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Toshio Sekiya 77a8a43c6e Refactor programs lis1.c to list5.c.
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<h1 id="periodic-events">Periodic Events</h1>
<p>This chapter was written by Paul Schulz <a
href="mailto:paul@mawsonlakes.org"
class="email">paul@mawsonlakes.org</a>.</p>
<h2 id="how-do-we-create-an-animation">How do we create an
animation?</h2>
<p>In this section we will continue to build on our previous work. We
will create an analog clock application. By adding a function which
periodically redraws GtkDrawingArea, the clock will be able to
continuously display the time.</p>
<p>The application uses a compiled in ‘resource’ file, so if the GTK4
libraries and their dependencies are installed and available, the
application will run from anywhere.</p>
<p>The program also makes use of some standard mathematical and time
handling functions.</p>
<p>The clocks mechanics were taken from a Cairo drawing example, using
gtkmm4, which can be found <a
href="https://developer-old.gnome.org/gtkmm-tutorial/stable/sec-drawing-clock-example.html.en">here</a>.</p>
<p>The complete code is at the end.</p>
<h2 id="drawing-the-clock-face-hour-minute-and-second-hands">Drawing the
clock face, hour, minute and second hands</h2>
<p>The <code>draw_clock()</code> function does all the work. See the
in-file comments for an explanation of how the Cairo drawing works.</p>
<p>For a detailed reference of what each of the Cairo functions does see
the <a
href="https://www.cairographics.org/manual/cairo-cairo-t.html">cairo_t
reference</a>.</p>
<div class="sourceCode" id="cb1"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb1-1"><a href="#cb1-1"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb1-2"><a href="#cb1-2"></a>draw_clock <span class="op">(</span>GtkDrawingArea <span class="op">*</span>area<span class="op">,</span> cairo_t <span class="op">*</span>cr<span class="op">,</span> <span class="dt">int</span> width<span class="op">,</span> <span class="dt">int</span> height<span class="op">,</span> gpointer user_data<span class="op">)</span> <span class="op">{</span></span>
<span id="cb1-3"><a href="#cb1-3"></a></span>
<span id="cb1-4"><a href="#cb1-4"></a> <span class="co">// Scale to unit square and translate (0, 0) to be (0.5, 0.5), i.e.</span></span>
<span id="cb1-5"><a href="#cb1-5"></a> <span class="co">// the center of the window</span></span>
<span id="cb1-6"><a href="#cb1-6"></a> cairo_scale<span class="op">(</span>cr<span class="op">,</span> width<span class="op">,</span> height<span class="op">);</span></span>
<span id="cb1-7"><a href="#cb1-7"></a> cairo_translate<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.5</span><span class="op">,</span> <span class="fl">0.5</span><span class="op">);</span></span>
<span id="cb1-8"><a href="#cb1-8"></a></span>
<span id="cb1-9"><a href="#cb1-9"></a> <span class="co">// Set the line width and save the cairo drawing state.</span></span>
<span id="cb1-10"><a href="#cb1-10"></a> cairo_set_line_width<span class="op">(</span>cr<span class="op">,</span> m_line_width<span class="op">);</span></span>
<span id="cb1-11"><a href="#cb1-11"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-12"><a href="#cb1-12"></a></span>
<span id="cb1-13"><a href="#cb1-13"></a> <span class="co">// Set the background to a slightly transparent green.</span></span>
<span id="cb1-14"><a href="#cb1-14"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.337</span><span class="op">,</span> <span class="fl">0.612</span><span class="op">,</span> <span class="fl">0.117</span><span class="op">,</span> <span class="fl">0.9</span><span class="op">);</span> <span class="co">// green</span></span>
<span id="cb1-15"><a href="#cb1-15"></a> cairo_paint<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-16"><a href="#cb1-16"></a></span>
<span id="cb1-17"><a href="#cb1-17"></a> <span class="co">// Resore back to precious drawing state and draw the circular path</span></span>
<span id="cb1-18"><a href="#cb1-18"></a> <span class="co">// representing the clockface. Save this state (including the path) so we</span></span>
<span id="cb1-19"><a href="#cb1-19"></a> <span class="co">// can reuse it.</span></span>
<span id="cb1-20"><a href="#cb1-20"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-21"><a href="#cb1-21"></a> cairo_arc<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> m_radius<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">2.0</span> <span class="op">*</span> M_PI<span class="op">);</span></span>
<span id="cb1-22"><a href="#cb1-22"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-23"><a href="#cb1-23"></a></span>
<span id="cb1-24"><a href="#cb1-24"></a> <span class="co">// Fill the clockface with white</span></span>
<span id="cb1-25"><a href="#cb1-25"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">1.0</span><span class="op">,</span> <span class="fl">1.0</span><span class="op">,</span> <span class="fl">1.0</span><span class="op">,</span> <span class="fl">0.8</span><span class="op">);</span></span>
<span id="cb1-26"><a href="#cb1-26"></a> cairo_fill_preserve<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-27"><a href="#cb1-27"></a> <span class="co">// Restore the path, paint the outside of the clock face.</span></span>
<span id="cb1-28"><a href="#cb1-28"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-29"><a href="#cb1-29"></a> cairo_stroke_preserve<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-30"><a href="#cb1-30"></a> <span class="co">// Set the &#39;clip region&#39; to the inside of the path (fill region).</span></span>
<span id="cb1-31"><a href="#cb1-31"></a> cairo_clip<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-32"><a href="#cb1-32"></a></span>
<span id="cb1-33"><a href="#cb1-33"></a> <span class="co">// Clock ticks</span></span>
