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<span class="navbar-brand">Gtk4 tutorial</span>
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<a class="nav-link" href="sec17.html">Prev: section17</a>
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<a class="nav-link" href="sec19.html">Next: section19</a>
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<h1 id="stateful-action">Stateful action</h1>
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<p>Some actions have states. The typical values of states is boolean or
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string. However, other types of states are possible if you want.</p>
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<p>Actions which have states are called stateful.</p>
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<h2 id="stateful-action-without-a-parameter">Stateful action without a
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parameter</h2>
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<p>Some menus are called toggle menu. For example, fullscreen menu has a
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state which has two values – fullscreen and non-fullscreen. The value of
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the state is changed every time the menu is clicked. An action
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corresponds to the fullscreen menu also have a state. Its value is TRUE
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or FALSE and it is called boolean value. TRUE corresponds to fullscreen
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and FALSE to non-fullscreen.</p>
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<p>The following is an example code to implement a fullscreen menu
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except the signal handler. The signal handler will be shown later.</p>
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<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>GSimpleAction <span class="op">*</span>act_fullscreen <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">"fullscreen"</span><span class="op">,</span></span>
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<span id="cb1-2"><a href="#cb1-2" 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>
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<span id="cb1-3"><a href="#cb1-3" aria-hidden="true" tabindex="-1"></a>g_signal_connect <span class="op">(</span>act_fullscreen<span class="op">,</span> <span class="st">"change-state"</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>fullscreen_changed<span class="op">),</span> win<span class="op">);</span></span>
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<span id="cb1-4"><a href="#cb1-4" aria-hidden="true" tabindex="-1"></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>
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<span id="cb1-5"><a href="#cb1-5" aria-hidden="true" tabindex="-1"></a><span class="op">...</span> <span class="op">...</span> <span class="op">...</span></span>
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<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">"Full Screen"</span><span class="op">,</span> <span class="st">"win.fullscreen"</span><span class="op">);</span></span></code></pre></div>
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<ul>
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<li><code>act_fullscreen</code> is a GSimpleAction instance. It is
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created with <code>g_simple_action_new_stateful</code>. The function has
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three arguments. The first argument “fullscreen” is the name of the
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action. The second argument is a parameter type. <code>NULL</code> means
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the action doesn’t have a parameter. The third argument is the initial
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state of the action. It is a GVariant value. GVariant will be explained
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in the next subsection. The function
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<code>g_variant_new_boolean (FALSE)</code> returns a GVariant value
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which is the boolean value <code>FALSE</code>. If there are two or more
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top level windows, each window has its own <code>act_fullscreen</code>
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action. So, the number of the actions is the same as the number of the
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windows.</li>
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<li>connects the action <code>act_fullscreen</code> and the
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“change-state” signal handler <code>fullscreen_changed</code>. If the
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fullscreen menu is clicked, then the corresponding action
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<code>act_fullscreen</code> is activated. But no handler is connected to
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the “activate” signal. Then, the default behavior for boolean-stated
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actions with a NULL parameter type like <code>act_fullscreen</code> is
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to toggle them via the “change-state” signal.</li>
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<li>The action is added to the GtkWindow <code>win</code>. Therefore,
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the scope of the action is “win” – window.</li>
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<li><code>menu_item_fullscreen</code> is a GMenuItem instance. There are
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two arguments. The first argument “Full Screen” is the label of
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<code>menu_item_fullscreen</code>. The second argument is an action. The
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action “win.fullscreen” has a prefix “win” and an action name
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“fullscreen”. The prefix says that the action belongs to the
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window.</li>
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</ul>
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<div class="sourceCode" id="cb2"><pre
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class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb2-1"><a href="#cb2-1"></a><span class="dt">static</span> <span class="dt">void</span></span>
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<span id="cb2-2"><a href="#cb2-2"></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> GtkWindow <span class="op">*</span>win<span class="op">)</span> <span class="op">{</span></span>
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<span id="cb2-3"><a href="#cb2-3"></a> <span class="cf">if</span> <span class="op">(</span>g_variant_get_boolean <span class="op">(</span>value<span class="op">))</span></span>
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<span id="cb2-4"><a href="#cb2-4"></a> gtk_window_maximize <span class="op">(</span>win<span class="op">);</span></span>
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<span id="cb2-5"><a href="#cb2-5"></a> <span class="cf">else</span></span>
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<span id="cb2-6"><a href="#cb2-6"></a> gtk_window_unmaximize <span class="op">(</span>win<span class="op">);</span></span>
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<span id="cb2-7"><a href="#cb2-7"></a> g_simple_action_set_state <span class="op">(</span>action<span class="op">,</span> value<span class="op">);</span></span>
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<span id="cb2-8"><a href="#cb2-8"></a><span class="op">}</span></span></code></pre></div>
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<ul>
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<li>The handler <code>fullscreen_changed</code> has three parameters.
