GTK+ Forums

Chrishas · Familiar Face Joined: 09 May 2008 Posts: 5

I have the following function in C:

Micah Carrick · Posted: Fri May 09, 2008 3:59 pm Post subject: gtk_entry_get_text

GtkWidget *username;
GtkWidget *password;
username = gtk_entry_new();
password = gtk_entry_new();
username = text[0];
password = text[1];

You're saying password is a pointer to a GtkWidget, assigning it to the return value of gtk_entry_new () and then reassigning it to text[1] which is passed to the function, presumptively an array.

So there are lots of issues here. I would try this line of code:
GTK_IS_ENTRY(password)
And I'll think you'll find that it is not an entry.

Can you paste the code that calls this function?

Chrishas · Familiar Face Joined: 09 May 2008 Posts: 5

Here's the code:

Micah Carrick · Posted: Sat May 10, 2008 3:29 pm Post subject:

We typically use structs to hold our widget references when we need to pass more than one to a callback function as user_data. This example uses that method to pass and entry and a textview to a callback function: http://www.gtkforums.com/about906.html

It makes the code nice and easy to read and is a step closer to creating GObjects which you might pass around to callbacks.

Code: (C)

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typedef struct
{
GtkWidget *user_name;
GtkWidget *password;
} MyWidgets;

static void login()
{
GtkWidget *login_window;
GtkWidget *login_button;
GtkWidget *fixed;
GtkWidget *luser;
GtkWidget *lpass;
MyWidgets *widgets;

/* allocate space for MyWidgets struct */
widgets = g_slice_new (MyWidgets);

/* Create login window */
login_window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_container_set_border_width (GTK_CONTAINER (login_window), 10);
gtk_window_set_skip_taskbar_hint(GTK_WINDOW (login_window), TRUE);

/* Signal handling for close button */
g_signal_connect (G_OBJECT (login_window), "destroy",
G_CALLBACK (gtk_widget_destroy), G_OBJECT(login_window));

/* Create new fixed container */
fixed = gtk_fixed_new();

/* Add fixed container to window container */
login_button = gtk_button_new_with_label ("Login");
luser = gtk_label_new("Username");
lpass = gtk_label_new("Password");

widgets->user_name = gtk_entry_new();
widgets->password = gtk_entry_new();

g_signal_connect (G_OBJECT (login_button), "clicked",
G_CALLBACK (check_id), widgets);

gtk_entry_set_visibility(GTK_ENTRY (widgets->password),FALSE);

// Add widgets to their containers
gtk_container_add(GTK_CONTAINER(login_window), GTK_WIDGET(fixed));
gtk_fixed_put(GTK_FIXED(fixed), luser,1,1);
gtk_fixed_put(GTK_FIXED(fixed), lpass,1,40);
gtk_fixed_put(GTK_FIXED(fixed), widgets->user_name,100,1);
gtk_fixed_put(GTK_FIXED(fixed), widgets->password,100,40);
gtk_fixed_put(GTK_FIXED(fixed), login_button,100,80);

// Display Widgets
gtk_widget_show(fixed);
gtk_widget_show(luser);
gtk_widget_show(lpass);
gtk_widget_show(widgets->user_name);
gtk_widget_show(widgets->password);
gtk_widget_show(login_button);
gtk_widget_show(login_window);
gtk_grab_add(login_window);
}

Chrishas · Familiar Face Joined: 09 May 2008 Posts: 5

Thanks for the struct tip, that helps simplify the code, but the problem still persists with trying to get the text from the entry. Here is the error:

luhuadeng · Familiar Face Joined: 05 May 2008 Posts: 10

It should be
void click_id(GtkWidget *widget, MyWidgets *widgets)

Chrishas · Familiar Face Joined: 09 May 2008 Posts: 5

But it's a callback function, I can only pass one argument to it, unless you meant making it non static which doesn't really affect anything essential

luhuadeng · Familiar Face Joined: 05 May 2008 Posts: 10

Please replace your
click_id(MyWidget *widgets)
with
void click_id(GtkWidget *widget, MyWidgets *widgets)

the first para of the callback func is pass by default.this is difinde by the
button's "clicked" signal. The first para is reference to the button ,which
send the clicked signal.

static or not is does not matter here..

Micah Carrick · Posted: Mon May 12, 2008 3:02 pm Post subject:

As luhuadeng pointed out, the first argument to any callback function is the object which triggered the signal.

When writing callback functions, first check the manual for that signal's callback prototype. In the case of "clicked", the API documentation shows this:

Code: (C)
1 2	void user_function (GtkButton *button, gpointer user_data) : Run First / Action

This tells us that when writing our callback function for the clicked signal, we write a function returning void which accepts a GtkButton as the first parameter (we could do GtkWidget instead since a GtkButton is derived from GtkWidget) and the second parameter is our user data-- in this case, a MyWidgets struct. So it could end up looking like this:

Code: (C)
1	void check_id (GtkButton button, MyWidgets widgets)

Also, looking at your code, you have the GtkEntry references in the MyWidget structure, yet you are also creating 2 new entries referenced by 'username' and 'password'. So, the printf towards the bottom will be getting the text of an empty, newly created entry. I dont' think that's what you intended... is it?