evo/Gtk4-tutorial: GTK 4 tutorial for beginners

docs/sec14.html
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Toshio Sekiya
Update section 1-16. Some bugs are fixed.
21 дек 2022, 16:31
21 дек 2022, 16:31fe3fba6
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<h1 id="functions-in-gtknotebook">Functions in GtkNotebook</h1>
<p>GtkNotebook is a very important object in the text file editor
<code>tfe</code>. It connects the application and TfeTextView objects. A
set of public functions are declared in <code>tfenotebook.h</code>. The
word “tfenotebook” is used only in filenames. There’s no “TfeNotebook”
object.</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">void</span></span>
<span id="cb1-2"><a href="#cb1-2"></a>notebook_page_save<span class="op">(</span>GtkNotebook <span class="op">*</span>nb<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="dt">void</span></span>
<span id="cb1-5"><a href="#cb1-5"></a>notebook_page_close <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">);</span></span>
<span id="cb1-6"><a href="#cb1-6"></a></span>
<span id="cb1-7"><a href="#cb1-7"></a><span class="dt">void</span></span>
<span id="cb1-8"><a href="#cb1-8"></a>notebook_page_open <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">);</span></span>
<span id="cb1-9"><a href="#cb1-9"></a></span>
<span id="cb1-10"><a href="#cb1-10"></a><span class="dt">void</span></span>
<span id="cb1-11"><a href="#cb1-11"></a>notebook_page_new_with_file <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">,</span> GFile <span class="op">*</span>file<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="dt">void</span></span>
<span id="cb1-14"><a href="#cb1-14"></a>notebook_page_new <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">);</span></span></code></pre></div>
<p>This header file describes the public functions in
<code>tfenotebook.c</code>.</p>
<ul>
<li>1-2: <code>notebook_page_save</code> saves the current page to the
file of which the name specified in the tab. If the name is
<code>untitled</code> or <code>untitled</code> followed by digits,
FileChooserDialog appears and a user can choose or specify a
filename.</li>
<li>4-5: <code>notebook_page_close</code> closes the current page.</li>
<li>7-8: <code>notebook_page_open</code> shows a file chooser dialog and
a user can choose a file. The file is inserted to a new page.</li>
<li>10-11: <code>notebook_page_new_with_file</code> creates a new page
and a file given as an argument is read and inserted into the page.</li>
<li>13-14: <code>notebook_page_new</code> creates a new empty page.</li>
</ul>
<p>You probably find that the functions except
<code>notebook_page_close</code> are higher level functions of</p>
<ul>
<li><code>tfe_text_view_save</code></li>
<li><code>tef_text_view_open</code></li>
<li><code>tfe_text_view_new_with_file</code></li>
<li><code>tfe_text_view_new</code></li>
</ul>
<p>respectively.</p>
<p>There are two layers. One of them is <code>tfe_text_view ...</code>,
which is the lower level layer. The other is <code>note_book ...</code>,
which is the higher level layer.</p>
<p>Now let’s look at the program of each function.</p>
<h2 id="notebook_page_new">notebook_page_new</h2>
<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">char</span><span class="op">*</span></span>
<span id="cb2-2"><a href="#cb2-2"></a>get_untitled <span class="op">()</span> <span class="op">{</span></span>
<span id="cb2-3"><a href="#cb2-3"></a>  <span class="dt">static</span> <span class="dt">int</span> c <span class="op">=</span> <span class="op">-</span><span class="dv">1</span><span class="op">;</span></span>
<span id="cb2-4"><a href="#cb2-4"></a>  <span class="cf">if</span> <span class="op">(++</span>c <span class="op">==</span> <span class="dv">0</span><span class="op">)</span> </span>
