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<td align="left" valign="top"><p>
How do I make a text view scroll to the end of the buffer automatically ?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top">
<p>
A good way to keep a text buffer scrolled to the end is to place a
<a class="link" href="GtkTextMark.html" title="GtkTextMark">mark</a> at the end of the buffer, and
give it right gravity. The gravity has the effect that text inserted
at the mark gets inserted <span class="emphasis"><em>before</em></span>, keeping the mark
at the end. 
</p>
<p> 
To ensure that the end of the buffer remains visible, use
<a class="link" href="GtkTextView.html#gtk-text-view-scroll-to-mark"><code class="function">gtk_text_view_scroll_to_mark()</code></a> to scroll to the mark after
inserting new text.
</p>
<p>
The gtk-demo application contains an example of this technique. 
</p>
</td>
</tr>
<tr class="qandadiv"><td align="left" valign="top" colspan="2"><h5 class="title">
<a name="id3138336"></a>5. <a class="link" href="GtkTreeView.html" title="GtkTreeView"><span class="type">GtkTreeView</span></a>
</h5></td></tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138345"></a><a name="id3138347"></a><p><b>5.1.</b></p>
</td>
<td align="left" valign="top"><p>
How do I associate some data with a row in the tree?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
Remember that the <a class="link" href="GtkTreeModel.html" title="GtkTreeModel"><span class="type">GtkTreeModel</span></a> columns don't necessarily have to be displayed. 
So you can put non-user-visible data in your model just like any other data, 
and retrieve it with <a class="link" href="GtkTreeModel.html#gtk-tree-model-get"><code class="function">gtk_tree_model_get()</code></a>. See the 
<a class="link" href="TreeWidget.html" title="Tree and List Widget Overview">tree widget overview</a>.
</p></td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138382"></a><a name="id3138384"></a><p><b>5.2.</b></p>
</td>
<td align="left" valign="top"><p>
What's the <a class="link" href="GtkTreeView.html" title="GtkTreeView"><span class="type">GtkTreeView</span></a> equivalent of <a class="link" href="GtkCList.html#gtk-clist-find-row-from-data"><code class="function">gtk_clist_find_row_from_data()</code></a>?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
As there is no separate data column in the <a class="link" href="GtkTreeModel.html" title="GtkTreeModel"><span class="type">GtkTreeModel</span></a>, there's no
built in function to find the iter from data.  You can write a custom
searching function to walk the tree and find the data, or use
<a class="link" href="GtkTreeModel.html#gtk-tree-model-foreach"><code class="function">gtk_tree_model_foreach()</code></a>.
</p></td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138430"></a><a name="id3138432"></a><p><b>5.3.</b></p>
</td>
<td align="left" valign="top"><p>
How do I put an image and some text in the same column?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
You can pack more than one <a class="link" href="GtkCellRenderer.html" title="GtkCellRenderer"><span class="type">GtkCellRenderer</span></a> into a single <a class="link" href="GtkTreeViewColumn.html" title="GtkTreeViewColumn"><span class="type">GtkTreeViewColumn</span></a> 
using <a class="link" href="GtkTreeViewColumn.html#gtk-tree-view-column-pack-start"><code class="function">gtk_tree_view_column_pack_start()</code></a> or <a class="link" href="GtkTreeViewColumn.html#gtk-tree-view-column-pack-end"><code class="function">gtk_tree_view_column_pack_end()</code></a>. 
So pack both a <a class="link" href="GtkCellRendererPixbuf.html" title="GtkCellRendererPixbuf"><span class="type">GtkCellRendererPixbuf</span></a> and a <a class="link" href="GtkCellRendererText.html" title="GtkCellRendererText"><span class="type">GtkCellRendererText</span></a> into the 
column.
</p></td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138492"></a><a name="id3138494"></a><p><b>5.4.</b></p>
</td>
<td align="left" valign="top"><p>
I can set data easily on my <a class="link" href="GtkTreeStore.html" title="GtkTreeStore"><span class="type">GtkTreeStore</span></a>/<a class="link" href="GtkListStore.html" title="GtkListStore"><span class="type">GtkListStore</span></a> models using 
<a class="link" href="GtkListStore.html#gtk-list-store-set"><code class="function">gtk_list_store_set()</code></a> and <a class="link" href="GtkTreeStore.html#gtk-tree-store-set"><code class="function">gtk_tree_store_set()</code></a>, but can't read it back?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
Both the <a class="link" href="GtkTreeStore.html" title="GtkTreeStore"><span class="type">GtkTreeStore</span></a> and the <a class="link" href="GtkListStore.html" title="GtkListStore"><span class="type">GtkListStore</span></a> implement the <a class="link" href="GtkTreeModel.html" title="GtkTreeModel"><span class="type">GtkTreeModel</span></a>
interface.  Consequentially, the can use any function this interface 
implements. The easiest way to read a set of data back is to use 
<a class="link" href="GtkTreeModel.html#gtk-tree-model-get"><code class="function">gtk_tree_model_get()</code></a>.
</p></td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138565"></a><a name="id3138567"></a><p><b>5.5.</b></p>
</td>
<td align="left" valign="top"><p>
How do I change the way that numbers are formatted by <a class="link" href="GtkTreeView.html" title="GtkTreeView"><span class="type">GtkTreeView</span></a>?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top">
<p>
Use <a class="link" href="GtkTreeView.html#gtk-tree-view-insert-column-with-data-func"><code class="function">gtk_tree_view_insert_column_with_data_func()</code></a>
or <a class="link" href="GtkTreeViewColumn.html#gtk-tree-view-column-set-cell-data-func"><code class="function">gtk_tree_view_column_set_cell_data_func()</code></a> and do the conversion from i
number to string yourself (with, say, <a
href="/usr/share/gtk-doc/html/glib/glib-String-Utility-Functions.html#g-strdup-printf"
><code class="function">g_strdup_printf()</code></a>).
</p>
<p>
The following example demonstrates this:
</p>
<div class="informalexample"><pre class="programlisting">
enum 
{
  DOUBLE_COLUMN,
  N_COLUMNS
};

