ref: 816516360c7609916a889b5d0f38759e49507e7f
parent: 91015cb41d8f56777f93394f5a60914bc0c0f330
author: Alexei Podtelezhnikov <[email protected]>
date: Wed Nov 1 18:51:03 EDT 2017
[smooth] Fix complex rendering at high ppem. We used to split large glyphs into horizontal bands and continue bisecting them still horizontally if that was not enough. This is guaranteed to fail when a single scanline cannot fit into the rendering memory pool. Now we bisect the bands vertically so that the smallest unit is a column of the band height, which is guranteed to fit into memory. * src/smooth/ftgrays.c (gray_convert_glyph): Implement it.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2017-11-01 Alexei Podtelezhnikov <[email protected]>
+
+ [smooth] Fix complex rendering at high ppem.
+
+ We used to split large glyphs into horizontal bands and continue
+ bisecting them still horizontally if that was not enough. This is
+ guaranteed to fail when a single scanline cannot fit into the
+ rendering memory pool. Now we bisect the bands vertically so that
+ the smallest unit is a column of the band height, which is guranteed
+ to fit into memory.
+
+ * src/smooth/ftgrays.c (gray_convert_glyph): Implement it.
+
2017-10-20 Alexei Podtelezhnikov <[email protected]>
[smooth] Improve complex rendering at high ppem.
--- a/src/smooth/ftgrays.c
+++ b/src/smooth/ftgrays.c
@@ -1736,35 +1736,43 @@
static int
gray_convert_glyph( RAS_ARG )
{+ const TCoord yMin = ras.min_ey;
+ const TCoord yMax = ras.max_ey;
+ const TCoord xMin = ras.min_ex;
+ const TCoord xMax = ras.max_ex;
+
TCell buffer[FT_MAX_GRAY_POOL];
- TCoord band_size = FT_MAX_GRAY_POOL / 8;
- TCoord count = ras.max_ey - ras.min_ey;
- int num_bands;
- TCoord min, max, max_y;
+ size_t height = (size_t)( yMax - yMin );
+ size_t n = FT_MAX_GRAY_POOL / 8;
+ TCoord y;
TCoord bands[32]; /* enough to accommodate bisections */
TCoord* band;
/* set up vertical bands */
- if ( count > band_size )
+ if ( height > n )
{/* two divisions rounded up */
- num_bands = (int)( ( count + band_size - 1) / band_size );
- band_size = ( count + num_bands - 1 ) / num_bands;
+ n = ( height + n - 1 ) / n;
+ height = ( height + n - 1 ) / n;
}
- min = ras.min_ey;
- max_y = ras.max_ey;
+ /* memory management */
+ n = ( height * sizeof ( PCell ) + sizeof ( TCell ) - 1 ) / sizeof ( TCell );
- for ( ; min < max_y; min = max )
+ ras.cells = buffer + n;
+ ras.max_cells = (FT_PtrDist)( FT_MAX_GRAY_POOL - n );
+ ras.ycells = (PCell*)buffer;
+
+ for ( y = yMin; y < yMax; )
{- max = min + band_size;
- if ( max > max_y )
- max = max_y;
+ ras.min_ey = y;
+ y += height;
+ ras.max_ey = FT_MIN( y, yMax );
band = bands;
- band[1] = min;
- band[0] = max;
+ band[1] = xMin;
+ band[0] = xMax;
do
{@@ -1772,27 +1780,12 @@
int error;
- /* memory management */
- {- size_t ycount = (size_t)width;
- size_t cell_start;
+ FT_MEM_ZERO( ras.ycells, height * sizeof ( PCell ) );
-
- cell_start = ( ycount * sizeof ( PCell ) + sizeof ( TCell ) - 1 ) /
- sizeof ( TCell );
-
- ras.cells = buffer + cell_start;
- ras.max_cells = (FT_PtrDist)( FT_MAX_GRAY_POOL - cell_start );
- ras.num_cells = 0;
-
- ras.ycells = (PCell*)buffer;
- while ( ycount )
- ras.ycells[--ycount] = NULL;
- }
-
+ ras.num_cells = 0;
ras.invalid = 1;
- ras.min_ey = band[1];
- ras.max_ey = band[0];
+ ras.min_ex = band[1];
+ ras.max_ex = band[0];
error = gray_convert_glyph_inner( RAS_VAR );
@@ -1808,8 +1801,7 @@
/* render pool overflow; we will reduce the render band by half */
width >>= 1;
- /* This is too complex for a single scanline; there must */
- /* be some problems. */
+ /* this should never happen even with tiny rendering pool */
if ( width == 0 )
{FT_TRACE7(( "gray_convert_glyph: rotten glyph\n" ));