Review Request 129281: [Konsole] Render text at primary font's baseline

[Christoph Feck]

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https://git.reviewboard.kde.org/r/129281/
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(Updated Dec. 7, 2016, 7:18 p.m.)


Status
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This change has been marked as submitted.


Review request for KDE Frameworks and Konsole.


Changes
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Submitted with commit 7e2f9d839f5af447a0fc7fd178dd5d8f58e489bb by Christoph Feck to branch master.


Bugs: 371687
    http://bugs.kde.org/show_bug.cgi?id=371687


Repository: konsole


Description
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When Konsole draws a line of text, it first computes the rectangle of the line that the text covers (taking into account cells width and height), then passes this rectangle to the drawText(QRect, flags, text) call.

Qt detects if the selected font does not offer all characters in the text, and substitutes individual characters with a different font. Due to designer choices, the same font point size does not lead to same pixel height (or ascent size) in all fonts, so the substituted characters might be larger than the characters from the primary font.

Using a rectangle causes Qt to position glyphs relative to the bounding box of the text, instead of anchored to the baseline.

This patch uses a pixel position instead of a rectangle to draw the text, taking into account only the baseline of the primary font.

I have added all "frameworks" developers to increase possible test coverage.


Diffs
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  src/TerminalDisplay.cpp 39a8b84 

Diff: https://git.reviewboard.kde.org/r/129281/diff/


Testing
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On my system, lines with substituted Unicode characters are no longer shifted away from the baseline, and therefore do not appear cropped.

Further testing is needed, as there are many (equivalent, similar, or different) bug reports about font rendering on different systems, see https://bugs.kde.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=CONFIRMED&component=font&product=konsole


Thanks,

Christoph Feck

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