<span id="cb1-34"><a href="#cb1-34"></a> <span class="cf">for</span> <span class="op">(</span><span class="dt">int</span> i <span class="op">=</span> <span class="dv">0</span><span class="op">;</span> i <span class="op">&lt;</span> <span class="dv">12</span><span class="op">;</span> i<span class="op">++)</span></span>
<span id="cb1-35"><a href="#cb1-35"></a> <span class="op">{</span></span>
<span id="cb1-36"><a href="#cb1-36"></a> <span class="co">// Major tick size</span></span>
<span id="cb1-37"><a href="#cb1-37"></a> <span class="dt">double</span> inset <span class="op">=</span> <span class="fl">0.05</span><span class="op">;</span></span>
<span id="cb1-38"><a href="#cb1-38"></a></span>
<span id="cb1-39"><a href="#cb1-39"></a> <span class="co">// Save the graphics state, restore after drawing tick to maintain pen</span></span>
<span id="cb1-40"><a href="#cb1-40"></a> <span class="co">// size</span></span>
<span id="cb1-41"><a href="#cb1-41"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-42"><a href="#cb1-42"></a> cairo_set_line_cap<span class="op">(</span>cr<span class="op">,</span> CAIRO_LINE_CAP_ROUND<span class="op">);</span></span>
<span id="cb1-43"><a href="#cb1-43"></a></span>
<span id="cb1-44"><a href="#cb1-44"></a> <span class="co">// Minor ticks are shorter, and narrower.</span></span>
<span id="cb1-45"><a href="#cb1-45"></a> <span class="cf">if</span><span class="op">(</span>i <span class="op">%</span> <span class="dv">3</span> <span class="op">!=</span> <span class="dv">0</span><span class="op">)</span></span>
<span id="cb1-46"><a href="#cb1-46"></a> <span class="op">{</span></span>
<span id="cb1-47"><a href="#cb1-47"></a> inset <span class="op">*=</span> <span class="fl">0.8</span><span class="op">;</span></span>
<span id="cb1-48"><a href="#cb1-48"></a> cairo_set_line_width<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.03</span><span class="op">);</span></span>
<span id="cb1-49"><a href="#cb1-49"></a> <span class="op">}</span></span>
<span id="cb1-50"><a href="#cb1-50"></a></span>
<span id="cb1-51"><a href="#cb1-51"></a> <span class="co">// Draw tick mark</span></span>
<span id="cb1-52"><a href="#cb1-52"></a> cairo_move_to<span class="op">(</span></span>
<span id="cb1-53"><a href="#cb1-53"></a> cr<span class="op">,</span></span>
<span id="cb1-54"><a href="#cb1-54"></a> <span class="op">(</span>m_radius <span class="op">-</span> inset<span class="op">)</span> <span class="op">*</span> cos <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">),</span></span>
<span id="cb1-55"><a href="#cb1-55"></a> <span class="op">(</span>m_radius <span class="op">-</span> inset<span class="op">)</span> <span class="op">*</span> sin <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">));</span></span>
<span id="cb1-56"><a href="#cb1-56"></a> cairo_line_to<span class="op">(</span></span>
<span id="cb1-57"><a href="#cb1-57"></a> cr<span class="op">,</span></span>
<span id="cb1-58"><a href="#cb1-58"></a> m_radius <span class="op">*</span> cos <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">),</span></span>
<span id="cb1-59"><a href="#cb1-59"></a> m_radius <span class="op">*</span> sin <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">));</span></span>
<span id="cb1-60"><a href="#cb1-60"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-61"><a href="#cb1-61"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span> <span class="co">/* stack-pen-size */</span></span>
<span id="cb1-62"><a href="#cb1-62"></a> <span class="op">}</span></span>
<span id="cb1-63"><a href="#cb1-63"></a></span>
<span id="cb1-64"><a href="#cb1-64"></a> <span class="co">// Draw the analog hands</span></span>
<span id="cb1-65"><a href="#cb1-65"></a></span>
<span id="cb1-66"><a href="#cb1-66"></a> <span class="co">// Get the current Unix time, convert to the local time and break into time</span></span>
<span id="cb1-67"><a href="#cb1-67"></a> <span class="co">// structure to read various time parts.</span></span>
<span id="cb1-68"><a href="#cb1-68"></a> <span class="dt">time_t</span> rawtime<span class="op">;</span></span>
<span id="cb1-69"><a href="#cb1-69"></a> time<span class="op">(&amp;</span>rawtime<span class="op">);</span></span>
<span id="cb1-70"><a href="#cb1-70"></a> <span class="kw">struct</span> tm <span class="op">*</span> timeinfo <span class="op">=</span> localtime <span class="op">(&amp;</span>rawtime<span class="op">);</span></span>
<span id="cb1-71"><a href="#cb1-71"></a></span>
<span id="cb1-72"><a href="#cb1-72"></a> <span class="co">// Calculate the angles of the hands of our clock</span></span>
<span id="cb1-73"><a href="#cb1-73"></a> <span class="dt">double</span> hours <span class="op">=</span> timeinfo<span class="op">-&gt;</span>tm_hour <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">;</span></span>
<span id="cb1-74"><a href="#cb1-74"></a> <span class="dt">double</span> minutes <span class="op">=</span> timeinfo<span class="op">-&gt;</span>tm_min <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">30.0</span><span class="op">;</span></span>
<span id="cb1-75"><a href="#cb1-75"></a> <span class="dt">double</span> seconds <span class="op">=</span> timeinfo<span class="op">-&gt;</span>tm_sec <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">30.0</span><span class="op">;</span></span>
<span id="cb1-76"><a href="#cb1-76"></a></span>
<span id="cb1-77"><a href="#cb1-77"></a> <span class="co">// Save the graphics state</span></span>
<span id="cb1-78"><a href="#cb1-78"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-79"><a href="#cb1-79"></a> cairo_set_line_cap<span class="op">(</span>cr<span class="op">,</span> CAIRO_LINE_CAP_ROUND<span class="op">);</span></span>
<span id="cb1-80"><a href="#cb1-80"></a></span>
<span id="cb1-81"><a href="#cb1-81"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-82"><a href="#cb1-82"></a></span>