<span id="cb2-5"><a href="#cb2-5"></a>    <span class="cf">return</span> g_strdup_printf<span class="op">(</span><span class="st">&quot;Untitled&quot;</span><span class="op">);</span></span>
<span id="cb2-6"><a href="#cb2-6"></a>  <span class="cf">else</span></span>
<span id="cb2-7"><a href="#cb2-7"></a>    <span class="cf">return</span> g_strdup_printf <span class="op">(</span><span class="st">&quot;Untitled%u&quot;</span><span class="op">,</span> c<span class="op">);</span></span>
<span id="cb2-8"><a href="#cb2-8"></a><span class="op">}</span></span>
<span id="cb2-9"><a href="#cb2-9"></a></span>
<span id="cb2-10"><a href="#cb2-10"></a><span class="dt">static</span> <span class="dt">void</span></span>
<span id="cb2-11"><a href="#cb2-11"></a>notebook_page_build <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">,</span> GtkWidget <span class="op">*</span>tv<span class="op">,</span> <span class="dt">const</span> <span class="dt">char</span> <span class="op">*</span>filename<span class="op">)</span> <span class="op">{</span></span>
<span id="cb2-12"><a href="#cb2-12"></a>  GtkWidget <span class="op">*</span>scr <span class="op">=</span> gtk_scrolled_window_new <span class="op">();</span></span>
<span id="cb2-13"><a href="#cb2-13"></a>  GtkNotebookPage <span class="op">*</span>nbp<span class="op">;</span></span>
<span id="cb2-14"><a href="#cb2-14"></a>  GtkWidget <span class="op">*</span>lab<span class="op">;</span></span>
<span id="cb2-15"><a href="#cb2-15"></a>  <span class="dt">int</span> i<span class="op">;</span></span>
<span id="cb2-16"><a href="#cb2-16"></a></span>
<span id="cb2-17"><a href="#cb2-17"></a>  gtk_scrolled_window_set_child <span class="op">(</span>GTK_SCROLLED_WINDOW <span class="op">(</span>scr<span class="op">),</span> tv<span class="op">);</span></span>
<span id="cb2-18"><a href="#cb2-18"></a>  lab <span class="op">=</span> gtk_label_new <span class="op">(</span>filename<span class="op">);</span></span>
<span id="cb2-19"><a href="#cb2-19"></a>  i <span class="op">=</span> gtk_notebook_append_page <span class="op">(</span>nb<span class="op">,</span> scr<span class="op">,</span> lab<span class="op">);</span></span>
<span id="cb2-20"><a href="#cb2-20"></a>  nbp <span class="op">=</span> gtk_notebook_get_page <span class="op">(</span>nb<span class="op">,</span> scr<span class="op">);</span></span>
<span id="cb2-21"><a href="#cb2-21"></a>  g_object_set <span class="op">(</span>nbp<span class="op">,</span> <span class="st">&quot;tab-expand&quot;</span><span class="op">,</span> TRUE<span class="op">,</span> NULL<span class="op">);</span></span>
<span id="cb2-22"><a href="#cb2-22"></a>  gtk_notebook_set_current_page <span class="op">(</span>nb<span class="op">,</span> i<span class="op">);</span></span>
<span id="cb2-23"><a href="#cb2-23"></a>  g_signal_connect <span class="op">(</span>GTK_TEXT_VIEW <span class="op">(</span>tv<span class="op">),</span> <span class="st">&quot;change-file&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>file_changed_cb<span class="op">),</span> nb<span class="op">);</span></span>
<span id="cb2-24"><a href="#cb2-24"></a><span class="op">}</span></span>
<span id="cb2-25"><a href="#cb2-25"></a></span>
<span id="cb2-26"><a href="#cb2-26"></a><span class="dt">void</span></span>
<span id="cb2-27"><a href="#cb2-27"></a>notebook_page_new <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb2-28"><a href="#cb2-28"></a>  g_return_if_fail<span class="op">(</span>GTK_IS_NOTEBOOK <span class="op">(</span>nb<span class="op">));</span></span>
<span id="cb2-29"><a href="#cb2-29"></a></span>
<span id="cb2-30"><a href="#cb2-30"></a>  GtkWidget <span class="op">*</span>tv<span class="op">;</span></span>
<span id="cb2-31"><a href="#cb2-31"></a>  <span class="dt">char</span> <span class="op">*</span>filename<span class="op">;</span></span>
<span id="cb2-32"><a href="#cb2-32"></a></span>
