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  1. Qt
  2. QTBUG-7768

fontMetrics.boundingRect() and drawText(boundingRect) disagree about text width metrics

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    • Icon: Bug Bug
    • Resolution: Done
    • Icon: P2: Important P2: Important
    • 6.3.0 Alpha
    • 4.6.1, 6.2.0
    • GUI: Text handling
    • None
    • 4748369eb2e458e12f5228a113b9a6dda440b24b (qt/tqtc-qtbase/dev)

      When I use

      QRect bounds = QFontMetrics.boundingRect(0, 0, maxWidth, 0, Qt::TextWordWrap, string);

      the resulting bounds rectangle is not always big enough to render the same string using the call

      drawText(bounds, Qt::TextWordWrap, string);

      because those two functions use different algorithms to calculate the font width metrics that affect the word break position.

      In the first attached screen shot, the bounding rectangle of the string "Effets de bureau" is used to draw the text, which gets then cropped to "Effets de".

      In the second screen shot, the bounding rectangle returned by QFontMetrics is enlarged by 2 pixels in width, and drawText() now renders the string
      correctly.

      This bug depends on used font, font size, server DPI, and actual text, so no test case to reproduce.

        1. fontmetrics-width-italicfont.cpp
          3 kB
        2. qtbug-7768-qt6.tgz
          1 kB
        3. Screenshot_20210514_003635.png
          Screenshot_20210514_003635.png
          98 kB
        4. Screenshot_20211014_120927.png
          Screenshot_20211014_120927.png
          92 kB
        5. text1.jpeg
          text1.jpeg
          10 kB
        6. text2.jpeg
          text2.jpeg
          11 kB
        For Gerrit Dashboard: QTBUG-7768
        # Subject Branch Project Status CR V
        376365,13 Fix inconsistencies between advanceWidth and bounding rects dev qt/qtbase Status: MERGED +2 0

            allan.jensen Allan Sandfeld Jensen
            cfeck Christoph Feck
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              Created:
              Updated:
              Resolved:

                There are no open Gerrit changes