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<h1>GUI Programming with GTK - 3</h1>
<h4>ArticleCategory:</h4>
SoftwareDevelopment
<h4>AuthorImage:</h4>
<img src="../../common/images/OzcanGungor.jpg" alt=
"Ozcan Gungor" width="114" height="147">
<h4>TranslationInfo:</h4>
original in tr <a href=
"mailto:ozcangungor(at)netscape.net">Özcan
Güngör</a><br>
en to tr <a href=
"mailto:ozcangungor(at)netscape.net">Özcan
Güngör</a> <br>
<br>
<h4>AboutTheAuthor</h4>
I'm doing at the moment my military service as Linux, Oracle
administrator and web programmer.
<h4>Abstract</h4>
<p>In these article series, we will learn how to write
graphical user interfaces (GUIs) using GTK. I do not have any
idea how long it will last. In order to understand these
articles, you should know the following about the C programming
language:</p>
<ul>
<li>Variables</li>
<li>Functions</li>
<li>Pointers</li>
</ul>
It is recommended to read the previous articles:<br>
<a href="../../English/May2003/article295.shtml">GUI
Programming with GTK</a>,<br>
<a href="../../English/July2003/article303.shtml">GUI
Programming with GTK - 2</a> .<br> This article
is a little bit shorter than the others as I'm doing my military
service. <br>
<h4>ArticleIllustration:</h4>
<img src="../../common/images/illustration295.jpg" alt="GTK"
width="195" height="172">
<h4>ArticleBody:</h4>
<h3>Toggle Button</h3>
<p>This button looks like a normal button but has two states:
Pressed or not. To create a toogle button one of the following
function is used:</p>
<pre class="code">
GtkWidget *toggle=gtk_toggle_button_new(void);
GtkWidget *toggle=gtk_toggle_button_new_with_label(const gchar *label);
</pre>
<p>The first function creates a toggle button without a text label
in it but the second one creates it with the string <i>label</i> on
it.<br>
You can set its state with the following function:<br>
</p>
<pre class="code">
gtk_toggle_button_set_active (GtkToggleButton *toggle_button,
gboolean is_active);
</pre>
<p>where <i>toggle_button</i> is the button whose state you
want to change and <i>is_active</i> is the state (0 or 1). When
it is 0, then the button is not in
"pressed" state; when it is 1, the button is in "pressed" state.</p>
<p>To get the state of the button, the following function can
be used:</p>
<pre class="code">
gboolean gtk_toggle_button_get_active(GtkToggleButton *button);
</pre>
<p>The "toggled" event can be connected to a toggle button.</p>
<p>Here is an example:</p>
<pre class="code">
#include <gtk/gtk.h>
void togg(GtkWidget *widget, gpointer *data){
if (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(data)))
g_print("State is 1\n");
else
g_print("State is 0\n");
}
int main( int argc,char *argv[] )
{
GtkWidget *window;
GtkWidget *button;
gtk_init (&argc, &argv);
/* Create a new window */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "Toggle Button");
/* Connect destroy event to the window. */
gtk_signal_connect (GTK_OBJECT (window), "destroy",
GTK_SIGNAL_FUNC(gtk_main_quit), NULL);
/* Creates a toggle button */
button=gtk_toggle_button_new_with_label("I'm a toggle button");
/* Add the button to window */
gtk_container_add(GTK_CONTAINER(window),button);
/* Connect "toggled" event to the button */
gtk_signal_connect (GTK_OBJECT (button), "toggled",
GTK_SIGNAL_FUNC(togg),(gpointer *)button);
gtk_widget_show(button);
gtk_widget_show (window);
gtk_main ();
return(0);
}
</pre>
<h3>Check Button</h3>
<p>The check button ( it is also known as check box ) is a subclass
of the toggle button. It can be used to select some options.<br>
To create a check button, the following fuction is used:</p>
<pre class="code">
GtkWidget* gtk_check_button_new (void);
GtkWidget* gtk_check_button_new_with_label (const gchar *label);
</pre>
<p>The explanations are the same as for toggle button.</p>
<p>The example :</p>
<pre class="code">
#include <gtk/gtk.h>
void togg(GtkWidget *widget, gpointer *data){
if (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(data)))
g_print("State is 1\n");
else
g_print("State is 0\n");
}