<span id="cb1-83"><a href="#cb1-83"></a> <span class="co">// Draw the seconds hand</span></span>
<span id="cb1-84"><a href="#cb1-84"></a> cairo_set_line_width<span class="op">(</span>cr<span class="op">,</span> m_line_width <span class="op">/</span> <span class="fl">3.0</span><span class="op">);</span></span>
<span id="cb1-85"><a href="#cb1-85"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.7</span><span class="op">,</span> <span class="fl">0.7</span><span class="op">,</span> <span class="fl">0.7</span><span class="op">,</span> <span class="fl">0.8</span><span class="op">);</span> <span class="co">// gray</span></span>
<span id="cb1-86"><a href="#cb1-86"></a> cairo_move_to<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">);</span></span>
<span id="cb1-87"><a href="#cb1-87"></a> cairo_line_to<span class="op">(</span>cr<span class="op">,</span></span>
<span id="cb1-88"><a href="#cb1-88"></a> sin<span class="op">(</span>seconds<span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.9</span><span class="op">),</span></span>
<span id="cb1-89"><a href="#cb1-89"></a> <span class="op">-</span>cos<span class="op">(</span>seconds<span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.9</span><span class="op">));</span></span>
<span id="cb1-90"><a href="#cb1-90"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-91"><a href="#cb1-91"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-92"><a href="#cb1-92"></a></span>
<span id="cb1-93"><a href="#cb1-93"></a> <span class="co">// Draw the minutes hand</span></span>
<span id="cb1-94"><a href="#cb1-94"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.117</span><span class="op">,</span> <span class="fl">0.337</span><span class="op">,</span> <span class="fl">0.612</span><span class="op">,</span> <span class="fl">0.9</span><span class="op">);</span> <span class="co">// blue</span></span>
<span id="cb1-95"><a href="#cb1-95"></a> cairo_move_to<span class="op">(</span>cr<span class="op">,</span> <span class="dv">0</span><span class="op">,</span> <span class="dv">0</span><span class="op">);</span></span>
<span id="cb1-96"><a href="#cb1-96"></a> cairo_line_to<span class="op">(</span>cr<span class="op">,</span></span>
<span id="cb1-97"><a href="#cb1-97"></a> sin<span class="op">(</span>minutes <span class="op">+</span> seconds <span class="op">/</span> <span class="dv">60</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.8</span><span class="op">),</span></span>
<span id="cb1-98"><a href="#cb1-98"></a> <span class="op">-</span>cos<span class="op">(</span>minutes <span class="op">+</span> seconds <span class="op">/</span> <span class="dv">60</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.8</span><span class="op">));</span></span>
<span id="cb1-99"><a href="#cb1-99"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-100"><a href="#cb1-100"></a></span>
<span id="cb1-101"><a href="#cb1-101"></a> <span class="co">// draw the hours hand</span></span>
<span id="cb1-102"><a href="#cb1-102"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.337</span><span class="op">,</span> <span class="fl">0.612</span><span class="op">,</span> <span class="fl">0.117</span><span class="op">,</span> <span class="fl">0.9</span><span class="op">);</span> <span class="co">// green</span></span>
<span id="cb1-103"><a href="#cb1-103"></a> cairo_move_to<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">);</span></span>
<span id="cb1-104"><a href="#cb1-104"></a> cairo_line_to<span class="op">(</span>cr<span class="op">,</span></span>
<span id="cb1-105"><a href="#cb1-105"></a> sin<span class="op">(</span>hours <span class="op">+</span> minutes <span class="op">/</span> <span class="fl">12.0</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.5</span><span class="op">),</span></span>
<span id="cb1-106"><a href="#cb1-106"></a> <span class="op">-</span>cos<span class="op">(</span>hours <span class="op">+</span> minutes <span class="op">/</span> <span class="fl">12.0</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.5</span><span class="op">));</span></span>
<span id="cb1-107"><a href="#cb1-107"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-108"><a href="#cb1-108"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-109"><a href="#cb1-109"></a></span>
<span id="cb1-110"><a href="#cb1-110"></a> <span class="co">// Draw a little dot in the middle</span></span>
<span id="cb1-111"><a href="#cb1-111"></a> cairo_arc<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> m_line_width <span class="op">/</span> <span class="fl">3.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">2.0</span> <span class="op">*</span> M_PI<span class="op">);</span></span>
<span id="cb1-112"><a href="#cb1-112"></a> cairo_fill<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb1-113"><a href="#cb1-113"></a><span class="op">}</span></span></code></pre></div>
<p>In order for the clock to be drawn, the drawing function
<code>draw_clock()</code> needs to be registered with GTK4. This is done
in the <code>app_activate()</code> function (on line 24).</p>
<p>Whenever the application needs to redraw the GtkDrawingArea, it will
now call <code>draw_clock()</code>.</p>
<p>There is still a problem though. In order to animate the clock we
need to also tell the application that the clock needs to be redrawn
every second. This process starts by registering (on the next line, line
15) a timeout function with <code>g_timeout_add()</code> that will
wakeup and run another function <code>time_handler</code>, every second
(or 1000ms).</p>
<div class="sourceCode" id="cb2"><pre
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>
<span id="cb2-2"><a href="#cb2-2"></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="cb2-3"><a href="#cb2-3"></a> GtkWidget <span class="op">*</span>win<span class="op">;</span></span>