<span id="cb2-33"><a href="#cb2-33"></a>  <span class="cf">if</span> <span class="op">((</span>tv <span class="op">=</span> tfe_text_view_new <span class="op">())</span> <span class="op">==</span> NULL<span class="op">)</span></span>
<span id="cb2-34"><a href="#cb2-34"></a>    <span class="cf">return</span><span class="op">;</span></span>
<span id="cb2-35"><a href="#cb2-35"></a>  filename <span class="op">=</span> get_untitled <span class="op">();</span></span>
<span id="cb2-36"><a href="#cb2-36"></a>  notebook_page_build <span class="op">(</span>nb<span class="op">,</span> tv<span class="op">,</span> filename<span class="op">);</span></span>
<span id="cb2-37"><a href="#cb2-37"></a>  g_free <span class="op">(</span>filename<span class="op">);</span></span>
<span id="cb2-38"><a href="#cb2-38"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>26-38: <code>notebook_page_new</code> function.</li>
<li>28: <code>g_return_if_fail</code> is used to check the
argument.</li>
<li>33-34: Creates TfeTextView object. If it fails, no notebook page is
created and the function returns to the caller.</li>
<li>35: Creates filename, which is “Untitled”, “Untitled1”, … .</li>
<li>1-8: <code>get_untitled</code> function.</li>
<li>3: Static variable <code>c</code> is initialized at the first call
of this function. After that <code>c</code> keeps its value unless it is
changed explicitly.</li>
<li>4-7: Increases <code>c</code> by one and if it is zero, it returns
“Untitled”. If it is a positive integer, it returns “Untitled&lt;the
integer&gt;”, for example, “Untitled1”, “Untitled2”, and so on. The
function <code>g_strdup_printf</code> creates a string and it should be
freed by <code>g_free</code> when it becomes useless. The caller of
<code>get_untitled</code> is in charge of freeing the string.</li>
<li>36: calls <code>notebook_page_build</code> to build the contents of
the page.</li>
<li>37: frees <code>filename</code>.</li>
<li>10- 24: <code>notebook_page_build</code> function. A parameter with
<code>const</code> qualifier doesn’t change in the function. It means
that the argument <code>filename</code> is owned by the caller. The
caller needs to free it when it becomes useless.</li>
<li>12: Creates GtkScrolledWindow.</li>
<li>17: Inserts <code>tv</code> to GtkscrolledWindow as a child.</li>
<li>18-19: Creates GtkLabel, then appends <code>scr</code> and
<code>lab</code> to the GtkNotebook instance <code>nb</code>.</li>
<li>20-21: Sets “tab-expand” property to TRUE. The function
<code>g_object_set</code> sets properties on an object. The object is
any object derived from GObject. In many cases, an object has its own
function to set its properties, but sometimes not. In that case, use
<code>g_object_set</code> to set the property.</li>
<li>22: Sets the current page to the newly created page.</li>
<li>23: Connects “change-file” signal and <code>file_changed_cb</code>
handler.</li>
</ul>
<h2 id="notebook_page_new_with_file">notebook_page_new_with_file</h2>
<div class="sourceCode" id="cb3"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb3-1"><a href="#cb3-1"></a><span class="dt">void</span></span>
<span id="cb3-2"><a href="#cb3-2"></a>notebook_page_new_with_file <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">,</span> GFile <span class="op">*</span>file<span class="op">)</span> <span class="op">{</span></span>
<span id="cb3-3"><a href="#cb3-3"></a>  g_return_if_fail<span class="op">(</span>GTK_IS_NOTEBOOK <span class="op">(</span>nb<span class="op">));</span></span>
<span id="cb3-4"><a href="#cb3-4"></a>  g_return_if_fail<span class="op">(</span>G_IS_FILE <span class="op">(</span>file<span class="op">));</span></span>
<span id="cb3-5"><a href="#cb3-5"></a></span>
<span id="cb3-6"><a href="#cb3-6"></a>  GtkWidget <span class="op">*</span>tv<span class="op">;</span></span>
<span id="cb3-7"><a href="#cb3-7"></a>  <span class="dt">char</span> <span class="op">*</span>filename<span class="op">;</span></span>