GtkListStore *mycolumns;
GtkTreeView *treeview;

void 
my_cell_double_to_text (GtkTreeViewColumn *tree_column,
	                GtkCellRenderer   *cell, 
                        GtkTreeModel      *tree_model,
	                GtkTreeIter       *iter, 
                        gpointer           data)
{
  GtkCellRendererText *cell_text = (GtkCellRendererText *)cell;
  gdouble d;
  gchar *text;

  /* Get the double value from the model. */
  gtk_tree_model_get (tree_model, iter, (gint)data, &amp;d, -1);
  /* Now we can format the value ourselves. */
  text = g_strdup_printf ("%.2f", d);
  g_object_set (cell, "text", text, NULL);
  g_free (text);
}

void 
set_up_new_columns (GtkTreeView *myview)
{
  GtkCellRendererText *renderer;
  GtkTreeViewColumn *column;
  GtkListStore *mycolumns;

  /* Create the data model and associate it with the given TreeView */
  mycolumns = gtk_list_store_new (N_COLUMNS, G_TYPE_DOUBLE);
  gtk_tree_view_set_model (myview, GTK_TREE_MODEL (mycolumns));

  /* Create a GtkCellRendererText */
  renderer = gtk_cell_renderer_text_new ();

  /* Create a new column that has a title ("Example column"),
   * uses the above created renderer that will render the double
   * value into text from the associated model's rows. 
   */
  column = gtk_tree_view_column_new ();
  gtk_tree_view_column_set_title  (column, "Example column");
  renderer = gtk_cell_renderer_text_new ();
  gtk_tree_view_column_pack_start (column, renderer, TRUE);