<span id="cb2-4"><a href="#cb2-4"></a> GtkWidget <span class="op">*</span>clock<span class="op">;</span></span>
<span id="cb2-5"><a href="#cb2-5"></a> GtkBuilder <span class="op">*</span>build<span class="op">;</span></span>
<span id="cb2-6"><a href="#cb2-6"></a></span>
<span id="cb2-7"><a href="#cb2-7"></a> build <span class="op">=</span> gtk_builder_new_from_resource <span class="op">(</span><span class="st">&quot;/com/github/ToshioCP/tfc/tfc.ui&quot;</span><span class="op">);</span></span>
<span id="cb2-8"><a href="#cb2-8"></a> win <span class="op">=</span> GTK_WIDGET <span class="op">(</span>gtk_builder_get_object <span class="op">(</span>build<span class="op">,</span> <span class="st">&quot;win&quot;</span><span class="op">));</span></span>
<span id="cb2-9"><a href="#cb2-9"></a> gtk_window_set_application <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">),</span> GTK_APPLICATION <span class="op">(</span>app<span class="op">));</span></span>
<span id="cb2-10"><a href="#cb2-10"></a></span>
<span id="cb2-11"><a href="#cb2-11"></a> clock <span class="op">=</span> GTK_WIDGET <span class="op">(</span>gtk_builder_get_object <span class="op">(</span>build<span class="op">,</span> <span class="st">&quot;clock&quot;</span><span class="op">));</span></span>
<span id="cb2-12"><a href="#cb2-12"></a> g_object_unref<span class="op">(</span>build<span class="op">);</span></span>
<span id="cb2-13"><a href="#cb2-13"></a></span>
<span id="cb2-14"><a href="#cb2-14"></a> gtk_drawing_area_set_draw_func<span class="op">(</span>GTK_DRAWING_AREA <span class="op">(</span>clock<span class="op">),</span> draw_clock<span class="op">,</span> NULL<span class="op">,</span> NULL<span class="op">);</span></span>
<span id="cb2-15"><a href="#cb2-15"></a> g_timeout_add<span class="op">(</span><span class="dv">1000</span><span class="op">,</span> <span class="op">(</span>GSourceFunc<span class="op">)</span> time_handler<span class="op">,</span> <span class="op">(</span>gpointer<span class="op">)</span> clock<span class="op">);</span></span>
<span id="cb2-16"><a href="#cb2-16"></a> gtk_widget_show<span class="op">(</span>win<span class="op">);</span></span>
<span id="cb2-17"><a href="#cb2-17"></a></span>
<span id="cb2-18"><a href="#cb2-18"></a><span class="op">}</span></span></code></pre></div>
<p>Our <code>time_handler()</code> function is very simple, as it just
calls <code>gtk_widget_queue_draw()</code> which schedules a redraw of
the widget.</p>
<div class="sourceCode" id="cb3"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb3-1"><a href="#cb3-1"></a>gboolean</span>
<span id="cb3-2"><a href="#cb3-2"></a>time_handler<span class="op">(</span>GtkWidget<span class="op">*</span> widget<span class="op">)</span> <span class="op">{</span></span>
<span id="cb3-3"><a href="#cb3-3"></a> gtk_widget_queue_draw<span class="op">(</span>widget<span class="op">);</span></span>
<span id="cb3-4"><a href="#cb3-4"></a></span>
<span id="cb3-5"><a href="#cb3-5"></a> <span class="cf">return</span> TRUE<span class="op">;</span></span>
<span id="cb3-6"><a href="#cb3-6"></a><span class="op">}</span></span></code></pre></div>
<p>.. and that is all there is to it. If you compile and run the example
you will get a ticking analog clock.</p>
<p>If you get this working, you can try modifying some of the code in
<code>draw_clock()</code> to tweak the application (such as change the
color or size and length of the hands) or even add text, or create a
digital clock.</p>
<h2 id="the-complete-code">The Complete code</h2>
<p>You can find the source files in the <code>tfc</code> directory. it
can be compiled with <code>./comp tfc</code>.</p>
<p><code>tfc.c</code></p>
<div class="sourceCode" id="cb4"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb4-1"><a href="#cb4-1"></a><span class="pp">#include </span><span class="im">&lt;gtk/gtk.h&gt;</span></span>
<span id="cb4-2"><a href="#cb4-2"></a><span class="pp">#include </span><span class="im">&lt;math.h&gt;</span></span>
<span id="cb4-3"><a href="#cb4-3"></a><span class="pp">#include </span><span class="im">&lt;time.h&gt;</span></span>
<span id="cb4-4"><a href="#cb4-4"></a></span>
<span id="cb4-5"><a href="#cb4-5"></a><span class="dt">float</span> m_radius <span class="op">=</span> <span class="fl">0.42</span><span class="op">;</span></span>
<span id="cb4-6"><a href="#cb4-6"></a><span class="dt">float</span> m_line_width <span class="op">=</span> <span class="fl">0.05</span><span class="op">;</span></span>
<span id="cb4-7"><a href="#cb4-7"></a></span>
<span id="cb4-8"><a href="#cb4-8"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb4-9"><a href="#cb4-9"></a>draw_clock <span class="op">(</span>GtkDrawingArea <span class="op">*</span>area<span class="op">,</span> cairo_t <span class="op">*</span>cr<span class="op">,</span> <span class="dt">int</span> width<span class="op">,</span> <span class="dt">int</span> height<span class="op">,</span> gpointer user_data<span class="op">)</span> <span class="op">{</span></span>
<span id="cb4-10"><a href="#cb4-10"></a></span>
<span id="cb4-11"><a href="#cb4-11"></a> <span class="co">// Scale to unit square and translate (0, 0) to be (0.5, 0.5), i.e.</span></span>
<span id="cb4-12"><a href="#cb4-12"></a> <span class="co">// the center of the window</span></span>
<span id="cb4-13"><a href="#cb4-13"></a> cairo_scale<span class="op">(</span>cr<span class="op">,</span> width<span class="op">,</span> height<span class="op">);</span></span>
<span id="cb4-14"><a href="#cb4-14"></a> cairo_translate<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.5</span><span class="op">,</span> <span class="fl">0.5</span><span class="op">);</span></span>
<span id="cb4-15"><a href="#cb4-15"></a></span>
<span id="cb4-16"><a href="#cb4-16"></a> <span class="co">// Set the line width and save the cairo drawing state.</span></span>
