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<h1 id="stateful-action">Stateful action</h1>
<p>Some actions have states. The typical values of states is boolean or
string. However, other types of states are possible if you want.</p>
<p>There’s an example <code>menu2_int16.c</code> in the
<code>src/men</code> directory. It behaves the same as
<code>menu2.c</code>. But it uses gint16 type of states instead of
string type.</p>
<p>Actions which have states are called stateful.</p>
<h2 id="stateful-action-without-a-parameter">Stateful action without a
parameter</h2>
<p>Some menus are called toggle menu. For example, fullscreen menu has a
state which has two values – fullscreen and non-fullscreen. The value of
the state is changed every time the menu is clicked. An action
corresponds to the fullscreen menu also have a state. Its value is TRUE
or FALSE and it is called boolean value. TRUE corresponds to fullscreen
and FALSE to non-fullscreen.</p>
<p>The following is an example code to implement a fullscreen menu
except the signal handler. The signal handler will be described after
the explanation of this code.</p>
<div class="sourceCode" id="cb1"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb1-1"><a href="#cb1-1" aria-hidden="true" tabindex="-1"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb1-2"><a href="#cb1-2" aria-hidden="true" tabindex="-1"></a>app_activate <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">,</span> gpointer user_data<span class="op">)</span> <span class="op">{</span></span>
<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a> <span class="op">...</span> <span class="op">...</span> <span class="op">...</span></span>
<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></a> GSimpleAction <span class="op">*</span>act_fullscreen <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">&quot;fullscreen&quot;</span><span class="op">,</span></span>
<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a> NULL<span class="op">,</span> g_variant_new_boolean <span class="op">(</span>FALSE<span class="op">));</span></span>
<span id="cb1-6"><a href="#cb1-6" aria-hidden="true" tabindex="-1"></a> GMenuItem <span class="op">*</span>menu_item_fullscreen <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Full Screen&quot;</span><span class="op">,</span> <span class="st">&quot;win.fullscreen&quot;</span><span class="op">);</span></span>
<span id="cb1-7"><a href="#cb1-7" aria-hidden="true" tabindex="-1"></a> g_signal_connect <span class="op">(</span>act_fullscreen<span class="op">,</span> <span class="st">&quot;change-state&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>fullscreen_changed<span class="op">),</span> win<span class="op">);</span></span>
<span id="cb1-8"><a href="#cb1-8" aria-hidden="true" tabindex="-1"></a> <span class="op">...</span> <span class="op">...</span> <span class="op">...</span></span>
<span id="cb1-9"><a href="#cb1-9" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li><code>act_fullscreen</code> is a GSimpleAction instance. It is
created with <code>g_simple_action_new_stateful</code>. The function has
three arguments. The first argument “fullscreen” is the name of the
action. The second argument is a parameter type. <code>NULL</code> means
the action doesn’t have a parameter. The third argument is the initial
state of the action. It is a GVariant value. GVariant will be explained
in the next subsection. The function
<code>g_variant_new_boolean (FALSE)</code> returns a GVariant value
which is the boolean value <code>FALSE</code>.</li>
<li><code>menu_item_fullscreen</code> is a GMenuItem instance. There are
two arguments. The first argument “Full Screen” is a label of
<code>menu_item_fullscreen</code>. The second argument is an action. The
action “win.fullscreen” has a prefix “win” and an action name
“fullscreen”. The prefix says that the action belongs to the
window.</li>
<li>connects the action <code>act_fullscreen</code> and the
“change-state” signal handler <code>fullscreen_changed</code>. If the
fullscreen menu is clicked, then the corresponding action
<code>act_fullscreen</code> is activated. But no handler is connected to
the “activate” signal. Then, the default behavior for boolean-stated
actions with a NULL parameter type like <code>act_fullscreen</code> is
to toggle them via the “change-state” signal.</li>
</ul>
<p>The following is the “change-state” signal handler.</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb2-1"><a href="#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb2-2"><a href="#cb2-2" aria-hidden="true" tabindex="-1"></a>fullscreen_changed<span class="op">(</span>GSimpleAction <span class="op">*</span>action<span class="op">,</span> GVariant <span class="op">*</span>value<span class="op">,</span> gpointer win<span class="op">)</span> <span class="op">{</span></span>
<span id="cb2-3"><a href="#cb2-3" aria-hidden="true" tabindex="-1"></a> <span class="cf">if</span> <span class="op">(</span>g_variant_get_boolean <span class="op">(</span>value<span class="op">))</span></span>
<span id="cb2-4"><a href="#cb2-4" aria-hidden="true" tabindex="-1"></a> gtk_window_maximize <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb2-5"><a href="#cb2-5" aria-hidden="true" tabindex="-1"></a> <span class="cf">else</span></span>
<span id="cb2-6"><a href="#cb2-6" aria-hidden="true" tabindex="-1"></a> gtk_window_unmaximize <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb2-7"><a href="#cb2-7" aria-hidden="true" tabindex="-1"></a> g_simple_action_set_state <span class="op">(</span>action<span class="op">,</span> value<span class="op">);</span></span>
<span id="cb2-8"><a href="#cb2-8" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>There are three parameters. The first parameter is the action which
emits the “change-state” signal. The second parameter is the value of
the new state of the action. The third parameter is a user data which is
set in <code>g_signal_connect</code>.</li>
<li>If the value is boolean type and <code>TRUE</code>, then it
maximizes the window. Otherwise unmaximizes.</li>
