Make the handling of the "maximum text lines" setting in Icons View more robust
Review Request #113871 - Created Nov. 15, 2013 and submitted
If the user sets a maximum number of text lines in the settings, this number is translated into a maximum height in pixels using QFontMetrics::lineSpacing(). In In KStandardItemListWidgetInformant::itemSizeHint(int, const KItemListView*), this maximum height limits the size that is reserved for the item. However, in KStandardItemListWidget::updateIconsLayoutTextCache(), the maximum height is translated back into a maximum number of lines, which limits the number of lines that are created using the QTextLayout. This approach can lead to problems if the real height of the layouted text is 1 pixel more or less than QFontMetrics::lineSpacing() times "number of lines". According to Christoph's analysis, this is the reason for the blurry icons in bug 323841. I propose to change this by not storing a "maximum height" inside the "maximum size" explicitly, but store a maximum number of lines and a maximum with (for Compact View) separately, and then use the number of lines also to calculate the required size in KStandardItemListWidgetInformant::itemSizeHint(int, const KItemListView*). This should make sure that the correct height is reserved for each item. It also makes the code a bit simpler IMHO.
I could not see any regressions. I was not able to reproduce the bug, so I cannot really verify if this patch really fixes it. @Christoph: your comment in bug 323841 sounds like you could reproduce the problem? Could you have a look at this patch? Thanks in advance!
Currently compiling, and reading the patch in the meantime. From what I see, this patch may not fix the issue, because you still use textHeight += line.height(). It might be need to changed to a final textHeight = lineCount * lineSpacing(), but before you start hacking, let me test it :)
So after playing around with some custom fonts, I could finally reproduce these bugs :) Settings (Icons view mode): Icon Size isn't relevant Width: Small Max. Lines: 2 Font: Custom Font (Font: Clean - Style: Regular - Size: 9.0) I can confirm that this patch fixes these bugs, so please ship it! I have also found two other layouting/view bugs while I was trying to reproduce these bugs, I'll have a look at them, open new bug reports and hopefully provide patches.