From 596157365aeff6bb842fe741f8cf322890a952fe Mon Sep 17 00:00:00 2001 From: Nikolaus Waxweiler Date: Wed, 18 May 2016 06:57:59 +0200 Subject: [PATCH] [truetype] New implementation of v38 bytecode interpreter [1/3]. This patch prepares data structures and the like. See added comments in `ttinterp.h' for more information on this and the following commits in the series. * devel/ftoption.h, include/freetype/config/ftoption.h (TT_CONFIG_OPTION_SUBPIXEL_HINTING): Assign values to differentiate between subpixel versions. (TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY, TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL): New macros. * include/freetype/ftttdrv.h (TT_INTERPRETER_VERSION_40): New macro. * include/freetype/internal/tttypes.h (TT_FaceRec): Updated. * src/truetype/ttinterp.h (TT_ExecContextRec): Define new fields `subpixel_hinting_lean', `vertical_lcd_lean', `backwards_compatibility', `iupx_called', iupy_called', and `grayscale_cleartype' for new hinting mode. * src/truetype/ttdriver.c (tt_property_set): Handle v38 and v40 interpreters conditionally. * src/truetype/ttgload.c (TT_Hint_Glyph): Save phantom points unless in v38 backwards compatibility mode. Updated. (compute_glyph_metrics): Add v38 backwards compatibility mode constraint for adjusting advance widths. Updated. (tt_loader_init): Handle new flags `subpixel_hinting_lean', `grayscale_cleartype', and `vertical_lcd_lean'. Updated. (tt_get_metrics, TT_Process_Simple_Glyph, TT_LOADER_SET_PP): Updated. * src/truetype/ttobjs.c (tt_driver_init): Conditionally set default interpreter version number. * src/truetype/ttsubpix.c, src/truetype/ttsubpix.h: Updated. --- ChangeLog | 44 ++++++++ devel/ftoption.h | 62 ++++++++--- include/freetype/config/ftoption.h | 62 ++++++++--- include/freetype/ftcffdrv.h | 8 +- include/freetype/ftttdrv.h | 61 +++++++---- include/freetype/internal/tttypes.h | 4 +- src/truetype/ttdriver.c | 5 +- src/truetype/ttgload.c | 159 +++++++++++++++++++++------- src/truetype/ttinterp.h | 136 +++++++++++++++++++++++- src/truetype/ttobjs.c | 8 +- src/truetype/ttsubpix.c | 6 +- src/truetype/ttsubpix.h | 4 +- 12 files changed, 453 insertions(+), 106 deletions(-) diff --git a/ChangeLog b/ChangeLog index d4ac785de..a36547d0f 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,47 @@ +2016-05-17 Nikolaus Waxweiler + + [truetype] New implementation of v38 bytecode interpreter [1/3]. + + This patch prepares data structures and the like. + + See added comments in `ttinterp.h' for more information on this and + the following commits in the series. + + * devel/ftoption.h, include/freetype/config/ftoption.h + (TT_CONFIG_OPTION_SUBPIXEL_HINTING): Assign values to differentiate + between subpixel versions. + (TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY, + TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL): New macros. + + * include/freetype/ftttdrv.h (TT_INTERPRETER_VERSION_40): New macro. + + * include/freetype/internal/tttypes.h (TT_FaceRec): Updated. + + * src/truetype/ttinterp.h (TT_ExecContextRec): Define new fields + `subpixel_hinting_lean', `vertical_lcd_lean', + `backwards_compatibility', `iupx_called', iupy_called', and + `grayscale_cleartype' for new hinting mode. + + * src/truetype/ttdriver.c (tt_property_set): Handle v38 and v40 + interpreters conditionally. + + * src/truetype/ttgload.c (TT_Hint_Glyph): Save phantom points unless + in v38 backwards compatibility mode. + Updated. + (compute_glyph_metrics): Add v38 backwards compatibility mode + constraint for adjusting advance widths. + Updated. + (tt_loader_init): Handle new flags `subpixel_hinting_lean', + `grayscale_cleartype', and `vertical_lcd_lean'. + Updated. + (tt_get_metrics, TT_Process_Simple_Glyph, TT_LOADER_SET_PP): + Updated. + + * src/truetype/ttobjs.c (tt_driver_init): Conditionally set + default interpreter version