<li>Sets the state of the action with <code>value</code>. Note: the
second argument was the toggled state value, but at this stage the state
of the action has the original value. So, you need to set the state with
the new value by <code>g_simple_action_set_state</code>.</li>
</ul>
<p>You can use “activate” signal instead of “change-state” signal, or
both signals. But the way above is the simplest and the best.</p>
<h3 id="gvariant">GVariant</h3>
<p>GVarient can contain boolean, string or other type values. For
example, the following program assigns TRUE to <code>value</code> whose
type is GVariant.</p>
<div class="sourceCode" id="cb3"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb3-1"><a href="#cb3-1" aria-hidden="true" tabindex="-1"></a>GVariant <span class="op">*</span>value <span class="op">=</span> g_variant_new_boolean <span class="op">(</span>TRUE<span class="op">);</span></span></code></pre></div>
<p>Another example is:</p>
<div class="sourceCode" id="cb4"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb4-1"><a href="#cb4-1" aria-hidden="true" tabindex="-1"></a>GVariant <span class="op">*</span>value2 <span class="op">=</span> g_variant_new_string <span class="op">(</span><span class="st">&quot;Hello&quot;</span><span class="op">);</span></span></code></pre></div>
<p><code>value2</code> is a GVariant and it has a string type value
“Hello”. GVariant can contain other types like int16, int32, int64,
double and so on.</p>
<p>If you want to get the original value, use g_variant_get series
functions. For example, you can get the boolean value by
g_variant_get_boolean.</p>
<div class="sourceCode" id="cb5"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb5-1"><a href="#cb5-1" aria-hidden="true" tabindex="-1"></a>gboolean <span class="dt">bool</span> <span class="op">=</span> g_variant_get_boolean <span class="op">(</span>value<span class="op">);</span></span></code></pre></div>
<p>Because <code>value</code> has been created as a boolean type
GVariant and <code>TRUE</code> value, <code>bool</code> equals
<code>TRUE</code>. In the same way, you can get a string from
<code>value2</code></p>
<div class="sourceCode" id="cb6"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb6-1"><a href="#cb6-1" aria-hidden="true" tabindex="-1"></a><span class="dt">const</span> <span class="dt">char</span> <span class="op">*</span>str <span class="op">=</span> g_variant_get_string <span class="op">(</span>value2<span class="op">,</span> NULL<span class="op">);</span></span></code></pre></div>
<p>The second parameter is a pointer to gsize type variable (gsize is
defined as unsigned long). If it isn’t NULL, then the length of the
string will be set by the function. If it is NULL, nothing happens. The
returned string <code>str</code> can’t be changed.</p>
<h2 id="stateful-action-with-a-parameter">Stateful action with a
parameter</h2>
<p>Another example of stateful actions is an action corresponds to color
select menus. For example, there are three menus and each menu has red,
green or blue color respectively. They determine the background color of
a certain widget. One action is connected to the three menus. The action
has a state which values are “red”, “green” and “blue”. The values are
string. Those colors are given to the signal handler as a parameter.</p>
<div class="sourceCode" id="cb7"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb7-1"><a href="#cb7-1" aria-hidden="true" tabindex="-1"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb7-2"><a href="#cb7-2" aria-hidden="true" tabindex="-1"></a>app_activate <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">,</span> gpointer user_data<span class="op">)</span> <span class="op">{</span></span>
<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a> <span class="op">...</span> <span class="op">...</span> <span class="op">...</span></span>
<span id="cb7-4"><a href="#cb7-4" aria-hidden="true" tabindex="-1"></a> GSimpleAction <span class="op">*</span>act_color <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">&quot;color&quot;</span><span class="op">,</span></span>
<span id="cb7-5"><a href="#cb7-5" aria-hidden="true" tabindex="-1"></a> g_variant_type_new<span class="op">(</span><span class="st">&quot;s&quot;</span><span class="op">),</span> g_variant_new_string <span class="op">(</span><span class="st">&quot;red&quot;</span><span class="op">));</span></span>
<span id="cb7-6"><a href="#cb7-6" aria-hidden="true" tabindex="-1"></a> GMenuItem <span class="op">*</span>menu_item_red <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Red&quot;</span><span class="op">,</span> <span class="st">&quot;win.color::red&quot;</span><span class="op">);</span></span>
<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a> GMenuItem <span class="op">*</span>menu_item_green <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Green&quot;</span><span class="op">,</span> <span class="st">&quot;win.color::green&quot;</span><span class="op">);</span></span>
<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a> GMenuItem <span class="op">*</span>menu_item_blue <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Blue&quot;</span><span class="op">,</span> <span class="st">&quot;win.color::blue&quot;</span><span class="op">);</span></span>
<span id="cb7-9"><a href="#cb7-9" aria-hidden="true" tabindex="-1"></a> g_signal_connect <span class="op">(</span>act_color<span class="op">,</span> <span class="st">&quot;activate&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>color_activated<span class="op">),</span> win<span class="op">);</span></span>
<span id="cb7-10"><a href="#cb7-10" aria-hidden="true" tabindex="-1"></a> <span class="op">...</span> <span class="op">...</span> <span class="op">...</span></span>
<span id="cb7-11"><a href="#cb7-11" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li><code>act_color</code> is a GSimpleAction instance. It is created
with <code>g_simple_action_new_stateful</code>. The function has three
arguments. The first argument “color” is the name of the action. The
second argument is a parameter type which is GVariantType.