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The first parameter is the action which emits the “change-state” signal.
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The second parameter is the value of the new state of the action. The
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third parameter is a user data which is set in
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<code>g_signal_connect</code>.</li>
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<li>If the value is boolean type and <code>TRUE</code>, then it
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maximizes the window. Otherwise unmaximizes.</li>
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<li>Sets the state of the action with <code>value</code>. Note: the
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second argument was the toggled state value, but at this stage the state
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of the action has the original value. So, you need to set the state with
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the new value by <code>g_simple_action_set_state</code>.</li>
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</ul>
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<p>You can use “activate” signal instead of “change-state” signal, or
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both signals. But the way above is the simplest and the best.</p>
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<h3 id="gvariant">GVariant</h3>
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<p>GVarient can contain boolean, string or other type values. For
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example, the following program assigns TRUE to <code>value</code> whose
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type is GVariant.</p>
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<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>
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<p>Another example is:</p>
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<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">"Hello"</span><span class="op">);</span></span></code></pre></div>
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<p><code>value2</code> is a GVariant and it has a string type value
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“Hello”. GVariant can contain other types like int16, int32, int64,
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double and so on.</p>
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<p>If you want to get the original value, use g_variant_get series
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functions. For example, you can get the boolean value with
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g_variant_get_boolean.</p>
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<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>
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<p>Because <code>value</code> has been created as a boolean type
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GVariant and <code>TRUE</code> value, <code>bool</code> equals
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<code>TRUE</code>. In the same way, you can get a string from
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<code>value2</code></p>
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<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>
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<p>The second parameter is a pointer to gsize type variable (gsize is
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defined as unsigned long). If it isn’t NULL, then the length of the
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string will be set by the function. If it is NULL, nothing happens. The
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returned string <code>str</code> can’t be changed.</p>
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<h2 id="stateful-action-with-a-parameter">Stateful action with a
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parameter</h2>
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<p>Another example of stateful actions is an action corresponds to color
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select menus. For example, there are three menus and each menu has red,
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green or blue color respectively. They determine the background color of
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a GtkLabel widget. One action is connected to the three menus. The
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action has a state whose value is “red”, “green” or “blue”. The values
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are string. Those colors are given to the signal handler as a
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parameter.</p>
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<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="op">...</span> <span class="op">...</span> <span class="op">...</span></span>
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<span id="cb7-2"><a href="#cb7-2" 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">"color"</span><span class="op">,</span></span>
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<span id="cb7-3"><a href="#cb7-3" aria-hidden="true" tabindex="-1"></a> g_variant_type_new<span class="op">(</span><span class="st">"s"</span><span class="op">),</span> g_variant_new_string <span class="op">(</span><span class="st">"red"</span><span class="op">));</span></span>
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<span id="cb7-4"><a href="#cb7-4" 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">"Red"</span><span class="op">,</span> <span class="st">"app.color::red"</span><span class="op">);</span></span>
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<span id="cb7-5"><a href="#cb7-5" 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">"Green"</span><span class="op">,</span> <span class="st">"app.color::green"</span><span class="op">);</span></span>
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<span id="cb7-6"><a href="#cb7-6" 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">"Blue"</span><span class="op">,</span> <span class="st">"app.color::blue"</span><span class="op">);</span></span>
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<span id="cb7-7"><a href="#cb7-7" aria-hidden="true" tabindex="-1"></a>g_signal_connect <span class="op">(</span>act_color<span class="op">,</span> <span class="st">"activate"</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>color_activated<span class="op">),</span> NULL<span class="op">);</span></span>
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<span id="cb7-8"><a href="#cb7-8" aria-hidden="true" tabindex="-1"></a><span class="op">...</span> <span class="op">...</span> <span class="op">...</span></span></code></pre></div>
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<ul>
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<li><code>act_color</code> is a GSimpleAction instance. It is created
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with <code>g_simple_action_new_stateful</code>. The function has three
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arguments. The first argument “color” is the name of the action. The
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second argument is a parameter type which is GVariantType.
