qiurui
/
qtbase
mirror of https://github.com/qt/qtbase.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Fix log_clusters calculation in HarfBuzz-NG code path 

The old code wasn't good enough to catch all the glyph (de)composition cases,
thus leading to an assertion in QTextLayout's addNextCluster() helper.

The new code catches all the corner cases and introduces somewhat
better performance to the HB-NG shaper backend.

Change-Id: I5b6c673395a4a039dc55b200abbf74b0ba5d0829
Reviewed-by: Ahmed Saidi <justroftest@gmail.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
This commit is contained in:
Konstantin Ritt 2014-02-09 00:46:40 +02:00 committed by The Qt Project
parent 15f3191981
commit c77222c0e7
1 changed files with 16 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
src/gui/text/qtextengine.cpp
View File

@ -1105,18 +1105,6 @@ int QTextEngine::shapeTextWithHarfbuzzNG(const QScriptItem &si, const ushort *st
buffer_flags |= HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES;
hb_buffer_set_flags(buffer, hb_buffer_flags_t(buffer_flags));
const uint num_codes = hb_buffer_get_length(buffer);
{
// adjust clusters
hb_glyph_info_t *infos = hb_buffer_get_glyph_infos(buffer, 0);
const ushort *uc = string + item_pos;
for (uint i = 0, code_pos = 0; i < item_length; ++i, ++code_pos) {
if (QChar::isHighSurrogate(uc[i]) && i + 1 < item_length && QChar::isLowSurrogate(uc[i + 1]))
++i;
infos[code_pos].cluster = code_pos + item_glyph_pos;
}
}
// shape
bool shapedOk = false;
@ -1139,8 +1127,7 @@ int QTextEngine::shapeTextWithHarfbuzzNG(const QScriptItem &si, const ushort *st
if (si.analysis.bidiLevel % 2)
hb_buffer_reverse(buffer);
remaining_glyphs -= num_codes;
remaining_glyphs -= item_glyph_pos;
// ensure we have enough space for shaped glyphs and metrics
const uint num_glyphs = hb_buffer_get_length(buffer);
@ -1151,44 +1138,36 @@ int QTextEngine::shapeTextWithHarfbuzzNG(const QScriptItem &si, const ushort *st
// fetch the shaped glyphs and metrics
QGlyphLayout g = availableGlyphs(&si).mid(glyphs_shaped, num_glyphs);
if (num_glyphs > num_codes)
moveGlyphData(g.mid(num_glyphs), g.mid(num_codes), remaining_glyphs);
if (num_glyphs != item_glyph_pos)
moveGlyphData(g.mid(num_glyphs), g.mid(item_glyph_pos), remaining_glyphs);
ushort *log_clusters = logClusters(&si) + item_pos;
hb_glyph_info_t *infos = hb_buffer_get_glyph_infos(buffer, 0);
hb_glyph_position_t *positions = hb_buffer_get_glyph_positions(buffer, 0);
uint last_cluster = -1;
uint str_pos = 0;
uint last_cluster = ~0u;
uint last_glyph_pos = glyphs_shaped;
for (uint i = 0; i < num_glyphs; ++i) {
g.glyphs[i] = infos[i].codepoint;
log_clusters[i] = infos[i].cluster;
g.advances_x[i] = QFixed::fromFixed(positions[i].x_advance);
g.advances_y[i] = QFixed::fromFixed(positions[i].y_advance);
g.offsets[i].x = QFixed::fromFixed(positions[i].x_offset);
g.offsets[i].y = QFixed::fromFixed(positions[i].y_offset);
if (infos[i].cluster != last_cluster) {
last_cluster = infos[i].cluster;
uint cluster = infos[i].cluster;
if (last_cluster != cluster) {
// fix up clusters so that the cluster indices will be monotonic
// and thus we never return out-of-order indices
while (last_cluster++ < cluster && str_pos < item_length)
log_clusters[str_pos++] = last_glyph_pos;
last_glyph_pos = i + glyphs_shaped;
last_cluster = cluster;
g.attributes[i].clusterStart = true;
}
}
{
// adjust clusters
uint glyph_pos = 0;
for (uint i = 0; i < item_length; ++i) {
if (i + item_pos != infos[glyph_pos].cluster) {
for (uint j = glyph_pos + 1; j < num_glyphs; ++j) {
if (i + item_pos <= infos[j].cluster) {
if (i + item_pos == infos[j].cluster)
glyph_pos = j;
break;
}
}
}
log_clusters[i] = glyph_pos + item_glyph_pos;
}
}
while (str_pos < item_length)
log_clusters[str_pos++] = last_glyph_pos;
if (engineIdx != 0) {
for (quint32 i = 0; i < num_glyphs; ++i)