<code>g_variant_type_new("s")</code> creates GVariantType which is a
string type (<code>G_VARIANT_TYPE_STRING</code>). The third argument is
the initial state of the action. It is a GVariant. GVariantType will be
explained in the next subsection. The function
<code>g_variant_new_string ("red")</code> returns a GVariant value which
has the string value “red”.</li>
<li><code>menu_item_red</code> is a GMenuItem instance. There are two
arguments. The first argument “Red” is the label of
<code>menu_item_red</code>. The second argument is a detailed action.
Its prefix is “win”, action name is “color” and target is “red”. Target
is sent to the action as a parameter. The same goes for
<code>menu_item_green</code> and <code>menu_item_blue</code>.</li>
<li>connects the action <code>act_color</code> and the “activate” signal
handler <code>color_activated</code>. If one of the three menus is
clicked, then the action <code>act_color</code> is activated with the
target (parameter) which is given by the menu. No handler is connected
to “change-state” signal. Then the default behavior is to call
<code>g_simple_action_set_state()</code> to set the state to the
requested value.</li>
</ul>
<p>The following is the “activate” signal handler.</p>
<div class="sourceCode" id="cb8"><pre class="sourceCode c"><code class="sourceCode c"><span id="cb8-1"><a href="#cb8-1" aria-hidden="true" tabindex="-1"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb8-2"><a href="#cb8-2" aria-hidden="true" tabindex="-1"></a>color_activated<span class="op">(</span>GSimpleAction <span class="op">*</span>action<span class="op">,</span> GVariant <span class="op">*</span>parameter<span class="op">,</span> gpointer win<span class="op">)</span> <span class="op">{</span></span>
<span id="cb8-3"><a href="#cb8-3" aria-hidden="true" tabindex="-1"></a> <span class="dt">char</span> <span class="op">*</span>color <span class="op">=</span> g_strdup_printf <span class="op">(</span><span class="st">&quot;label#lb {background-color: %s;}&quot;</span><span class="op">,</span></span>
<span id="cb8-4"><a href="#cb8-4" aria-hidden="true" tabindex="-1"></a> g_variant_get_string <span class="op">(</span>parameter<span class="op">,</span> NULL<span class="op">));</span></span>
<span id="cb8-5"><a href="#cb8-5" aria-hidden="true" tabindex="-1"></a> gtk_css_provider_load_from_data <span class="op">(</span>provider<span class="op">,</span> color<span class="op">,</span> <span class="op">-</span><span class="dv">1</span><span class="op">);</span></span>
<span id="cb8-6"><a href="#cb8-6" aria-hidden="true" tabindex="-1"></a> g_free <span class="op">(</span>color<span class="op">);</span></span>
<span id="cb8-7"><a href="#cb8-7" aria-hidden="true" tabindex="-1"></a> g_action_change_state <span class="op">(</span>G_ACTION <span class="op">(</span>action<span class="op">),</span> parameter<span class="op">);</span></span>
<span id="cb8-8"><a href="#cb8-8" aria-hidden="true" tabindex="-1"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>There are three parameters. The first parameter is the action which
emits the “activate” signal. The second parameter is the parameter given
to the action. It is a color specified by the menu. The third parameter
is a user data which is set in <code>g_signal_connect</code>.</li>
<li><code>color</code> is a CSS string created by
<code>g_strdup_printf</code>. The parameter of
<code>g_strdup_printf</code> is the same as printf C standard function.