int main( int argc,char *argv[] )
{
GtkWidget *window;
GtkWidget *button;
gtk_init (&argc, &argv);
/* Create a new window */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "Check Button");
/* Connect destroy event to the window. */
gtk_signal_connect (GTK_OBJECT (window), "destroy",
GTK_SIGNAL_FUNC(gtk_main_quit), NULL);
/* Creates a check button */
button=gtk_check_button_new_with_label("I'm a check button");
/* Add the button to window */
gtk_container_add(GTK_CONTAINER(window),button);
/* Connect "toggled" event to the button */
gtk_signal_connect (GTK_OBJECT (button), "toggled",
GTK_SIGNAL_FUNC(togg), (gpointer *)button);
gtk_widget_show(button);
gtk_widget_show (window);
gtk_main ();
return(0);
}
</pre>
<h3>Label</h3>
<p>Labels let you put any text anywhere in window.<br>
To create a label just use the following function:</p>
<pre class="code">
GtkWidget* gtk_label_new(const gchar *text);
</pre>
<p>With the function</p>
<pre class="code">
gtk_label_set_text(GtkLabel *label, gchar *text);
</pre>
<p>you can change the string on a label at anytime.</p>
<pre class="code">
gtk_label_set_justify(GtkLabel *label, GtkJustification jtype);
</pre>
<p>The gtk_label_set_justify funtion is used to justify the text on the label.
<i>jtype</i> can be</p>
<ul>
<li>GTK_JUSTIFY_LEFT to put the text to the left,</li>
<li>GTK_JUSTIFY_RIGHT to put the text to the rigth,</li>
<li>GTK_JUSTIFY_CENTER to put the text in the center,</li>
<li>GTK_JUSTIFY_FILL to make the text cover the whole
label.</li>
</ul>
<pre class="code">
gtk_label_set_line_wrap (GtkLabel *label,gboolean wrap);
</pre>
<p>is used to make the text splittable into many pieces when
the text is longer than the place it should fit. When <i>wrap</i> is
1, then text will <i>wrap</i> to the next line, otherwise not.
</p>
<pre class="code">
gtk_label_get(GtkLabel *label, gchar **str)
</pre>
<p>is used to get the text on the label into <i>str</i>.</p>
<h3>ToolTips</h3>
<p>Tooltip is a text that appears when the mouse is on a
widget. For example, you can set a tip for a button and the
text "send the information"
appears when your mouse is over it.</p>
<p>To do that a GtkToolTips widget must be created first:</p>
<pre class="code">
GtkToolTips* gtk_tooltips_new();
</pre>
<p>Then this tooltip is attached to a widget:</p>
<pre class="code">
gtk_tooltips_set_tip(GtkTooltips *tooltips, GtkWidget *widget,
const gchar *tip_text,const gchar *tip_private);
</pre>
<p>A little example:</p>
<pre class="code">
#include <gtk/gtk.h>
int main( int argc,char *argv[] )
{
GtkWidget *window;
GtkWidget *button;
GtkTooltips *tip;
gtk_init (&argc, &argv);
/* Create a new window */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "Tooltips");
/* Connect destroy event to the window. */
gtk_signal_connect (GTK_OBJECT (window), "destroy",
GTK_SIGNAL_FUNC (gtk_main_quit), NULL);
/* Creates a button */
button=gtk_button_new_with_label("I'm a Button");
/* Add the button to window */
gtk_container_add(GTK_CONTAINER(window),button);
/* Creates a tooltips*/
tip=gtk_tooltips_new();
/* Attache this tooltips to button with text*/
gtk_tooltips_set_tip(tip, button, "Click me!",NULL);
gtk_widget_show(button);
gtk_widget_show (window);
gtk_main ();
return(0);
}
</pre>
<p>Some other functions:</p>
<pre class="code">
gtk_tooltips_enable (GtkTooltips *tooltips);
</pre>
<p>Enables the tooltips.</p>
<pre class="code">
gtk_tooltips_disable (GtkTooltips *tooltips);
</pre>
<p>Disables tooltips.</p>
<p>To get any tooltip data of a wigdet, we need</p>
<pre class="code">
GtkTooltipsData* gtk_tooltips_get_data(GtkWidget *widget);
</pre>
<p>GtkTooltipsData is a struct in the following way:
</p>
<pre class="code">
struct _GtkTooltipsData
{
GtkTooltips *tooltips;
GtkWidget *widget;
gchar *tip_text;
gchar *tip_private;
GdkFont *font;
gint width;
GList *row;
};
</pre>
To set the delay of the appearing text,
<pre class="code">
gtk_tooltips_set_delay (GtkTooltips *tip, guint delay)
</pre>
<h3><br>
Combo Box</h3>
<p>A combo box is an editable text field combined with a pull-down menu.
