New subject: [Bug 54943] The gdipdrawstring function uses the wrong width when rendering CJK fonts

16 May 2023

      https://bugs.winehq.org/show_bug.cgi?id=54943

            Bug ID: 54943
           Summary: The gdipdrawstring function uses the wrong width when
                    rendering CJK fonts
           Product: Wine
           Version: 8.6
          Hardware: x86-64
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdiplus
          Assignee: wine-bugs(a)winehq.org
          Reporter: 399989567(a)qq.com
      Distribution: ---

1. First create a LOGFONT, and make lfwidth=0, and use the font Tahoma
2. Use Font "font(hdc, &lf)" to create the font
3. Use " graphics.DrawString(string, -1, &font, { 1.0f,1.0f,0,0 }, &format,
&brush);"  to render the string
where
        WCHAR string[] = L "这里有一些错误".

You will find the Chinese font is too narrow.If you fail to render, make sure
your lfCharSet=134

ps：Don't say there is no Chinese in tahoma so there is a rendering problem, it
has nothing to do with this bug

I researched the bug and found that it is related to the implementation of
gdipdrawstring. The function finally calls GDI32_GdipDrawDriverString, which
uses SelectObject to select the font and ExtTextOutW to output the font.

So the problem can be well abstracted out, the reason for the problem is in the
last selectobject lf.lfwidth=7 (instead of the 0 you set at the beginning)

ps:7 is the result of my computer's calculation

So we can write a simple demo to reproduce this problem:
1.lf.lfWidth = 0;
2.hUnderline = CreateFontIndirectA(&lf);
3.SelectObject(hdc, hUnderline);
4.ExtTextOutW(hdc, x, y, 0, NULL, string, lstrlenW(string), NULL);

5.lf.lfWidth = 7;
6.hUnderline = CreateFontIndirectA(&lf);
7.SelectObject(hdc, hUnderline);
8.ExtTextOutW(hdc, x, y, 0, NULL, string, lstrlenW(string), NULL);

You can find that the strings in 4 are drawn at the correct width, while the
strings in 8 are too narrow; I don't know how to fix this bug, as it also
affects the calculation of the string width

I hope I can get an answer

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[Bug 54943] New: The gdipdrawstring function uses the wrong width when rendering CJK fonts

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