<span id="cb4-17"><a href="#cb4-17"></a> cairo_set_line_width<span class="op">(</span>cr<span class="op">,</span> m_line_width<span class="op">);</span></span>
<span id="cb4-18"><a href="#cb4-18"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-19"><a href="#cb4-19"></a></span>
<span id="cb4-20"><a href="#cb4-20"></a> <span class="co">// Set the background to a slightly transparent green.</span></span>
<span id="cb4-21"><a href="#cb4-21"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.337</span><span class="op">,</span> <span class="fl">0.612</span><span class="op">,</span> <span class="fl">0.117</span><span class="op">,</span> <span class="fl">0.9</span><span class="op">);</span> <span class="co">// green</span></span>
<span id="cb4-22"><a href="#cb4-22"></a> cairo_paint<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-23"><a href="#cb4-23"></a></span>
<span id="cb4-24"><a href="#cb4-24"></a> <span class="co">// Resore back to precious drawing state and draw the circular path</span></span>
<span id="cb4-25"><a href="#cb4-25"></a> <span class="co">// representing the clockface. Save this state (including the path) so we</span></span>
<span id="cb4-26"><a href="#cb4-26"></a> <span class="co">// can reuse it.</span></span>
<span id="cb4-27"><a href="#cb4-27"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-28"><a href="#cb4-28"></a> cairo_arc<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> m_radius<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">2.0</span> <span class="op">*</span> M_PI<span class="op">);</span></span>
<span id="cb4-29"><a href="#cb4-29"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-30"><a href="#cb4-30"></a></span>
<span id="cb4-31"><a href="#cb4-31"></a> <span class="co">// Fill the clockface with white</span></span>
<span id="cb4-32"><a href="#cb4-32"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">1.0</span><span class="op">,</span> <span class="fl">1.0</span><span class="op">,</span> <span class="fl">1.0</span><span class="op">,</span> <span class="fl">0.8</span><span class="op">);</span></span>
<span id="cb4-33"><a href="#cb4-33"></a> cairo_fill_preserve<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-34"><a href="#cb4-34"></a> <span class="co">// Restore the path, paint the outside of the clock face.</span></span>
<span id="cb4-35"><a href="#cb4-35"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-36"><a href="#cb4-36"></a> cairo_stroke_preserve<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-37"><a href="#cb4-37"></a> <span class="co">// Set the &#39;clip region&#39; to the inside of the path (fill region).</span></span>
<span id="cb4-38"><a href="#cb4-38"></a> cairo_clip<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-39"><a href="#cb4-39"></a></span>
<span id="cb4-40"><a href="#cb4-40"></a> <span class="co">// Clock ticks</span></span>
<span id="cb4-41"><a href="#cb4-41"></a> <span class="cf">for</span> <span class="op">(</span><span class="dt">int</span> i <span class="op">=</span> <span class="dv">0</span><span class="op">;</span> i <span class="op">&lt;</span> <span class="dv">12</span><span class="op">;</span> i<span class="op">++)</span></span>
<span id="cb4-42"><a href="#cb4-42"></a> <span class="op">{</span></span>
<span id="cb4-43"><a href="#cb4-43"></a> <span class="co">// Major tick size</span></span>
<span id="cb4-44"><a href="#cb4-44"></a> <span class="dt">double</span> inset <span class="op">=</span> <span class="fl">0.05</span><span class="op">;</span></span>
<span id="cb4-45"><a href="#cb4-45"></a></span>
<span id="cb4-46"><a href="#cb4-46"></a> <span class="co">// Save the graphics state, restore after drawing tick to maintain pen</span></span>
<span id="cb4-47"><a href="#cb4-47"></a> <span class="co">// size</span></span>
<span id="cb4-48"><a href="#cb4-48"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-49"><a href="#cb4-49"></a> cairo_set_line_cap<span class="op">(</span>cr<span class="op">,</span> CAIRO_LINE_CAP_ROUND<span class="op">);</span></span>
<span id="cb4-50"><a href="#cb4-50"></a></span>
<span id="cb4-51"><a href="#cb4-51"></a> <span class="co">// Minor ticks are shorter, and narrower.</span></span>
<span id="cb4-52"><a href="#cb4-52"></a> <span class="cf">if</span><span class="op">(</span>i <span class="op">%</span> <span class="dv">3</span> <span class="op">!=</span> <span class="dv">0</span><span class="op">)</span></span>
<span id="cb4-53"><a href="#cb4-53"></a> <span class="op">{</span></span>
<span id="cb4-54"><a href="#cb4-54"></a> inset <span class="op">*=</span> <span class="fl">0.8</span><span class="op">;</span></span>
<span id="cb4-55"><a href="#cb4-55"></a> cairo_set_line_width<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.03</span><span class="op">);</span></span>
<span id="cb4-56"><a href="#cb4-56"></a> <span class="op">}</span></span>
<span id="cb4-57"><a href="#cb4-57"></a></span>
<span id="cb4-58"><a href="#cb4-58"></a> <span class="co">// Draw tick mark</span></span>
<span id="cb4-59"><a href="#cb4-59"></a> cairo_move_to<span class="op">(</span></span>
<span id="cb4-60"><a href="#cb4-60"></a> cr<span class="op">,</span></span>
<span id="cb4-61"><a href="#cb4-61"></a> <span class="op">(</span>m_radius <span class="op">-</span> inset<span class="op">)</span> <span class="op">*</span> cos <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">),</span></span>
<span id="cb4-62"><a href="#cb4-62"></a> <span class="op">(</span>m_radius <span class="op">-</span> inset<span class="op">)</span> <span class="op">*</span> sin <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">));</span></span>
<span id="cb4-63"><a href="#cb4-63"></a> cairo_line_to<span class="op">(</span></span>
<span id="cb4-64"><a href="#cb4-64"></a> cr<span class="op">,</span></span>
<span id="cb4-65"><a href="#cb4-65"></a> m_radius <span class="op">*</span> cos <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">),</span></span>