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<code>g_variant_type_new("s")</code> creates GVariantType which is a
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string type (<code>G_VARIANT_TYPE_STRING</code>). The third argument is
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the initial state of the action. It is a GVariant. GVariantType will be
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explained in the next subsection. The function
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<code>g_variant_new_string ("red")</code> returns a GVariant value which
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has the string value “red”.</li>
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<li><code>menu_item_red</code> is a GMenuItem instance. There are two
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arguments. The first argument “Red” is the label of
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<code>menu_item_red</code>. The second argument is a detailed action.
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Its prefix is “app”, action name is “color” and target is “red”. Target
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is sent to the action as a parameter. The same goes for
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<code>menu_item_green</code> and <code>menu_item_blue</code>.</li>
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<li>connects the action <code>act_color</code> and the “activate” signal
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handler <code>color_activated</code>. If one of the three menus is
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clicked, then the action <code>act_color</code> is activated with the
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target (parameter) which is given by the menu.</li>
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</ul>
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<p>The following is the “activate” signal handler.</p>
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<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>
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<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> <span class="op">{</span></span>
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<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">"label.lb {background-color: %s;}"</span><span class="op">,</span></span>
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<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 left out because the fourth argument of the
|
||
<code>g_signal_connect</code> is NULL.</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. <code>label.lb</code> is a
|
||
selector. <code>lable</code> is a node name of GtkLabel and
|
||
<code>lb</code> is a class. <code>label.lb</code> selects GtkLabel which
|
||
has lb class. For example, menus have GtkLabel to display their labels,
|
||
but they don’t have <code>lb</code> class. So, the CSS doesn’t change
|
||
the their background color. <code>{background-color %s}</code> makes the
|
||
background color the one from <code>parameter</code>.</li>
|
||
<li>Frees the string <code>color</code>.</li>
|
||
<li>Changes the state by <code>g_action_change_state</code>.</li>
|
||
</ul>
|
||
<p>Note: If you haven’t set an “activate” signal handler, the signal is
|
||
forwarded to “change-state” signal. So, you can use “change-state”
|
||
signal instead of “activate” signal. See
|
||
<code>src/menu/menu2_change_state.c</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.</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"><glib.h></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">"s"</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">"%s</span><span class="sc">\n</span><span class="st">"</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">Example</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 any
|
||
labels. 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"><gtk/gtk.h></span></span>
|
||
<span id="cb10-2"><a href="#cb10-2"></a></span>
|
||
<span id="cb10-3"><a href="#cb10-3"></a><span class="co">/* The provider below provides application wide CSS data. */</span></span>
|
||
<span id="cb10-4"><a href="#cb10-4"></a>GtkCssProvider <span class="op">*</span>provider<span class="op">;</span></span>
|
||
<span id="cb10-5"><a href="#cb10-5"></a></span>
|
||