You can enter a value or select one of the pull-down entries.</p>
<p>A combo box can be created with</p>
<pre class="code">
GtkWidget *gtk_combo_new();
</pre>
<p>And we need a list of options which is a GList struct.</p>
<pre class="code">
GList *glist=NULL;
</pre>
<p>And the options can be appended to the list with</p>
<pre class="code">
GList *g_list_append(GList *list, gchar *option);
</pre>
<p>Then this list needs to be added to the combo box</p>
<pre class="code">
gtk_combo_set_popdown_strings(GtkCombo *combo, GList *List);
</pre>
<p>The combo box is ready. To read the selected option use:</p>
<pre class="code">
gchar *gtk_entry_get_text(GtkEntry *entry);
</pre>
<p><i>entry</i> is GTK_ENTRY(GTK_COMBO(combo)->entry)) in
this case.</p>
<pre class="code">
gtk_combo_set_use_arrows(GtkCombo *combo,gint val);
</pre>
<p>This function is used to enable or disable up/down keys on
the keyboard to change the value on a combo box. When <i>val</i>
is 0, these keys do not function, otherwise these keys change
the value. But when the value on a combo box is different from the
values in the list, <b>these keys don't function</b>.</p>
<pre class="code">
gtk_combo_set_use_arrows_always(GtkCombo *combo,gint val);
</pre>
<p>This function is the same as <i>gtk_combo_set_use_arrows</i>
but when the value on a combo box is different form the values in
the list, <b>these keys function</b>.</p>
<pre class="code">
gtk_combo_set_value_in_list(GtkCombo *combo, gboolean val,
gboolean ok_if_empty);
</pre>
<p>When <i>val</i> is 1, you can enter a value in the list. When
<i>ok_if_empty</i> is 1, the value may be blank.</p>
<pre class="code">
#include <gtk/gtk.h>
void act(GtkWidget *widget, gpointer *data){
g_print((gchar *)data);
}
int main( int argc,char *argv[] ) {
GtkWidget *window;
GtkWidget *combo;
GtkWidget *button;
GtkWidget *box;
GList *list=NULL;
list=g_list_append(list,"Slackware");
list=g_list_append(list,"RedHat");
list=g_list_append(list,"SuSE");
gtk_init (&argc, &argv);
/* Create a new window */
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_title (GTK_WINDOW (window), "Combo Box");
/* Connect destroy event to the window. */
gtk_signal_connect (GTK_OBJECT (window), "destroy",
GTK_SIGNAL_FUNC(gtk_main_quit), NULL);
/* Create a new horizontal box */
box=gtk_hbox_new(1,0);
gtk_container_add(GTK_CONTAINER(window),box);
/* Creates a combo box */
combo=gtk_combo_new();
/* Sets the list */
gtk_combo_set_popdown_strings(GTK_COMBO(combo),list);
/* Enables up/down keys change the value. */
gtk_combo_set_use_arrows_always(GTK_COMBO(combo),1);
gtk_box_pack_start(GTK_BOX(box), combo,1,1,1);
button=gtk_button_new_with_label("Write it");
gtk_signal_connect(GTK_OBJECT(button),"clicked",GTK_SIGNAL_FUNC(act),
gtk_entry_get_text(GTK_ENTRY(GTK_COMBO(combo)->entry)));
gtk_box_pack_start(GTK_BOX(box), button,1,1,1);
gtk_widget_show(box);
gtk_widget_show(combo);
gtk_widget_show(button);
gtk_widget_show (window);
gtk_main ();
return(0);
}
</pre>
All comments are welcome.
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