<span id="cb4-66"><a href="#cb4-66"></a> m_radius <span class="op">*</span> sin <span class="op">(</span>i <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">));</span></span>
<span id="cb4-67"><a href="#cb4-67"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-68"><a href="#cb4-68"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span> <span class="co">/* stack-pen-size */</span></span>
<span id="cb4-69"><a href="#cb4-69"></a> <span class="op">}</span></span>
<span id="cb4-70"><a href="#cb4-70"></a></span>
<span id="cb4-71"><a href="#cb4-71"></a> <span class="co">// Draw the analog hands</span></span>
<span id="cb4-72"><a href="#cb4-72"></a></span>
<span id="cb4-73"><a href="#cb4-73"></a> <span class="co">// Get the current Unix time, convert to the local time and break into time</span></span>
<span id="cb4-74"><a href="#cb4-74"></a> <span class="co">// structure to read various time parts.</span></span>
<span id="cb4-75"><a href="#cb4-75"></a> <span class="dt">time_t</span> rawtime<span class="op">;</span></span>
<span id="cb4-76"><a href="#cb4-76"></a> time<span class="op">(&amp;</span>rawtime<span class="op">);</span></span>
<span id="cb4-77"><a href="#cb4-77"></a> <span class="kw">struct</span> tm <span class="op">*</span> timeinfo <span class="op">=</span> localtime <span class="op">(&amp;</span>rawtime<span class="op">);</span></span>
<span id="cb4-78"><a href="#cb4-78"></a></span>
<span id="cb4-79"><a href="#cb4-79"></a> <span class="co">// Calculate the angles of the hands of our clock</span></span>
<span id="cb4-80"><a href="#cb4-80"></a> <span class="dt">double</span> hours <span class="op">=</span> timeinfo<span class="op">-&gt;</span>tm_hour <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">6.0</span><span class="op">;</span></span>
<span id="cb4-81"><a href="#cb4-81"></a> <span class="dt">double</span> minutes <span class="op">=</span> timeinfo<span class="op">-&gt;</span>tm_min <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">30.0</span><span class="op">;</span></span>
<span id="cb4-82"><a href="#cb4-82"></a> <span class="dt">double</span> seconds <span class="op">=</span> timeinfo<span class="op">-&gt;</span>tm_sec <span class="op">*</span> M_PI <span class="op">/</span> <span class="fl">30.0</span><span class="op">;</span></span>
<span id="cb4-83"><a href="#cb4-83"></a></span>
<span id="cb4-84"><a href="#cb4-84"></a> <span class="co">// Save the graphics state</span></span>
<span id="cb4-85"><a href="#cb4-85"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-86"><a href="#cb4-86"></a> cairo_set_line_cap<span class="op">(</span>cr<span class="op">,</span> CAIRO_LINE_CAP_ROUND<span class="op">);</span></span>
<span id="cb4-87"><a href="#cb4-87"></a></span>
<span id="cb4-88"><a href="#cb4-88"></a> cairo_save<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-89"><a href="#cb4-89"></a></span>
<span id="cb4-90"><a href="#cb4-90"></a> <span class="co">// Draw the seconds hand</span></span>
<span id="cb4-91"><a href="#cb4-91"></a> cairo_set_line_width<span class="op">(</span>cr<span class="op">,</span> m_line_width <span class="op">/</span> <span class="fl">3.0</span><span class="op">);</span></span>
<span id="cb4-92"><a href="#cb4-92"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.7</span><span class="op">,</span> <span class="fl">0.7</span><span class="op">,</span> <span class="fl">0.7</span><span class="op">,</span> <span class="fl">0.8</span><span class="op">);</span> <span class="co">// gray</span></span>
<span id="cb4-93"><a href="#cb4-93"></a> cairo_move_to<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">);</span></span>
<span id="cb4-94"><a href="#cb4-94"></a> cairo_line_to<span class="op">(</span>cr<span class="op">,</span></span>
<span id="cb4-95"><a href="#cb4-95"></a> sin<span class="op">(</span>seconds<span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.9</span><span class="op">),</span></span>
<span id="cb4-96"><a href="#cb4-96"></a> <span class="op">-</span>cos<span class="op">(</span>seconds<span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.9</span><span class="op">));</span></span>
<span id="cb4-97"><a href="#cb4-97"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-98"><a href="#cb4-98"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-99"><a href="#cb4-99"></a></span>
<span id="cb4-100"><a href="#cb4-100"></a> <span class="co">// Draw the minutes hand</span></span>
<span id="cb4-101"><a href="#cb4-101"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.117</span><span class="op">,</span> <span class="fl">0.337</span><span class="op">,</span> <span class="fl">0.612</span><span class="op">,</span> <span class="fl">0.9</span><span class="op">);</span> <span class="co">// blue</span></span>
<span id="cb4-102"><a href="#cb4-102"></a> cairo_move_to<span class="op">(</span>cr<span class="op">,</span> <span class="dv">0</span><span class="op">,</span> <span class="dv">0</span><span class="op">);</span></span>
<span id="cb4-103"><a href="#cb4-103"></a> cairo_line_to<span class="op">(</span>cr<span class="op">,</span></span>
<span id="cb4-104"><a href="#cb4-104"></a> sin<span class="op">(</span>minutes <span class="op">+</span> seconds <span class="op">/</span> <span class="dv">60</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.8</span><span class="op">),</span></span>
<span id="cb4-105"><a href="#cb4-105"></a> <span class="op">-</span>cos<span class="op">(</span>minutes <span class="op">+</span> seconds <span class="op">/</span> <span class="dv">60</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.8</span><span class="op">));</span></span>
<span id="cb4-106"><a href="#cb4-106"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-107"><a href="#cb4-107"></a></span>
<span id="cb4-108"><a href="#cb4-108"></a> <span class="co">// draw the hours hand</span></span>
