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New upstream version 3.23.2

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Andrea Azzarone
2018-08-09 13:46:53 +03:00
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docs/reference/gtk/html/gtk-question-index.html
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@ -3,12 +3,12 @@
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Common Questions: GTK+ 3 Reference Manual</title>
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<meta name="generator" content="DocBook XSL Stylesheets Vsnapshot">
<link rel="home" href="index.html" title="GTK+ 3 Reference Manual">
<link rel="up" href="gtk.html" title="Part I. GTK+ Overview">
<link rel="prev" href="gtk-resources.html" title="Mailing lists and bug reports">
<link rel="next" href="chap-drawing-model.html" title="The GTK+ Drawing Model">
<meta name="generator" content="GTK-Doc V1.27 (XML mode)">
<meta name="generator" content="GTK-Doc V1.28 (XML mode)">
<link rel="stylesheet" href="style.css" type="text/css">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
@ -144,10 +144,19 @@ after creating it ?
<p>
If <span class="structname">GtkFoo</span> isn't a toplevel window, then
</p>
<div class="informalexample"><pre class="programlisting">
foo = gtk_foo_new ();
gtk_widget_destroy (foo);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">foo </span><span class="symbol">=</span><span class="normal"> </span><span class="function">gtk_foo_new</span><span class="normal"> </span><span class="symbol">();</span>
<span class="function"><a href="GtkWidget.html#gtk-widget-destroy">gtk_widget_destroy</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">foo</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
is a memory leak, because no one assumed the initial floating
reference. If you are using a widget and you aren't immediately
@ -159,19 +168,37 @@ To get this, you must acquire a reference to the widget and drop the
floating reference (<span class="quote">“<span class="quote">ref and sink</span>”</span> in GTK+ parlance) after
creating it:
</p>
<div class="informalexample"><pre class="programlisting">
foo = gtk_foo_new ();
g_object_ref_sink (foo);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">foo </span><span class="symbol">=</span><span class="normal"> </span><span class="function">gtk_foo_new</span><span class="normal"> </span><span class="symbol">();</span>
<span class="function">g_object_ref_sink</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">foo</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
When you want to get rid of the widget, you must call <a class="link" href="GtkWidget.html#gtk-widget-destroy" title="gtk_widget_destroy ()"><code class="function">gtk_widget_destroy()</code></a>
to break any external connections to the widget before dropping your
reference:
</p>
<div class="informalexample"><pre class="programlisting">
gtk_widget_destroy (foo);
g_object_unref (foo);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="function"><a href="GtkWidget.html#gtk-widget-destroy">gtk_widget_destroy</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">foo</span><span class="symbol">);</span>
<span class="function">g_object_unref</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">foo</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
When you immediately add a widget to a container, it takes care of
assuming the initial floating reference and you don't have to worry
@ -225,11 +252,21 @@ request that all translated strings are returned in UTF-8, then call
convenience.
Conventionally, people define macros as follows for convenience:
</p>
<div class="informalexample"><pre class="programlisting">
#define _(x) gettext (x)
#define N_(x) x
#define C_(ctx,x) pgettext (ctx, x)
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="preproc">#define</span><span class="normal"> </span><span class="function">_</span><span class="symbol">(</span><span class="normal">x</span><span class="symbol">)</span><span class="normal"> </span><span class="function">gettext</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">x</span><span class="symbol">)</span>
<span class="preproc">#define</span><span class="normal"> </span><span class="function">N_</span><span class="symbol">(</span><span class="normal">x</span><span class="symbol">)</span><span class="normal"> x</span>
<span class="preproc">#define</span><span class="normal"> </span><span class="function">C_</span><span class="symbol">(</span><span class="normal">ctx</span><span class="symbol">,</span><span class="normal">x</span><span class="symbol">)</span><span class="normal"> </span><span class="function">pgettext</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">ctx</span><span class="symbol">,</span><span class="normal"> x</span><span class="symbol">)</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
You use <code class="function">N_()</code> (N stands for no-op) to mark a string for translation in
a location where a function call to <code class="function">gettext()</code> is not allowed, such as
@ -245,21 +282,41 @@ parts of your program.
