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Details

Type: Bug
Resolution: Done
Priority: P1: Critical
Fix Version/s: 5.0.0 RC 1
Affects Version/s: 5.0.0 Beta 1
Component/s: GUI: Font handling
Labels:
None
Environment:
Windows

Commits:
cbf476242608a575595651a2eb8c40588a4631a4

Description

A windows font GDI handle can be leaked in QWindowsFontEngine::alphaMapForGlyph. This is causing steady leak in our application. It is caused by an early function return in the code without cleanup.

BUG FOUND IN: qtbase/src/plugins/platforms/windows/qwindowsfontengine.cpp (line 1170)
CODE:

HFONT font = hfont;
    if (m_fontEngineData->clearTypeEnabled) {
        LOGFONT lf = m_logfont;
        lf.lfQuality = ANTIALIASED_QUALITY;
        font = CreateFontIndirect(&lf);
    }
    QImage::Format mask_format = QWindowsNativeImage::systemFormat();
    mask_format = QImage::Format_RGB32;

    QWindowsNativeImage *mask = drawGDIGlyph(font, glyph, 0, xform, mask_format);
    if (mask == 0)
        return QImage();
...

POSSIBLE CLEANUP SOLUTION:

HFONT font = hfont;
	bool createdFont = false;
    if (m_fontEngineData->clearTypeEnabled) {
        LOGFONT lf = m_logfont;
        lf.lfQuality = ANTIALIASED_QUALITY;
        font = CreateFontIndirect(&lf);
		createdFont = true;
    }
    QImage::Format mask_format = QWindowsNativeImage::systemFormat();
    mask_format = QImage::Format_RGB32;

    QWindowsNativeImage *mask = drawGDIGlyph(font, glyph, 0, xform, mask_format);
    if (mask == 0){
		if(createdFont){
			DeleteObject(font);
		}
        return QImage();
    }