<span id="cb4-109"><a href="#cb4-109"></a> cairo_set_source_rgba<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.337</span><span class="op">,</span> <span class="fl">0.612</span><span class="op">,</span> <span class="fl">0.117</span><span class="op">,</span> <span class="fl">0.9</span><span class="op">);</span> <span class="co">// green</span></span>
<span id="cb4-110"><a href="#cb4-110"></a> cairo_move_to<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">);</span></span>
<span id="cb4-111"><a href="#cb4-111"></a> cairo_line_to<span class="op">(</span>cr<span class="op">,</span></span>
<span id="cb4-112"><a href="#cb4-112"></a> sin<span class="op">(</span>hours <span class="op">+</span> minutes <span class="op">/</span> <span class="fl">12.0</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.5</span><span class="op">),</span></span>
<span id="cb4-113"><a href="#cb4-113"></a> <span class="op">-</span>cos<span class="op">(</span>hours <span class="op">+</span> minutes <span class="op">/</span> <span class="fl">12.0</span><span class="op">)</span> <span class="op">*</span> <span class="op">(</span>m_radius <span class="op">*</span> <span class="fl">0.5</span><span class="op">));</span></span>
<span id="cb4-114"><a href="#cb4-114"></a> cairo_stroke<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-115"><a href="#cb4-115"></a> cairo_restore<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-116"><a href="#cb4-116"></a></span>
<span id="cb4-117"><a href="#cb4-117"></a> <span class="co">// Draw a little dot in the middle</span></span>
<span id="cb4-118"><a href="#cb4-118"></a> cairo_arc<span class="op">(</span>cr<span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> m_line_width <span class="op">/</span> <span class="fl">3.0</span><span class="op">,</span> <span class="fl">0.0</span><span class="op">,</span> <span class="fl">2.0</span> <span class="op">*</span> M_PI<span class="op">);</span></span>
<span id="cb4-119"><a href="#cb4-119"></a> cairo_fill<span class="op">(</span>cr<span class="op">);</span></span>
<span id="cb4-120"><a href="#cb4-120"></a><span class="op">}</span></span>
<span id="cb4-121"><a href="#cb4-121"></a></span>
<span id="cb4-122"><a href="#cb4-122"></a></span>
<span id="cb4-123"><a href="#cb4-123"></a>gboolean</span>
<span id="cb4-124"><a href="#cb4-124"></a>time_handler<span class="op">(</span>GtkWidget<span class="op">*</span> widget<span class="op">)</span> <span class="op">{</span></span>
<span id="cb4-125"><a href="#cb4-125"></a> gtk_widget_queue_draw<span class="op">(</span>widget<span class="op">);</span></span>
<span id="cb4-126"><a href="#cb4-126"></a></span>
<span id="cb4-127"><a href="#cb4-127"></a> <span class="cf">return</span> TRUE<span class="op">;</span></span>
<span id="cb4-128"><a href="#cb4-128"></a><span class="op">}</span></span>
<span id="cb4-129"><a href="#cb4-129"></a></span>
<span id="cb4-130"><a href="#cb4-130"></a></span>
<span id="cb4-131"><a href="#cb4-131"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb4-132"><a href="#cb4-132"></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="cb4-133"><a href="#cb4-133"></a> GtkWidget <span class="op">*</span>win<span class="op">;</span></span>
<span id="cb4-134"><a href="#cb4-134"></a> GtkWidget <span class="op">*</span>clock<span class="op">;</span></span>
<span id="cb4-135"><a href="#cb4-135"></a> GtkBuilder <span class="op">*</span>build<span class="op">;</span></span>
<span id="cb4-136"><a href="#cb4-136"></a></span>
<span id="cb4-137"><a href="#cb4-137"></a> build <span class="op">=</span> gtk_builder_new_from_resource <span class="op">(</span><span class="st">&quot;/com/github/ToshioCP/tfc/tfc.ui&quot;</span><span class="op">);</span></span>
<span id="cb4-138"><a href="#cb4-138"></a> win <span class="op">=</span> GTK_WIDGET <span class="op">(</span>gtk_builder_get_object <span class="op">(</span>build<span class="op">,</span> <span class="st">&quot;win&quot;</span><span class="op">));</span></span>
<span id="cb4-139"><a href="#cb4-139"></a> gtk_window_set_application <span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">),</span> GTK_APPLICATION <span class="op">(</span>app<span class="op">));</span></span>
<span id="cb4-140"><a href="#cb4-140"></a></span>
<span id="cb4-141"><a href="#cb4-141"></a> clock <span class="op">=</span> GTK_WIDGET <span class="op">(</span>gtk_builder_get_object <span class="op">(</span>build<span class="op">,</span> <span class="st">&quot;clock&quot;</span><span class="op">));</span></span>
<span id="cb4-142"><a href="#cb4-142"></a> g_object_unref<span class="op">(</span>build<span class="op">);</span></span>
<span id="cb4-143"><a href="#cb4-143"></a></span>
<span id="cb4-144"><a href="#cb4-144"></a> gtk_drawing_area_set_draw_func<span class="op">(</span>GTK_DRAWING_AREA <span class="op">(</span>clock<span class="op">),</span> draw_clock<span class="op">,</span> NULL<span class="op">,</span> NULL<span class="op">);</span></span>
<span id="cb4-145"><a href="#cb4-145"></a> g_timeout_add<span class="op">(</span><span class="dv">1000</span><span class="op">,</span> <span class="op">(</span>GSourceFunc<span class="op">)</span> time_handler<span class="op">,</span> <span class="op">(</span>gpointer<span class="op">)</span> clock<span class="op">);</span></span>
<span id="cb4-146"><a href="#cb4-146"></a> gtk_widget_show<span class="op">(</span>win<span class="op">);</span></span>
<span id="cb4-147"><a href="#cb4-147"></a></span>
<span id="cb4-148"><a href="#cb4-148"></a><span class="op">}</span></span>
<span id="cb4-149"><a href="#cb4-149"></a></span>
<span id="cb4-150"><a href="#cb4-150"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb4-151"><a href="#cb4-151"></a>app_open <span class="op">(</span>GApplication <span class="op">*</span>app<span class="op">,</span> GFile <span class="op">**</span>files<span class="op">,</span> gint n_files<span class="op">,</span> gchar <span class="op">*</span>hint<span class="op">,</span> gpointer user_data<span class="op">)</span> <span class="op">{</span></span>