<p>
Code using these macros ends up looking like this:
</p>
<div class="informalexample"><pre class="programlisting">
#include &lt;gi18n.h&gt;
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
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7
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9
10
11
12
13</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="preproc">#include</span><span class="normal"> </span><span class="string">&lt;gi18n.h&gt;</span>
static const char *global_variable = N_("Translate this string");
<span class="keyword">static</span><span class="normal"> </span><span class="keyword">const</span><span class="normal"> </span><span class="type">char</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">global_variable </span><span class="symbol">=</span><span class="normal"> </span><span class="function">N_</span><span class="symbol">(</span><span class="string">"Translate this string"</span><span class="symbol">);</span>
static void
make_widgets (void)
{
GtkWidget *label1;
GtkWidget *label2;
<span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">make_widgets</span><span class="normal"> </span><span class="symbol">(</span><span class="type">void</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="usertype">GtkWidget</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">label1</span><span class="symbol">;</span>
<span class="normal"> </span><span class="usertype">GtkWidget</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">label2</span><span class="symbol">;</span>
<span class="normal"> label1 </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkLabel.html#gtk-label-new">gtk_label_new</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">_</span><span class="symbol">(</span><span class="string">"Another string to translate"</span><span class="symbol">));</span>
<span class="normal"> label2 </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkLabel.html#gtk-label-new">gtk_label_new</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">_</span><span class="symbol">(</span><span class="normal">global_variable</span><span class="symbol">));</span>
<span class="symbol">...</span></pre></td>
</tr>
</tbody>
</table>
</div>
label1 = gtk_label_new (_("Another string to translate"));
label2 = gtk_label_new (_(global_variable));
...
</pre></div>
<p>
</p>
<p>
@ -274,9 +331,17 @@ defined to hold your libraries translation domain,
<code class="filename">gi18n-lib.h</code> can be included to provide
the following convenience:
</p>
<div class="informalexample"><pre class="programlisting">
#define _(x) dgettext (GETTEXT_PACKAGE, x)
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="preproc">#define</span><span class="normal"> </span><span class="function">_</span><span class="symbol">(</span><span class="normal">x</span><span class="symbol">)</span><span class="normal"> </span><span class="function">dgettext</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">GETTEXT_PACKAGE</span><span class="symbol">,</span><span class="normal"> x</span><span class="symbol">)</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
</td>
@ -324,26 +389,51 @@ converted to UTF-8 before being handed over to GTK+. The following example
writes the content of a IS0-8859-1 encoded text file to
<code class="literal">stdout</code>:
</p>
<div class="informalexample"><pre class="programlisting">
gchar *text, *utf8_text;
gsize length;
GError *error = NULL;
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
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9
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13
14
15
16
17
18</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="usertype">gchar</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">text</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">utf8_text</span><span class="symbol">;</span>
<span class="usertype">gsize</span><span class="normal"> length</span><span class="symbol">;</span>
<span class="usertype">GError</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">error </span><span class="symbol">=</span><span class="normal"> NULL</span><span class="symbol">;</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="function">g_file_get_contents</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">filename</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">text</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">length</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">))</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> utf8_text </span><span class="symbol">=</span><span class="normal"> </span><span class="function">g_convert</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">text</span><span class="symbol">,</span><span class="normal"> length</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"UTF-8"</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"ISO-8859-1"</span><span class="symbol">,</span>
