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More memory efficient and faster preview generation.
There is no need to allocate a very large image buffer, just enough for the thumbnail preview. For a little filtering, use the two-stage scaling. See http://labs.qt.nokia.com/2009/01/26/creating-thumbnail-preview/ for the details. This tecnique is adopted from my live preview implementation for Arora: http://ariya.ofilabs.com/2008/07/be-my-mirror-my-sword-and-shield.html.
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@ -264,16 +264,21 @@ QPixmap WebTab::renderTabPreview()
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renderWidth -= verticalScrollBarWidth;
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renderHeight -= horizontalScrollBarHeight;
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QPixmap pageImage(renderWidth, renderHeight);
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const int previewWidth = 230;
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const int previewHeight = 150;
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qreal scalingFactor = 2 * static_cast<qreal>(previewWidth) / renderWidth;
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QPixmap pageImage(2 * previewWidth, 2 * previewHeight);
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pageImage.fill(Qt::transparent);
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QPainter p(&pageImage);
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p.scale(scalingFactor, scalingFactor);
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m_view->page()->mainFrame()->render(&p, QWebFrame::ContentsLayer);
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p.end();
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page->setViewportSize(oldSize);
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return pageImage.scaled(230, 150, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
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return pageImage.scaled(previewWidth, previewHeight, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
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}
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void WebTab::showNotification(QWidget* notif)
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