diff options
Diffstat (limited to 'modules/freetype2/src/autofit/afloader.c')
| -rw-r--r-- | modules/freetype2/src/autofit/afloader.c | 708 |
1 files changed, 708 insertions, 0 deletions
diff --git a/modules/freetype2/src/autofit/afloader.c b/modules/freetype2/src/autofit/afloader.c new file mode 100644 index 0000000000..c8082796fe --- /dev/null +++ b/modules/freetype2/src/autofit/afloader.c @@ -0,0 +1,708 @@ +/**************************************************************************** + * + * afloader.c + * + * Auto-fitter glyph loading routines (body). + * + * Copyright (C) 2003-2023 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. + * + */ + + +#include "afglobal.h" +#include "afloader.h" +#include "afhints.h" +#include "aferrors.h" +#include "afmodule.h" + +#include <freetype/internal/ftcalc.h> + + + /* Initialize glyph loader. */ + + FT_LOCAL_DEF( void ) + af_loader_init( AF_Loader loader, + AF_GlyphHints hints ) + { + FT_ZERO( loader ); + + loader->hints = hints; + } + + + /* Reset glyph loader and compute globals if necessary. */ + + FT_LOCAL_DEF( FT_Error ) + af_loader_reset( AF_Loader loader, + AF_Module module, + FT_Face face ) + { + FT_Error error = FT_Err_Ok; + + + loader->face = face; + loader->globals = (AF_FaceGlobals)face->autohint.data; + + if ( !loader->globals ) + { + error = af_face_globals_new( face, &loader->globals, module ); + if ( !error ) + { + face->autohint.data = + (FT_Pointer)loader->globals; + face->autohint.finalizer = + (FT_Generic_Finalizer)af_face_globals_free; + } + } + + return error; + } + + + /* Finalize glyph loader. */ + + FT_LOCAL_DEF( void ) + af_loader_done( AF_Loader loader ) + { + loader->face = NULL; + loader->globals = NULL; + loader->hints = NULL; + } + + +#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 ) ) + + + static FT_Error + af_loader_embolden_glyph_in_slot( AF_Loader loader, + FT_Face face, + AF_StyleMetrics style_metrics ) + { + FT_Error error = FT_Err_Ok; + + FT_GlyphSlot slot = face->glyph; + AF_FaceGlobals globals = loader->globals; + AF_WritingSystemClass writing_system_class; + + FT_Size_Metrics* size_metrics = &face->size->internal->autohint_metrics; + + FT_Pos stdVW = 0; + FT_Pos stdHW = 0; + + FT_Bool size_changed = size_metrics->x_ppem != + globals->stem_darkening_for_ppem; + + FT_Fixed em_size = af_intToFixed( face->units_per_EM ); + + FT_Matrix scale_down_matrix = { 0x10000L, 0, 0, 0x10000L }; + + + /* Skip stem darkening for broken fonts. */ + if ( !face->units_per_EM ) + { + error = FT_ERR( Corrupted_Font_Header ); + goto Exit; + } + + /* + * We depend on the writing system (script analyzers) to supply + * standard widths for the script of the glyph we are looking at. If + * it can't deliver, stem darkening is disabled. + */ + writing_system_class = + af_writing_system_classes[style_metrics->style_class->writing_system]; + + if ( writing_system_class->style_metrics_getstdw ) + writing_system_class->style_metrics_getstdw( style_metrics, + &stdHW, + &stdVW ); + else + { + error = FT_ERR( Unimplemented_Feature ); + goto Exit; + } + + if ( size_changed || + ( stdVW > 0 && stdVW != globals->standard_vertical_width ) ) + { + FT_Fixed darken_by_font_units_x, darken_x; + + + darken_by_font_units_x = + af_loader_compute_darkening( loader, + face, + stdVW ) ; + darken_x = FT_MulFix( darken_by_font_units_x, + size_metrics->x_scale ); + + globals->standard_vertical_width = stdVW; + globals->stem_darkening_for_ppem = size_metrics->x_ppem; + globals->darken_x = af_fixedToInt( darken_x ); + } + + if ( size_changed || + ( stdHW > 0 && stdHW != globals->standard_horizontal_width ) ) + { + FT_Fixed darken_by_font_units_y, darken_y; + + + darken_by_font_units_y = + af_loader_compute_darkening( loader, + face, + stdHW ) ; + darken_y = FT_MulFix( darken_by_font_units_y, + size_metrics->y_scale ); + + globals->standard_horizontal_width = stdHW; + globals->stem_darkening_for_ppem = size_metrics->x_ppem; + globals->darken_y = af_fixedToInt( darken_y ); + + /* + * Scale outlines down on the Y-axis to keep them inside their blue + * zones. The stronger the emboldening, the stronger the downscaling + * (plus heuristical padding to prevent outlines still falling out + * their zones due to rounding). + * + * Reason: `FT_Outline_Embolden' works by shifting the rightmost + * points of stems farther to the right, and topmost points farther + * up. This positions points on the Y-axis outside their + * pre-computed blue zones and leads to distortion when applying the + * hints in the code further below. Code outside this emboldening + * block doesn't know we are presenting it with modified outlines the + * analyzer didn't see! + * + * An unfortunate side effect of downscaling is that the emboldening + * effect is slightly decreased. The loss becomes more pronounced + * versus the CFF driver at smaller sizes, e.g., at 9ppem and below. + */ + globals->scale_down_factor = + FT_DivFix( em_size - ( darken_by_font_units_y + af_intToFixed( 8 ) ), + em_size ); + } + + FT_Outline_EmboldenXY( &slot->outline, + globals->darken_x, + globals->darken_y ); + + scale_down_matrix.yy = globals->scale_down_factor; + FT_Outline_Transform( &slot->outline, &scale_down_matrix ); + + Exit: + return error; + } + + + /* Load the glyph at index into the current slot of a face and hint it. */ + + FT_LOCAL_DEF( FT_Error ) + af_loader_load_glyph( AF_Loader loader, + AF_Module module, + FT_Face face, + FT_UInt glyph_index, + FT_Int32 load_flags ) + { + FT_Error error; + + FT_Size size = face->size; + FT_Size_Internal size_internal = size->internal; + FT_GlyphSlot slot = face->glyph; + FT_Slot_Internal slot_internal = slot->internal; + FT_GlyphLoader gloader = slot_internal->loader; + + AF_GlyphHints hints = loader->hints; + AF_ScalerRec scaler; + AF_StyleMetrics style_metrics; + FT_UInt style_options = AF_STYLE_NONE_DFLT; + AF_StyleClass style_class; + AF_WritingSystemClass writing_system_class; + + + FT_ZERO( &scaler ); + + if ( !size_internal->autohint_metrics.x_scale || + size_internal->autohint_mode != FT_LOAD_TARGET_MODE( load_flags ) ) + { + /* switching between hinting modes usually means different scaling */ + /* values; this later on enforces recomputation of everything */ + /* related to the current size */ + + size_internal->autohint_mode = FT_LOAD_TARGET_MODE( load_flags ); + size_internal->autohint_metrics = size->metrics; + +#ifdef AF_CONFIG_OPTION_TT_SIZE_METRICS + { + FT_Size_Metrics* size_metrics = &size_internal->autohint_metrics; + + + /* set metrics to integer values and adjust scaling accordingly; */ + /* this is the same setup as with TrueType fonts, cf. function */ + /* `tt_size_reset' in file `ttobjs.c' */ + size_metrics->ascender = FT_PIX_ROUND( + FT_MulFix( face->ascender, + size_metrics->y_scale ) ); + size_metrics->descender = FT_PIX_ROUND( + FT_MulFix( face->descender, + size_metrics->y_scale ) ); + size_metrics->height = FT_PIX_ROUND( + FT_MulFix( face->height, + size_metrics->y_scale ) ); + + size_metrics->x_scale = FT_DivFix( size_metrics->x_ppem << 6, + face->units_per_EM ); + size_metrics->y_scale = FT_DivFix( size_metrics->y_ppem << 6, + face->units_per_EM ); + size_metrics->max_advance = FT_PIX_ROUND( + FT_MulFix( face->max_advance_width, + size_metrics->x_scale ) ); + } +#endif /* AF_CONFIG_OPTION_TT_SIZE_METRICS */ + } + + /* + * TODO: This code currently doesn't support fractional advance widths, + * i.e., placing hinted glyphs at anything other than integer + * x-positions. This is only relevant for the warper code, which + * scales and shifts glyphs to optimize blackness of stems (hinting on + * the x-axis by nature places things on pixel integers, hinting on the + * y-axis only, i.e., LIGHT mode, doesn't touch the x-axis). The delta + * values of the scaler would need to be adjusted. + */ + scaler.face = face; + scaler.x_scale = size_internal->autohint_metrics.x_scale; + scaler.x_delta = 0; + scaler.y_scale = size_internal->autohint_metrics.y_scale; + scaler.y_delta = 0; + + scaler.render_mode = FT_LOAD_TARGET_MODE( load_flags ); + scaler.flags = 0; + + /* note that the fallback style can't be changed anymore */ + /* after the first call of `af_loader_load_glyph' */ + error = af_loader_reset( loader, module, face ); + if ( error ) + goto Exit; + + /* + * Glyphs (really code points) are assigned to scripts. Script + * analysis is done lazily: For each glyph that passes through here, + * the corresponding script analyzer is called, but returns immediately + * if it has been run already. + */ + error = af_face_globals_get_metrics( loader->globals, glyph_index, + style_options, &style_metrics ); + if ( error ) + goto Exit; + + style_class = style_metrics->style_class; + writing_system_class = + af_writing_system_classes[style_class->writing_system]; + + loader->metrics = style_metrics; + + if ( writing_system_class->style_metrics_scale ) + writing_system_class->style_metrics_scale( style_metrics, &scaler ); + else + style_metrics->scaler = scaler; + + if ( writing_system_class->style_hints_init ) + { + error = writing_system_class->style_hints_init( hints, + style_metrics ); + if ( error ) + goto Exit; + } + + /* + * Do the main work of `af_loader_load_glyph'. Note that we never have + * to deal with composite glyphs as those get loaded into + * FT_GLYPH_FORMAT_OUTLINE by the recursed `FT_Load_Glyph' function. + * In the rare cases where FT_LOAD_NO_RECURSE is set, it implies + * FT_LOAD_NO_SCALE and as such the auto-hinter is never called. + */ + load_flags |= FT_LOAD_NO_SCALE | + FT_LOAD_IGNORE_TRANSFORM | + FT_LOAD_LINEAR_DESIGN; + load_flags &= ~FT_LOAD_RENDER; + + error = FT_Load_Glyph( face, glyph_index, load_flags ); + if ( error ) + goto Exit; + + /* + * Apply stem darkening (emboldening) here before hints are applied to + * the outline. Glyphs are scaled down proportionally to the + * emboldening so that curve points don't fall outside their + * precomputed blue zones. + * + * Any emboldening done by the font driver (e.g., the CFF driver) + * doesn't reach here because the autohinter loads the unprocessed + * glyphs in font units for analysis (functions `af_*_metrics_init_*') + * and then above to prepare it for the rasterizers by