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<tr><td colspan="5" class="shortcuts"><nobr><a href="#id3664728" class="shortcut">Top</a>
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<a href="#id3664882" class="shortcut">Description</a>
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<a href="#id3664805" class="shortcut">Object Hierarchy</a>
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<a href="#id3664859" class="shortcut">Implemented Interfaces</a></nobr></td></tr>
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<div class="refentry" lang="en">
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<a name="GtkDrawingArea"></a><div class="titlepage"></div>
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<div class="refnamediv"><table width="100%"><tr>
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<a name="id3664728"></a><span class="refentrytitle">GtkDrawingArea</span>
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<p>GtkDrawingArea — A widget for custom user interface elements</p>
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<td valign="top" align="right"></td>
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<div class="refsynopsisdiv">
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<pre class="synopsis">
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#include <gtk/gtk.h>
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<a href="GtkDrawingArea.html#GtkDrawingArea-struct">GtkDrawingArea</a>;
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<a href="GtkWidget.html" title="GtkWidget">GtkWidget</a>* <a href="GtkDrawingArea.html#gtk-drawing-area-new">gtk_drawing_area_new</a> (void);
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void <a href="GtkDrawingArea.html#gtk-drawing-area-size">gtk_drawing_area_size</a> (<a href="GtkDrawingArea.html" title="GtkDrawingArea">GtkDrawingArea</a> *darea,
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<div class="refsect1" lang="en">
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<a name="id3664805"></a><h2>Object Hierarchy</h2>
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<pre class="synopsis">
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+----GInitiallyUnowned
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+----<a href="GtkObject.html" title="GtkObject">GtkObject</a>
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+----<a href="GtkWidget.html" title="GtkWidget">GtkWidget</a>
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+----<a href="GtkCurve.html" title="GtkCurve">GtkCurve</a>
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<div class="refsect1" lang="en">
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<a name="id3664859"></a><h2>Implemented Interfaces</h2>
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GtkDrawingArea implements
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AtkImplementorIface.</p>
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<div class="refsect1" lang="en">
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<a name="id3664882"></a><h2>Description</h2>
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The <a href="GtkDrawingArea.html" title="GtkDrawingArea"><span class="type">GtkDrawingArea</span></a> widget is used for creating custom user interface
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elements. It's essentially a blank widget; you can draw on
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<code class="literal">widget->window</code>. After creating a drawing area,
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the application may want to connect to:
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<div class="itemizedlist"><ul type="disc">
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Mouse and button press signals to respond to input from
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the user. (Use <a href="GtkWidget.html#gtk-widget-add-events"><code class="function">gtk_widget_add_events()</code></a> to enable events
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you wish to receive.)
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The "realize" signal to take any necessary actions
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when the widget is instantiated on a particular display.
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(Create GDK resources in response to this signal.)
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The "configure_event" signal to take any necessary actions
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when the widget changes size.
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The "expose_event" signal to handle redrawing the
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contents of the widget.
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The following code portion demonstrates using a drawing
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area to display a circle in the normal widget foreground
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Note that GDK automatically clears the exposed area
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to the background color before sending the expose event, and
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that drawing is implicitly clipped to the exposed area.
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<div class="example">
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<a name="id3664971"></a><p class="title"><b>Example 33. Simple <span class="structname">GtkDrawingArea</span> usage.</b></p>
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<div class="example-contents"><pre class="programlisting">
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expose_event_callback (GtkWidget *widget, GdkEventExpose *event, gpointer data)
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gdk_draw_arc (widget->window,
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widget->style->fg_gc[GTK_WIDGET_STATE (widget)],
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0, 0, widget->allocation.width, widget->allocation.height,
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GtkWidget *drawing_area = gtk_drawing_area_new ();
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gtk_widget_set_size_request (drawing_area, 100, 100);
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g_signal_connect (G_OBJECT (drawing_area), "expose_event",
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G_CALLBACK (expose_event_callback), NULL);
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<br class="example-break"><p>
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Expose events are normally delivered when a drawing area first comes
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onscreen, or when it's covered by another window and then uncovered
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(exposed). You can also force an expose event by adding to the "damage
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region" of the drawing area's window; <a href="GtkWidget.html#gtk-widget-queue-draw-area"><code class="function">gtk_widget_queue_draw_area()</code></a> and
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href="../gdk/gdk-Windows.html#gdk-window-invalidate-rect"
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><code class="function">gdk_window_invalidate_rect()</code></a> are equally good ways to do this. You'll
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then get an expose event for the invalid region.
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The available routines for drawing are documented on the <a
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href="../gdk/gdk-Drawing-Primitives.html"
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>GDK Drawing Primitives</a> page.