<span id="cb3-8"><a href="#cb3-8"></a></span>
<span id="cb3-9"><a href="#cb3-9"></a>  <span class="cf">if</span> <span class="op">((</span>tv <span class="op">=</span> tfe_text_view_new_with_file <span class="op">(</span>file<span class="op">))</span> <span class="op">==</span> NULL<span class="op">)</span></span>
<span id="cb3-10"><a href="#cb3-10"></a>    <span class="cf">return</span><span class="op">;</span> <span class="co">/* read error */</span></span>
<span id="cb3-11"><a href="#cb3-11"></a>  filename <span class="op">=</span> g_file_get_basename <span class="op">(</span>file<span class="op">);</span></span>
<span id="cb3-12"><a href="#cb3-12"></a>  notebook_page_build <span class="op">(</span>nb<span class="op">,</span> tv<span class="op">,</span> filename<span class="op">);</span></span>
<span id="cb3-13"><a href="#cb3-13"></a>  g_free <span class="op">(</span>filename<span class="op">);</span></span>
<span id="cb3-14"><a href="#cb3-14"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>9-10: Calls <code>tfe_text_view_new_with_file</code>. If the
function returns NULL, an error has happend. Then, it does nothing and
returns.</li>
<li>11-13: Gets the filename, builds the contents of the page and frees
<code>filename</code>.</li>
</ul>
<h2 id="notebook_page_open">notebook_page_open</h2>
<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="dt">static</span> <span class="dt">void</span></span>
<span id="cb4-2"><a href="#cb4-2"></a>open_response <span class="op">(</span>TfeTextView <span class="op">*</span>tv<span class="op">,</span> <span class="dt">int</span> response<span class="op">,</span> GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb4-3"><a href="#cb4-3"></a>  GFile <span class="op">*</span>file<span class="op">;</span></span>
<span id="cb4-4"><a href="#cb4-4"></a>  <span class="dt">char</span> <span class="op">*</span>filename<span class="op">;</span></span>
<span id="cb4-5"><a href="#cb4-5"></a></span>
<span id="cb4-6"><a href="#cb4-6"></a>  <span class="cf">if</span> <span class="op">(</span>response <span class="op">!=</span> TFE_OPEN_RESPONSE_SUCCESS<span class="op">)</span> <span class="op">{</span></span>
<span id="cb4-7"><a href="#cb4-7"></a>    g_object_ref_sink <span class="op">(</span>tv<span class="op">);</span></span>
<span id="cb4-8"><a href="#cb4-8"></a>    g_object_unref <span class="op">(</span>tv<span class="op">);</span></span>
<span id="cb4-9"><a href="#cb4-9"></a>  <span class="op">}</span><span class="cf">else</span> <span class="op">{</span></span>
<span id="cb4-10"><a href="#cb4-10"></a>    file <span class="op">=</span> tfe_text_view_get_file <span class="op">(</span>tv<span class="op">);</span></span>
<span id="cb4-11"><a href="#cb4-11"></a>    filename <span class="op">=</span> g_file_get_basename <span class="op">(</span>file<span class="op">);</span></span>
<span id="cb4-12"><a href="#cb4-12"></a>    g_object_unref <span class="op">(</span>file<span class="op">);</span></span>
<span id="cb4-13"><a href="#cb4-13"></a>    notebook_page_build <span class="op">(</span>nb<span class="op">,</span> GTK_WIDGET <span class="op">(</span>tv<span class="op">),</span> filename<span class="op">);</span></span>
<span id="cb4-14"><a href="#cb4-14"></a>    g_free <span class="op">(</span>filename<span class="op">);</span></span>
<span id="cb4-15"><a href="#cb4-15"></a>  <span class="op">}</span></span>
<span id="cb4-16"><a href="#cb4-16"></a><span class="op">}</span></span>
<span id="cb4-17"><a href="#cb4-17"></a></span>
<span id="cb4-18"><a href="#cb4-18"></a><span class="dt">void</span></span>
<span id="cb4-19"><a href="#cb4-19"></a>notebook_page_open <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb4-20"><a href="#cb4-20"></a>  g_return_if_fail<span class="op">(</span>GTK_IS_NOTEBOOK <span class="op">(</span>nb<span class="op">));</span></span>
<span id="cb4-21"><a href="#cb4-21"></a></span>
