cairo-scaled-fonts.html

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

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<td>
<span class="term">double&#160;<em class="structfield"><code>height</code></em>;</span></td>
<td> the recommended vertical distance between baselines when
         setting consecutive lines of text with the font. This
         is greater than <em class="parameter"><code>ascent</code></em>+<em class="parameter"><code>descent</code></em> by a
         quantity known as the <em class="firstterm">line spacing</em>
         or <em class="firstterm">external leading</em>. When space
         is at a premium, most fonts can be set with only
         a distance of <em class="parameter"><code>ascent</code></em>+<em class="parameter"><code>descent</code></em> between lines.
</td>
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<td>
<span class="term">double&#160;<em class="structfield"><code>max_x_advance</code></em>;</span></td>
<td> the maximum distance in the X direction that
        the the origin is advanced for any glyph in the font.
</td>
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<td>
<span class="term">double&#160;<em class="structfield"><code>max_y_advance</code></em>;</span></td>
<td> the maximum distance in the Y direction that
        the the origin is advanced for any glyph in the font.
        this will be zero for normal fonts used for horizontal
        writing. (The scripts of East Asia are sometimes written
        vertically.)
</td>
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<div class="refsect2" lang="en">
<a name="id2532979"></a><h3>
<a name="cairo-scaled-font-extents"></a>cairo_scaled_font_extents ()</h3>
<a class="indexterm" name="id2532990"></a><pre class="programlisting">void        cairo_scaled_font_extents       (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font,
                                             <a href="cairo-Scaled-Fonts.html#cairo-font-extents-t">cairo_font_extents_t</a> *extents);</pre>
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<div class="refsect2" lang="en">
<a name="id2533020"></a><h3>
<a name="cairo-text-extents-t"></a>cairo_text_extents_t</h3>
<a class="indexterm" name="id2533032"></a><pre class="programlisting">typedef struct {
    double x_bearing;
    double y_bearing;
    double width;
    double height;
    double x_advance;
    double y_advance;
} cairo_text_extents_t;
</pre>
<p>
The <a href="cairo-Scaled-Fonts.html#cairo-text-extents-t"><span class="type">cairo_text_extents_t</span></a> structure stores the extents of a single
glyph or a string of glyphs in user-space coordinates. Because text
extents are in user-space coordinates, they are mostly, but not
entirely, independent of the current transformation matrix. If you call
<code class="literal">cairo_scale(cr, 2.0, 2.0)</code>, text will
be drawn twice as big, but the reported text extents will not be
doubled. They will change slightly due to hinting (so you can't
assume that metrics are independent of the transformation matrix),
but otherwise will remain unchanged.</p>
<p>

</p>
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<td>
<span class="term">double&#160;<em class="structfield"><code>x_bearing</code></em>;</span></td>
<td> the horizontal distance from the origin to the
  leftmost part of the glyphs as drawn. Positive if the
  glyphs lie entirely to the right of the origin.
</td>
</tr>
<tr>
<td>
<span class="term">double&#160;<em class="structfield"><code>y_bearing</code></em>;</span></td>
<td> the vertical distance from the origin to the
  topmost part of the glyphs as drawn. Positive only if the
  glyphs lie completely below the origin; will usually be
  negative.
</td>
</tr>
<tr>
<td>
<span class="term">double&#160;<em class="structfield"><code>width</code></em>;</span></td>
<td> width of the glyphs as drawn
</td>
</tr>
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<td>
<span class="term">double&#160;<em class="structfield"><code>height</code></em>;</span></td>
<td> height of the glyphs as drawn
</td>
</tr>
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<td>
<span class="term">double&#160;<em class="structfield"><code>x_advance</code></em>;</span></td>
<td>distance to advance in the X direction
   after drawing these glyphs
</td>
</tr>
<tr>
<td>
<span class="term">double&#160;<em class="structfield"><code>y_advance</code></em>;</span></td>
<td> distance to advance in the Y direction
  after drawing these glyphs. Will typically be zero except
  for vertical text layout as found in East-Asian languages.
</td>
</tr>
</tbody>
</table></div>
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<hr>
<div class="refsect2" lang="en">
<a name="id2581275"></a><h3>
<a name="cairo-scaled-font-text-extents"></a>cairo_scaled_font_text_extents ()</h3>
<a class="indexterm" name="id2581291"></a><pre class="programlisting">void        cairo_scaled_font_text_extents  (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font,
                                             const char *utf8,
                                             <a href="cairo-Scaled-Fonts.html#cairo-text-extents-t">cairo_text_extents_t</a> *extents);</pre>
<p>Since  1.2
</p>
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<div class="refsect2" lang="en">
<a name="id2581334"></a><h3>
<a name="cairo-scaled-font-glyph-extents"></a>cairo_scaled_font_glyph_extents ()</h3>
<a class="indexterm" name="id2581347"></a><pre class="programlisting">void        cairo_scaled_font_glyph_extents (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font,
                                             <a href="cairo-Text.html#cairo-glyph-t">cairo_glyph_t</a> *glyphs,
                                             int num_glyphs,
                                             <a href="cairo-Scaled-Fonts.html#cairo-text-extents-t">cairo_text_extents_t</a> *extents);</pre>
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<hr>
<div class="refsect2" lang="en">
<a name="id2581392"></a><h3>
<a name="cairo-scaled-font-get-font-face"></a>cairo_scaled_font_get_font_face ()</h3>
<a class="indexterm" name="id2581408"></a><pre class="programlisting"><a href="cairo-cairo-font-face-t.html#cairo-font-face-t">cairo_font_face_t</a>* cairo_scaled_font_get_font_face
                                            (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font);</pre>
<p>Since  1.2
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2581439"></a><h3>
<a name="cairo-scaled-font-get-font-options"></a>cairo_scaled_font_get_font_options ()</h3>
<a class="indexterm" name="id2581455"></a><pre class="programlisting">void        cairo_scaled_font_get_font_options
                                            (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font,
                                             <a href="cairo-Font-Options.html#cairo-font-options-t">cairo_font_options_t</a> *options);</pre>
<p>Since  1.2
</p>
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<hr>
<div class="refsect2" lang="en">
<a name="id2581491"></a><h3>
<a name="cairo-scaled-font-get-font-matrix"></a>cairo_scaled_font_get_font_matrix ()</h3>
<a class="indexterm" name="id2581507"></a><pre class="programlisting">void        cairo_scaled_font_get_font_matrix
                                            (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font,
                                             <a href="cairo-cairo-matrix-t.html#cairo-matrix-t">cairo_matrix_t</a> *font_matrix);</pre>
<p>Since  1.2
</p>
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<hr>
<div class="refsect2" lang="en">
<a name="id2581545"></a><h3>
<a name="cairo-scaled-font-get-ctm"></a>cairo_scaled_font_get_ctm ()</h3>
<a class="indexterm" name="id2581559"></a><pre class="programlisting">void        cairo_scaled_font_get_ctm       (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font,
                                             <a href="cairo-cairo-matrix-t.html#cairo-matrix-t">cairo_matrix_t</a> *ctm);</pre>
<p>Since  1.2
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2581595"></a><h3>
<a name="cairo-scaled-font-get-type"></a>cairo_scaled_font_get_type ()</h3>
<a class="indexterm" name="id2581609"></a><pre class="programlisting"><a href="cairo-cairo-font-face-t.html#cairo-font-type-t">cairo_font_type_t</a> cairo_scaled_font_get_type
                                            (<a href="cairo-Scaled-Fonts.html#cairo-scaled-font-t">cairo_scaled_font_t</a> *scaled_font);</pre>
<p>Since  1.2
</p>
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