ |
| /* TT_RunIns */ |
| /* */ |
| /* <Description> */ |
| /* Executes one or more instruction in the execution context. This */ |
| /* is the main function of the TrueType opcode interpreter. */ |
| /* */ |
| /* <Input> */ |
| /* exec :: A handle to the target execution context. */ |
| /* */ |
| /* <Return> */ |
| /* FreeType error code. 0 means success. */ |
| /* */ |
| /* <Note> */ |
| /* Only the object manager and debugger should call this function. */ |
| /* */ |
| /* This function is publicly exported because it is directly */ |
| /* invoked by the TrueType debugger. */ |
| /* */ |
| FT_EXPORT( FT_Error ) |
| TT_RunIns( TT_ExecContext exec ); |
| |
| |
| FT_END_HEADER |
| |
| #endif /* TTINTERP_H_ */ |
| |
| |
| /* END */ |