<span id="cb10-6"><a href="#cb10-6"></a><span class="dt">static</span> <span class="dt">void</span></span>
|
||
<span id="cb10-7"><a href="#cb10-7"></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> GtkWindow <span class="op">*</span>win<span class="op">)</span> <span class="op">{</span></span>
|
||
<span id="cb10-8"><a href="#cb10-8"></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="cb10-9"><a href="#cb10-9"></a> gtk_window_maximize <span class="op">(</span>win<span class="op">);</span></span>
|
||
<span id="cb10-10"><a href="#cb10-10"></a> <span class="cf">else</span></span>
|
||
<span id="cb10-11"><a href="#cb10-11"></a> gtk_window_unmaximize <span class="op">(</span>win<span class="op">);</span></span>
|
||
<span id="cb10-12"><a href="#cb10-12"></a> g_simple_action_set_state <span class="op">(</span>action<span class="op">,</span> value<span class="op">);</span></span>
|
||
<span id="cb10-13"><a href="#cb10-13"></a><span class="op">}</span></span>
|
||
<span id="cb10-14"><a href="#cb10-14"></a></span>
|
||
<span id="cb10-15"><a href="#cb10-15"></a><span class="dt">static</span> <span class="dt">void</span></span>
|
||
<span id="cb10-16"><a href="#cb10-16"></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> <span class="op">{</span></span>
|
||
<span id="cb10-17"><a href="#cb10-17"></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">"label.lb {background-color: %s;}"</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="cb10-18"><a href="#cb10-18"></a> <span class="co">/* Change the CSS data in the provider. */</span></span>
|
||
<span id="cb10-19"><a href="#cb10-19"></a> <span class="co">/* Previous data is thrown away. */</span></span>
|
||
<span id="cb10-20"><a href="#cb10-20"></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="cb10-21"><a href="#cb10-21"></a> g_free <span class="op">(</span>color<span class="op">);</span></span>
|
||
<span id="cb10-22"><a href="#cb10-22"></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="cb10-23"><a href="#cb10-23"></a><span class="op">}</span></span>
|
||
<span id="cb10-24"><a href="#cb10-24"></a></span>
|
||
<span id="cb10-25"><a href="#cb10-25"></a><span class="dt">static</span> <span class="dt">void</span></span>
|
||
<span id="cb10-26"><a href="#cb10-26"></a>remove_provider <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">,</span> GtkCssProvider <span class="op">*</span>provider<span class="op">)</span> <span class="op">{</span></span>
|
||
<span id="cb10-27"><a href="#cb10-27"></a> GdkDisplay <span class="op">*</span>display <span class="op">=</span> gdk_display_get_default<span class="op">();</span></span>
|
||
<span id="cb10-28"><a href="#cb10-28"></a> </span>
|
||
<span id="cb10-29"><a href="#cb10-29"></a> gtk_style_context_remove_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="cb10-30"><a href="#cb10-30"></a> g_object_unref <span class="op">(</span>provider<span class="op">);</span></span>
|
||
<span id="cb10-31"><a href="#cb10-31"></a><span class="op">}</span></span>
|
||
<span id="cb10-32"><a href="#cb10-32"></a></span>
|
||
<span id="cb10-33"><a href="#cb10-33"></a><span class="dt">static</span> <span class="dt">void</span></span>
|
||
<span id="cb10-34"><a href="#cb10-34"></a>app_activate <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">)</span> <span class="op">{</span></span>
|
||
<span id="cb10-35"><a href="#cb10-35"></a> GtkWindow <span class="op">*</span>win <span class="op">=</span> GTK_WINDOW <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="cb10-36"><a href="#cb10-36"></a> gtk_window_set_title <span class="op">(</span>win<span class="op">,</span> <span class="st">"menu2"</span><span class="op">);</span></span>
|
||
<span id="cb10-37"><a href="#cb10-37"></a> gtk_window_set_default_size <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="cb10-38"><a href="#cb10-38"></a></span>
|
||
<span id="cb10-39"><a href="#cb10-39"></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="cb10-40"><a href="#cb10-40"></a> gtk_widget_add_css_class <span class="op">(</span>lb<span class="op">,</span> <span class="st">"lb"</span><span class="op">);</span> <span class="co">/* the class is used by CSS Selector */</span></span>
|
||
<span id="cb10-41"><a href="#cb10-41"></a> gtk_window_set_child <span class="op">(</span>win<span class="op">,</span> lb<span class="op">);</span></span>
|
||
<span id="cb10-42"><a href="#cb10-42"></a></span>
|
||
<span id="cb10-43"><a href="#cb10-43"></a> GSimpleAction <span class="op">*</span>act_fullscreen</span>