<code>g_variant_get_string</code> gets the string contained in
<code>parameter</code>. You mustn’t change or free the string.</li>
<li>Sets the color of the css provider.</li>
<li>Frees the string <code>color</code>.</li>
<li>Changes the state by <code>g_action_change_state</code>. The
function just sets the state of the action to the parameter by
<code>g_simple_action_set_state</code>. Therefore, you can use
<code>g_simple_action_set_state</code> instead of
<code>g_action_change_state</code>.</li>
</ul>
<p>Note: If you have set a “change-state” signal handler,
<code>g_action_change_state</code> will emit “change-state” signal
instead of calling <code>g_simple_action_set_state</code>.</p>
<h3 id="gvarianttype">GVariantType</h3>
<p>GVariantType gives a type of GVariant. GVariant can contain many
kinds of types. And the type often needs to be recognized at runtime.
GVariantType provides such functionality.</p>
<p>GVariantType is created with a string which expresses a type.</p>
<ul>
<li>“b” means boolean type.</li>
<li>“s” means string type.</li>
</ul>
<p>The following program is a simple example. It finally outputs the
string “s”.</p>
<div class="sourceCode" id="cb9"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb9-1"><a href="#cb9-1"></a><span class="pp">#include </span><span class="im">&lt;glib.h&gt;</span></span>
<span id="cb9-2"><a href="#cb9-2"></a></span>
<span id="cb9-3"><a href="#cb9-3"></a><span class="dt">int</span></span>
<span id="cb9-4"><a href="#cb9-4"></a>main <span class="op">(</span><span class="dt">int</span> argc<span class="op">,</span> <span class="dt">char</span> <span class="op">**</span>argv<span class="op">)</span> <span class="op">{</span></span>
<span id="cb9-5"><a href="#cb9-5"></a> GVariantType <span class="op">*</span>vtype <span class="op">=</span> g_variant_type_new <span class="op">(</span><span class="st">&quot;s&quot;</span><span class="op">);</span></span>
<span id="cb9-6"><a href="#cb9-6"></a> <span class="dt">const</span> <span class="dt">char</span> <span class="op">*</span>type_string <span class="op">=</span> g_variant_type_peek_string <span class="op">(</span>vtype<span class="op">);</span></span>
<span id="cb9-7"><a href="#cb9-7"></a> g_print <span class="op">(</span><span class="st">&quot;%s</span><span class="sc">\n</span><span class="st">&quot;</span><span class="op">,</span>type_string<span class="op">);</span></span>
<span id="cb9-8"><a href="#cb9-8"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li><code>g_variant_type_new</code> creates GVariantType. It uses a type
string “s” which means string.</li>
<li><code>g_variant_type_peek_string</code> takes a peek at
<code>vtype</code>. It is the string “s” given to <code>vtype</code>
when it was created.</li>
<li>prints the string to the terminal.</li>
</ul>
<h2 id="example-code">Example code</h2>
<p>The following code includes stateful actions above. This program has
menus like this:</p>
<figure>
<img src="image/menu2.png" alt="menu2" />
<figcaption aria-hidden="true">menu2</figcaption>
</figure>
<ul>
<li>Fullscreen menu toggles the size of the window between maximum and
non-maximum. If the window is maximum size, which is called full screen,
then a check mark is put before “fullscreen” label.</li>
<li>Red, green and blue menu determines the back ground color of the
label, which is the child widget of the window. The menus have radio
buttons on the left of the menus. And the radio button of the selected
menu turns on.</li>
<li>Quit menu quits the application.</li>
</ul>
<p>The code is as follows.</p>
<div class="sourceCode" id="cb10"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb10-1"><a href="#cb10-1"></a><span class="pp">#include </span><span class="im">&lt;gtk/gtk.h&gt;</span></span>
<span id="cb10-2"><a href="#cb10-2"></a></span>
<span id="cb10-3"><a href="#cb10-3"></a><span class="dt">static</span> GtkCssProvider <span class="op">*</span>provider<span class="op">;</span></span>
<span id="cb10-4"><a href="#cb10-4"></a></span>
<span id="cb10-5"><a href="#cb10-5"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb10-6"><a href="#cb10-6"></a>fullscreen_changed<span class="op">(</span>GSimpleAction <span class="op">*</span>action<span class="op">,</span> GVariant <span class="op">*</span>value<span class="op">,</span> gpointer win<span class="op">)</span> <span class="op">{</span></span>
<span id="cb10-7"><a href="#cb10-7"></a> <span class="cf">if</span> <span class="op">(</span>g_variant_get_boolean <span class="op">(</span>value<span class="op">))</span></span>
