Edit
kc3-lang/freetype/src/autofit/afloader.c
Alexei Podtelezhnikov
- src/autofit/afloader.c
-
/**************************************************************************** * * afloader.c * * Auto-fitter glyph loading routines (body). * * Copyright (C) 2003-2024 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 = 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 */