|
||
<span id="cb10-44"><a href="#cb10-44"></a> <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">"fullscreen"</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="cb10-45"><a href="#cb10-45"></a> g_signal_connect <span class="op">(</span>act_fullscreen<span class="op">,</span> <span class="st">"change-state"</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="cb10-46"><a href="#cb10-46"></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="cb10-47"><a href="#cb10-47"></a></span>
|
||
<span id="cb10-48"><a href="#cb10-48"></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="cb10-49"><a href="#cb10-49"></a></span>
|
||
<span id="cb10-50"><a href="#cb10-50"></a> gtk_window_present <span class="op">(</span>win<span class="op">);</span></span>
|
||
<span id="cb10-51"><a href="#cb10-51"></a><span class="op">}</span></span>
|
||
<span id="cb10-52"><a href="#cb10-52"></a></span>
|
||
<span id="cb10-53"><a href="#cb10-53"></a><span class="dt">static</span> <span class="dt">void</span></span>
|
||
<span id="cb10-54"><a href="#cb10-54"></a>app_startup <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">)</span> <span class="op">{</span></span>
|
||
<span id="cb10-55"><a href="#cb10-55"></a> GSimpleAction <span class="op">*</span>act_color</span>
|
||
<span id="cb10-56"><a href="#cb10-56"></a> <span class="op">=</span> g_simple_action_new_stateful <span class="op">(</span><span class="st">"color"</span><span class="op">,</span> g_variant_type_new<span class="op">(</span><span class="st">"s"</span><span class="op">),</span> g_variant_new_string <span class="op">(</span><span class="st">"red"</span><span class="op">));</span></span>
|
||
<span id="cb10-57"><a href="#cb10-57"></a> GSimpleAction <span class="op">*</span>act_quit</span>
|
||
<span id="cb10-58"><a href="#cb10-58"></a> <span class="op">=</span> g_simple_action_new <span class="op">(</span><span class="st">"quit"</span><span class="op">,</span> NULL<span class="op">);</span></span>
|
||
<span id="cb10-59"><a href="#cb10-59"></a> g_signal_connect <span class="op">(</span>act_color<span class="op">,</span> <span class="st">"activate"</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>color_activated<span class="op">),</span> NULL<span class="op">);</span></span>
|
||
<span id="cb10-60"><a href="#cb10-60"></a> g_signal_connect_swapped <span class="op">(</span>act_quit<span class="op">,</span> <span class="st">"activate"</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>g_application_quit<span class="op">),</span> app<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_color<span class="op">));</span></span>
|
||
<span id="cb10-62"><a href="#cb10-62"></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="cb10-63"><a href="#cb10-63"></a></span>
|
||
<span id="cb10-64"><a href="#cb10-64"></a> GMenu <span class="op">*</span>menubar <span class="op">=</span> g_menu_new <span class="op">();</span></span>
|
||
<span id="cb10-65"><a href="#cb10-65"></a> GMenu <span class="op">*</span>menu <span class="op">=</span> g_menu_new <span class="op">();</span></span>
|
||
<span id="cb10-66"><a href="#cb10-66"></a> GMenu <span class="op">*</span>section1 <span class="op">=</span> g_menu_new <span class="op">();</span></span>
|
||
<span id="cb10-67"><a href="#cb10-67"></a> GMenu <span class="op">*</span>section2 <span class="op">=</span> g_menu_new <span class="op">();</span></span>
|
||
<span id="cb10-68"><a href="#cb10-68"></a> GMenu <span class="op">*</span>section3 <span class="op">=</span> g_menu_new <span class="op">();</span></span>
|
||
<span id="cb10-69"><a href="#cb10-69"></a> GMenuItem <span class="op">*</span>menu_item_fullscreen <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">"Full Screen"</span><span class="op">,</span> <span class="st">"win.fullscreen"</span><span class="op">);</span></span>
|
||
<span id="cb10-70"><a href="#cb10-70"></a> GMenuItem <span class="op">*</span>menu_item_red <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">"Red"</span><span class="op">,</span> <span class="st">"app.color::red"</span><span class="op">);</span></span>
|
||
<span id="cb10-71"><a href="#cb10-71"></a> GMenuItem <span class="op">*</span>menu_item_green <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">"Green"</span><span class="op">,</span> <span class="st">"app.color::green"</span><span class="op">);</span></span>
|
||
