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<base href="https://bugs.freedesktop.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect cache algorithm in _cairo_ft_unscaled_font_set_scale"
href="https://bugs.freedesktop.org/show_bug.cgi?id=96357">96357</a>
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<th>Summary</th>
<td>Incorrect cache algorithm in _cairo_ft_unscaled_font_set_scale
</td>
</tr>
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<th>Product</th>
<td>cairo
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>All
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
</td>
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<th>Component</th>
<td>freetype font backend
</td>
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<th>Assignee</th>
<td>david@freetype.org
</td>
</tr>
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<th>Reporter</th>
<td>bulkmail@joshuagranick.com
</td>
</tr>
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<th>QA Contact</th>
<td>cairo-bugs@cairographics.org
</td>
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<div>
<pre>The `_cairo_ft_unscaled_font_set_scale` method has an incorrect method of
detecting whether it needs to call FT_Set_Char_Size to resize a glyph.
Use font APIs with different matrix values multiple text API calls with
different cairo_matrix_t values (but a constant font size) is one example that
breaks. Glyphs will be rendered with mixed sizes as a result. This also can
occur if other libraries referencing the shared FT_Face, such as using harfbuzz
together with cairo.
Commenting the following code (lines 811-816 in cairo 1.15.2) temporarily
resolves the problem:
if (unscaled->have_scale &&
scale->xx == unscaled->current_scale.xx &&
scale->yx == unscaled->current_scale.yx &&
scale->xy == unscaled->current_scale.xy &&
scale->yy == unscaled->current_scale.yy)
return CAIRO_STATUS_SUCCESS;
It would be ideal determine what is needed to fix this calculation. Thank you!</pre>
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