<span id="cb10-8"><a href="#cb10-8"></a> gtk_window_maximize <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb10-9"><a href="#cb10-9"></a> <span class="cf">else</span></span>
<span id="cb10-10"><a href="#cb10-10"></a> gtk_window_unmaximize <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb10-11"><a href="#cb10-11"></a> g_simple_action_set_state <span class="op">(</span>action<span class="op">,</span> value<span class="op">);</span></span>
<span id="cb10-12"><a href="#cb10-12"></a><span class="op">}</span></span>
<span id="cb10-13"><a href="#cb10-13"></a></span>
<span id="cb10-14"><a href="#cb10-14"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb10-15"><a href="#cb10-15"></a>color_activated<span class="op">(</span>GSimpleAction <span class="op">*</span>action<span class="op">,</span> GVariant <span class="op">*</span>parameter<span class="op">,</span> gpointer win<span class="op">)</span> <span class="op">{</span></span>
<span id="cb10-16"><a href="#cb10-16"></a> <span class="dt">char</span> <span class="op">*</span>color <span class="op">=</span> g_strdup_printf <span class="op">(</span><span class="st">&quot;label#lb {background-color: %s;}&quot;</span><span class="op">,</span> g_variant_get_string <span class="op">(</span>parameter<span class="op">,</span> NULL<span class="op">));</span></span>
<span id="cb10-17"><a href="#cb10-17"></a> gtk_css_provider_load_from_data <span class="op">(</span>provider<span class="op">,</span> color<span class="op">,</span> <span class="op">-</span><span class="dv">1</span><span class="op">);</span></span>
<span id="cb10-18"><a href="#cb10-18"></a> g_free <span class="op">(</span>color<span class="op">);</span></span>
<span id="cb10-19"><a href="#cb10-19"></a> g_action_change_state <span class="op">(</span>G_ACTION <span class="op">(</span>action<span class="op">),</span> parameter<span class="op">);</span></span>
<span id="cb10-20"><a href="#cb10-20"></a><span class="op">}</span></span>
<span id="cb10-21"><a href="#cb10-21"></a></span>
<span id="cb10-22"><a href="#cb10-22"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb10-23"><a href="#cb10-23"></a>quit_activated<span class="op">(</span>GSimpleAction <span class="op">*</span>action<span class="op">,</span> GVariant <span class="op">*</span>parameter<span class="op">,</span> gpointer app<span class="op">)</span></span>
<span id="cb10-24"><a href="#cb10-24"></a><span class="op">{</span></span>
<span id="cb10-25"><a href="#cb10-25"></a> g_application_quit <span class="op">(</span>G_APPLICATION<span class="op">(</span>app<span class="op">));</span></span>
<span id="cb10-26"><a href="#cb10-26"></a><span class="op">}</span></span>
<span id="cb10-27"><a href="#cb10-27"></a></span>
<span id="cb10-28"><a href="#cb10-28"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb10-29"><a href="#cb10-29"></a>app_activate <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">,</span> gpointer user_data<span class="op">)</span> <span class="op">{</span></span>
<span id="cb10-30"><a href="#cb10-30"></a> GtkWidget <span class="op">*</span>win <span class="op">=</span> gtk_application_window_new <span class="op">(</span>GTK_APPLICATION <span class="op">(</span>app<span class="op">));</span></span>
<span id="cb10-31"><a href="#cb10-31"></a> gtk_window_set_title <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">),</span> <span class="st">&quot;menu2&quot;</span><span class="op">);</span></span>
<span id="cb10-32"><a href="#cb10-32"></a> gtk_window_set_default_size <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">),</span> <span class="dv">400</span><span class="op">,</span> <span class="dv">300</span><span class="op">);</span></span>
<span id="cb10-33"><a href="#cb10-33"></a></span>
<span id="cb10-34"><a href="#cb10-34"></a> GtkWidget <span class="op">*</span>lb <span class="op">=</span> gtk_label_new <span class="op">(</span>NULL<span class="op">);</span></span>
<span id="cb10-35"><a href="#cb10-35"></a> gtk_widget_set_name <span class="op">(</span>lb<span class="op">,</span> <span class="st">&quot;lb&quot;</span><span class="op">);</span> <span class="co">/* the name is used by CSS Selector */</span></span>
<span id="cb10-36"><a href="#cb10-36"></a> gtk_window_set_child <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">),</span> lb<span class="op">);</span></span>
<span id="cb10-37"><a href="#cb10-37"></a></span>
<span id="cb10-38"><a href="#cb10-38"></a> GSimpleAction <span class="op">*</span>act_fullscreen</span>