<span class="normal"> NULL</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">error</span><span class="symbol">);</span>
<span class="normal"> </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">error </span><span class="symbol">!=</span><span class="normal"> NULL</span><span class="symbol">)</span>
<span class="normal"> </span><span class="cbracket">{</span>
<span class="normal"> </span><span class="function">fprintf</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Couldn't convert file %s to UTF-8</span><span class="specialchar">\n</span><span class="string">"</span><span class="symbol">,</span><span class="normal"> filename</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function">g_error_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">error</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="normal"> </span><span class="keyword">else</span>
<span class="normal"> </span><span class="function">g_print</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">utf8_text</span><span class="symbol">);</span>
<span class="normal"> </span><span class="cbracket">}</span>
<span class="keyword">else</span>
<span class="normal"> </span><span class="function">fprintf</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">stderr</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"Unable to read file %s</span><span class="specialchar">\n</span><span class="string">"</span><span class="symbol">,</span><span class="normal"> filename</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
if (g_file_get_contents (filename, &amp;text, &amp;length, NULL))
{
utf8_text = g_convert (text, length, "UTF-8", "ISO-8859-1",
NULL, NULL, &amp;error);
if (error != NULL)
{
fprintf ("Couldn't convert file %s to UTF-8\n", filename);
g_error_free (error);
}
else
g_print (utf8_text);
}
else
fprintf (stderr, "Unable to read file %s\n", filename);
</pre></div>
<p>
</p>
<p>
@ -394,13 +484,25 @@ Here is an example showing the three approaches using the copyright sign
in UTF-8 by the two bytes 194, 169, or <code class="literal">"\302\251"</code> as
a string literal:
</p>
<div class="informalexample"><pre class="programlisting">
g_print ("direct UTF-8: ©");
g_print ("escaped UTF-8: \302\251");
text = g_convert ("runtime conversion: ©", -1, "ISO-8859-1", "UTF-8", NULL, NULL, NULL);
g_print(text);
g_free (text);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="function">g_print</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"direct UTF-8: ©"</span><span class="symbol">);</span>
<span class="function">g_print</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"escaped UTF-8: </span><span class="specialchar">\3</span><span class="string">02</span><span class="specialchar">\2</span><span class="string">51"</span><span class="symbol">);</span>
<span class="normal">text </span><span class="symbol">=</span><span class="normal"> </span><span class="function">g_convert</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"runtime conversion: ©"</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">-</span><span class="number">1</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"ISO-8859-1"</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"UTF-8"</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">);</span>
<span class="function">g_print</span><span class="symbol">(</span><span class="normal">text</span><span class="symbol">);</span>
<span class="function">g_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">text</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
<p>
@ -439,17 +541,35 @@ C++ will not implicitly convert an integer to an enumeration.
This comes up when using bitfields; in C you can write the following
code:
</p>
<div class="informalexample"><pre class="programlisting">
gdk_window_set_events (gdk_window,
GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="function">gdk_window_set_events</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">gdk_window</span><span class="symbol">,</span>
<span class="normal"> GDK_BUTTON_PRESS_MASK </span><span class="symbol">|</span><span class="normal"> GDK_BUTTON_RELEASE_MASK</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
while in C++ you must write:
</p>
<div class="informalexample"><pre class="programlisting">
gdk_window_set_events (gdk_window,
(GdkEventMask) GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="function">gdk_window_set_events</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">gdk_window</span><span class="symbol">,</span>
<span class="normal"> </span><span class="symbol">(</span><span class="normal">GdkEventMask</span><span class="symbol">)</span><span class="normal"> GDK_BUTTON_PRESS_MASK </span><span class="symbol">|</span><span class="normal"> GDK_BUTTON_RELEASE_MASK</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
There are very few functions that require this cast, however.
</p>
@ -510,14 +630,27 @@ How do I draw text ?
<p>
To draw a piece of text, use a Pango layout and <code class="function">pango_cairo_show_layout()</code>.