<span id="cb4-152"><a href="#cb4-152"></a> app_activate<span class="op">(</span>app<span class="op">,</span>user_data<span class="op">);</span></span>
<span id="cb4-153"><a href="#cb4-153"></a><span class="op">}</span></span>
<span id="cb4-154"><a href="#cb4-154"></a></span>
<span id="cb4-155"><a href="#cb4-155"></a><span class="dt">int</span></span>
<span id="cb4-156"><a href="#cb4-156"></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="cb4-157"><a href="#cb4-157"></a> GtkApplication <span class="op">*</span>app<span class="op">;</span></span>
<span id="cb4-158"><a href="#cb4-158"></a> <span class="dt">int</span> stat<span class="op">;</span></span>
<span id="cb4-159"><a href="#cb4-159"></a></span>
<span id="cb4-160"><a href="#cb4-160"></a> app <span class="op">=</span> gtk_application_new <span class="op">(</span><span class="st">&quot;com.github.ToshioCP.tfc&quot;</span><span class="op">,</span> G_APPLICATION_HANDLES_OPEN<span class="op">);</span></span>
<span id="cb4-161"><a href="#cb4-161"></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="cb4-162"><a href="#cb4-162"></a> g_signal_connect <span class="op">(</span>app<span class="op">,</span> <span class="st">&quot;open&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>app_open<span class="op">),</span> NULL<span class="op">);</span></span>
<span id="cb4-163"><a href="#cb4-163"></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="cb4-164"><a href="#cb4-164"></a> g_object_unref <span class="op">(</span>app<span class="op">);</span></span>
<span id="cb4-165"><a href="#cb4-165"></a> <span class="cf">return</span> stat<span class="op">;</span></span>
<span id="cb4-166"><a href="#cb4-166"></a><span class="op">}</span></span></code></pre></div>
<p><code>tfc.ui</code></p>
<div class="sourceCode" id="cb5"><pre
class="sourceCode numberSource xml numberLines"><code class="sourceCode xml"><span id="cb5-1"><a href="#cb5-1"></a><span class="fu">&lt;?xml</span><span class="ot"> version=</span><span class="st">&quot;1.0&quot;</span><span class="ot"> encoding=</span><span class="st">&quot;UTF-8&quot;</span><span class="fu">?&gt;</span></span>
<span id="cb5-2"><a href="#cb5-2"></a>&lt;<span class="kw">interface</span>&gt;</span>
<span id="cb5-3"><a href="#cb5-3"></a> &lt;<span class="kw">object</span><span class="ot"> class=</span><span class="st">&quot;GtkApplicationWindow&quot;</span><span class="ot"> id=</span><span class="st">&quot;win&quot;</span>&gt;</span>
<span id="cb5-4"><a href="#cb5-4"></a> &lt;<span class="kw">property</span><span class="ot"> name=</span><span class="st">&quot;title&quot;</span>&gt;Clock&lt;/<span class="kw">property</span>&gt;</span>
<span id="cb5-5"><a href="#cb5-5"></a> &lt;<span class="kw">property</span><span class="ot"> name=</span><span class="st">&quot;default-width&quot;</span>&gt;200&lt;/<span class="kw">property</span>&gt;</span>
<span id="cb5-6"><a href="#cb5-6"></a> &lt;<span class="kw">property</span><span class="ot"> name=</span><span class="st">&quot;default-height&quot;</span>&gt;200&lt;/<span class="kw">property</span>&gt;</span>
<span id="cb5-7"><a href="#cb5-7"></a> &lt;<span class="kw">child</span>&gt;</span>
<span id="cb5-8"><a href="#cb5-8"></a> &lt;<span class="kw">object</span><span class="ot"> class=</span><span class="st">&quot;GtkDrawingArea&quot;</span><span class="ot"> id=</span><span class="st">&quot;clock&quot;</span>&gt;</span>
<span id="cb5-9"><a href="#cb5-9"></a> &lt;<span class="kw">property</span><span class="ot"> name=</span><span class="st">&quot;hexpand&quot;</span>&gt;TRUE&lt;/<span class="kw">property</span>&gt;</span>
<span id="cb5-10"><a href="#cb5-10"></a> &lt;<span class="kw">property</span><span class="ot"> name=</span><span class="st">&quot;vexpand&quot;</span>&gt;TRUE&lt;/<span class="kw">property</span>&gt;</span>
<span id="cb5-11"><a href="#cb5-11"></a> &lt;/<span class="kw">object</span>&gt;</span>
<span id="cb5-12"><a href="#cb5-12"></a> &lt;/<span class="kw">child</span>&gt;</span>
<span id="cb5-13"><a href="#cb5-13"></a> &lt;/<span class="kw">object</span>&gt;</span>
<span id="cb5-14"><a href="#cb5-14"></a>&lt;/<span class="kw">interface</span>&gt;</span></code></pre></div>
<p><code>tfc.gresource.xml</code></p>
<div class="sourceCode" id="cb6"><pre
class="sourceCode numberSource xml numberLines"><code class="sourceCode xml"><span id="cb6-1"><a href="#cb6-1"></a><span class="fu">&lt;?xml</span><span class="ot"> version=</span><span class="st">&quot;1.0&quot;</span><span class="ot"> encoding=</span><span class="st">&quot;UTF-8&quot;</span><span class="fu">?&gt;</span></span>
<span id="cb6-2"><a href="#cb6-2"></a>&lt;<span class="kw">gresources</span>&gt;</span>
<span id="cb6-3"><a href="#cb6-3"></a> &lt;<span class="kw">gresource</span><span class="ot"> prefix=</span><span class="st">&quot;/com/github/ToshioCP/tfc&quot;</span>&gt;</span>
<span id="cb6-4"><a href="#cb6-4"></a> &lt;<span class="kw">file</span>&gt;tfc.ui&lt;/<span class="kw">file</span>&gt;</span>
<span id="cb6-5"><a href="#cb6-5"></a> &lt;/<span class="kw">gresource</span>&gt;</span>
<span id="cb6-6"><a href="#cb6-6"></a>&lt;/<span class="kw">gresources</span>&gt;</span></code></pre></div>
<p><code>comp</code></p>
<div class="sourceCode" id="cb7"><pre
class="sourceCode numberSource numberLines"><code class="sourceCode"><span id="cb7-1"><a href="#cb7-1"></a>glib-compile-resources $1.gresource.xml --target=$1.gresource.c --generate-source</span>
<span id="cb7-2"><a href="#cb7-2"></a>gcc `pkg-config --cflags gtk4` $1.gresource.c $1.c `pkg-config --libs gtk4` -lm</span></code></pre></div>
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