number. + + * src/truetype/ttsubpix.c, src/truetype/ttsubpix.h: Updated. + 2016-05-17 Werner Lemberg [cff] Fix matrix scaling (#47848). diff --git a/devel/ftoption.h b/devel/ftoption.h index b354efdcd..2360ec693 100644 --- a/devel/ftoption.h +++ b/devel/ftoption.h @@ -586,23 +586,53 @@ FT_BEGIN_HEADER /*************************************************************************/ /* */ /* Define TT_CONFIG_OPTION_SUBPIXEL_HINTING if you want to compile */ - /* EXPERIMENTAL subpixel hinting support into the TrueType driver. This */ - /* replaces the native TrueType hinting mechanism when anything but */ - /* FT_RENDER_MODE_MONO is requested. */ + /* subpixel hinting support into the TrueType driver. This modifies the */ + /* TrueType hinting mechanism when anything but FT_RENDER_MODE_MONO is */ + /* requested. */ /* */ - /* Enabling this causes the TrueType driver to ignore instructions under */ - /* certain conditions. This is done in accordance with the guide here, */ - /* with some minor differences: */ + /* In particular, it modifies the bytecode interpreter to interpret (or */ + /* not) instructions in a certain way so that all TrueType fonts look */ + /* like they do in a Windows ClearType (DirectWrite) environment. See */ + /* [1] for a technical overview on what this means. See `ttinterp.h' */ + /* for more details on the LEAN option. */ /* */ - /* http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx */ + /* There are three options. */ /* */ - /* By undefining this, you only compile the code necessary to hint */ - /* TrueType glyphs with native TT hinting. */ + /* 1. This option is associated with the `Infinality' moniker. */ + /* Contributed by an individual nicknamed Infinality with the goal of */ + /* making TrueType fonts render better than on Windows. A high */ + /* amount of configurability and flexibility, down to rules for */ + /* single glyphs in fonts, but also very slow. Its experimental and */ + /* slow nature and the original developer losing interest meant that */ + /* this option was never enabled in default builds. */ /* */ - /* This option requires TT_CONFIG_OPTION_BYTECODE_INTERPRETER to be */ - /* defined. */ + /* 2. The new default mode for the TrueType driver. The Infinality code */ + /* base was stripped to the bare minimum and all configurability */ + /* removed in the name of speed and simplicity. The configurability */ + /* was mainly aimed at legacy fonts like Arial, Times New Roman, or */ + /* Courier. Legacy fonts are fonts that modify vertical stems to */ + /* achieve clean black-and-white bitmaps. The new mode focuses on */ + /* applying a minimal set of rules to all fonts indiscriminately so */ + /* that modern and web fonts render well while legacy fonts render */ + /* okay. */ /* */ -#define TT_CONFIG_OPTION_SUBPIXEL_HINTING + /* 3. Compile both. */ + /* */ + /* By undefining these, you get rendering behavior like on Windows */ + /* without ClearType, i.e., Windows XP without ClearType enabled and */ + /* Win9x (interpreter version v35). Or not, depending on how much */ + /* hinting blood and testing tears the font designer put into a given */ + /* font. If you define one or both subpixel hinting options, you can */ + /* switch between between v35 and the ones you define. */ + /* */ + /* This option requires TT_CONFIG_OPTION_BYTECODE_INTERPRETER to be */ + /* defined. */ + /* */ + /* [1] http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx */ + /* */ +/* #define TT_CONFIG_OPTION_SUBPIXEL_HINTING 1 */ +/* #define TT_CONFIG_OPTION_SUBPIXEL_HINTING 2 */ +#define TT_CONFIG_OPTION_SUBPIXEL_HINTING 1 | 2 /*************************************************************************/ @@ -811,6 +841,14 @@ FT_BEGIN_HEADER */ #ifdef TT_CONFIG_OPTION_BYTECODE_INTERPRETER #define TT_USE_BYTECODE_INTERPRETER + +#if TT_CONFIG_OPTION_SUBPIXEL_HINTING & 1 +#define TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY +#endif + +#if TT_CONFIG_OPTION_SUBPIXEL_HINTING & 2 +#define TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL +#endif #endif diff --git a/include/freetype/config/ftoption.h b/include/freetype/config/ftoption.h index a8097feb0..1447908b9 100644 --- a/include/freetype/config/ftoption.h +++ b/include/freetype/config/ftoption.h @@ -586,23 +586,53 @@ FT_BEGIN_HEADER /*************************************************************************/ /* */ /* Define TT_CONFIG_OPTION_SUBPIXEL_HINTING if you want to compile */ - /* EXPERIMENTAL subpixel hinting support into the TrueType driver. This */ - /* replaces the native TrueType hinting mechanism when anything but */ - /* FT_RENDER_MODE_MONO is requested. */ + /* subpixel hinting support into the TrueType driver. This modifies the */ + /* TrueType hinting mechanism when anything but FT_RENDER_MODE_MONO is */ + /* requested. */ /* */ - /* Enabling this causes the TrueType driver to ignore instructions under */ - /* certain conditions. This is done in accordance with the guide here, */ - /* with some minor differences: */ + /* In particular, it modifies the bytecode interpreter to interpret (or */ + /* not) instructions in a certain way so that all TrueType fonts look */ + /* like they do in a Windows ClearType (DirectWrite) environment. See */ + /* [1] for a technical overview on what this means. See `ttinterp.h' */ + /* for more details on the LEAN option. */ /* */ - /* http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx */ + /* There are three options. */ /* */ - /* By undefining this, you only compile the code necessary to hint */ - /* TrueType glyphs with native TT hinting. */ + /* 1. This option is associated with the `Infinality' moniker. */ + /* Contributed by an individual nicknamed Infinality with the goal of */ + /* making TrueType fonts render better than on Windows. A high */ + /* amount of configurability and flexibility, down to rules for */ + /* single glyphs in fonts, but also very slow. Its experimental and */ + /* slow nature and the original developer losing interest meant that */ + /* this option was never enabled in default builds. */ /* */ - /* This option requires TT_CONFIG_OPTION_BYTECODE_INTERPRETER to be */ - /* defined. */ + /* 2. The new default mode for the TrueType driver. The Infinality code */ + /* base was stripped to the bare minimum and all configurability */ + /* removed in the name of speed and simplicity. The configurability */ + /* was mainly aimed at legacy fonts like Arial, Times New Roman, or */ + /* Courier. Legacy fonts are fonts that modify vertical stems to */ + /* achieve clean black-and-white bitmaps. The new mode focuses on */ + /* applying a minimal set of rules to all fonts indiscriminately so */ + /* that modern and web fonts render well while legacy fonts render */ + /* okay. */ /* */ -/* #define TT_CONFIG_OPTION_SUBPIXEL_HINTING */ + /* 3. Compile both. */ + /* */ + /* By undefining these, you get rendering behavior like on Windows */ + /* without ClearType, i.e., Windows XP without ClearType enabled and */ + /* Win9x (interpreter version v35). Or not, depending on how much */ + /* hinting blood and testing tears the font designer put into a given */ + /* font. If you define one or both subpixel hinting options, you can */ + /* switch between between v35 and the ones you define. */ + /* */ + /* This option requires TT_CONFIG_OPTION_BYTECODE_INTERPRETER to be */ + /* defined. */ + /* */ + /* [1] http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx */ + /* */ +/* #define TT_CONFIG_OPTION_SUBPIXEL_HINTING 1 */ +#define TT_CONFIG_OPTION_SUBPIXEL_HINTING 2 +/* #define TT_CONFIG_OPTION_SUBPIXEL_HINTING 1 | 2 */ /*************************************************************************/ @@ -811,6 +841,14 @@ FT_BEGIN_HEADER */ #ifdef TT_CONFIG_OPTION_BYTECODE_INTERPRETER #define TT_USE_BYTECODE_INTERPRETER + +#if TT_CONFIG_OPTION_SUBPIXEL_HINTING & 1 +#define TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY +#endif + +#if TT_CONFIG_OPTION_SUBPIXEL_HINTING & 2 +#define TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL +#endif #endif diff --git a/include/freetype/ftcffdrv.h b/include/freetype/ftcffdrv.h index b0b429999..ad34541fd 100644 --- a/include/freetype/ftcffdrv.h +++ b/include/freetype/ftcffdrv.h @@ -110,7 +110,7 @@ FT_BEGIN_HEADER * to minimize distortion. * * @order: - * hinting-engine + * hinting-engine[cff] * no-stem-darkening[cff] * darkening-parameters[cff] * @@ -120,7 +120,7 @@ FT_BEGIN_HEADER /************************************************************************** * * @property: - * hinting-engine + * hinting-engine[cff] * * @description: * Thanks to Adobe, which contributed a new hinting (and parsing) @@ -157,8 +157,8 @@ FT_BEGIN_HEADER * FT_CFF_HINTING_XXX * * @description: - * A list of constants used for the @hinting-engine property to select - * the hinting engine for CFF fonts. + * A list of constants used for the @hinting-engine[cff] property to + * select the hinting engine for CFF fonts. * * @values: * FT_CFF_HINTING_FREETYPE :: diff --git a/include/freetype/ftttdrv.h b/include/freetype/ftttdrv.h index 6c02e6576..0d868bc25 100644 --- a/include/freetype/ftttdrv.h +++ b/include/freetype/ftttdrv.h @@ -138,31 +138,37 @@ FT_BEGIN_HEADER * interpreter-version * * @description: - * Currently, two versions are available, representing the bytecode - * interpreter with and without subpixel hinting support, - * respectively. The default is subpixel support if - * TT_CONFIG_OPTION_SUBPIXEL_HINTING is defined, and no subpixel - * support otherwise (since it isn't available then). + + * Currently, three versions are available, two representing the + * bytecode interpreter with subpixel hinting support (old `Infinality' + * code and new stripped-down and higher performance `minimal' code) and + * one without, respectively. The default is subpixel support if + * TT_CONFIG_OPTION_SUBPIXEL_HINTING is defined, and no subpixel support + * otherwise (since it isn't available then). * * If subpixel hinting is on, many TrueType bytecode instructions behave * differently compared to B/W or grayscale rendering (except if `native - * ClearType' is selected by the font). The main idea is to render at a - * much increased horizontal resolution, then sampling down the created - * output to subpixel precision. However, many older fonts are not - * suited to this and must be specially taken care of by applying - * (hardcoded) font-specific tweaks. + * ClearType' is selected by the font). Microsoft's main idea is to + * render at a much increased horizontal resolution, then sampling down + * the created output to subpixel precision. However, many older fonts + * are not suited to this and must be specially taken care of by + * applying (hardcoded) tweaks in Microsoft's interpreter. * * Details on subpixel hinting and some of the necessary tweaks can be * found in Greg Hitchcock's whitepaper at - * `http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'. + * `http://www.microsoft.com/typography/cleartype/truetypecleartype.aspx'. + * Note that FreeType currently doesn't really `subpixel hint' (6x1, 6x2, + * or 6x5 supersampling) like discussed in the paper. Depending on the + * chosen interpreter, it simply ignores instructions on vertical stems + * to arrive at very similar results. * - * The following example code demonstrates how to activate subpixel + * The following example code demonstrates how to deactivate subpixel * hinting (omitting the error handling). * * { * FT_Library library; * FT_Face face; - * FT_UInt interpreter_version = TT_INTERPRETER_VERSION_38; + * FT_UInt interpreter_version = TT_INTERPRETER_VERSION_35; * * * FT_Init_FreeType( &library ); @@ -197,9 +203,19 @@ FT_BEGIN_HEADER * * TT_INTERPRETER_VERSION_38 :: * Version~38 corresponds to MS rasterizer v.1.9; it is roughly - * equivalent to the hinting provided by DirectWrite ClearType (as - * can be found, for example, in the Internet Explorer~9 running on - * Windows~7). + * equivalent to the hinting provided by DirectWrite ClearType (as can + * be found, for example, in the Internet Explorer~9 running on + * Windows~7). It is used in FreeType to select the `Infinality' + * subpixel hinting code. The code may be removed in a future + * version. + * + * TT_INTERPRETER_VERSION_40 :: + * Version~40 corresponds to MS rasterizer v.2.1; it is roughly + * equivalent to the hinting provided by DirectWrite ClearType (as can + * be found, for example, in Microsoft's Edge Browser on Windows~10). + * It is used in FreeType to select the `minimal' subpixel hinting + * code, a stripped-down and higher performance version of the + * `Infinality' code. * * @note: * This property controls the behaviour of the bytecode interpreter @@ -207,9 +223,9 @@ FT_BEGIN_HEADER * get rasterized! In particular, it does not control subpixel color * filtering. * - * If FreeType has not been compiled with configuration option - * FT_CONFIG_OPTION_SUBPIXEL_HINTING, selecting version~38 causes an - * `FT_Err_Unimplemented_Feature' error. + * If FreeType has not been compiled with the configuration option + * FT_CONFIG_OPTION_SUBPIXEL_HINTING, selecting version~38 or~40 causes + * an `FT_Err_Unimplemented_Feature' error. * * Depending on the graphics framework, Microsoft uses different * bytecode and rendering engines. As a consequence, the version @@ -290,13 +306,14 @@ FT_BEGIN_HEADER * the version~1 gasp table exclusively (like Color ClearType), while * v1.6 only respects the values of version~0 (bits 0 and~1). * - * FreeType doesn't provide all capabilities of the most recent - * ClearType incarnation, thus we identify our subpixel support as - * version~38. + * Keep in mind that the features of the above interpreter versions + * might not map exactly to FreeType features or behavior because it is + * a fundamentally different library with different internals. * */ #define TT_INTERPRETER_VERSION_35 35 #define TT_INTERPRETER_VERSION_38 38 +#define TT_INTERPRETER_VERSION_40 40 /* */ diff --git a/include/freetype/internal/tttypes.h b/include/freetype/internal/tttypes.h index 8f1a642d5..4110d5028 100644 --- a/include/freetype/internal/tttypes.h +++ b/include/freetype/internal/tttypes.h @@ -1386,12 +1386,12 @@ FT_BEGIN_HEADER FT_ULong horz_metrics_offset; FT_ULong vert_metrics_offset; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY /* since 2.4.12 */ FT_ULong sph_found_func_flags; /* special functions found */ /* for this face */ FT_Bool sph_compatibility_mode; -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ } TT_FaceRec; diff --git a/src/truetype/ttdriver.c b/src/truetype/ttdriver.c index abbd1277b..c9d4081ef 100644 --- a/src/truetype/ttdriver.c +++ b/src/truetype/ttdriver.c @@ -73,8 +73,11 @@ if ( *interpreter_version == TT_INTERPRETER_VERSION_35 -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY || *interpreter_version == TT_INTERPRETER_VERSION_38 +#endif +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + || *interpreter_version == TT_INTERPRETER_VERSION_40 #endif ) driver->interpreter_version = *interpreter_version; diff --git a/src/truetype/ttgload.c b/src/truetype/ttgload.c index 90828eaf3..b02bd103e 100644 --- a/src/truetype/ttgload.c +++ b/src/truetype/ttgload.c @@ -122,7 +122,7 @@ FT_UInt glyph_index ) { TT_Face face = loader->face; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( face ); #endif @@ -153,7 +153,7 @@ loader->top_bearing = top_bearing; loader->vadvance = advance_height; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 && loader->exec ) { @@ -165,7 +165,7 @@ /* backwards compatibility mode on and off. */ sph_set_tweaks( loader, glyph_index ); } -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ if ( !loader->linear_def ) { @@ -733,7 +733,8 @@ TT_Hint_Glyph( TT_Loader loader, FT_Bool is_composite ) { -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#if defined TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY || \ + defined TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL TT_Face face = loader->face; TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( face ); #endif @@ -816,13 +817,23 @@ #endif - /* save glyph phantom points */ - loader->pp1 = zone->cur[zone->n_points - 4]; - loader->pp2 = zone->cur[zone->n_points - 3]; - loader->pp3 = zone->cur[zone->n_points - 2]; - loader->pp4 = zone->cur[zone->n_points - 1]; +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + /* Save possibly modified glyph phantom points unless in v40 backwards */ + /* compatibility mode, where no movement on the x axis means no reason */ + /* to change bearings or advance widths. */ + if ( !( driver->interpreter_version == TT_INTERPRETER_VERSION_40 && + !loader->exec->backwards_compatibility ) ) + { +#endif + loader->pp1 = zone->cur[zone->n_points - 4]; + loader->pp2 = zone->cur[zone->n_points - 3]; + loader->pp3 = zone->cur[zone->n_points - 2]; + loader->pp4 = zone->cur[zone->n_points - 1]; +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + } +#endif -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 ) { if ( loader->exec->sph_tweak_flags & SPH_TWEAK_DEEMBOLDEN ) @@ -831,7 +842,7 @@ else if ( loader->exec->sph_tweak_flags & SPH_TWEAK_EMBOLDEN ) FT_Outline_EmboldenXY( &loader->gloader->current.outline, 24, 0 ); } -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ return FT_Err_Ok; } @@ -897,7 +908,7 @@ } { -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY TT_Face face = loader->face; TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( face ); @@ -916,7 +927,7 @@ FT_Bool do_scale = FALSE; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 ) { @@ -947,7 +958,7 @@ } else -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ { /* scale the glyph */ @@ -1078,7 +1089,7 @@ : -subglyph->transform.yx; int c = subglyph->transform.xy > 0 ? subglyph->transform.xy : -subglyph->transform.xy; - int d = subglyph->transform.yy > 0 ? subglyph->transform.yy + int d = subglyph->transform.yy > 0 ? subglyph->transform.yy : -subglyph->transform.yy; int m = a > b ? a : b; int n = c > d ? c : d; @@ -1324,7 +1335,8 @@ * (3) for everything else. * */ -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING + /* XXX merge infinality + lean datafields? */ +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY #define TT_LOADER_SET_PP( loader ) \ do \ @@ -1350,7 +1362,7 @@ (loader)->pp4.y = (loader)->pp3.y - (loader)->vadvance; \ } while ( 0 ) -#else /* !TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#else /* !TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ #define TT_LOADER_SET_PP( loader ) \ do \ @@ -1366,7 +1378,7 @@ (loader)->pp4.y = (loader)->pp3.y - (loader)->vadvance; \ } while ( 0 ) -#endif /* !TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* !TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ /* a utility function to retrieve i-th node from given FT_List */ @@ -1978,7 +1990,8 @@ FT_UInt glyph_index ) { TT_Face face = loader->face; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#if defined TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY || \ + defined TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( face ); #endif @@ -2005,11 +2018,18 @@ glyph->metrics.horiBearingY = bbox.yMax; glyph->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; - /* adjust advance width to the value contained in the hdmx table */ - /* unless FT_LOAD_COMPUTE_METRICS is set */ - if ( !face->postscript.isFixedPitch && - IS_HINTED( loader->load_flags ) && - !