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-rw-r--r--modules/freetype2/src/autofit/afloader.c708
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diff --git a/modules/freetype2/src/autofit/afloader.c b/modules/freetype2/src/autofit/afloader.c
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+/****************************************************************************
+ *
+ * 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 */