Re: How to create a GdkImage from a file.

Please direct questions like this to gtk-app-devel- list gnome org ... gtk-devel-list is for discussion of the development *of* gtk+, not *with* it.

On Dec 20, 2006, at 8:35 AM, Prasanna Kumar K wrote:

I want to genetate a GdkImage from a file .. (so that this GdkImage can be passed to gdk_draw_image())
I used following calls..

GtkImage *gtk_image = NULL;
GdkImage *gdk_image = NULL;
GdkBitmap *gdk_bitmap = NULL;

gtk_image_set_from_file (gtk_image, "1.jpg");
gtk_image_set_from_image (gtk_image, gdk_image, gdk_bitmap);
gdk_draw_image (pixmap,  widget->style->white_gc,  gdk_image,
                              0, 0,  60, 60, 100, 100);

but while running the appliction I'm getting following error..
Gtk-CRITICAL **: gtk_image_set_from_file: assertion `GTK_IS_IMAGE (image)' failed

can anyone tell what is the problem.

Firstly, you're passing NULL for the image to set_from_image(); it doesn't like that.

GtkImage != GdkImage. GtkImage is a widget that displays images. GdkImage is basically a wrapper for XImage, which is a client-side image resource.

You're also calling set_image() instead of get_image(). You could do this sort of thing:

    gtk_image_set_from_file (gtk_image, filename);
    gtk_image_get_image (gtk_image, &gdk_image, &mask);

but that's very wasteful, using the GtkImage just to perform I/O for you.

Instead, I think what you actually want is to use a GdkPixbuf, which is a 24-bit client-side resource that is easier to use than GdkImage. It goes something like this:

    GdkPixbuf * pixbuf;
    GError * error = NULL;

    pixbuf = gdk_pixbuf_new_from_file ("1.jpg", &error);
    if (pixbuf) {
        gdk_draw_pixbuf (pixmap, widget->style->fg_gc, pixbuf,
                         0, 0, dest_x, dest_y,
                         gdk_pixbuf_get_width (pixbuf),
                         gdk_pixbuf_get_height (pixbuf,
                         dest_x, dest_y);
    } else {
        /* error contains failure info */

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