<span id="cb10-72"><a href="#cb10-72"></a> GMenuItem <span class="op">*</span>menu_item_blue <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">"Blue"</span><span class="op">,</span> <span class="st">"app.color::blue"</span><span class="op">);</span></span>
|
||
<span id="cb10-73"><a href="#cb10-73"></a> GMenuItem <span class="op">*</span>menu_item_quit <span class="op">=</span> g_menu_item_new <span class="op">(</span><span class="st">"Quit"</span><span class="op">,</span> <span class="st">"app.quit"</span><span class="op">);</span></span>
|
||
<span id="cb10-74"><a href="#cb10-74"></a></span>
|
||
<span id="cb10-75"><a href="#cb10-75"></a> g_menu_append_item <span class="op">(</span>section1<span class="op">,</span> menu_item_fullscreen<span class="op">);</span></span>
|
||
<span id="cb10-76"><a href="#cb10-76"></a> g_menu_append_item <span class="op">(</span>section2<span class="op">,</span> menu_item_red<span class="op">);</span></span>
|
||
<span id="cb10-77"><a href="#cb10-77"></a> g_menu_append_item <span class="op">(</span>section2<span class="op">,</span> menu_item_green<span class="op">);</span></span>
|
||
<span id="cb10-78"><a href="#cb10-78"></a> g_menu_append_item <span class="op">(</span>section2<span class="op">,</span> menu_item_blue<span class="op">);</span></span>
|
||
<span id="cb10-79"><a href="#cb10-79"></a> g_menu_append_item <span class="op">(</span>section3<span class="op">,</span> menu_item_quit<span class="op">);</span></span>
|
||
<span id="cb10-80"><a href="#cb10-80"></a> g_object_unref <span class="op">(</span>menu_item_red<span class="op">);</span></span>
|
||
<span id="cb10-81"><a href="#cb10-81"></a> g_object_unref <span class="op">(</span>menu_item_green<span class="op">);</span></span>
|
||
<span id="cb10-82"><a href="#cb10-82"></a> g_object_unref <span class="op">(</span>menu_item_blue<span class="op">);</span></span>
|
||
<span id="cb10-83"><a href="#cb10-83"></a> g_object_unref <span class="op">(</span>menu_item_fullscreen<span class="op">);</span></span>
|
||
<span id="cb10-84"><a href="#cb10-84"></a> g_object_unref <span class="op">(</span>menu_item_quit<span class="op">);</span></span>
|
||
<span id="cb10-85"><a href="#cb10-85"></a></span>
|
||
<span id="cb10-86"><a href="#cb10-86"></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="cb10-87"><a href="#cb10-87"></a> g_menu_append_section <span class="op">(</span>menu<span class="op">,</span> <span class="st">"Color"</span><span class="op">,</span> G_MENU_MODEL <span class="op">(</span>section2<span class="op">));</span></span>
|
||
<span id="cb10-88"><a href="#cb10-88"></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="cb10-89"><a href="#cb10-89"></a> g_menu_append_submenu <span class="op">(</span>menubar<span class="op">,</span> <span class="st">"Menu"</span><span class="op">,</span> G_MENU_MODEL <span class="op">(</span>menu<span class="op">));</span></span>
|
||
<span id="cb10-90"><a href="#cb10-90"></a></span>
|
||
<span id="cb10-91"><a href="#cb10-91"></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="cb10-92"><a href="#cb10-92"></a></span>
|
||
<span id="cb10-93"><a href="#cb10-93"></a> provider <span class="op">=</span> gtk_css_provider_new <span class="op">();</span></span>
|
||
<span id="cb10-94"><a href="#cb10-94"></a> <span class="co">/* Initialize the css data */</span></span>
|
||
<span id="cb10-95"><a href="#cb10-95"></a> gtk_css_provider_load_from_data <span class="op">(</span>provider<span class="op">,</span> <span class="st">"label.lb {background-color: red;}"</span><span class="op">,</span> <span class="op">-</span><span class="dv">1</span><span class="op">);</span></span>
|
||
<span id="cb10-96"><a href="#cb10-96"></a> <span class="co">/* Add CSS to the default GdkDisplay. */</span></span>
|
||
<span id="cb10-97"><a href="#cb10-97"></a> GdkDisplay <span class="op">*</span>display <span class="op">=</span> gdk_display_get_default <span class="op">();</span></span>
|
||
<span id="cb10-98"><a href="#cb10-98"></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="cb10-99"><a href="#cb10-99"></a> GTK_STYLE_PROVIDER_PRIORITY_APPLICATION<span class="op">);</span></span>
|
||
<span id="cb10-100"><a href="#cb10-100"></a> g_signal_connect <span class="op">(</span>app<span class="op">,</span> <span class="st">"shutdown"</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>remove_provider<span class="op">),</span> provider<span class="op">);</span></span>
|
||
<span id="cb10-101"><a href="#cb10-101"></a><span class="op">}</span></span>
|
||
