[maemo-developers] What is the difference between GtkImage, GdkImage, GdkPixmap and GdkBitmap?

[From: LIU Chun Hung]

>> Suppose I want to create a new RGB bitmap with 3 x 3 in size and I want
>> to
>> set all pixel values to be 0. After clicking a button, all pixel values
>> will change to 255. Which one of the above types should I use? Should
>> GdkImage be used as I can see there are functions to change the pixel
>> values (gdk_image_put_pixel) in this type, but not in other types.
>
> You would use a GdkImage to manipulate the pixels, and a GtkImage to
> display it.
>
Yes, it is exactly what I want to do, but I don't know how to do it. Can
anyone guide me to do it?

The first thing to do is to create a new GdkImage. I use this function,
gdk_image_new(GdkImageType type, GdkVisual *visual, gint width, gint
height) to create.

type = GDK_IMAGE_SHARED;
width = 3;
height = 3;
visual = ?

For the GdkVisual*, I don't know how to initialize it.
I have tried with different methods as below, but errors will occur when I
run the program.

visual = gdk_visual_get_system();
example_font_selector[11303]: GLIB CRITICAL ** Gdk -
gdk_screen_get_system_visual: assertion `GDK_IS_SCREEN (screen)' failed

visual = gdk_visual_get_best();
qemu: uncaught target signal 11 (Segmentation fault) - exiting

visual = gdk_visual_get_best_with_depth(8);
qemu: uncaught target signal 11 (Segmentation fault) - exiting

visual = gdk_visual_get_best_with_type(GDK_VISUAL_TRUE_COLOR);
qemu: uncaught target signal 11 (Segmentation fault) - exiting

visual = gdk_visual_get_best_with_both(8, GDK_VISUAL_TRUE_COLOR);
qemu: uncaught target signal 11 (Segmentation fault) - exiting

In fact, which one should I use?