ref: 596157365aeff6bb842fe741f8cf322890a952fe
parent: 119e8e41ef1c5ff00d41ac64f8b9eef3b79a1cee
author: Nikolaus Waxweiler <[email protected]>
date: Wed May 18 02:57:59 EDT 2016
[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.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,47 @@
+2016-05-17 Nikolaus Waxweiler <[email protected]>
+
+ [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 <[email protected]>
[cff] Fix matrix scaling (#47848).
--- a/devel/ftoption.h
+++ b/devel/ftoption.h
@@ -586,23 +586,53 @@
/*************************************************************************/
/* */
/* 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 @@
*/
#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
--- a/include/freetype/config/ftoption.h
+++ b/include/freetype/config/ftoption.h
@@ -586,23 +586,53 @@
/*************************************************************************/
/* */
/* 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 @@
*/
#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
--- a/include/freetype/ftcffdrv.h
+++ b/include/freetype/ftcffdrv.h
@@ -110,7 +110,7 @@
* to minimize distortion.
*
* @order:
- * hinting-engine
+ * hinting-engine[cff]
* no-stem-darkening[cff]
* darkening-parameters[cff]
*
@@ -120,7 +120,7 @@
/**************************************************************************
*
* @property:
- * hinting-engine
+ * hinting-engine[cff]
*
* @description:
* Thanks to Adobe, which contributed a new hinting (and parsing)
@@ -157,8 +157,8 @@
* 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 ::
--- a/include/freetype/ftttdrv.h
+++ b/include/freetype/ftttdrv.h
@@ -138,31 +138,37 @@
* 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 );
@@ -197,10 +203,20 @@
*
* 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
* and thus how outlines get hinted. It does *not* control how glyph
@@ -207,9 +223,9 @@
* 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 @@
* 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
/* */
--- a/include/freetype/internal/tttypes.h
+++ b/include/freetype/internal/tttypes.h
@@ -1386,12 +1386,12 @@
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;
--- 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;
--- 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;
+ FT_Bool grayscale = TRUE;
+#ifdef TT_SUPPORT_SUBPIXEL_HINTING_MINIMAL
+ FT_Bool subpixel_hinting_lean;
+ FT_Bool grayscale_cleartype;
+#endif
-#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING
- TT_Driver driver = (TT_Driver)FT_FACE_DRIVER( face );
-
+#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;
@@ -2275,8 +2301,27 @@
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 )
{subpixel_hinting = FT_BOOL( ( FT_LOAD_TARGET_MODE( load_flags ) !=
@@ -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
--- a/src/truetype/ttinterp.h
+++ b/src/truetype/ttinterp.h
@@ -99,7 +99,7 @@
} TT_CallRec, *TT_CallStack;
-#ifdef TT_CONFIG_OPTION_SUBPIXEL_HINTING
+#ifdef TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY
/*************************************************************************/
/* */
@@ -138,7 +138,7 @@
} SPH_Font_Class;
-#endif /* TT_CONFIG_OPTION_SUBPIXEL_HINTING */
+#endif /* TT_SUPPORT_SUBPIXEL_HINTING_INFINALITY */
/*************************************************************************/
@@ -247,9 +247,135 @@
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_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;
--- 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 */
--- 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 */
--- 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 @@
#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