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href="../gdk/gdk-Pixbufs.html#gdk-pixbuf-render-to-drawable"
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><code class="function">gdk_pixbuf_render_to_drawable()</code></a> for drawing a <a
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href="../gdk-pixbuf/gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"
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><span class="type">GdkPixbuf</span></a>.
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To receive mouse events on a drawing area, you will need to enable
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them with <a href="GtkWidget.html#gtk-widget-add-events"><code class="function">gtk_widget_add_events()</code></a>. To receive keyboard events, you
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will need to set the <a href="GtkWidget.html#GTK-CAN-FOCUS:CAPS"><span class="type">GTK_CAN_FOCUS</span></a> flag on the drawing area, and
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should probably draw some user-visible indication that the drawing
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area is focused. Use the <a href="GtkWidget.html#GTK-HAS-FOCUS:CAPS"><code class="function">GTK_HAS_FOCUS()</code></a> macro in your expose event
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handler to decide whether to draw the focus indicator. See
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<a href="GtkStyle.html#gtk-paint-focus"><code class="function">gtk_paint_focus()</code></a> for one way to draw focus.
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<div class="refsect1" lang="en">
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<a name="id3665120"></a><h2>Details</h2>
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<div class="refsect2" lang="en">
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<a name="id3665130"></a><h3>
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<a name="GtkDrawingArea-struct"></a>GtkDrawingArea</h3>
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<a class="indexterm" name="id3665144"></a><pre class="programlisting">typedef struct _GtkDrawingArea GtkDrawingArea;</pre>
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The <a href="GtkDrawingArea.html" title="GtkDrawingArea"><span class="type">GtkDrawingArea</span></a> struct contains private data only, and
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should be accessed using the functions below.
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<div class="refsect2" lang="en">
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<a name="id3665169"></a><h3>
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<a name="gtk-drawing-area-new"></a>gtk_drawing_area_new ()</h3>
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<a class="indexterm" name="id3665182"></a><pre class="programlisting"><a href="GtkWidget.html" title="GtkWidget">GtkWidget</a>* gtk_drawing_area_new (void);</pre>
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Creates a new drawing area.
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<div class="variablelist"><table border="0">
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<col align="left" valign="top">
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<td><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></td>
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<td>a new <a href="GtkDrawingArea.html" title="GtkDrawingArea"><span class="type">GtkDrawingArea</span></a>
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<div class="refsect2" lang="en">
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<a name="id3665227"></a><h3>
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<a name="gtk-drawing-area-size"></a>gtk_drawing_area_size ()</h3>
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<a class="indexterm" name="id3665243"></a><pre class="programlisting">void gtk_drawing_area_size (<a href="GtkDrawingArea.html" title="GtkDrawingArea">GtkDrawingArea</a> *darea,
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<div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
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<h3 class="title">Warning</h3>
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<p><code class="literal">gtk_drawing_area_size</code> is deprecated and should not be used in newly-written code.</p>
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(Use <a href="GtkWidget.html#gtk-widget-set-size-request"><code class="function">gtk_widget_set_size_request()</code></a> instead.)
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Sets the size that the drawing area will request
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in response to a "size_request" signal. The
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drawing area may actually be allocated a size
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larger than this depending on how it is packed
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within the enclosing containers.
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<div class="variablelist"><table border="0">
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<col align="left" valign="top">
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<td><span class="term"><em class="parameter"><code>darea</code></em> :</span></td>
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<td>a <a href="GtkDrawingArea.html" title="GtkDrawingArea"><span class="type">GtkDrawingArea</span></a>.
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<td><span class="term"><em class="parameter"><code>width</code></em> :</span></td>
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<td>the width to request.
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<td><span class="term"><em class="parameter"><code>height</code></em> :</span></td>
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<td>the height to request.
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<div class="refsect1" lang="en">
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<a name="id3665370"></a><h2>See Also</h2>
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Sometimes <a href="GtkImage.html" title="GtkImage"><span class="type">GtkImage</span></a> is a useful alternative to a drawing area.
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href="../gdk/gdk-Bitmaps-and-Pixmaps.html#GdkPixmap"
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><span class="type">GdkPixmap</span></a> in the <a href="GtkImage.html" title="GtkImage"><span class="type">GtkImage</span></a> and draw to the <a
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href="../gdk/gdk-Bitmaps-and-Pixmaps.html#GdkPixmap"
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><span class="type">GdkPixmap</span></a>,
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calling <a href="GtkWidget.html#gtk-widget-queue-draw"><code class="function">gtk_widget_queue_draw()</code></a> on the <a href="GtkImage.html" title="GtkImage"><span class="type">GtkImage</span></a> when you want to
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refresh to the screen.