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Fix an assertion in the BiDi algorithm 

The algorithm has been treating DirB inconsistently so far.
initScriptAnalysisAndIsolatePairs was treating it differently
than generateDireationalRuns leading to assertions.
It wasn't visible in our test data, as DirB is in almost all cases the
paragraph separator, where we split strings anyway.

Change-Id: I7dc0e7bbcf30ee84d8781ea06097da023e371f05
Fixes: QTBUG-73238
Reviewed-by: Robert Loehning <robert.loehning@qt.io>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
bb10
Lars Knoll 2019-01-25 10:17:18 +01:00
parent 4247d7c5a0
commit 79f2a9e666
2 changed files with 34 additions and 14 deletions
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42
src/gui/text/qtextengine.cpp
View File

@ -252,8 +252,6 @@ struct QBidiAlgorithm {
void initScriptAnalysisAndIsolatePairs(Vector<IsolatePair> &isolatePairs)
{
isolatePairs.append({ -1, length }); // treat the whole string as one isolate
int isolateStack[128];
int isolateLevel = 0;
// load directions of string, and determine isolate pairs
@ -304,6 +302,14 @@ struct QBidiAlgorithm {
case QChar::DirS:
case QChar::DirB:
analysis[pos].bidiFlags = QScriptAnalysis::BidiResetToParagraphLevel;
if (uc == QChar::ParagraphSeparator) {
// close all open isolates as we start a new paragraph
while (isolateLevel > 0) {
--isolateLevel;
if (isolateLevel < 128)
isolatePairs[isolateStack[isolateLevel]].end = pos;
}
}
break;
default:
break;
@ -434,21 +440,21 @@ struct QBidiAlgorithm {
doEmbed(true, true, false);
break;
case QChar::DirLRI:
++isolatePairPosition;
Q_ASSERT(isolatePairs.at(isolatePairPosition).start == i);
doEmbed(false, false, true);
++isolatePairPosition;
break;
case QChar::DirRLI:
++isolatePairPosition;
Q_ASSERT(isolatePairs.at(isolatePairPosition).start == i);
doEmbed(true, false, true);
++isolatePairPosition;
break;
case QChar::DirFSI: {
++isolatePairPosition;
const auto &pair = isolatePairs.at(isolatePairPosition);
Q_ASSERT(pair.start == i);
bool isRtl = QStringView(text + pair.start + 1, pair.end - pair.start - 1).isRightToLeft();
doEmbed(isRtl, false, true);
++isolatePairPosition;
break;
}
@ -492,16 +498,24 @@ struct QBidiAlgorithm {
analysis[i].bidiDirection = (level & 1) ? QChar::DirR : QChar::DirL;
break;
case QChar::DirB:
// paragraph separator, go down to base direction
appendRun(i - 1);
while (stack.counter > 1) {
// there might be remaining isolates on the stack that are missing a PDI. Those need to get
// a continuation indicating to take the eos from the end of the string (ie. the paragraph level)
const auto &t = stack.top();
if (t.isIsolate) {
runs[t.runBeforeIsolate].continuation = -2;
// paragraph separator, go down to base direction, reset all state
if (text[i].unicode() == QChar::ParagraphSeparator) {
appendRun(i - 1);
while (stack.counter > 1) {
// there might be remaining isolates on the stack that are missing a PDI. Those need to get
// a continuation indicating to take the eos from the end of the string (ie. the paragraph level)
const auto &t = stack.top();
if (t.isIsolate) {
runs[t.runBeforeIsolate].continuation = -2;
}
--stack.counter;
}
--stack.counter;
continuationFrom = -1;
lastRunWithContent = -1;
validIsolateCount = 0;
overflowIsolateCount = 0;
overflowEmbeddingCount = 0;
level = baseLevel;
}
break;
default:

6
tests/auto/other/qcomplextext/tst_qcomplextext.cpp
View File

@ -68,6 +68,12 @@ void tst_QComplexText::bidiReorderString_data()
<< (int) data->basicDir;
data++;
}
QString isolateAndBoundary = QString(QChar(0x2068 /* DirFSI */)) + QChar(0x1c /* DirB */) + QChar(0x2069 /* DirPDI */);
QTest::newRow( "isolateAndBoundary" )
<< QString::fromUtf8( data->logical )
<< QString::fromUtf8( data->visual )
<< (int) QChar::DirL;
}
void tst_QComplexText::bidiReorderString()