From bf2ba9e3d43ae4dacbdd4e1ab5648cbbb81cb885 Mon Sep 17 00:00:00 2001 From: Nikolaus Waxweiler Date: Mon, 2 Nov 2015 13:12:34 +0100 Subject: [PATCH] [autofit] Implement darkening computation function. This is a crude adaption of the original `cf2_computeDarkening' function. * src/autofit/afloader.c (af_intToFixed, af_fixedToInt, af_floatToFixed): New macros, taken from `cf2fixed.h'. (af_loader_compute_darkening): New function. * src/autofit/afloader.h: Updated. --- ChangeLog | 12 ++++ src/autofit/afloader.c | 137 +++++++++++++++++++++++++++++++++++++++++ src/autofit/afloader.h | 5 ++ 3 files changed, 154 insertions(+) diff --git a/ChangeLog b/ChangeLog index c380fb570..e9aaefed4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,15 @@ +2015-11-02 Nikolaus Waxweiler + + [autofit] Implement darkening computation function. + + This is a crude adaption of the original `cf2_computeDarkening' + function. + + * src/autofit/afloader.c (af_intToFixed, af_fixedToInt, + af_floatToFixed): New macros, taken from `cf2fixed.h'. + (af_loader_compute_darkening): New function. + * src/autofit/afloader.h: Updated. + 2015-11-02 Nikolaus Waxweiler [autofit] Add functions to get standard widths for writing systems. diff --git a/src/autofit/afloader.c b/src/autofit/afloader.c index 722ffd31e..615743e00 100644 --- a/src/autofit/afloader.c +++ b/src/autofit/afloader.c @@ -405,4 +405,141 @@ } + /* + * Compute amount of font units the face should be emboldened by, in + * analogy to the CFF driver's `cf2_computeDarkening' function. See there + * for details of the algorithm. + * + * XXX: Currently a crude adaption of the original algorithm. Do better? + */ +#define af_intToFixed( i ) \ + ( (FT_Fixed)( (FT_UInt32)(i) << 16 ) ) +#define af_fixedToInt( x ) \ + ( (FT_Short)( ( (FT_UInt32)(x) + 0x8000U ) >> 16 ) ) +#define af_floatToFixed( f ) \ + ( (FT_Fixed)( (f) * 65536.0 + 0.5 ) ) + + FT_LOCAL_DEF( FT_Int32 ) + af_loader_compute_darkening( AF_Loader loader, + FT_Face face, + FT_Pos standard_width ) + { + AF_Module module = loader->globals->module; + + FT_UShort units_per_EM; + FT_Fixed ppem, em_ratio; + FT_Fixed stem_width, stem_width_per_1000, scaled_stem, darken_amount; + FT_Int log_base_2; + FT_Int x1, y1, x2, y2, x3, y3, x4, y4; + + + ppem = FT_MAX( af_intToFixed( 4 ), + af_intToFixed( face->size->metrics.x_ppem ) ); + units_per_EM = face->units_per_EM; + + em_ratio = FT_DivFix( af_intToFixed( 1000 ), + af_intToFixed ( units_per_EM ) ); + if ( em_ratio < af_floatToFixed( .01 ) ) + { + /* If something goes wrong, don't embolden. */ + return 0; + } + + x1 = module->darken_params[0]; + y1 = module->darken_params[1]; + x2 = module->darken_params[2]; + y2 = module->darken_params[3]; + x3 = module->darken_params[4]; + y3 = module->darken_params[5]; + x4 = module->darken_params[6]; + y4 = module->darken_params[7]; + + if ( standard_width <= 0 ) + { + stem_width = af_intToFixed( 75 ); /* taken from cf2font.c */ + stem_width_per_1000 = stem_width; + } + else + { + stem_width = af_intToFixed( standard_width ); + stem_width_per_1000 = FT_MulFix( stem_width, em_ratio ); + } + + log_base_2 = FT_MSB( (FT_UInt32)stem_width_per_1000 ) + + FT_MSB( (FT_UInt32)ppem ); + + if ( log_base_2 >= 46 ) + { + /* possible overflow */ + scaled_stem = af_intToFixed( x4 ); + } + else + scaled_stem = FT_MulFix( stem_width_per_1000, ppem ); + + /* now apply the darkening parameters */ + if ( scaled_stem < af_intToFixed( x1 ) ) + darken_amount = FT_DivFix( af_intToFixed( y1 ), ppem ); + + else if ( scaled_stem < af_intToFixed( x2 ) ) + { + FT_Int xdelta = x2 - x1; + FT_Int ydelta = y2 - y1; + FT_Int x = stem_width_per_1000 - + FT_DivFix( af_intToFixed( x1 ), ppem ); + + + if ( !xdelta ) + goto Try_x3; + + darken_amount = FT_MulDiv( x, ydelta, xdelta ) + + FT_DivFix( af_intToFixed( y1 ), ppem ); + } + + else if ( scaled_stem < af_intToFixed( x3 ) ) + { + Try_x3: + { + FT_Int xdelta = x3 - x2; + FT_Int ydelta = y3 - y2; + FT_Int x = stem_width_per_1000 - + FT_DivFix( af_intToFixed( x2 ), ppem ); + + + if ( !xdelta ) + goto Try_x4; + + darken_amount = FT_MulDiv( x, ydelta, xdelta ) + + FT_DivFix( af_intToFixed( y2 ), ppem ); + } + } + + else if ( scaled_stem < af_intToFixed( x4 ) ) + { + Try_x4: + { + FT_Int xdelta = x4 - x3; + FT_Int ydelta = y4 - y3; + FT_Int x = stem_width_per_1000 - + FT_DivFix( af_intToFixed( x3 ), ppem ); + + + if ( !xdelta ) + goto Use_y4; + + darken_amount = FT_MulDiv( x, ydelta, xdelta ) + + FT_DivFix( af_intToFixed( y3 ), ppem ); + } + } + + else + { + Use_y4: + darken_amount = FT_DivFix( af_intToFixed( y4 ), ppem ); + } + + /* Convert darken_amount from per 1000 em to true character space. */ + return af_fixedToInt( FT_DivFix( darken_amount, em_ratio ) ); + } + + /* END */ diff --git a/src/autofit/afloader.h b/src/autofit/afloader.h index 37cfd1423..4c4affcd2 100644 --- a/src/autofit/afloader.h +++ b/src/autofit/afloader.h @@ -75,6 +75,11 @@ FT_BEGIN_HEADER FT_UInt gindex, FT_Int32 load_flags ); + FT_LOCAL_DEF( FT_Int32 ) + af_loader_compute_darkening( AF_Loader loader, + FT_Face face, + FT_Pos standard_width ); + /* */