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| author | Milian Wolff <milian.wolff@kdab.com> | 2012-09-03 15:45:43 (GMT) |
|---|---|---|
| committer | Qt by Nokia <qt-info@nokia.com> | 2012-09-05 12:46:45 (GMT) |
| commit | da034a9a68ce75b7b7b48758f43f1cb69699549a (patch) | |
| tree | d8ecb20c1bb64e8d55699735f2344ffae7b559c9 /src/gui | |
| parent | 356a74042d51b9d12b892bfdfb2e59322a3f9c73 (diff) | |
| download | Qt-da034a9a68ce75b7b7b48758f43f1cb69699549a.zip Qt-da034a9a68ce75b7b7b48758f43f1cb69699549a.tar.gz Qt-da034a9a68ce75b7b7b48758f43f1cb69699549a.tar.bz2 | |
Optimize QTextEngine::findItem by using a binary search.
This is basically a backport from Qt5:
- revert the revert: 22995948cd3f46780be5d8016708aeef0cd7b066
- backport from qtbase: 487583459ea7958f24cd579888a662bcce26caf3
this fixes the off-by-one error in the binary search
Task-number: QTBUG-17209
Task-number: QTBUG-231
Change-Id: I7f62fb33cf919ecd7fb2246ae01bb23559e11bf4
Reviewed-by: Jiang Jiang <jiang.jiang@nokia.com>
Diffstat (limited to 'src/gui')
| -rw-r--r-- | src/gui/text/qtextengine.cpp | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp index 3af0355..bb453d5 100644 --- a/src/gui/text/qtextengine.cpp +++ b/src/gui/text/qtextengine.cpp @@ -1656,12 +1656,19 @@ int QTextEngine::findItem(int strPos) const { itemize(); - int item; - for (item = layoutData->items.size()-1; item > 0; --item) { - if (layoutData->items[item].position <= strPos) - break; + int left = 1; + int right = layoutData->items.size()-1; + while (left <= right) { + int middle = ((right-left)/2)+left; + if (strPos > layoutData->items[middle].position) + left = middle+1; + else if (strPos < layoutData->items[middle].position) + right = middle-1; + else { + return middle; + } } - return item; + return right; } QFixed QTextEngine::width(int from, int len) const |