<span id="cb10-39"><a href="#cb10-39"></a> <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">&quot;fullscreen&quot;</span><span class="op">,</span> NULL<span class="op">,</span> g_variant_new_boolean <span class="op">(</span>FALSE<span class="op">));</span></span>
<span id="cb10-40"><a href="#cb10-40"></a> GSimpleAction <span class="op">*</span>act_color</span>
<span id="cb10-41"><a href="#cb10-41"></a> <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">&quot;color&quot;</span><span class="op">,</span> g_variant_type_new<span class="op">(</span><span class="st">&quot;s&quot;</span><span class="op">),</span> g_variant_new_string <span class="op">(</span><span class="st">&quot;red&quot;</span><span class="op">));</span></span>
<span id="cb10-42"><a href="#cb10-42"></a> GSimpleAction <span class="op">*</span>act_quit</span>
<span id="cb10-43"><a href="#cb10-43"></a> <span class="op">=</span> g_simple_action_new <span class="op">(</span><span class="st">&quot;quit&quot;</span><span class="op">,</span> NULL<span class="op">);</span></span>
<span id="cb10-44"><a href="#cb10-44"></a></span>
<span id="cb10-45"><a href="#cb10-45"></a> GMenu <span class="op">*</span>menubar <span class="op">=</span> g_menu_new <span class="op">();</span></span>
<span id="cb10-46"><a href="#cb10-46"></a> GMenu <span class="op">*</span>menu <span class="op">=</span> g_menu_new <span class="op">();</span></span>
<span id="cb10-47"><a href="#cb10-47"></a> GMenu <span class="op">*</span>section1 <span class="op">=</span> g_menu_new <span class="op">();</span></span>
<span id="cb10-48"><a href="#cb10-48"></a> GMenu <span class="op">*</span>section2 <span class="op">=</span> g_menu_new <span class="op">();</span></span>
<span id="cb10-49"><a href="#cb10-49"></a> GMenu <span class="op">*</span>section3 <span class="op">=</span> g_menu_new <span class="op">();</span></span>
<span id="cb10-50"><a href="#cb10-50"></a> GMenuItem <span class="op">*</span>menu_item_fullscreen <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Full Screen&quot;</span><span class="op">,</span> <span class="st">&quot;win.fullscreen&quot;</span><span class="op">);</span></span>
<span id="cb10-51"><a href="#cb10-51"></a> GMenuItem <span class="op">*</span>menu_item_red <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Red&quot;</span><span class="op">,</span> <span class="st">&quot;win.color::red&quot;</span><span class="op">);</span></span>
<span id="cb10-52"><a href="#cb10-52"></a> GMenuItem <span class="op">*</span>menu_item_green <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Green&quot;</span><span class="op">,</span> <span class="st">&quot;win.color::green&quot;</span><span class="op">);</span></span>
<span id="cb10-53"><a href="#cb10-53"></a> GMenuItem <span class="op">*</span>menu_item_blue <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Blue&quot;</span><span class="op">,</span> <span class="st">&quot;win.color::blue&quot;</span><span class="op">);</span></span>
<span id="cb10-54"><a href="#cb10-54"></a> GMenuItem <span class="op">*</span>menu_item_quit <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">&quot;Quit&quot;</span><span class="op">,</span> <span class="st">&quot;app.quit&quot;</span><span class="op">);</span></span>
<span id="cb10-55"><a href="#cb10-55"></a></span>
<span id="cb10-56"><a href="#cb10-56"></a> g_signal_connect <span class="op">(</span>act_fullscreen<span class="op">,</span> <span class="st">&quot;change-state&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>fullscreen_changed<span class="op">),</span> win<span class="op">);</span></span>
<span id="cb10-57"><a href="#cb10-57"></a> g_signal_connect <span class="op">(</span>act_color<span class="op">,</span> <span class="st">&quot;activate&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>color_activated<span class="op">),</span> win<span class="op">);</span></span>
<span id="cb10-58"><a href="#cb10-58"></a> g_signal_connect <span class="op">(</span>act_quit<span class="op">,</span> <span class="st">&quot;activate&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>quit_activated<span class="op">),</span> app<span class="op">);</span></span>
<span id="cb10-59"><a href="#cb10-59"></a> g_action_map_add_action <span class="op">(</span>G_ACTION_MAP <span class="op">(</span>win<span class="op">),</span> G_ACTION <span class="op">(</span>act_fullscreen<span class="op">));</span></span>
<span id="cb10-60"><a href="#cb10-60"></a> g_action_map_add_action <span class="op">(</span>G_ACTION_MAP <span class="op">(</span>win<span class="op">),</span> G_ACTION <span class="op">(</span>act_color<span class="op">));</span></span>
