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class="structfield"><code>area</code></em> field to let you determine the region that you needed to redraw. In GTK+ 2.x, this field exists for compatibility and as a simple interface. However, there is also a <em class="structfield"><code>region</code></em> field which contains a fine-grained region. The <em class="structfield"><code>area</code></em> field is simply the bounding rectangle of the <em class="structfield"><code>region</code></em>. </p><p> Widgets that are very expensive to re-render, such as an image editor, may prefer to use the <em class="structfield"><code>GdkEventExpose.region</code></em> field to paint as little as possible. Widgets that just use a few drawing primitives, such as labels and buttons, may prefer to use the traditional <em class="structfield"><code>GdkEventExpose.area</code></em> field for simplicity. </p><p> Regions have an internal representation that is accessible as a list of rectangles. To turn the <em class="structfield"><code>GdkEventExpose.region</code></em> field into such a list, use <ahref="/usr/share/gtk-doc/html/gdk/gdk-Points-Rectangles-and-Regions.html#gdk-region-get-rectangles"><code class="function">gdk_region_get_rectangles()</code></a>: </p><a name="gdkregion-get-rectangles"></a><pre class="programlisting">static gbooleanmy_widget_expose_event_handler (GtkWidget *widget, GdkEventExpose *event){ GdkRectangle *rects; int n_rects; int i; gdk_region_get_rectangles (event->region, &rects, &n_rects); for (i = 0; i < n_rects; i++) { /* Repaint rectangle: (rects[i].x, rects[i].y), * (rects[i].width, rects[i].height) */ } g_free (rects); return FALSE;} </pre></div></body></html>⌨️ 快捷键说明
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