How to create a GUI(Graphical User Interface) using C programming Language.. (part 5)

Hi, everyone it’s been a long time., yes, ok now I’m back with some Tech things. As promised , today I’m going to blog about how to create Mini-Calculator with C language GUI. So before get started I thing it’s better to read past articles on this topic, because some guys informed they didn’t get it very clear. I think that happens because they didn’t go through the past articles related to this one before read the fresh one 😀 .

Mini Calculator v 1.0

So here is related articles …. read them first

1) How to create a GUI(Graphical User Interface) using C programming Language..

2) How to create a GUI(Graphical User Interface) using C programming Language.. (part 2)

3) How to create a GUI(Graphical User Interface) using C programming Language.. (part 3)

4) How to create a GUI(Graphical User Interface) using C programming Language.. (part 4)

Now open Glade Software and create a user interface with these settings.

• For the main Window
  

General–> Name= mainWindow
General–>Resizable= No
Common–>Height request = 400
Common–>Width request=250

• For Display Label

General–>Name=displayLabel

General–>Label=Mini-Calculator v1.0 | gihansblog.com

• For Text Entry

General–>Name=textEntry

• For Exit Button

General–>Name=exitButton

General–>Label=Exit

Signals–>Clicked=on_exitButton_clicked

• For  Button 0 to 9

General–>Name=no1Button

General–>Label=1

Signals–>Clicked=on_no1Button_clicked

General–>Name=no2Button

General–>Label=2

Signals–>Clicked=on_no2Button_clicked ………

• For + Button

General–>Name=addButton

General–>Label=+

Signals–>Clicked=on_addButton_clicked

• For – Button

General–>Name=subButton

General–>Label= –

Signals–>Clicked=on_subButton_clicked

• For x Button

General–>Name=mulButton

General–>Label= x

Signals–>Clicked=on_mulButton_clicked

• For ÷ Button

General–>Name=divButton

General–>Label=  ÷

Signals–>Clicked=on_divButton_clicked

• For √ Button

General–>Name=sqrtButton

General–>Label= √

Signals–>Clicked=on_divButton_clicked

After you finish with Glade it should be similar to this..

Now open Colde Blocks gtk project. Erase the default contents of main.c . Here I have changed the structure of the project like this ..

1) main.c

2) callbacks.c

3) callbacks.h

main.c contains the main method of programm, and callbacks.c contains the rest of methods and callback.h header file contains functions prototypes of methods that contains callback.c

DOWNLOAD  the Source code!

Here I’m not going to explain all the things, because I’ve already explained most of it in previous articles.

Code Explained…

GladeXML *xml;
GtkWidget *textValue;

gdouble display;
gdouble primaryTotal=0;//primary total
gdouble mainTotal=0;

gchar *d_string;

int clickedButton=0;// find the clicked buttton default is zero ‘0’.
                    /*
                    Values of ‘clickedButton’
                    ————————
                    plusButton_clicked –>1
                    subButton_clicked  –>2
                    mulButton_clicked  –>3
                    divButton_clicked  –>4
                    */

Mainly in here, what we do with a calculator is do some calculation. For example think we are going to do this operation “1+2”. So first what we do is hit the “1” button and hit “+” and “2”, then press “=” to get the result on the text entry. In this algorithm , when pressing the “1” button it gives the “1” value to the text entry and when “+” button clicked it stores the display value in display variable and get the sum with primaryTotal variable and put it to again primaryTotal . Then we press “2”. So now this also displays on the text entry, then “=” button clicked ,it should chose the correct operation(at this time, it is “+”) in the operation primaryTotal value should do the related operation with display then should put it again into mainTotal. For example in addition it should be

mainTotal=primaryTotal+display;

G_MODULE_EXPORT void on_no1Button_clicked(GtkWidget *widget, gpointer *data)
{
    /* Find the Glade XML tree containing widget. */
    xml = glade_get_widget_tree(GTK_WIDGET( widget ));

    /* Pull the widgets out of the tree */
    textValue= glade_xml_get_widget(xml, “textEntry”);

    gtk_entry_append_text(GTK_ENTRY(textValue),”1″);
}
Here first line gets the widget tree to a GladeXML type variable. Then second line gets the textEntry value to the GtkWidget type variable called textValue. Third line set “1” to the textEntry object as append action. Like this all 0-9 button code works.