</p>
<div class="informalexample"><pre class="programlisting">
layout = gtk_widget_create_pango_layout (widget, text);
fontdesc = pango_font_description_from_string ("Luxi Mono 12");
pango_layout_set_font_description (layout, fontdesc);
pango_cairo_show_layout (cr, layout);
pango_font_description_free (fontdesc);
g_object_unref (layout);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">layout </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkWidget.html#gtk-widget-create-pango-layout">gtk_widget_create_pango_layout</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">widget</span><span class="symbol">,</span><span class="normal"> text</span><span class="symbol">);</span>
<span class="normal">fontdesc </span><span class="symbol">=</span><span class="normal"> </span><span class="function">pango_font_description_from_string</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Luxi Mono 12"</span><span class="symbol">);</span>
<span class="function">pango_layout_set_font_description</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">layout</span><span class="symbol">,</span><span class="normal"> fontdesc</span><span class="symbol">);</span>
<span class="function">pango_cairo_show_layout</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">cr</span><span class="symbol">,</span><span class="normal"> layout</span><span class="symbol">);</span>
<span class="function">pango_font_description_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">fontdesc</span><span class="symbol">);</span>
<span class="function">g_object_unref</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">layout</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
<p>
@ -542,14 +675,27 @@ How do I measure the size of a piece of text ?
To obtain the size of a piece of text, use a Pango layout and
<code class="function">pango_layout_get_pixel_size()</code>, using code like the following:
</p>
<div class="informalexample"><pre class="programlisting">
layout = gtk_widget_create_pango_layout (widget, text);
fontdesc = pango_font_description_from_string ("Luxi Mono 12");
pango_layout_set_font_description (layout, fontdesc);
pango_layout_get_pixel_size (layout, &amp;width, &amp;height);
pango_font_description_free (fontdesc);
g_object_unref (layout);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="normal">layout </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkWidget.html#gtk-widget-create-pango-layout">gtk_widget_create_pango_layout</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">widget</span><span class="symbol">,</span><span class="normal"> text</span><span class="symbol">);</span>
<span class="normal">fontdesc </span><span class="symbol">=</span><span class="normal"> </span><span class="function">pango_font_description_from_string</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"Luxi Mono 12"</span><span class="symbol">);</span>
<span class="function">pango_layout_set_font_description</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">layout</span><span class="symbol">,</span><span class="normal"> fontdesc</span><span class="symbol">);</span>
<span class="function">pango_layout_get_pixel_size</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">layout</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">width</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">height</span><span class="symbol">);</span>
<span class="function">pango_font_description_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">fontdesc</span><span class="symbol">);</span>
<span class="function">g_object_unref</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">layout</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
<p>
@ -581,9 +727,17 @@ the call away if it appears that the value is not being used.
A common workaround for this problem is to store the result in a volatile
variable, which keeps the compiler from optimizing the call away.
</p>
<div class="informalexample"><pre class="programlisting">
volatile GType dummy = GTK_TYPE_BLAH;
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">volatile</span><span class="normal"> </span><span class="usertype">GType</span><span class="normal"> dummy </span><span class="symbol">=</span><span class="normal"> GTK_TYPE_BLAH</span><span class="symbol">;</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
</td>
@ -602,22 +756,36 @@ How do I create a transparent toplevel window ?
<p>
To make a window transparent, it needs to use a visual which supports that.
This is done by getting the RGBA visual of the screen with
<a href="../html/GdkScreen.html#gdk-screen-get-rgba-visual"><code class="function">gdk_screen_get_rgba_visual()</code></a> and setting it on the window. Note that
<a href="../html/GdkScreen.html#gdk-screen-get-rgba-visual"><code class="function">gdk_screen_get_rgba_visual()</code></a> will return <code class="literal">NULL</code> if transparent windows
<code class="function">gdk_screen_get_rgba_visual()</code> and setting it on the window. Note that
<code class="function">gdk_screen_get_rgba_visual()</code> will return <code class="literal">NULL</code> if transparent windows
are not supported on the screen, you should fall back to
<a href="../html/GdkScreen.html#gdk-screen-get-system-visual"><code class="function">gdk_screen_get_system_visual()</code></a> in that case. Additionally, note that this
<code class="function">gdk_screen_get_system_visual()</code> in that case. Additionally, note that this
will change from screen to screen, so it needs to be repeated whenever the
window is moved to a different screen.
