Re: [gtk-list] Re: Two more Gtk questions (fast frame rates and thread safety)

[Rob Browning <rlb cs utexas edu>]

Raph Levien <raph@acm.org> writes:

> gtk_image is basically a wrapper around XImage. In general, to use
> it you have to supply images in the bit depth of the underlying
> visual. Gsumi has a three-way switch statement supporting 8-bit,
> 16-bit, and 24-bit (packed as 32-bit) images.

OK, I thought I wanted to use a drawing area widget, and draw the
GdkImage there, but it sounds like what I may want to do is use an
image widget and then let it handle the details of displaying the
GdkImage.

Do I understand the distinctions among the various display widgets
correctly?

  drawing area: general purpose widget allowing you to draw whatever
    to its content area

  image: more special purpose widget designed to display an image

  preview: full blown image display widget including dithering, etc.

If all that's more or less right, then is it possible to set a
GtkImage up so that your own code gets called after any redraw?  I
wanted to use that to annotate a given video frame with drawing
primitives.  I'm talking about structural annotations like lines,
boxes, etc.

I suppose I could do the same thing (probably more efficiently) by
drawing to the gdk_image directly before using gtk_image_set to
display it, but I didn't know if there was any easy way to do that; is
there?

Thanks again
-- 
Rob