GtkDrawingArea alignment

[yanxin <ycui wmsvision com>]

I draw a vbox first-> then pack the GtkDrawingArea into the vbox-> then
packed a label into the box, then pack the vbox into a GtkButton. In the
expose event, I use gdk_draw_rgb_32_image() to update the image of the
drawing area, but the image is always aligned to the left. How to make
the image align in the middle of the vbox?

========= here is part of my code to trigger the expose event
===========
 if ( psPixbuf ) {
  /* Update the current image */
  psImage->psPixbuf = psPixbuf;
  psImage->psMask = psMask;
  /* Determine the refresh area of the image. */
  rect.x      = 0;
  rect.y      = 0;
  rect.width  = gdk_pixbuf_get_width( psPixbuf );
  rect.height = gdk_pixbuf_get_height( psPixbuf );

  if( psImage->psButton &&
  (psImage->eTextAlignment == align_Top ||
   psImage->eTextAlignment == align_Bottom) )
   rect.x =
    (psImage->psDrawingArea->allocation.width -
    gdk_pixbuf_get_width(psPixbuf) )/2;

  /* Trigger an expose_event to flush the changes to the
  * drawing area
  */
  gtk_widget_draw( psDrawingArea, &rect );
 }
=================================
Thanks

Yanxin