</p>
<div class="informalexample"><pre class="programlisting">
GdkVisual *visual;
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="usertype">GdkVisual</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">visual</span><span class="symbol">;</span>
visual = gdk_screen_get_rgba_visual (screen);
if (visual == NULL)
visual = gdk_screen_get_system_visual (screen);
<span class="normal">visual </span><span class="symbol">=</span><span class="normal"> </span><span class="function">gdk_screen_get_rgba_visual</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">screen</span><span class="symbol">);</span>
<span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">visual </span><span class="symbol">==</span><span class="normal"> NULL</span><span class="symbol">)</span>
<span class="normal"> visual </span><span class="symbol">=</span><span class="normal"> </span><span class="function">gdk_screen_get_system_visual</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">screen</span><span class="symbol">);</span>
<span class="function"><a href="GtkWidget.html#gtk-widget-set-visual">gtk_widget_set_visual</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">GTK_WIDGET</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">window</span><span class="symbol">),</span><span class="normal"> visual</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
gtk_widget_set_visual (GTK_WIDGET (window), visual);
</pre></div>
<p>
To fill the alpha channel on the window simply use cairos
RGBA drawing capabilities.
@ -744,21 +912,40 @@ How do I change the font of a widget?
This has several possible answers, depending on what exactly you want to
achieve. One option is <a class="link" href="GtkWidget.html#gtk-widget-override-font" title="gtk_widget_override_font ()"><code class="function">gtk_widget_override_font()</code></a>.
</p>
<div class="informalexample"><pre class="programlisting">
PangoFontDesc *font_desc = pango_font_description_new ();
pango_font_description_set_size (font_desc, 40);
gtk_widget_override_font (widget, font);
pango_font_description_free (font_desc);
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="usertype">PangoFontDesc</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">font_desc </span><span class="symbol">=</span><span class="normal"> </span><span class="function">pango_font_description_new</span><span class="normal"> </span><span class="symbol">();</span>
<span class="function">pango_font_description_set_size</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">font_desc</span><span class="symbol">,</span><span class="normal"> </span><span class="number">40</span><span class="symbol">);</span>
<span class="function"><a href="GtkWidget.html#gtk-widget-override-font">gtk_widget_override_font</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">widget</span><span class="symbol">,</span><span class="normal"> font</span><span class="symbol">);</span>
<span class="function">pango_font_description_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">font_desc</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
</p>
<p>
If you want to make the text of a label larger, you can use
<a class="link" href="GtkLabel.html#gtk-label-set-markup" title="gtk_label_set_markup ()"><code class="function">gtk_label_set_markup()</code></a>:
</p>
<div class="informalexample"><pre class="programlisting">
gtk_label_set_markup (label, "&lt;big&gt;big text&lt;/big&gt;");
</pre></div>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="function"><a href="GtkLabel.html#gtk-label-set-markup">gtk_label_set_markup</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">label</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"&lt;big&gt;big text&lt;/big&gt;"</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p>
This is preferred for many apps because it's a relative size to the
user's chosen font size. See <code class="function">g_markup_escape_text()</code> if you are
@ -816,17 +1003,33 @@ or <a class="link" href="GtkTextIter.html#gtk-text-iter-get-text" title="gtk_tex
</p>
<p>
</p>
<div class="informalexample"><pre class="programlisting">
GtkTextIter start, end;
GtkTextBuffer *buffer;
char *text;
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="usertype">GtkTextIter</span><span class="normal"> start</span><span class="symbol">,</span><span class="normal"> end</span><span class="symbol">;</span>
<span class="usertype">GtkTextBuffer</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">buffer</span><span class="symbol">;</span>
<span class="type">char</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">text</span><span class="symbol">;</span>
<span class="normal">buffer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkTextView.html#gtk-text-view-get-buffer">gtk_text_view_get_buffer</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">GTK_TEXT_VIEW</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">text_view</span><span class="symbol">));</span>
<span class="function"><a href="GtkTextBuffer.html#gtk-text-buffer-get-bounds">gtk_text_buffer_get_bounds</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">buffer</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">start</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">end</span><span class="symbol">);</span>
