Re: [gtk-list] How to use GdkColor?

[FOCUS gpf <jmiguel ceselsa es>]

erwin.verhulst@philips.com wrote:

> Hi
>
> I've attached a simple program that draws a rectangle when you click with the mouse in the window. It worked fine until I wanted to chance the color of the rectangle. The program compiles OK, but when I try to run it the following message appears.
>
> * ERROR * sigsegv caught
>
> What is wrong with the program?
>
> Can somebody get me on track?
>
> Thanks,
>
> Erwin , NL
>
> P.S. I've got this program from the GTK-list. I've lost the GOOD man's name, but who ever it was, THANKS A MILLION.
>
>   --------------------------------------------------------------------------------
>
> #include <glib.h>
> #include <gdk/gdk.h>
> #include <gtk/gtk.h>
>
> GtkWidget *drawingarea = NULL;
>
> void destroy_window (GtkWidget *widget, gpointer client_data)
>         {
>         gtk_main_quit ();
>         }
>
> gint area_event (GtkWidget *widget, GdkEvent *event, gpointer *data)
>         {
>         gint x, y;
>         GdkModifierType state;

    /* GdkColor *color1; */
        GdkColor    color1;
/*
        Here, you're using undefined memory area:

>         color1->red = 65;
>         color1->green = 0;
>         color1->blue = 0;

>         gdk_gc_set_foreground (widget->style->fg_gc[1], color1);

*/
        color1.red = 65;
        color1.green = 0;
        color1.blue = 0;
        /* I'm not sure if it is the best way, but you must know the pixel value for your color */
        gdk_colormap_alloc_color(gtk_widget_get_colormap(widget), &color1, FALSE, TRUE);

        gdk_gc_set_foreground(widget->style->fg_gc[1], &color1);


>
>
>          /* Check if we've received a button pressed event */
>         if (event->type == GDK_BUTTON_PRESS )
>                 {
>                 gdk_window_get_pointer (drawingarea->window, &x, &y, &state);
>                 gdk_draw_rectangle (drawingarea->window,widget->style->fg_gc[1],1,(gint)x,(gint)y,30,5);
>                 }
>         return(0);
>        }
>
> gint main (gint argc, gchar *argv[])
>         {
>         GtkWidget *window, *window2;
>
>         gtk_init (&argc,&argv);
>
>         window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>         gtk_window_set_title (GTK_WINDOW(window), "Dessine-moi un point");
>         gtk_window_set_policy (GTK_WINDOW(window), TRUE, TRUE, TRUE);
>
>         gtk_signal_connect (GTK_OBJECT(window), "delete_event",
>                 (GtkSignalFunc)destroy_window, (gpointer)window);
>         gtk_signal_connect (GTK_OBJECT(window), "destroy",
>                 (GtkSignalFunc)destroy_window, (gpointer)window);
>
>
>         window2 = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>         gtk_window_set_title (GTK_WINDOW(window2), "21 rectangles");
>         gtk_window_set_policy (GTK_WINDOW(window2), TRUE, TRUE, TRUE);
>
>         gtk_signal_connect (GTK_OBJECT(window2), "delete_event",
>                 (GtkSignalFunc)destroy_window, (gpointer)window2);
>         gtk_signal_connect (GTK_OBJECT(window2), "destroy",
>                 (GtkSignalFunc)destroy_window, (gpointer)window2);
>
>
>         drawingarea = gtk_drawing_area_new ();
>         gtk_drawing_area_size (GTK_DRAWING_AREA(drawingarea), 300, 300);
>
>         gtk_widget_set_events (drawingarea, GDK_BUTTON_PRESS_MASK |
>                                         GDK_POINTER_MOTION_MASK |
>                                         GDK_POINTER_MOTION_HINT_MASK);
>
>         gtk_signal_connect (GTK_OBJECT(drawingarea), "event",
>                 (GtkSignalFunc)area_event, NULL);
>
>         gtk_container_add (GTK_CONTAINER(window), drawingarea);
>
>         gtk_widget_show (drawingarea);
>         gtk_widget_show (window);
>
>         gtk_main ();
>
>         return(0);
>        }