  /* Append the new column after the GtkTreeView's previous columns. */
  gtk_tree_view_append_column (GTK_TREE_VIEW (myview), column);
  /* Since we created the column by hand, we can set it up for our
   * needs, e.g. set its minimum and maximum width, etc.
   */
  /* Set up a custom function that will be called when the column content
   * is rendered. We use the func_data pointer as an index into our
   * model. This is convenient when using multi column lists. 
   */
  gtk_tree_view_column_set_cell_data_func (column, renderer,
	                                   my_cell_double_to_text, 
                                           (gpointer)DOUBLE_COLUMN, NULL);
}
</pre></div>
<p>
</p>
</td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138636"></a><a name="id3138639"></a><p><b>5.6.</b></p>
</td>
<td align="left" valign="top"><p>
How do I hide the expander arrows in my tree view ?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
Set the expander-column property of the tree view to a hidden column.
See <a class="link" href="GtkTreeView.html#gtk-tree-view-set-expander-column"><code class="function">gtk_tree_view_set_expander_column()</code></a> and <a class="link" href="GtkTreeViewColumn.html#gtk-tree-view-column-set-visible"><code class="function">gtk_tree_view_column_set_visible()</code></a>.
</p></td>
</tr>
<tr class="qandadiv"><td align="left" valign="top" colspan="2"><h5 class="title">
<a name="id3138704"></a>6. Using cairo with GTK+</h5></td></tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138709"></a><a name="id3138711"></a><p><b>6.1.</b></p>
</td>
<td align="left" valign="top"><p>
How do I use cairo to draw in GTK+ applications ?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
USe <a
href="/usr/share/gtk-doc/html/gdk/gdk-Cairo-Interaction.html#gdk-cairo-create"
><code class="function">gdk_cairo_create()</code></a> to obtain a cairo context for drawing
on a GDK window or pixmap. See <a
href="/usr/share/gtk-doc/html/gdk/gdk-Cairo-Interaction.html"
>Cairo 
Interaction</a> for some more useful functions.
</p></td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3138737"></a><a name="id3138739"></a><p><b>6.2.</b></p>
</td>
<td align="left" valign="top"><p>
I have created a cairo context with <a
href="/usr/share/gtk-doc/html/gdk/gdk-Cairo-Interaction.html#gdk-cairo-create"
><code class="function">gdk_cairo_create()</code></a>, but when I
later use it, my drawing does not show up. Why is that ?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top">
<p>
All drawing in GTK+ is normally done in an expose handler, and GTK+
creates a temporary pixmap for double-buffering the drawing. If you 
create a cairo context outside the expose handler, it is backed
by the GDK window itself, not the double-buffering pixmap. Consequently,
any drawing you do with that cairo context gets overwritten at the 
end of the expose handler, when the double-buffering pixmap is copied
back.
</p>
<p>
Possible solutions to this problem are:
</p>
<div class="itemizedlist"><ul type="disc">
<li><p>
Turn off double-buffering, with <a class="link" href="GtkWidget.html#gtk-widget-set-double-buffered"><code class="function">gtk_widget_set_double_buffered()</code></a>.
This is not ideal, since it can cause some flickering.
</p></li>
<li><p>
Create the cairo context inside the expose handler. If you do this,
<code class="function">gdk_create_cairo()</code> arranges for it to be backed by the double-buffering 
pixmap. This is the preferred solution, and is used throughout GTK+
itself.
</p></li>
</ul></div>
<p>
</p>
</td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3136473"></a><a name="id3136475"></a><p><b>6.3.</b></p>
</td>
<td align="left" valign="top"><p>
Can I improve the performance of my application by using the
Glitz backend of cairo ?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
No. The GDK X11 backend uses the cairo X backend (and the other
GDK backends use their respective native cairo backends). The
GTK+ developers believe that the best way to improving the GDK
drawing performance is to optimize the cairo X backend and the
relevant code paths in the X server that is uses (mostly the
Render extension).
</p></td>
</tr>
<tr class="question">
<td align="left" valign="top">
<a name="id3136492"></a><a name="id3136494"></a><p><b>6.4.</b></p>
</td>
<td align="left" valign="top"><p>
Can I use cairo to draw on a <a
href="/usr/share/gtk-doc/html/gdk-pixbuf/gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf"
><span class="type">GdkPixbuf</span></a> ?
</p></td>
</tr>
<tr class="answer">
<td align="left" valign="top"></td>
<td align="left" valign="top"><p>
No, at least not yet. The cairo image surface does not support the
pixel format used by GdkPixbuf. 
</p></td>
</tr>
</tbody>
</table></div>
</div>
<div class="footnotes">
<br><hr width="100" align="left">
<div class="footnote"><p><sup>[<a name="ftn.id3137402" href="#id3137402" class="para">1</a>] </sup> If the file load fails, 
<a class="link" href="GtkImage.html#gtk-image-new-from-file"><code class="function">gtk_image_new_from_file()</code></a> will display no image graphic &#8212; to detect 
a failed load yourself, use <a
href="/usr/share/gtk-doc/html/gdk-pixbuf/gdk-pixbuf-file-loading.html#gdk-pixbuf-new-from-file"
><code class="function">gdk_pixbuf_new_from_file()</code></a> directly, then 
<a class="link" href="GtkImage.html#gtk-image-new-from-pixbuf"><code class="function">gtk_image_new_from_pixbuf()</code></a>.</p></div>
</div>
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