ref: d682e510627086df010b0677003f8ac5e612e913
parent: 6bda921da0f996fc389caac77950d39cd05c855e
author: Nikolaus Waxweiler <[email protected]>
date: Mon Nov 2 04:06:36 EST 2015
[autofit] Add stem-darkening properties. Actual code follows in a later commit. * include/freetype/ftautoh.h: Document `no-stem-darkening' and `darkening-parameters'. * src/autofit/afmodule.h: New fields `no_stem_darkening' and `darken_params'. * src/autofit/afmodule.c (af_property_set, af_property_get): Handle them. (af_autofitter_init): Initialize them.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2015-11-02 Nikolaus Waxweiler <[email protected]>
+
+ [autofit] Add stem-darkening properties.
+
+ Actual code follows in a later commit.
+
+ * include/freetype/ftautoh.h: Document `no-stem-darkening' and
+ `darkening-parameters'.
+
+ * src/autofit/afmodule.h: New fields `no_stem_darkening' and
+ `darken_params'.
+
+ * src/autofit/afmodule.c (af_property_set, af_property_get):
+ Handle them.
+ (af_autofitter_init): Initialize them.
+
2015-11-02 Bungeman <[email protected]>
[ftfuzzer] Add support for multiple files (patch #8779).
--- a/include/freetype/ftautoh.h
+++ b/include/freetype/ftautoh.h
@@ -439,6 +439,58 @@
*/
+ /**************************************************************************
+ *
+ * @property:
+ * no-stem-darkening
+ *
+ * @description:
+ * *Experimental* *only*
+ *
+ * The main purpose of emboldening glyphs or `stem darkening' is to
+ * enhance readability at smaller sizes. The smaller the size, the more
+ * emboldening is applied to keep glyphs from `thinning out'. All
+ * glyphs that pass through the autohinter will be emboldened unless
+ * this property is set to TRUE.
+ *
+ * See the description of the CFF driver for algorithmic details. Total
+ * consistency with the CFF driver is currently not achieved because the
+ * emboldening method differs and glyphs must be scaled down on the
+ * Y-axis to keep outline points inside their precomputed blue zones.
+ * The smaller the size (especially 9ppem and down), the higher the loss
+ * of emboldening versus the CFF driver.
+ *
+ * *ATTENTION*: This feature has been developed with linear alpha
+ * blending and gamma correction of glyphs in mind: A rendering library
+ * must apply linear alpha blending while compositing glyph bitmaps onto
+ * a surface and then apply gamma correction to the glyph pixels to get
+ * from linear space to display space (unless the display works in
+ * linear space). Internal testing at Adobe found that a gamma
+ * correction value of 1.8 gives good results across a wide range of
+ * displays with a sRGB gamma curve or a similar one.
+ *
+ * If this is not possible, it might be better to disable stem
+ * darkening. Currently, this can only be done globally.
+ *
+ */
+
+
+ /**************************************************************************
+ *
+ * @property:
+ * darkening-parameters
+ *
+ * @description:
+ * *Experimental* *only*
+ *
+ * See the description of the CFF driver for details. This
+ * implementation appropriates the
+ * CFF_CONFIG_OPTION_DARKENING_PARAMETER_* #defines for consistency.
+ * Note the differences described in @no-stem-darkening.
+ *
+ */
+
+
/* */
--- a/src/autofit/afmodule.c
+++ b/src/autofit/afmodule.c
@@ -177,7 +177,47 @@
return error;
}
#endif /* AF_CONFIG_OPTION_USE_WARPER */
+ else if ( !ft_strcmp( property_name, "darkening-parameters" ) )
+ {+ FT_Int* darken_params = (FT_Int*)value;
+ FT_Int x1 = darken_params[0];
+ FT_Int y1 = darken_params[1];
+ FT_Int x2 = darken_params[2];
+ FT_Int y2 = darken_params[3];
+ FT_Int x3 = darken_params[4];
+ FT_Int y3 = darken_params[5];
+ FT_Int x4 = darken_params[6];
+ FT_Int y4 = darken_params[7];
+
+
+ if ( x1 < 0 || x2 < 0 || x3 < 0 || x4 < 0 ||
+ y1 < 0 || y2 < 0 || y3 < 0 || y4 < 0 ||
+ x1 > x2 || x2 > x3 || x3 > x4 ||
+ y1 > 500 || y2 > 500 || y3 > 500 || y4 > 500 )
+ return FT_THROW( Invalid_Argument );
+
+ module->darken_params[0] = x1;
+ module->darken_params[1] = y1;
+ module->darken_params[2] = x2;
+ module->darken_params[3] = y2;
+ module->darken_params[4] = x3;
+ module->darken_params[5] = y3;
+ module->darken_params[6] = x4;
+ module->darken_params[7] = y4;
+
+ return error;
+ }
+ else if ( !ft_strcmp( property_name, "no-stem-darkening" ) )
+ {+ FT_Bool* no_stem_darkening = (FT_Bool*)value;
+
+
+ module->no_stem_darkening = *no_stem_darkening;
+
+ return error;
+ }
+
FT_TRACE0(( "af_property_set: missing property `%s'\n",
property_name ));
return FT_THROW( Missing_Property );
@@ -253,7 +293,34 @@
return error;
}
#endif /* AF_CONFIG_OPTION_USE_WARPER */
+ else if ( !ft_strcmp( property_name, "darkening-parameters" ) )
+ {+ FT_Int* darken_params = module->darken_params;
+ FT_Int* val = (FT_Int*)value;
+
+ val[0] = darken_params[0];
+ val[1] = darken_params[1];
+ val[2] = darken_params[2];
+ val[3] = darken_params[3];
+ val[4] = darken_params[4];
+ val[5] = darken_params[5];
+ val[6] = darken_params[6];
+ val[7] = darken_params[7];
+
+ return error;
+ }
+ else if ( !ft_strcmp( property_name, "no-stem-darkening" ) )
+ {+ FT_Bool no_stem_darkening = module->no_stem_darkening;
+ FT_Bool* val = (FT_Bool*)value;
+
+
+ *val = no_stem_darkening;
+
+ return error;
+ }
+
FT_TRACE0(( "af_property_get: missing property `%s'\n",
property_name ));
return FT_THROW( Missing_Property );
@@ -299,11 +366,21 @@
AF_Module module = (AF_Module)ft_module;
- module->fallback_style = AF_STYLE_FALLBACK;
- module->default_script = AF_SCRIPT_DEFAULT;
+ module->fallback_style = AF_STYLE_FALLBACK;
+ module->default_script = AF_SCRIPT_DEFAULT;
#ifdef AF_CONFIG_OPTION_USE_WARPER
- module->warping = 0;
+ module->warping = 0;
#endif
+ module->no_stem_darkening = FALSE;
+
+ module->darken_params[0] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_X1;
+ module->darken_params[1] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_Y1;
+ module->darken_params[2] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_X2;
+ module->darken_params[3] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_Y2;
+ module->darken_params[4] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_X3;
+ module->darken_params[5] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_Y3;
+ module->darken_params[6] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_X4;
+ module->darken_params[7] = CFF_CONFIG_OPTION_DARKENING_PARAMETER_Y4;
return FT_Err_Ok;
}
--- a/src/autofit/afmodule.h
+++ b/src/autofit/afmodule.h
@@ -41,6 +41,8 @@
#ifdef AF_CONFIG_OPTION_USE_WARPER
FT_Bool warping;
#endif
+ FT_Bool no_stem_darkening;
+ FT_Int darken_params[8];
} AF_ModuleRec, *AF_Module;