Commit 0417e54bec27aed35421a53271aaf0484adc892e
2022-07-22T16:22:19
[base] Build outlines in amortized constant time. When resizing the loader's points and contours, resize them to at least 1.5 times their current size. The code currently only reserves as much space as is currently required, leading to O(n^2) runtime when adding points one at a time. This change does not attempt to ever shrink the loader's point and contour storage since this was not attempted previously either. The 1.5 multiple was chosen as a trade-off between potentially unused space and the runtime. * src/base/ftgloader.c (FT_GlyphLoader_CheckPoints): Implement it. Fixes #1173.
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diff --git a/src/base/ftgloadr.c b/src/base/ftgloadr.c
index 90cc09c..b2cdabf 100644
--- a/src/base/ftgloadr.c
+++ b/src/base/ftgloadr.c
@@ -212,7 +212,7 @@
FT_Outline* current = &loader->current.outline;
FT_Bool adjust = 0;
- FT_UInt new_max, old_max;
+ FT_UInt new_max, old_max, min_new_max;
error = FT_GlyphLoader_CreateExtra( loader );
@@ -226,14 +226,19 @@
if ( new_max > old_max )
{
- new_max = FT_PAD_CEIL( new_max, 8 );
-
if ( new_max > FT_OUTLINE_POINTS_MAX )
{
error = FT_THROW( Array_Too_Large );
goto Exit;
}
+ min_new_max = old_max + ( old_max >> 1 );
+ if ( new_max < min_new_max )
+ new_max = min_new_max;
+ new_max = FT_PAD_CEIL( new_max, 8 );
+ if ( new_max > FT_OUTLINE_POINTS_MAX )
+ new_max = FT_OUTLINE_POINTS_MAX;
+
if ( FT_RENEW_ARRAY( base->points, old_max, new_max ) ||
FT_RENEW_ARRAY( base->tags, old_max, new_max ) )
goto Exit;
@@ -265,14 +270,19 @@
n_contours;
if ( new_max > old_max )
{
- new_max = FT_PAD_CEIL( new_max, 4 );
-
if ( new_max > FT_OUTLINE_CONTOURS_MAX )
{
error = FT_THROW( Array_Too_Large );
goto Exit;
}
+ min_new_max = old_max + ( old_max >> 1 );
+ if ( new_max < min_new_max )
+ new_max = min_new_max;
+ new_max = FT_PAD_CEIL( new_max, 4 );
+ if ( new_max > FT_OUTLINE_CONTOURS_MAX )
+ new_max = FT_OUTLINE_CONTOURS_MAX;
+
if ( FT_RENEW_ARRAY( base->contours, old_max, new_max ) )
goto Exit;