Hi, this is the third part of the How to create a GUI(Graphical User Interface) using C programming Language.. (part 2) post as I promised. In today’s post I’m going to tell you how to create and run Simple hello world GUI program.
And it includes how display a message when click a button.
Ok now open a new glade project and draw a GUI like above image. You have three components one label and two buttons.
Then set properties like this.
- For the main Window
General–> Name= mainWindow
General–>Resizable= No
Common–>Height request = 400
Common–>Width request=200
- For Display Label
General–>Name=displayLabel
General–>Label=Display
- For Display Button
General–>Name=displayButton
General–>Label=Display
Signals–>Clicked=on_displayButton_clicked
- For Exit Button
General–>Name=exitButton
General–>Label=Exit
Signals–>Clicked=on_exitButton_clicked
Then save it as hello.glade in libglade format.
Now open CodeBlock’s Gtk+ project. When you open a new it will automatically generates some codes, so erase and clear main.c .Then copy paste this code into your main.c .
Then copy your hello.glade file into CodeBlock project folder.
#include <stdio.h>
#include <gtk/gtk.h>
#include <glade/glade.h>
/*
Author : Gihan De Silva
gihansblog.com
*/
GladeXML *xml;
GtkWidget *widget;
GtkWidget *display;
G_MODULE_EXPORT void on_displayButton_clicked(GtkButton *button,gpointer *data)
{
/* Find the Glade XML tree containing widget. */
xml = glade_get_widget_tree(GTK_WIDGET( widget ));
/* Pull the widgets out of the tree */
display= glade_xml_get_widget(xml, “displayLabel”);
gtk_label_set_text(GTK_LABEL(display),”Hello World!\n gihansblog.com”);
}
G_MODULE_EXPORT void on_exitButton_clicked(GtkButton *button,gpointer *data)
{
gtk_main_quit();
}
int main(int argc, char *argv[])
{
gtk_init(&argc, &argv);
/*import glade file*/
xml = glade_xml_new(“hello.glade”, NULL, NULL);
/* get a widget (useful if you want to change something) */
widget = glade_xml_get_widget(xml, “mainWindow”);
/* connect signal handlers */
glade_xml_signal_autoconnect(xml);
/*show widget*/
gtk_widget_show (widget);
gtk_main();
return 0;
}
Now run the project. If everything ok it will look like this and will function well :D.
The program in CodeBlocks…
Main Code Explained…
First we should initialise gtk in our code.
gtk_init(&argc, &argv);
Then we have to import our .glade file into our program and convert it into xml file format.
xml = glade_xml_new(“hello.glade”, NULL, NULL);
Now signals of widgets should be functioning with this line.
glade_xml_signal_autoconnect(xml);
And with this line, it will show the GUI at run time.
gtk_widget_show (widget);
Then call gtk main method
gtk_main();
Exit Button Code Explained…
In the exit button we call
gtk_main_quit();
to quit fro the program.
Display Button Code Explained…
Then find the Glade XML tree containing widget.
xml = glade_get_widget_tree(GTK_WIDGET( widget ));
Now pull the label widgets out of the tree
display= glade_xml_get_widget(xml, “displayLabel”);
Display the message on the label
gtk_label_set_text(GTK_LABEL(display),”Hello World!\n gihansblog.com”);
Ok that’s all for today :D. If you want, you can DOWNLOAD my CodeBlock project here!. In next post I will show you how to add a Text Entry widget to your application.
Thank you
Gihan De Silva
Gihan's Blog.. 
You can educate yourself right out of a relationship with God.
If you’ve got a skill, protect it.
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Yes of course this a wordpress blog and I use Freshy theme 🙂 (http://theme.wordpress.com/themes/freshy/) Only thing I’ve done to the theme is changing the header. If you need any help regarding changing your blog page from Blogger to WordPress read my article on that : https://gihansblog.wordpress.com/2011/06/24/convert-your-blogger-bolg-into-wordpress-or-wordpress-blog-into-blogger/
😀
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hello, i want one help regarding theme. i don’t know how can i apply a theme in the gtk application. if any body have any idea please help me.
please send to my mail pani_rabi@sify.com
thanks in advance .
Can You please explain more about how did u do:
“Now open CodeBlock’s Gtk+ project. When you open a new it will automatically generates some codes, so erase and clear main.c .Then copy paste this code into your main.c .”
how can we make the relation ?
cheers
I am having some problem here ..
ravi@ravi:~/gtk/hello$ gcc -Wall -g main.c `pkg-config gtk+-2.0 –cflags –libs` -I/usr/include/libglade-2.0/ -lglade-2.0ravi@ravi:~/gtk/hello$ ./a.out
(a.out:15605): libglade-WARNING **: could not find glade file ‘hello.glade’
(a.out:15605): libglade-CRITICAL **: glade_xml_get_widget: assertion `self != NULL’ failed
(a.out:15605): libglade-CRITICAL **: glade_xml_signal_autoconnect: assertion `self != NULL’ failed
(a.out:15605): Gtk-CRITICAL **: IA__gtk_widget_show: assertion `GTK_IS_WIDGET (widget)’ failed
what should i do now ?