<span id="cb4-22"><a href="#cb4-22"></a>  GtkWidget <span class="op">*</span>tv<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="cf">if</span> <span class="op">((</span>tv <span class="op">=</span> tfe_text_view_new <span class="op">())</span> <span class="op">==</span> NULL<span class="op">)</span></span>
<span id="cb4-25"><a href="#cb4-25"></a>    <span class="cf">return</span><span class="op">;</span></span>
<span id="cb4-26"><a href="#cb4-26"></a>  g_signal_connect <span class="op">(</span>TFE_TEXT_VIEW <span class="op">(</span>tv<span class="op">),</span> <span class="st">&quot;open-response&quot;</span><span class="op">,</span> G_CALLBACK <span class="op">(</span>open_response<span class="op">),</span> nb<span class="op">);</span></span>
<span id="cb4-27"><a href="#cb4-27"></a>  tfe_text_view_open <span class="op">(</span>TFE_TEXT_VIEW <span class="op">(</span>tv<span class="op">),</span> GTK_WINDOW <span class="op">(</span>gtk_widget_get_ancestor <span class="op">(</span>GTK_WIDGET <span class="op">(</span>nb<span class="op">),</span> GTK_TYPE_WINDOW<span class="op">)));</span></span>
<span id="cb4-28"><a href="#cb4-28"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>18-28: <code>notebook_page_open</code> function.</li>
<li>24-25: Creates TfeTextView object. If NULL is returned, an error has
happened. Then, it returns to the caller.</li>
<li>26: Connects the signal “open-response” and the handler
<code>open_response</code>.</li>
<li>27: Calls <code>tfe_text_view_open</code>. The “open-response”
signal will be emitted later to inform the result of opening and reading
a file.</li>
<li>1-16: <code>open_response</code> handler.</li>
<li>6-8: If the response code is not
<code>TFE_OPEN_RESPONSE_SUCCESS</code>, it has failed to open and read a
new file. Then, what <code>notebook_page_open</code> did in advance need
to be canceled. The instance <code>tv</code> hasn’t been a child widget
of GtkScrolledWindow yet. Such instance has floating reference. Floating
reference will be explained later. You need to call
<code>g_object_ref_sink</code> first. Then the floating reference is
converted into an ordinary reference. Now you call
<code>g_object_unref</code> to decrease the reference count by one.</li>
<li>9-15: Otherwise, everything is okay. Gets the filename, builds the
contents of the page and frees <code>filename</code>.</li>
</ul>
<h2 id="floating-reference">Floating reference</h2>
<p>All the widgets are derived from GInitiallyUnowned. GObject and
GInitiallyUnowned are almost the same. The difference is like this. When
an instance of GInitiallyUnowned is created, the instance has a floating
reference and its reference count is zero. On the other hand, when an
instance of GObject (not GInitiallyUnowned) is created, no floating
reference is given. And the instance has a normal reference count
instead of floating reference. Their descendants inherits them, so every
widget has a floating reference at first. Non-widget class, for example,
GtkTextBuffer is a direct sub class of GObject and it doesn’t have
floating reference. Its reference count is one when it is created.</p>
<p>The function <code>g_object_ref_sink</code> converts the floating
reference into an ordinary reference. If the instance doesn’t have a
floating reference, <code>g_object_ref_sink</code> simply increases the
reference count by one. It is used when an widget is added to another
widget as a child.</p>
<pre><code>GtkTextView *tv = gtk_text_view_new (); // floating reference
GtkScrolledWindow *scr = gtk_scrolled_window_new ();
gtk_scrolled_window_set_child (scr, tv); // tv&#39;s reference count is one</code></pre>
<p>When <code>tv</code> is added to <code>scr</code> as a child,
<code>g_object_ref_sink</code> is used.</p>
<pre><code>g_object_ref_sink (tv);</code></pre>
<p>So, the floating reference is converted into an ordinary reference.