<span class="normal">text </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkTextIter.html#gtk-text-iter-get-text">gtk_text_iter_get_text</a></span><span class="normal"> </span><span class="symbol">(&amp;</span><span class="normal">start</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">end</span><span class="symbol">);</span>
<span class="comment">/* use text */</span>
<span class="function">g_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">text</span><span class="symbol">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view));
gtk_text_buffer_get_bounds (buffer, &amp;start, &amp;end);
text = gtk_text_iter_get_text (&amp;start, &amp;end);
/* use text */
g_free (text);
</pre></div>
<p>
</p>
</td>
@ -956,72 +1159,143 @@ from number to string yourself (with, say, <code class="function">g_strdup_print
<p>
The following example demonstrates this:
</p>
<div class="informalexample"><pre class="programlisting">
enum
{
DOUBLE_COLUMN,
N_COLUMNS
};
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="keyword">enum</span>
<span class="cbracket">{</span>
<span class="normal"> DOUBLE_COLUMN</span><span class="symbol">,</span>
<span class="normal"> N_COLUMNS</span>
<span class="cbracket">}</span><span class="symbol">;</span>
GtkListStore *mycolumns;
GtkTreeView *treeview;
<span class="usertype">GtkListStore</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">mycolumns</span><span class="symbol">;</span>
<span class="usertype">GtkTreeView</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">treeview</span><span class="symbol">;</span>
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;
<span class="type">void</span>
<span class="function">my_cell_double_to_text</span><span class="normal"> </span><span class="symbol">(</span><span class="usertype">GtkTreeViewColumn</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">tree_column</span><span class="symbol">,</span>
<span class="normal"> </span><span class="usertype">GtkCellRenderer</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">cell</span><span class="symbol">,</span>
<span class="normal"> </span><span class="usertype">GtkTreeModel</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">tree_model</span><span class="symbol">,</span>
<span class="normal"> </span><span class="usertype">GtkTreeIter</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">iter</span><span class="symbol">,</span>
<span class="normal"> </span><span class="usertype">gpointer</span><span class="normal"> data</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="usertype">GtkCellRendererText</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">cell_text </span><span class="symbol">=</span><span class="normal"> </span><span class="symbol">(</span><span class="normal"><a href="GtkCellRendererText.html#GtkCellRendererText-struct">GtkCellRendererText</a> </span><span class="symbol">*)</span><span class="normal">cell</span><span class="symbol">;</span>
<span class="normal"> </span><span class="usertype">gdouble</span><span class="normal"> d</span><span class="symbol">;</span>
<span class="normal"> </span><span class="usertype">gchar</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">text</span><span class="symbol">;</span>
/* 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);
}
<span class="normal"> </span><span class="comment">/* Get the double value from the model. */</span>
<span class="normal"> </span><span class="function"><a href="GtkTreeModel.html#gtk-tree-model-get">gtk_tree_model_get</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">tree_model</span><span class="symbol">,</span><span class="normal"> iter</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">gint</span><span class="symbol">)</span><span class="normal">data</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">d</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">-</span><span class="number">1</span><span class="symbol">);</span>
<span class="normal"> </span><span class="comment">/* Now we can format the value ourselves. */</span>
<span class="normal"> text </span><span class="symbol">=</span><span class="normal"> </span><span class="function">g_strdup_printf</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"%.2f"</span><span class="symbol">,</span><span class="normal"> d</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function">g_object_set</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">cell</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"text"</span><span class="symbol">,</span><span class="normal"> text</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function">g_free</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">text</span><span class="symbol">);</span>
<span class="cbracket">}</span>
void
set_up_new_columns (GtkTreeView *myview)
{
GtkCellRendererText *renderer;
GtkTreeViewColumn *column;
GtkListStore *mycolumns;
<span class="type">void</span>
<span class="function">set_up_new_columns</span><span class="normal"> </span><span class="symbol">(</span><span class="usertype">GtkTreeView</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">myview</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal"> </span><span class="usertype">GtkCellRendererText</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">renderer</span><span class="symbol">;</span>
