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QWindowsXPStyle: use QVarLengthArray instead new for memory allocation

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Avoid the creation of a temporary buffer by using QVarLengthArray
instead. Normally GetRegionData() only returns one rect (~48bytes) so it
will fit into the QVLA without a memory allocation

Change-Id: I279693e17e2f9f2c1c75504c3e5c1de3d45084ec
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
This commit is contained in:
Christian Ehrlicher 2023-02-13 18:41:56 +01:00 committed by Volker Hilsheimer
parent 9b643bc6c9
commit b528e44f5a
1 changed files with 21 additions and 21 deletions
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42
src/plugins/styles/windowsvista/qwindowsvistastyle.cpp
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@ -504,29 +504,29 @@ QRegion QWindowsVistaStylePrivate::region(QWindowsThemeData &themeData)
QRegion region;
if (success) {
const auto numBytes = GetRegionData(dest, 0, nullptr);
if (numBytes == 0)
return QRegion();
char *buf = new (std::nothrow) char[numBytes];
if (!buf)
return QRegion();
RGNDATA *rd = reinterpret_cast<RGNDATA*>(buf);
if (GetRegionData(dest, numBytes, rd) == 0) {
delete [] buf;
return QRegion();
QVarLengthArray<char> buf(256);
RGNDATA *rd = reinterpret_cast<RGNDATA *>(buf.data());
if (GetRegionData(dest, buf.size(), rd) == 0) {
const auto numBytes = GetRegionData(dest, 0, nullptr);
if (numBytes > 0) {
buf.resize(numBytes);
rd = reinterpret_cast<RGNDATA *>(buf.data());
if (GetRegionData(dest, numBytes, rd) == 0)
rd = nullptr;
} else {
rd = nullptr;
}
}
RECT *r = reinterpret_cast<RECT*>(rd->Buffer);
for (uint i = 0; i < rd->rdh.nCount; ++i) {
QRect rect;
rect.setCoords(int(r->left * factor), int(r->top * factor), int((r->right - 1) * factor), int((r->bottom - 1) * factor));
++r;
region |= rect;
if (rd) {
RECT *r = reinterpret_cast<RECT *>(rd->Buffer);
for (uint i = 0; i < rd->rdh.nCount; ++i) {
QRect rect;
rect.setCoords(int(r->left * factor), int(r->top * factor),
int((r->right - 1) * factor), int((r->bottom - 1) * factor));
++r;
region |= rect;
}
}
delete [] buf;
}
DeleteObject(hRgn);