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[base] Overflow-resistant bitmap presetting. 

* src/base/ftobjs.c (ft_glyphslot_preset_bitmap): Implement it.
This commit is contained in:
Alexei Podtelezhnikov 2018-08-30 01:12:22 -04:00
parent 19be8620ec
commit 5d93a3fc8d
2 changed files with 45 additions and 26 deletions
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6
ChangeLog
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@ -1,3 +1,9 @@
2018-08-30 Alexei Podtelezhnikov <apodtele@gmail.com>
[base] Overflow-resistant bitmap presetting.
* src/base/ftobjs.c (ft_glyphslot_preset_bitmap): Implement it.
2018-08-29 Armin Hasitzka <prince.cherusker@gmail.com>
Fix numeric overflows.

65
src/base/ftobjs.c
View File

@ -342,6 +342,7 @@
}
/* overflow-resistant presetting of bitmap position and dimensions */
FT_BASE_DEF( void )
ft_glyphslot_preset_bitmap( FT_GlyphSlot slot,
FT_Render_Mode mode,
@ -352,7 +353,7 @@
FT_Pixel_Mode pixel_mode;
FT_BBox cbox;
FT_BBox cbox, pbox;
FT_Pos x_shift = 0;
FT_Pos y_shift = 0;
FT_Pos x_left, y_top;
@ -372,10 +373,17 @@
/* taking into account the origin shift */
FT_Outline_Get_CBox( outline, &cbox );
cbox.xMin += x_shift;
cbox.yMin += y_shift;
cbox.xMax += x_shift;
cbox.yMax += y_shift;
/* rough estimte of pixel box */
pbox.xMin = ( cbox.xMin >> 6 ) + ( x_shift >> 6 );
pbox.yMin = ( cbox.yMin >> 6 ) + ( y_shift >> 6 );
pbox.xMax = ( cbox.xMax >> 6 ) + ( x_shift >> 6 );
pbox.yMax = ( cbox.yMax >> 6 ) + ( y_shift >> 6 );
/* tiny remainder box */
cbox.xMin = ( cbox.xMin & 63 ) + ( x_shift & 63 );
cbox.yMin = ( cbox.yMin & 63 ) + ( y_shift & 63 );
cbox.xMax = ( cbox.xMax & 63 ) + ( x_shift & 63 );
cbox.yMax = ( cbox.yMax & 63 ) + ( y_shift & 63 );
switch ( mode )
{
@ -384,58 +392,63 @@
#if 1
/* undocumented but confirmed: bbox values get rounded */
/* unless the rounded box can collapse for a narrow glyph */
if ( cbox.xMax - cbox.xMin < 64 )
if ( pbox.xMax - pbox.xMin == 0 )
{
cbox.xMin = ( cbox.xMin + cbox.xMax ) / 2 - 32;
cbox.xMax = cbox.xMin + 64;
}
else if ( pbox.xMax - pbox.xMin == 1 )
{
cbox.xMin = cbox.xMax = ( cbox.xMin + cbox.xMax ) / 2;
}
cbox.xMin = FT_PIX_ROUND_LONG( cbox.xMin );
cbox.xMax = FT_PIX_ROUND_LONG( cbox.xMax );
pbox.xMin += ( cbox.xMin + 32 ) >> 6;
pbox.xMax += ( cbox.xMax + 32 ) >> 6;
if ( cbox.yMax - cbox.yMin < 64 )
if ( pbox.yMax - pbox.yMin == 0 )
{
cbox.yMin = ( cbox.yMin + cbox.yMax ) / 2 - 32;
cbox.yMax = cbox.yMin + 64;
}
else if ( pbox.yMax - pbox.yMin == 1 )
{
cbox.yMin = cbox.yMax = ( cbox.yMin + cbox.yMax ) / 2;
}
cbox.yMin = FT_PIX_ROUND_LONG( cbox.yMin );
cbox.yMax = FT_PIX_ROUND_LONG( cbox.yMax );
pbox.yMin += ( cbox.yMin + 32 ) >> 6;
pbox.yMax += ( cbox.yMax + 32 ) >> 6;
break;
#else
goto Round;
goto Adjust;
#endif
case FT_RENDER_MODE_LCD:
pixel_mode = FT_PIXEL_MODE_LCD;
ft_lcd_padding( &cbox, slot, mode );
goto Round;
goto Adjust;
case FT_RENDER_MODE_LCD_V:
pixel_mode = FT_PIXEL_MODE_LCD_V;
ft_lcd_padding( &cbox, slot, mode );
goto Round;
goto Adjust;
case FT_RENDER_MODE_NORMAL:
case FT_RENDER_MODE_LIGHT:
default:
pixel_mode = FT_PIXEL_MODE_GRAY;
Round:
cbox.xMin = FT_PIX_FLOOR( cbox.xMin );
cbox.yMin = FT_PIX_FLOOR( cbox.yMin );
cbox.xMax = FT_PIX_CEIL_LONG( cbox.xMax );
cbox.yMax = FT_PIX_CEIL_LONG( cbox.yMax );
Adjust:
pbox.xMin += cbox.xMin >> 6;
pbox.yMin += cbox.yMin >> 6;
pbox.xMax += ( cbox.xMax + 63 ) >> 6;
pbox.yMax += ( cbox.yMax + 63 ) >> 6;
}
x_shift = SUB_LONG( x_shift, cbox.xMin );
y_shift = SUB_LONG( y_shift, cbox.yMin );
x_left = pbox.xMin;
y_top = pbox.yMax;
x_left = cbox.xMin >> 6;
y_top = cbox.yMax >> 6;
width = ( (FT_ULong)cbox.xMax - (FT_ULong)cbox.xMin ) >> 6;
height = ( (FT_ULong)cbox.yMax - (FT_ULong)cbox.yMin ) >> 6;
width = pbox.xMax - pbox.xMin;
height = pbox.yMax - pbox.yMin;
switch ( pixel_mode )
{