<span id="cb10-61"><a href="#cb10-61"></a> g_action_map_add_action <span class="op">(</span>G_ACTION_MAP <span class="op">(</span>app<span class="op">),</span> G_ACTION <span class="op">(</span>act_quit<span class="op">));</span></span>
<span id="cb10-62"><a href="#cb10-62"></a></span>
<span id="cb10-63"><a href="#cb10-63"></a> g_menu_append_item <span class="op">(</span>section1<span class="op">,</span> menu_item_fullscreen<span class="op">);</span></span>
<span id="cb10-64"><a href="#cb10-64"></a> g_menu_append_item <span class="op">(</span>section2<span class="op">,</span> menu_item_red<span class="op">);</span></span>
<span id="cb10-65"><a href="#cb10-65"></a> g_menu_append_item <span class="op">(</span>section2<span class="op">,</span> menu_item_green<span class="op">);</span></span>
<span id="cb10-66"><a href="#cb10-66"></a> g_menu_append_item <span class="op">(</span>section2<span class="op">,</span> menu_item_blue<span class="op">);</span></span>
<span id="cb10-67"><a href="#cb10-67"></a> g_menu_append_item <span class="op">(</span>section3<span class="op">,</span> menu_item_quit<span class="op">);</span></span>
<span id="cb10-68"><a href="#cb10-68"></a> g_object_unref <span class="op">(</span>menu_item_red<span class="op">);</span></span>
<span id="cb10-69"><a href="#cb10-69"></a> g_object_unref <span class="op">(</span>menu_item_green<span class="op">);</span></span>
<span id="cb10-70"><a href="#cb10-70"></a> g_object_unref <span class="op">(</span>menu_item_blue<span class="op">);</span></span>
<span id="cb10-71"><a href="#cb10-71"></a> g_object_unref <span class="op">(</span>menu_item_fullscreen<span class="op">);</span></span>
<span id="cb10-72"><a href="#cb10-72"></a> g_object_unref <span class="op">(</span>menu_item_quit<span class="op">);</span></span>
<span id="cb10-73"><a href="#cb10-73"></a></span>
<span id="cb10-74"><a href="#cb10-74"></a> g_menu_append_section <span class="op">(</span>menu<span class="op">,</span> NULL<span class="op">,</span> G_MENU_MODEL <span class="op">(</span>section1<span class="op">));</span></span>
<span id="cb10-75"><a href="#cb10-75"></a> g_menu_append_section <span class="op">(</span>menu<span class="op">,</span> <span class="st">&quot;Color&quot;</span><span class="op">,</span> G_MENU_MODEL <span class="op">(</span>section2<span class="op">));</span></span>
<span id="cb10-76"><a href="#cb10-76"></a> g_menu_append_section <span class="op">(</span>menu<span class="op">,</span> NULL<span class="op">,</span> G_MENU_MODEL <span class="op">(</span>section3<span class="op">));</span></span>
<span id="cb10-77"><a href="#cb10-77"></a> g_menu_append_submenu <span class="op">(</span>menubar<span class="op">,</span> <span class="st">&quot;Menu&quot;</span><span class="op">,</span> G_MENU_MODEL <span class="op">(</span>menu<span class="op">));</span></span>
<span id="cb10-78"><a href="#cb10-78"></a></span>
<span id="cb10-79"><a href="#cb10-79"></a> gtk_application_set_menubar <span class="op">(</span>GTK_APPLICATION <span class="op">(</span>app<span class="op">),</span> G_MENU_MODEL <span class="op">(</span>menubar<span class="op">));</span></span>
<span id="cb10-80"><a href="#cb10-80"></a> gtk_application_window_set_show_menubar <span class="op">(</span>GTK_APPLICATION_WINDOW <span class="op">(</span>win<span class="op">),</span> TRUE<span class="op">);</span></span>
<span id="cb10-81"><a href="#cb10-81"></a></span>
<span id="cb10-82"><a href="#cb10-82"></a><span class="co">/* GtkCssProvider *provider = gtk_css_provider_new ();*/</span></span>
<span id="cb10-83"><a href="#cb10-83"></a> provider <span class="op">=</span> gtk_css_provider_new <span class="op">();</span></span>
<span id="cb10-84"><a href="#cb10-84"></a> GdkDisplay <span class="op">*</span>display <span class="op">=</span> gtk_widget_get_display <span class="op">(</span>GTK_WIDGET <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb10-85"><a href="#cb10-85"></a> gtk_css_provider_load_from_data <span class="op">(</span>provider<span class="op">,</span> <span class="st">&quot;label#lb {background-color: red;}&quot;</span><span class="op">,</span> <span class="op">-</span><span class="dv">1</span><span class="op">);</span></span>
<span id="cb10-86"><a href="#cb10-86"></a> gtk_style_context_add_provider_for_display <span class="op">(</span>display<span class="op">,</span> GTK_STYLE_PROVIDER <span class="op">(</span>provider<span class="op">),</span></span>
<span id="cb10-87"><a href="#cb10-87"></a> GTK_STYLE_PROVIDER_PRIORITY_USER<span class="op">);</span></span>
<span id="cb10-88"><a href="#cb10-88"></a></span>