That is to say, floating reference is deleted, and reference count turns
to one. Thanks to this, the caller doesn’t need to decrease tv’s
reference count. If an Object_A is not a descendant of
GInitiallyUnowned, the program is like this:</p>
<pre><code>Object_A *obj_a = object_a_new (); // reference count is one
GtkScrolledWindow *scr = gtk_scrolled_window_new ();
gtk_scrolled_window_set_child (scr, obj_a); // obj_a&#39;s reference count is two
// obj_a is referred by the caller (this program) and scrolled window
g_object_unref (obj_a); // obj_a&#39;s reference count is one because the caller no longer refers obj_a.</code></pre>
<p>This example tells us that the caller needs to unref
<code>obj_a</code>.</p>
<p>If you use <code>g_object_unref</code> to an instance that has a
floating reference, you need to convert the floating reference to a
normal reference in advance. See <a
href="https://docs.gtk.org/gobject/floating-refs.html">GObject API
reference</a> for further information.</p>
<h2 id="notebook_page_close">notebook_page_close</h2>
<div class="sourceCode" id="cb8"><pre
class="sourceCode numberSource C numberLines"><code class="sourceCode c"><span id="cb8-1"><a href="#cb8-1"></a><span class="dt">void</span></span>
<span id="cb8-2"><a href="#cb8-2"></a>notebook_page_close <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb8-3"><a href="#cb8-3"></a>  g_return_if_fail<span class="op">(</span>GTK_IS_NOTEBOOK <span class="op">(</span>nb<span class="op">));</span></span>
<span id="cb8-4"><a href="#cb8-4"></a></span>
<span id="cb8-5"><a href="#cb8-5"></a>  GtkWidget <span class="op">*</span>win<span class="op">;</span></span>
<span id="cb8-6"><a href="#cb8-6"></a>  <span class="dt">int</span> i<span class="op">;</span></span>
<span id="cb8-7"><a href="#cb8-7"></a></span>
<span id="cb8-8"><a href="#cb8-8"></a>  <span class="cf">if</span> <span class="op">(</span>gtk_notebook_get_n_pages <span class="op">(</span>nb<span class="op">)</span> <span class="op">==</span> <span class="dv">1</span><span class="op">)</span> <span class="op">{</span></span>
<span id="cb8-9"><a href="#cb8-9"></a>    win <span class="op">=</span> gtk_widget_get_ancestor <span class="op">(</span>GTK_WIDGET <span class="op">(</span>nb<span class="op">),</span> GTK_TYPE_WINDOW<span class="op">);</span></span>
<span id="cb8-10"><a href="#cb8-10"></a>    gtk_window_destroy<span class="op">(</span>GTK_WINDOW <span class="op">(</span>win<span class="op">));</span></span>
<span id="cb8-11"><a href="#cb8-11"></a>  <span class="op">}</span> <span class="cf">else</span> <span class="op">{</span></span>
<span id="cb8-12"><a href="#cb8-12"></a>    i <span class="op">=</span> gtk_notebook_get_current_page <span class="op">(</span>nb<span class="op">);</span></span>
<span id="cb8-13"><a href="#cb8-13"></a>    gtk_notebook_remove_page <span class="op">(</span>GTK_NOTEBOOK <span class="op">(</span>nb<span class="op">),</span> i<span class="op">);</span></span>
<span id="cb8-14"><a href="#cb8-14"></a>  <span class="op">}</span></span>
<span id="cb8-15"><a href="#cb8-15"></a><span class="op">}</span></span></code></pre></div>
<p>This function closes the current page. If the page is the only page
the notebook has, then the function destroys the top-level window and
quits the application.</p>
<ul>
