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 ) );
}
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_Fixed em_ratio = FT_DivFix( af_intToFixed( 1000 ), em_size );
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_intToFixed( af_loader_compute_darkening( loader,
face,
stdVW ) );
darken_x = FT_DivFix( FT_MulFix( darken_by_font_units_x,
size_metrics->x_scale ),
em_ratio );
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_intToFixed( af_loader_compute_darkening( loader,
face,
stdHW ) );
darken_y = FT_DivFix( FT_MulFix( darken_by_font_units_y,
size_metrics->y_scale ),
em_ratio );
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;
}
static FT_Error
af_loader_load_g( AF_Loader loader,
AF_Scaler scaler,
FT_UInt glyph_index,
FT_Int32 load_flags )
{
AF_Module module = loader->globals->module;
FT_Error error;
FT_Face face = loader->face;
AF_StyleMetrics metrics = loader->metrics;
AF_GlyphHints hints = loader->hints;
FT_GlyphSlot slot = face->glyph;
FT_Slot_Internal internal = slot->internal;
FT_GlyphLoader gloader = internal->loader;
FT_Int32 flags;
flags = load_flags | FT_LOAD_LINEAR_DESIGN;
error = FT_Load_Glyph( face, glyph_index, 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.
*/
if ( !module->no_stem_darkening )
{
AF_FaceGlobals globals = loader->globals;
AF_WritingSystemClass writing_system_class;
FT_Pos stdVW = 0;
FT_Pos stdHW = 0;
FT_Bool size_changed = face->size->metrics.x_ppem
!= globals->stem_darkening_for_ppem;
FT_Fixed em_size = af_intToFixed( face->units_per_EM );
FT_Fixed em_ratio = FT_DivFix( af_intToFixed( 1000 ), em_size );
FT_Matrix scale_down_matrix = { 0x10000L, 0, 0, 0x10000L };
/* Skip stem darkening for broken fonts. */
if ( !face->units_per_EM )
goto After_Emboldening;
/*
* 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 effectively disabled.
*/
writing_system_class =
AF_WRITING_SYSTEM_CLASSES_GET[metrics->style_class->writing_system];
if ( writing_system_class->style_metrics_getstdw )
writing_system_class->style_metrics_getstdw( metrics,
&stdHW,
&stdVW );
else
goto After_Emboldening;
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_intToFixed( af_loader_compute_darkening( loader,
face,
stdVW ) );
darken_x = FT_DivFix( FT_MulFix( darken_by_font_units_x,
face->size->metrics.x_scale ),
em_ratio );
globals->standard_vertical_width = stdVW;
globals->stem_darkening_for_ppem = face->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_intToFixed( af_loader_compute_darkening( loader,
face,
stdHW ) );
darken_y = FT_DivFix( FT_MulFix( darken_by_font_units_y,
face->size->metrics.y_scale ),
em_ratio );
globals->standard_horizontal_width = stdHW;
globals->stem_darkening_for_ppem = face->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 );
}
After_Emboldening:
loader->transformed = internal->glyph_transformed;
if ( loader->transformed )
{
FT_Matrix inverse;
loader->trans_matrix = internal->glyph_matrix;
loader->trans_delta = 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 */
{
#ifdef FT_CONFIG_OPTION_PIC
AF_FaceGlobals globals = loader->globals;
#endif
AF_StyleClass style_class = metrics->style_class;
AF_WritingSystemClass writing_system_class =
AF_WRITING_SYSTEM_CLASSES_GET[style_class->writing_system];
if ( writing_system_class->style_hints_apply )
writing_system_class->style_hints_apply( glyph_index,
hints,
&gloader->base.outline,
metrics );
}
/* 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 )
{
FT_Pos old_rsb, old_lsb, new_lsb;
FT_Pos pp1x_uh, pp2x_uh;
AF_AxisHints axis = &hints->axis[AF_DIMENSION_HORZ];
AF_Edge edge1 = axis->edges; /* leftmost edge */
AF_Edge edge2 = edge1 +
axis->num_edges - 1; /* rightmost edge */
if ( axis->num_edges > 1 && AF_HINTS_DO_ADVANCE( hints ) )
{
old_rsb = loader->pp2.x - edge2->opos;
old_lsb = edge1->opos;
new_lsb = edge1->pos;
/* remember unhinted values to later account */
/* for rounding errors */
pp1x_uh = new_lsb - old_lsb;
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;
}
}
else
{
FT_Pos pp1x = loader->pp1.x;
FT_Pos pp2x = loader->pp2.x;
loader->pp1.x = FT_PIX_ROUND( pp1x + hints->xmin_delta );
loader->pp2.x = FT_PIX_ROUND( pp2x + hints->xmax_delta );
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, metrics->scaler.x_scale );
vvector.y = FT_MulFix( vvector.y, 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 );
}
#if 1
/* 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 );
#endif
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 0
if ( !FT_IS_FIXED_WIDTH( slot->face ) )
slot->metrics.horiAdvance = loader->pp2.x - loader->pp1.x;
else
slot->metrics.horiAdvance = FT_MulFix( slot->metrics.horiAdvance,
x_scale );
#else
if ( scaler->render_mode != FT_RENDER_MODE_LIGHT &&
( FT_IS_FIXED_WIDTH( slot->face ) ||
( af_face_globals_is_digit( loader->globals, glyph_index ) &&
metrics->digits_have_same_width ) ) )
{
slot->metrics.horiAdvance = FT_MulFix( slot->metrics.horiAdvance,
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;
}
#endif
slot->metrics.vertAdvance = FT_MulFix( slot->metrics.vertAdvance,
metrics->scaler.y_scale );
slot->metrics.horiAdvance = FT_PIX_ROUND( slot->metrics.horiAdvance );
slot->metrics.vertAdvance = FT_PIX_ROUND( slot->metrics.vertAdvance );
#if 0
/* reassign all outline fields except flags to protect them */
slot->outline.n_contours = internal->loader->base.outline.n_contours;
slot->outline.n_points = internal->loader->base.outline.n_points;
slot->outline.points = internal->loader->base.outline.points;
slot->outline.tags = internal->loader->base.outline.tags;
slot->outline.contours = internal->loader->base.outline.contours;
#endif
slot->format = FT_GLYPH_FORMAT_OUTLINE;
}
Exit:
return error;
}