<span id="cb10-89"><a href="#cb10-89"></a><span class="co">/* gtk_widget_show (win);*/</span></span>
<span id="cb10-90"><a href="#cb10-90"></a> gtk_window_present <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb10-91"><a href="#cb10-91"></a><span class="op">}</span></span>
<span id="cb10-92"><a href="#cb10-92"></a></span>
<span id="cb10-93"><a href="#cb10-93"></a><span class="pp">#define APPLICATION_ID &quot;com.github.ToshioCP.menu2&quot;</span></span>
<span id="cb10-94"><a href="#cb10-94"></a></span>
<span id="cb10-95"><a href="#cb10-95"></a><span class="dt">int</span></span>
<span id="cb10-96"><a href="#cb10-96"></a>main <span class="op">(</span><span class="dt">int</span> argc<span class="op">,</span> <span class="dt">char</span> <span class="op">**</span>argv<span class="op">)</span> <span class="op">{</span></span>
<span id="cb10-97"><a href="#cb10-97"></a> GtkApplication <span class="op">*</span>app<span class="op">;</span></span>
<span id="cb10-98"><a href="#cb10-98"></a> <span class="dt">int</span> stat<span class="op">;</span></span>
<span id="cb10-99"><a href="#cb10-99"></a></span>
<span id="cb10-100"><a href="#cb10-100"></a> app <span class="op">=</span> gtk_application_new <span class="op">(</span>APPLICATION_ID<span class="op">,</span> G_APPLICATION_FLAGS_NONE<span class="op">);</span></span>
<span id="cb10-101"><a href="#cb10-101"></a> g_signal_connect <span class="op">(</span>app<span class="op">,</span> <span class="st">&quot;activate&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>app_activate<span class="op">),</span> NULL<span class="op">);</span></span>
<span id="cb10-102"><a href="#cb10-102"></a></span>
<span id="cb10-103"><a href="#cb10-103"></a> stat <span class="op">=</span>g_application_run <span class="op">(</span>G_APPLICATION <span class="op">(</span>app<span class="op">),</span> argc<span class="op">,</span> argv<span class="op">);</span></span>
<span id="cb10-104"><a href="#cb10-104"></a> g_object_unref <span class="op">(</span>app<span class="op">);</span></span>
<span id="cb10-105"><a href="#cb10-105"></a> <span class="cf">return</span> stat<span class="op">;</span></span>
<span id="cb10-106"><a href="#cb10-106"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>5-26: Signal handlers. They have already been explained.</li>
<li>30-36: <code>win</code> and <code>lb</code> are GtkApplicationWindow
and GtkLabel respectively. <code>win</code> has a title “menu2” and its
default size is 400x300. <code>lb</code> is named as “lb”. The name is
used in CSS. <code>lb</code> is set to <code>win</code> as a child.</li>
<li>38-43: Three actions are defined. They are:
<ul>
<li>stateful and has no parameter. It has a toggle state.</li>
<li>stateful and has a parameter. Parameter is a string type.</li>
<li>stateless and has no parameter.</li>
</ul></li>
<li>45-54: Creates GMenu and GMenuItem. There are three sections.</li>
<li>56-61: Signals are connected to handlers. And actions are added to
GActionMap. Because <code>act_fullscreen</code> and
<code>act_color</code> have “win” prefix and belong to
GtkApplicationWindow, they are added to <code>win</code>.
GtkApplicationWindow implements GActionModel interface like
GtkApplication. <code>act_quit</code> has “app” prefix and belongs to
GtkApplication. It is added to <code>app</code>.</li>
<li>63-77: Connects and builds the menus. Useless GMenuItem are
freed.</li>
<li>79-80: GMenuModel <code>menubar</code> is inserted to
<code>app</code>. Sets show menubar property of <code>win</code> to
<code>TRUE</code>. Note:
<code>gtk_application_window_set_show_menubar</code> creates
GtkPopoverMenubar from GMenuModel. This is a different point between GTK
3 and GTK 4. And you can use GtkPopoverMenubar directly and set it as a
descendant widget of the window. You may use GtkBox as a child widget of
the window and insert GtkPopoverMenubar as the first child of the
box.</li>
<li>82-87: Sets CSS. <code>provider</code> is GtkCssProvider which is
defined in line three as a static variable. Its CSS data is:
<code>label#lb {background-color: red;}</code>. “label#lb” is called
selector. “label” is the node of GtkLabel. “#” precedes an ID which is
an identifiable name of the widget. “lb” is the name of GtkLabel
<code>lb</code>. (See line 35). The style is surrounded by open and
close braces. The style is applied to GtkLabel which has a name “lb”.
Other GtkLabel have no effect from this. The provider is added to
GdkDisplay.</li>
<li>90: Shows the window.</li>
</ul>
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