<span class="normal"> </span><span class="usertype">GtkTreeViewColumn</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">column</span><span class="symbol">;</span>
<span class="normal"> </span><span class="usertype">GtkListStore</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">mycolumns</span><span class="symbol">;</span>
/* 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));
<span class="normal"> </span><span class="comment">/* Create the data model and associate it with the given TreeView */</span>
<span class="normal"> mycolumns </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkListStore.html#gtk-list-store-new">gtk_list_store_new</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">N_COLUMNS</span><span class="symbol">,</span><span class="normal"> G_TYPE_DOUBLE</span><span class="symbol">);</span>
<span class="normal"> </span><span class="function"><a href="GtkTreeView.html#gtk-tree-view-set-model">gtk_tree_view_set_model</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">myview</span><span class="symbol">,</span><span class="normal"> </span><span class="function">GTK_TREE_MODEL</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">mycolumns</span><span class="symbol">));</span>
/* Create a GtkCellRendererText */
renderer = gtk_cell_renderer_text_new ();
<span class="normal"> </span><span class="comment">/* Create a GtkCellRendererText */</span>
<span class="normal"> renderer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkCellRendererText.html#gtk-cell-renderer-text-new">gtk_cell_renderer_text_new</a></span><span class="normal"> </span><span class="symbol">();</span>
/* 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);
<span class="normal"> </span><span class="comment">/* Create a new column that has a title ("Example column"),</span>
<span class="comment"> * uses the above created renderer that will render the double</span>
<span class="comment"> * value into text from the associated model's rows.</span>
<span class="comment"> */</span>
<span class="normal"> column </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkTreeViewColumn.html#gtk-tree-view-column-new">gtk_tree_view_column_new</a></span><span class="normal"> </span><span class="symbol">();</span>
<span class="normal"> </span><span class="function"><a href="GtkTreeViewColumn.html#gtk-tree-view-column-set-title">gtk_tree_view_column_set_title</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">column</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"Example column"</span><span class="symbol">);</span>
<span class="normal"> renderer </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkCellRendererText.html#gtk-cell-renderer-text-new">gtk_cell_renderer_text_new</a></span><span class="normal"> </span><span class="symbol">();</span>
<span class="normal"> </span><span class="function"><a href="GtkTreeViewColumn.html#gtk-tree-view-column-pack-start">gtk_tree_view_column_pack_start</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">column</span><span class="symbol">,</span><span class="normal"> renderer</span><span class="symbol">,</span><span class="normal"> TRUE</span><span class="symbol">);</span>
<span class="normal"> </span><span class="comment">/* Append the new column after the GtkTreeView's previous columns. */</span>
<span class="normal"> </span><span class="function"><a href="GtkTreeView.html#gtk-tree-view-append-column">gtk_tree_view_append_column</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">GTK_TREE_VIEW</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">myview</span><span class="symbol">),</span><span class="normal"> column</span><span class="symbol">);</span>
<span class="normal"> </span><span class="comment">/* Since we created the column by hand, we can set it up for our</span>
<span class="comment"> * needs, e.g. set its minimum and maximum width, etc.</span>
<span class="comment"> */</span>
<span class="normal"> </span><span class="comment">/* Set up a custom function that will be called when the column content</span>
<span class="comment"> * is rendered. We use the func_data pointer as an index into our</span>
<span class="comment"> * model. This is convenient when using multi column lists.</span>
<span class="comment"> */</span>
<span class="normal"> </span><span class="function"><a href="GtkTreeViewColumn.html#gtk-tree-view-column-set-cell-data-func">gtk_tree_view_column_set_cell_data_func</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">column</span><span class="symbol">,</span><span class="normal"> renderer</span><span class="symbol">,</span>
<span class="normal"> my_cell_double_to_text</span><span class="symbol">,</span>
<span class="normal"> </span><span class="symbol">(</span><span class="normal">gpointer</span><span class="symbol">)</span><span class="normal">DOUBLE_COLUMN</span><span class="symbol">,</span><span class="normal"> NULL</span><span class="symbol">);</span>
<span class="cbracket">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
/* 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>
@ -1115,6 +1389,6 @@ a failed load yourself, use <code class="function">gdk_pixbuf_new_from_file()</c
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