( loader->load_flags & FT_LOAD_COMPUTE_METRICS ) ) + /* Adjust advance width to the value contained in the hdmx table */ + /* unless FT_LOAD_COMPUTE_METRICS is set or backwards compatibility */ + /* mode of the v40 interpreter is active. See `ttinterp.h' for */ + /* details on backwards compatibility mode. */ + if ( +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + !( driver->interpreter_version == TT_INTERPRETER_VERSION_40 && + ( loader->exec && loader->exec->backwards_compatibility ) ) && +#endif + !face->postscript.isFixedPitch && + IS_HINTED( loader->load_flags ) && + !( loader->load_flags & FT_LOAD_COMPUTE_METRICS ) ) { FT_Byte* widthp; @@ -2018,7 +2038,7 @@ size->root.metrics.x_ppem, glyph_index ); -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 ) { @@ -2036,7 +2056,7 @@ } else -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ { if ( widthp ) @@ -2225,6 +2245,10 @@ #ifdef TT_USE_BYTECODE_INTERPRETER FT_Bool pedantic = FT_BOOL( load_flags & FT_LOAD_PEDANTIC ); #endif +#if defined TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY || \ + defined TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( (TT_Face)glyph->face ); +#endif face = (TT_Face)glyph->face; @@ -2238,11 +2262,13 @@ if ( IS_HINTED( load_flags ) && !glyf_table_only ) { TT_ExecContext exec; - FT_Bool grayscale; - -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING - TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( face ); + FT_Bool grayscale = TRUE; +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + FT_Bool subpixel_hinting_lean; + FT_Bool grayscale_cleartype; +#endif +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY FT_Bool subpixel_hinting = FALSE; #if 0 @@ -2254,7 +2280,7 @@ FT_Bool subpixel_positioned; FT_Bool gray_cleartype; #endif -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ FT_Bool reexecute = FALSE; @@ -2275,7 +2301,26 @@ if ( !exec ) return FT_THROW( Could_Not_Find_Context ); -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + if ( driver->interpreter_version == TT_INTERPRETER_VERSION_40 ) + { + subpixel_hinting_lean = TRUE; + grayscale_cleartype = !FT_BOOL( load_flags & + FT_LOAD_TARGET_LCD || + load_flags & + FT_LOAD_TARGET_LCD_V ); + exec->vertical_lcd_lean = FT_BOOL( load_flags & + FT_LOAD_TARGET_LCD_V ); + } + else + { + subpixel_hinting_lean = FALSE; + grayscale_cleartype = FALSE; + exec->vertical_lcd_lean = FALSE; + } +#endif + +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 ) { @@ -2332,18 +2377,23 @@ } else -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ - { +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + if ( driver->interpreter_version == TT_INTERPRETER_VERSION_40 ) + grayscale = FT_BOOL( !subpixel_hinting_lean && + FT_LOAD_TARGET_MODE( load_flags ) != + FT_RENDER_MODE_MONO ); + else +#endif grayscale = FT_BOOL( FT_LOAD_TARGET_MODE( load_flags ) != - FT_RENDER_MODE_MONO ); - } + FT_RENDER_MODE_MONO ); error = TT_Load_Context( exec, face, size ); if ( error ) return error; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 ) { @@ -2371,9 +2421,37 @@ } else -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ { + +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + if ( driver->interpreter_version == TT_INTERPRETER_VERSION_40 ) + { + /* a change from mono to subpixel rendering (and vice versa) */ + /* requires a re-execution of the CVT program */ + if ( subpixel_hinting_lean != exec->subpixel_hinting_lean ) + { + FT_TRACE4(( "tt_loader_init: subpixel hinting change," + " re-executing `prep' table\n" )); + + exec->subpixel_hinting_lean = subpixel_hinting_lean; + reexecute = TRUE; + } + + /* a change from colored to grayscale subpixel rendering (and */ + /* vice versa) requires a re-execution of the CVT program */ + if ( grayscale_cleartype != exec->grayscale_cleartype ) + { + FT_TRACE4(( "tt_loader_init: grayscale subpixel hinting change," + " re-executing `prep' table\n" )); + + exec->grayscale_cleartype = grayscale_cleartype; + reexecute = TRUE; + } + } +#endif + /* a change from mono to grayscale rendering (and vice versa) */ /* requires a re-execution of the CVT program */ if ( grayscale != exec->grayscale ) @@ -2406,10 +2484,11 @@ if ( exec->GS.instruct_control & 2 ) exec->GS = tt_default_graphics_state; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY /* check whether we have a font hinted for ClearType -- */ /* note that this flag can also be modified in a glyph's bytecode */ - if ( exec->GS.instruct_control & 4 ) + if ( driver->interpreter_version == TT_INTERPRETER_VERSION_38 && + exec->GS.instruct_control & 4 ) exec->ignore_x_mode = 0; #endif diff --git a/src/truetype/ttinterp.h b/src/truetype/ttinterp.h index e5a02b961..df7ce51f1 100644 --- a/src/truetype/ttinterp.h +++ b/src/truetype/ttinterp.h @@ -99,7 +99,7 @@ FT_BEGIN_HEADER } TT_CallRec, *TT_CallStack; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY /*************************************************************************/ /* */ @@ -138,7 +138,7 @@ FT_BEGIN_HEADER } SPH_Font_Class; -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ /*************************************************************************/ @@ -247,9 +247,135 @@ FT_BEGIN_HEADER 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; /* are we hinting for grayscale? */ + FT_Bool grayscale; /* bi-level hinting and */ + /* grayscale rendering */ -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#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? */ @@ -279,7 +405,7 @@ FT_BEGIN_HEADER FT_ULong sph_in_func_flags; /* flags to indicate if in */ /* special functions */ -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ } TT_ExecContextRec; diff --git a/src/truetype/ttobjs.c b/src/truetype/ttobjs.c index a05f2167c..ed3be2dbe 100644 --- a/src/truetype/ttobjs.c +++ b/src/truetype/ttobjs.c @@ -1287,10 +1287,12 @@ TT_Driver driver = (TT_Driver)ttdriver; -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING - driver->interpreter_version = TT_INTERPRETER_VERSION_38; -#else driver->interpreter_version = TT_INTERPRETER_VERSION_35; +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY + driver->interpreter_version = TT_INTERPRETER_VERSION_38; +#endif +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL + driver->interpreter_version = TT_INTERPRETER_VERSION_40; #endif #else /* !TT_USE_BYTECODE_INTERPRETER */ diff --git a/src/truetype/ttsubpix.c b/src/truetype/ttsubpix.c index 5a8f26231..03950960a 100644 --- a/src/truetype/ttsubpix.c +++ b/src/truetype/ttsubpix.c @@ -27,7 +27,7 @@ #include "ttsubpix.h" -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY /*************************************************************************/ /* */ @@ -1000,12 +1000,12 @@ } } -#else /* !TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#else /* !TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ /* ANSI C doesn't like empty source files */ typedef int _tt_subpix_dummy; -#endif /* !TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* !TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ /* END */ diff --git a/src/truetype/ttsubpix.h b/src/truetype/ttsubpix.h index 6313baabb..86844da66 100644 --- a/src/truetype/ttsubpix.h +++ b/src/truetype/ttsubpix.h @@ -27,7 +27,7 @@ FT_BEGIN_HEADER -#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING +#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY /*************************************************************************/ /* */ @@ -100,7 +100,7 @@ FT_BEGIN_HEADER #define SPH_OPTION_SET_COMPATIBLE_WIDTHS FALSE #define SPH_OPTION_SET_RASTERIZER_VERSION 38 -#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */ +#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */ FT_END_HEADER