G_MODULE_EXPORT void on_addButton_clicked(GtkWidget *widget, gpointer *data)
{
    /* Find the Glade XML tree containing widget. */
    xml = glade_get_widget_tree(GTK_WIDGET( widget ));

    /* Pull the widgets out of the tree */
    textValue= glade_xml_get_widget(xml, “textEntry”);

    /* Get the string value form the Entry widgets */
    d_string=gtk_entry_get_text(GTK_ENTRY(textValue));

    /* convert it into the double */
    display=atof(d_string);

    /* Add it to the primary total */
    primaryTotal=primaryTotal+display;

    /* Clear the entry*/
    gtk_entry_set_text(GTK_ENTRY(textValue),””);

    /* Set clicked button as 1 ‘plusButton_clicked’ */
    clickedButton=1;
}
In this method first 3 lines are similar to above explanation. In third line I have used atof() function from math.h header. It converts the string value to double. Because we need double values to calculate the maths. Next line gets the sum of primaryTotal and display variables. Then clearing the textEntry field it sets clickedButton variable to 1, to mention that the operation is set to summation. Like wise, value of clickedButton says the operation to do.
Values of ‘clickedButton’
————————
plusButton_clicked –>1
subButton_clicked  –>2
mulButton_clicked  –>3
divButton_clicked  –>4

G_MODULE_EXPORT void on_equalButton_clicked(GtkWidget *widget, gpointer *data)
{
    /* Find the Glade XML tree containing widget. */
    xml = glade_get_widget_tree(GTK_WIDGET( widget ));

    /* Pull the widgets out of the tree */
    textValue= glade_xml_get_widget(xml, “textEntry”);

    /* Read the entry value and copy it to a char* */
    d_string=gtk_entry_get_text(GTK_ENTRY(textValue));

    /* convert the string to double*/
    display=atof(d_string);

    /*Do the oprations according to clicked button*/

        switch(clickedButton)
        {
            case 0 :{
                    break;
                    }

            case 1 :{
                    /* Do Addition*/
                    mainTotal=primaryTotal+display;
                    break;
                    }

            case 2 :{
                    /* Do Substraction*/
                    mainTotal=primaryTotal-display;
                    break;
                    }

            case 3 :{
                    /* Do Multipication*/
                    mainTotal=primaryTotal*display;
                    break;
                    }

            case 4 :{
                    /* Do Division*/
                    mainTotal=primaryTotal/display;
                    break;
                    }

        }// end switch

    /*convert double to string and print the value on entry*/
    gtk_entry_set_text(GTK_ENTRY(textValue),g_strdup_printf(“%f”,mainTotal));

    /* set total to zreo ‘0’*/
    primaryTotal=0;

    /* Set clickedButton value back to the default*/
}

In this method the switch structure decides which operation to do. After doing the related calculation in a case, it should display the main in text entry. But double values are not allowed in the text entry widget, so we have to convert it to String (char *) type.

gtk_entry_set_text(GTK_ENTRY(textValue),g_strdup_printf(“%f”,mainTotal)); this line is responsible for that conversion.

Now I think I’ve explained all the main things about the program here.

If you want the calculator look like the first image. You should do it with the Glade designer like this.

Open the Glade designer project and click on a button you want to add an image. Think you want to change the image of “1” button. Then click on “1” button then go to General tab under Properties check the radio button “Add custom button content”  . Now you see the appearance of the button is changed. Then click on image widget under Displays and Controls, after that click the “1” Button again.

Find some appropriate button image or draw something like this.

Then go to General tab under Properties and check radio button File Name and set the path for image file. 😀 then you will see it at the run time.

Ok that’s all for today . You can DOWNLOAD my CodeBlock project here!. Good luck.

Thank you

Gihan De Silva

How to create a GUI(Graphical User Interface) using C programming Language.. (part 4)

Hi,  after a long time I was able to find a time to write the blog, because these days I’m very busy with my exam and it will end 29^th  September. So until that I doubt I’d be able to write much. So sorry for that my all friends who read this.

Related articles..

1) How to create a GUI(Graphical User Interface) using C programming Language..

2) How to create a GUI(Graphical User Interface) using C programming Language.. (part 2)

3) How to create a GUI(Graphical User Interface) using C programming Language.. (part 3)

And this article focus on  how to use a Text Entry with button action signals.  And the purpose of this program is display the string in the label,which user enter in the text entry.

Contents…

1) Open a Code Blocks projects

2) Open a Glade Project

3) Set properties for the components

4) Code the C Gtk project

5) Run the project

Components

1) Window= mainWindow

2) Label= displayLabel

3) Text Entry= textEntry

4) Button= displayButton

5) Button= exitButton

Set properties

• 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

• For Text Entry

General–>Name=textEntry

Then save it as TextEntry.glade in libglade format in the CodeBlocks project folder.

In this C project I divided the whole project into three files.