<li>8-10: If the page is the only page the notebook has, it calls
<code>gtk_window_destroy</code> to destroys the top-level window.</li>
<li>11-13: Otherwise, removes the current page. The child widget
(TfeTextView) is also destroyed.</li>
</ul>
<h2 id="notebook_page_save">notebook_page_save</h2>
<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="dt">static</span> TfeTextView <span class="op">*</span></span>
<span id="cb9-2"><a href="#cb9-2"></a>get_current_textview <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb9-3"><a href="#cb9-3"></a>  <span class="dt">int</span> i<span class="op">;</span></span>
<span id="cb9-4"><a href="#cb9-4"></a>  GtkWidget <span class="op">*</span>scr<span class="op">;</span></span>
<span id="cb9-5"><a href="#cb9-5"></a>  GtkWidget <span class="op">*</span>tv<span class="op">;</span></span>
<span id="cb9-6"><a href="#cb9-6"></a></span>
<span id="cb9-7"><a href="#cb9-7"></a>  i <span class="op">=</span> gtk_notebook_get_current_page <span class="op">(</span>nb<span class="op">);</span></span>
<span id="cb9-8"><a href="#cb9-8"></a>  scr <span class="op">=</span> gtk_notebook_get_nth_page <span class="op">(</span>nb<span class="op">,</span> i<span class="op">);</span></span>
<span id="cb9-9"><a href="#cb9-9"></a>  tv <span class="op">=</span> gtk_scrolled_window_get_child <span class="op">(</span>GTK_SCROLLED_WINDOW <span class="op">(</span>scr<span class="op">));</span></span>
<span id="cb9-10"><a href="#cb9-10"></a>  <span class="cf">return</span> TFE_TEXT_VIEW <span class="op">(</span>tv<span class="op">);</span></span>
<span id="cb9-11"><a href="#cb9-11"></a><span class="op">}</span></span>
<span id="cb9-12"><a href="#cb9-12"></a></span>
<span id="cb9-13"><a href="#cb9-13"></a><span class="dt">void</span></span>
<span id="cb9-14"><a href="#cb9-14"></a>notebook_page_save <span class="op">(</span>GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb9-15"><a href="#cb9-15"></a>  g_return_if_fail<span class="op">(</span>GTK_IS_NOTEBOOK <span class="op">(</span>nb<span class="op">));</span></span>
<span id="cb9-16"><a href="#cb9-16"></a></span>
<span id="cb9-17"><a href="#cb9-17"></a>  TfeTextView <span class="op">*</span>tv<span class="op">;</span></span>
<span id="cb9-18"><a href="#cb9-18"></a></span>
<span id="cb9-19"><a href="#cb9-19"></a>  tv <span class="op">=</span> get_current_textview <span class="op">(</span>nb<span class="op">);</span></span>
<span id="cb9-20"><a href="#cb9-20"></a>  tfe_text_view_save <span class="op">(</span>TFE_TEXT_VIEW <span class="op">(</span>tv<span class="op">));</span></span>
<span id="cb9-21"><a href="#cb9-21"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>13-21: <code>notebook_page_save</code>.</li>
<li>19: Gets TfeTextView belongs to the current page.</li>
<li>20: Calls <code>tfe_text_view_save</code>.</li>
<li>1-11: <code>get_current_textview</code>. This function gets the
TfeTextView object belongs to the current page.</li>
<li>7: Gets the page number of the current page.</li>
<li>8: Gets the child widget <code>scr</code>, which is a
GtkScrolledWindow instance, of the current page.</li>
<li>9-10: Gets the child widget of <code>scr</code>, which is a
TfeTextView instance, and returns it.</li>
</ul>
<h2 id="file_changed_cb-handler">file_changed_cb handler</h2>
