Details
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Bug
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Resolution: Incomplete
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P3: Somewhat important
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None
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5.15.3
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None
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Linux hostname 5.15.32-gentoo-r1-x86_64 #2 SMP Sun May 22 08:57:50 BST 2022 x86_64 AMD Phenom(tm) II X3 705e Processor AuthenticAMD GNU/Linux
gcc version 11.2.1 20220115 (Gentoo 11.2.1_p20220115 p4)
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Linux/X11
Description
QIcon::paint(QPainter *painter, const QRect &rect, Qt::Alignment alignment, ...) according to the API documentation should "paint the icon with specified alignment, required mode, and state into the rectangle rect". However, there seems to be a questionable use of QIconEngine::actualSize() which means that the specified alignment has no effect.
const QSize size = d->engine->actualSize(rect.size(), mode, state); // Get the actual size of the icon that will be painted. The default implementation // of QIconEngine::actualSize() returns the size unchanged, so 'size' is identical // to rect.size() alignment = QGuiApplicationPrivate::visualAlignment(painter->layoutDirection(), alignment); // returns the 'alignment' unchanged in LTR mode int x = rect.x(); int y = rect.y(); int w = size.width(); int h = size.height(); // 'w' and 'h' are identical to rect.size().width() and rect.size().height() respectively if ((alignment & Qt::AlignVCenter) == Qt::AlignVCenter) y += rect.size().height()/2 - h/2; else if ((alignment & Qt::AlignBottom) == Qt::AlignBottom) y += rect.size().height() - h; if ((alignment & Qt::AlignRight) == Qt::AlignRight) x += rect.size().width() - w; else if ((alignment & Qt::AlignHCenter) == Qt::AlignHCenter) x += rect.size().width()/2 - w/2; // Because they are identical as above, this code has no effect regardless of // the 'alignment' flag QRect alignedRect(x, y, w, h); // 'alignedRect' is identical to 'rect' d->engine->paint(painter, alignedRect, mode, state); // The icon pixmap is painted centered within the original 'rect'
The result is that, where the specified 'rect' is larger than a standard icon size and the 'alignment' flag is expected to align the icon within that rectangle, the alignment is ignored. This can be seen happening in https://bugs.kde.org/show_bug.cgi?id=436794.
Replacing the call to QIconEngine::actualSize() with a dummy call that simply sets a standard icon size:
//const QSize size = d->engine->actualSize(rect.size(), mode, state);
const QSize size(16, 16);
fixes the problem for this case, but is obviously not acceptable as a general solution.