itself, + * independently of the font driver. So emboldening must be done here, + * within the autohinter. + * + * All glyphs to be autohinted pass through here one by one. The + * standard widths can therefore change from one glyph to the next, + * depending on what script a glyph is assigned to (each script has its + * own set of standard widths and other metrics). The darkening amount + * must therefore be recomputed for each size and + * `standard_{vertical,horizontal}_width' change. + * + * Ignore errors and carry on without emboldening. + * + */ + + /* stem darkening only works well in `light' mode */ + if ( scaler.render_mode == FT_RENDER_MODE_LIGHT && + ( !face->internal->no_stem_darkening || + ( face->internal->no_stem_darkening < 0 && + !module->no_stem_darkening ) ) ) + af_loader_embolden_glyph_in_slot( loader, face, style_metrics ); + + loader->transformed = slot_internal->glyph_transformed; + if ( loader->transformed ) + { + FT_Matrix inverse; + + + loader->trans_matrix = slot_internal->glyph_matrix; + loader->trans_delta = slot_internal->glyph_delta; + + inverse = loader->trans_matrix; + if ( !FT_Matrix_Invert( &inverse ) ) + FT_Vector_Transform( &loader->trans_delta, &inverse ); + } + + switch ( slot->format ) + { + case FT_GLYPH_FORMAT_OUTLINE: + /* translate the loaded glyph when an internal transform is needed */ + if ( loader->transformed ) + FT_Outline_Translate( &slot->outline, + loader->trans_delta.x, + loader->trans_delta.y ); + + /* compute original horizontal phantom points */ + /* (and ignore vertical ones) */ + loader->pp1.x = hints->x_delta; + loader->pp1.y = hints->y_delta; + loader->pp2.x = FT_MulFix( slot->metrics.horiAdvance, + hints->x_scale ) + hints->x_delta; + loader->pp2.y = hints->y_delta; + + /* be sure to check for spacing glyphs */ + if ( slot->outline.n_points == 0 ) + goto Hint_Metrics; + + /* now load the slot image into the auto-outline */ + /* and run the automatic hinting process */ + if ( writing_system_class->style_hints_apply ) + { + error = writing_system_class->style_hints_apply( + glyph_index, + hints, + &gloader->base.outline, + style_metrics ); + if ( error ) + goto Exit; + } + + /* we now need to adjust the metrics according to the change in */ + /* width/positioning that occurred during the hinting process */ + if ( scaler.render_mode != FT_RENDER_MODE_LIGHT ) + { + AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ]; + + + if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) ) + { + AF_Edge edge1 = axis->edges; /* leftmost edge */ + AF_Edge edge2 = edge1 + + axis->num_edges - 1; /* rightmost edge */ + + FT_Pos old_rsb = loader->pp2.x - edge2->opos; + /* loader->pp1.x is always zero at this point of time */ + FT_Pos old_lsb = edge1->opos; /* - loader->pp1.x */ + FT_Pos new_lsb = edge1->pos; + + /* remember unhinted values to later account */ + /* for rounding errors */ + FT_Pos pp1x_uh = new_lsb - old_lsb; + FT_Pos pp2x_uh = edge2->pos + old_rsb; + + + /* prefer too much space over too little space */ + /* for very small sizes */ + + if ( old_lsb < 24 ) + pp1x_uh -= 8; + + if ( old_rsb < 24 ) + pp2x_uh += 8; + + loader->pp1.x = FT_PIX_ROUND( pp1x_uh ); + loader->pp2.x = FT_PIX_ROUND( pp2x_uh ); + + if ( loader->pp1.x >= new_lsb && old_lsb > 0 ) + loader->pp1.x -= 64; + + if ( loader->pp2.x <= edge2->pos && old_rsb > 0 ) + loader->pp2.x += 64; + + slot->lsb_delta = loader->pp1.x - pp1x_uh; + slot->rsb_delta = loader->pp2.x - pp2x_uh; + } + else + { + FT_Pos pp1x = loader->pp1.x; + FT_Pos pp2x = loader->pp2.x; + + + loader->pp1.x = FT_PIX_ROUND( pp1x ); + loader->pp2.x = FT_PIX_ROUND( pp2x ); + + slot->lsb_delta = loader->pp1.x - pp1x; + slot->rsb_delta = loader->pp2.x - pp2x; + } + } + /* `light' mode uses integer advance widths */ + /* but sets `lsb_delta' and `rsb_delta' */ + else + { + FT_Pos pp1x = loader->pp1.x; + FT_Pos pp2x = loader->pp2.x; + + + loader->pp1.x = FT_PIX_ROUND( pp1x ); + loader->pp2.x = FT_PIX_ROUND( pp2x ); + + slot->lsb_delta = loader->pp1.x - pp1x; + slot->rsb_delta = loader->pp2.x - pp2x; + } + + break; + + default: + /* we don't support other formats (yet?) */ + error = FT_THROW( Unimplemented_Feature ); + } + + Hint_Metrics: + { + FT_BBox bbox; + FT_Vector vvector; + + + vvector.x = slot->metrics.vertBearingX - slot->metrics.horiBearingX; + vvector.y = slot->metrics.vertBearingY - slot->metrics.horiBearingY; + vvector.x = FT_MulFix( vvector.x, style_metrics->scaler.x_scale ); + vvector.y = FT_MulFix( vvector.y, style_metrics->scaler.y_scale ); + + /* transform the hinted outline if needed */ + if ( loader->transformed ) + { + FT_Outline_Transform( &gloader->base.outline, &loader->trans_matrix ); + FT_Vector_Transform( &vvector, &loader->trans_matrix ); + } + + /* we must translate our final outline by -pp1.x and compute */ + /* the new metrics */ + if ( loader->pp1.x ) + FT_Outline_Translate( &gloader->base.outline, -loader->pp1.x, 0 ); + + FT_Outline_Get_CBox( &gloader->base.outline, &bbox ); + + bbox.xMin = FT_PIX_FLOOR( bbox.xMin ); + bbox.yMin = FT_PIX_FLOOR( bbox.yMin ); + bbox.xMax = FT_PIX_CEIL( bbox.xMax ); + bbox.yMax = FT_PIX_CEIL( bbox.yMax ); + + slot->metrics.width = bbox.xMax - bbox.xMin; + slot->metrics.height = bbox.yMax - bbox.yMin; + slot->metrics.horiBearingX = bbox.xMin; + slot->metrics.horiBearingY = bbox.yMax; + + slot->metrics.vertBearingX = FT_PIX_FLOOR( bbox.xMin + vvector.x ); + slot->metrics.vertBearingY = FT_PIX_FLOOR( bbox.yMax + vvector.y ); + + /* for mono-width fonts (like Andale, Courier, etc.) we need */ + /* to keep the original rounded advance width; ditto for */ + /* digits if all have the same advance width */ + if ( scaler.render_mode != FT_RENDER_MODE_LIGHT && + ( FT_IS_FIXED_WIDTH( slot->face ) || + ( af_face_globals_is_digit( loader->globals, glyph_index ) && + style_metrics->digits_have_same_width ) ) ) + { + slot->metrics.horiAdvance = + FT_MulFix( slot->metrics.horiAdvance, + style_metrics->scaler.x_scale ); + + /* Set delta values to 0. Otherwise code that uses them is */ + /* going to ruin the fixed advance width. */ + slot->lsb_delta = 0; + slot->rsb_delta = 0; + } + else + { + /* non-spacing glyphs must stay as-is */ + if ( slot->metrics.horiAdvance ) + slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x; + } + + slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance, + style_metrics->scaler.y_scale ); + + slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance ); + slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance ); + + slot->format = FT_GLYPH_FORMAT_OUTLINE; + } + + Exit: + return error; + } + + + /* + * 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? + */ + FT_LOCAL_DEF( FT_Fixed ) + 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 FT_DivFix( darken_amount, em_ratio ); + } + + +/* END */ |