<p>The function <code>file_changed_cb</code> is a handler connected to
“change-file” signal. If a file in a TfeTextView instance is changed, it
emits this signal. This handler changes the label of the
GtkNotebookPage.</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="dt">static</span> <span class="dt">void</span></span>
<span id="cb10-2"><a href="#cb10-2"></a>file_changed_cb <span class="op">(</span>TfeTextView <span class="op">*</span>tv<span class="op">,</span> GtkNotebook <span class="op">*</span>nb<span class="op">)</span> <span class="op">{</span></span>
<span id="cb10-3"><a href="#cb10-3"></a>  GtkWidget <span class="op">*</span>scr<span class="op">;</span></span>
<span id="cb10-4"><a href="#cb10-4"></a>  GtkWidget <span class="op">*</span>label<span class="op">;</span></span>
<span id="cb10-5"><a href="#cb10-5"></a>  GFile <span class="op">*</span>file<span class="op">;</span></span>
<span id="cb10-6"><a href="#cb10-6"></a>  <span class="dt">char</span> <span class="op">*</span>filename<span class="op">;</span></span>
<span id="cb10-7"><a href="#cb10-7"></a></span>
<span id="cb10-8"><a href="#cb10-8"></a>  file <span class="op">=</span> tfe_text_view_get_file <span class="op">(</span>tv<span class="op">);</span></span>
<span id="cb10-9"><a href="#cb10-9"></a>  scr <span class="op">=</span> gtk_widget_get_parent <span class="op">(</span>GTK_WIDGET <span class="op">(</span>tv<span class="op">));</span></span>
<span id="cb10-10"><a href="#cb10-10"></a>  <span class="cf">if</span> <span class="op">(</span>G_IS_FILE <span class="op">(</span>file<span class="op">))</span> <span class="op">{</span></span>
<span id="cb10-11"><a href="#cb10-11"></a>    filename <span class="op">=</span> g_file_get_basename <span class="op">(</span>file<span class="op">);</span></span>
<span id="cb10-12"><a href="#cb10-12"></a>    g_object_unref <span class="op">(</span>file<span class="op">);</span></span>
<span id="cb10-13"><a href="#cb10-13"></a>  <span class="op">}</span> <span class="cf">else</span></span>
<span id="cb10-14"><a href="#cb10-14"></a>    filename <span class="op">=</span> get_untitled <span class="op">();</span></span>
<span id="cb10-15"><a href="#cb10-15"></a>  label <span class="op">=</span> gtk_label_new <span class="op">(</span>filename<span class="op">);</span></span>
<span id="cb10-16"><a href="#cb10-16"></a>  g_free <span class="op">(</span>filename<span class="op">);</span></span>
<span id="cb10-17"><a href="#cb10-17"></a>  gtk_notebook_set_tab_label <span class="op">(</span>nb<span class="op">,</span> scr<span class="op">,</span> label<span class="op">);</span></span>
<span id="cb10-18"><a href="#cb10-18"></a><span class="op">}</span></span></code></pre></div>
<ul>
<li>8: Gets the GFile instance from <code>tv</code>.</li>
<li>9: Gets the GkScrolledWindow instance which is the parent widget of
<code>tv</code>.</li>
<li>10-12: If <code>file</code> points GFile, then assigns the filename
of the GFile into <code>filename</code>. Then, unref the GFile object
<code>file</code>.</li>
<li>13-14: Otherwise (file is NULL), assigns untitled string to
<code>filename</code>.</li>
<li>15-16: Creates a GtkLabel instance <code>label</code> with the
filename and set the label of the GtkNotebookPage with
<code>label</code>.</li>
</ul>
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