1) main.c

2) callback.c

3) callback.h

The source code of main.c 

#include <stdio.h>
#include <gtk/gtk.h>
#include <glade/glade.h>

/*
Author : Gihan De Silva
gihansblog.com

Purpose: This program displays the string in the label,which user enter in the text entry.
*/
GladeXML *xml;
GtkWidget *widget;

int main(int argc, char *argv[])
{

gtk_init(&argc, &argv);

/*import glade file*/
xml = glade_xml_new(“TextEntry.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;
}

The source code of callback.c

#include <stdio.h>
#include <gtk/gtk.h>
#include <glade/glade.h>

GladeXML *xml;
GtkWidget *display;
GtkWidget *textValue;

gchar *d_string;

G_MODULE_EXPORT void on_displayButton_clicked(GtkButton *button,gpointer *data)
{

/* Pull the widgets out of the tree */
display= glade_xml_get_widget(xml, “displayLabel”);

textValue= glade_xml_get_widget(xml, “textEntry”);

/* Get the string value form the Entry widgets */
d_string=gtk_entry_get_text(GTK_ENTRY(textValue));

gtk_label_set_text(GTK_LABEL(display),d_string);
}

G_MODULE_EXPORT void on_exitButton_clicked(GtkButton *button,gpointer *data)
{
gtk_main_quit();
}

The source code of callback.h

G_MODULE_EXPORT void on_displayButton_clicked(GtkButton *button,gpointer *data);
G_MODULE_EXPORT void on_exitButton_clicked(GtkButton *button,gpointer *data);

Now run the gtk project and it will look like this.

And when you hit the Display button, it will display the content in the text entry..

Display Button Code Explained…

Here I’m not going to explain all the code because I already have explained them in previous articles. If you haven’t read previous article, you’d better to read them first. But I’m going to explain the specific things related to this article.

GladeXML *xml;
GtkWidget *display;
GtkWidget *textValue;

gchar *d_string;

G_MODULE_EXPORT void on_displayButton_clicked(GtkButton *button,gpointer *data)
{
/* Pull the widgets out of the tree */
display= glade_xml_get_widget(xml, “displayLabel”);

textValue= glade_xml_get_widget(xml, “textEntry”);

In these two lines, the program will take glade widgets into Gtk widgets.

/* Get the string value form the Entry widgets */
d_string=gtk_entry_get_text(GTK_ENTRY(textValue));

We can’t directly use GtkWidgets to set gtk label, because it needs gchar* type data. So in here we convert to into gchar* .

gtk_label_set_text(GTK_LABEL(display),d_string);

Now with above line we can set it to the label.

}

Ok that’s all for today . If you want, you can DOWNLOAD my CodeBlock project here!. In next post I will show you how to create a simple Calculator using Gtk and Glade.

Thank you

Gihan De Silva

How to create a GUI(Graphical User Interface) using C programming Language.. (part 3)

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

How to create a GUI(Graphical User Interface) using C programming Language..

How to create a GUI(Graphical User Interface) using C programming Language???  That was a big problem to me when I’m in the University first year. I knew Java GUI Designing, but couldn’t find way to do it in C language. I spent many time to learn that. I think now it’s time to share those knowledge :D. But since there are lot to discuss on that topic, I’m going to spelt the whole tutorial into several posts.  In this post I’ll discuss how to set up the development environment.

Setting up the development environment for C language GUI designing.

Ok let’s begin. First we need to have several tools for that.

1) Code Blocks IDE

2) Glade IDE

3) Gtk+

4) Libglade library

So install those things on your computer. I’ll give a hint to get it much easier. If you are Ubuntu user, go to Ubuntu software center or Synaptic package manager. Find code blocks and install. Then Find for Glade and before install, check all the Add-ons then install. In this way it will automatically install gtk+ and libglade. So you don’t want to worry about that:D.

A screen shot of Code Blocks IDE..

Now you have to configure Compiler and Debugger settings in Codeblocks IDE.

• Open Code Blocks–> goto Compiler and Debugger settings

• Select Other options in Compiler settings tab and paste this.

            `pkg-config –cflags gtk+-2.0 gmodule-export-2.0`
            `pkg-config –cflags libglade-2.0`

• Then select Other linker options in Linker settings tab and paste this.

           `pkg-config –libs gtk+-2.0 gmodule-export-2.0`
           `pkg-config –libs libglade-2.0`

A screen shot of Glade Interface designer…

But you always free to compile your program on the terminal too. If you wish to do so it should be like this.

gcc `pkg-config –cflags libglade-2.0 –libs gtk+-2.0“pkg-config –libs gtk+-2.0 gmodule-export-2.0` main.c

Ok thats all for now . In next post I’ll explain how to Design a GUI using Glade Interface Designer :D.

 

Thank you

Gihan Malan De Silva @ gihansblog.com