<span id="cb10-102"><a href="#cb10-102"></a></span>
|
||
<span id="cb10-103"><a href="#cb10-103"></a><span class="pp">#define APPLICATION_ID "com.github.ToshioCP.menu2"</span></span>
|
||
<span id="cb10-104"><a href="#cb10-104"></a></span>
|
||
<span id="cb10-105"><a href="#cb10-105"></a><span class="dt">int</span></span>
|
||
<span id="cb10-106"><a href="#cb10-106"></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="cb10-107"><a href="#cb10-107"></a> GtkApplication <span class="op">*</span>app<span class="op">;</span></span>
|
||
<span id="cb10-108"><a href="#cb10-108"></a> <span class="dt">int</span> stat<span class="op">;</span></span>
|
||
<span id="cb10-109"><a href="#cb10-109"></a></span>
|
||
<span id="cb10-110"><a href="#cb10-110"></a> app <span class="op">=</span> gtk_application_new <span class="op">(</span>APPLICATION_ID<span class="op">,</span> G_APPLICATION_DEFAULT_FLAGS<span class="op">);</span></span>
|
||
<span id="cb10-111"><a href="#cb10-111"></a> g_signal_connect <span class="op">(</span>app<span class="op">,</span> <span class="st">"startup"</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>app_startup<span class="op">),</span> NULL<span class="op">);</span></span>
|
||
<span id="cb10-112"><a href="#cb10-112"></a> g_signal_connect <span class="op">(</span>app<span class="op">,</span> <span class="st">"activate"</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="cb10-113"><a href="#cb10-113"></a></span>
|
||
<span id="cb10-114"><a href="#cb10-114"></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="cb10-115"><a href="#cb10-115"></a> g_object_unref <span class="op">(</span>app<span class="op">);</span></span>
|
||
<span id="cb10-116"><a href="#cb10-116"></a> <span class="cf">return</span> stat<span class="op">;</span></span>
|
||
<span id="cb10-117"><a href="#cb10-117"></a><span class="op">}</span></span></code></pre></div>
|
||
<ul>
|
||
<li>6-23: Signal handlers connected to the actions.</li>
|
||
<li>25-31: The handler <code>remove_provider</code> is called when the
|
||
application quits. It removes the provider from the display and releases
|
||
the provider.</li>
|
||
<li>33-51: An activate signal handler.</li>
|
||
<li>35-37: A new window is created and assigned to <code>win</code>. Its
|
||
title and default size are set to “menu2” and 400x300 respectively.</li>
|
||
<li>39-41: A new label is created and assigned to <code>lb</code> The
|
||
name is “lb”, which is used in CSS. It is added to <code>win</code> as a
|
||
child.</li>
|
||
<li>43-46: A toggle action is created and assigned to
|
||
<code>act_fullscreen</code>. It’s connected to the signal handler
|
||
<code>fullscreen_changed</code>. It’s added to the window, so the scope
|
||
is “win”. The action corresponds to the window. So, if there are two or
|
||
more windows, the actions are created two or more.</li>
|
||
<li>48: The function
|
||
<code>gtk_application_window_set_show_menubar</code> adds a menubar to
|
||
the window.</li>
|
||
<li>50: The window is shown.</li>
|
||
<li>53-101: A startup signal handler.</li>
|
||
<li>55-62: Two actions <code>act_color</code> and <code>act_quit</code>
|
||
are created. These actions exists only one because the startup handler
|
||
is called once. They are connected to their handlers and added to the
|
||
application. Their scopes are “app”.</li>
|
||
<li>64-89: Menus are built.</li>
|
||
<li>91: The menubar is added to the application.</li>
|
||
<li>93-100: A css provider is created, set the data and added to the
|
||
default display. The “shutdown” signal on the application is connected
|
||
to a handler “remove_provider”. So, the provider is removed from the
|
||
display and freed when the application quits.</li>
|
||
</ul>
|
||
<h2 id="compile">Compile</h2>
|
||
<p>Change your current directory to <code>src/menu</code>.</p>
|
||
<pre><code>$ comp menu2
|
||
$./a.out</code></pre>
|
||
<p>Then, you will see a window and the background color of the content
|
||
is red. You can change the size to maximum and change again to the
|
||
original size. You can change the background color to green or blue.</p>
|
||
<p>If you run the application again, another window will appear in the
|
||
same screen. Both of the window have the same background color. Because
|
||
the <code>act_color</code> action has “app” scope and the CSS is applied
|
||
to the default display shared by the windows.</p>
|
||
</div>
|
||
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>
|
||
</body>
|
||
</html>
|