Re: The Code of the Clip Mask Offset Problem

[andy ritger <ritger wolfram com>]

Well, if I understand you right, you want to have one xpm that contains
all the frames; e.g.:

_________________________________________________
|     |     |     |     |     |     |     |     |
|     |     |     |     |     |     |     |     |
|_____|_____|_____|_____|_____|_____|_____|_____|
1     2     3     4     5     6     7     8     

am I understanding?

I don't know if this conserves any more resources than having separate
xpms, but it's a fascinating idea -- like a real of movie film.

Anyway, the step I think you're missing is *moving* the clip mask so that
the appropriate portion of the clip mask lines up with portion of the xpm
that you are drawing to the screen.

I think this line:

  gdk_gc_set_clip_origin(gc, x, y);

should look more like:

  gdk_gc_set_clip_origin (gc,
                          actor->sprites[actor->seq].offsetx - x,
                          actor->sprites[actor->seq].offsety - y);

Thus the clip mask follows the movement of the entire pixmap, even though
you're only drawing part of it...

hope that helps

- andy




On Wed, 2 Feb 2000, Arndt Schwaiger wrote:

[ Hi there,
[ 
[ some freaks asked me for my problem code....here it is:
[ 
[ I am creating one big animation pixmap and its mask with this:
[ 
[ sprite32_pixmap = gdk_pixmap_create_from_xpm_d (drawing_area_widget->window, 
[          				        &sprite32_mask,
[ 						NULL,
[ 						(gchar **) sprite32_xpm);
[ 
[ sprite32_pixmap will be the big one and sprite32_mask its mask !
[ The image is 256 pixels width and 32 pixels high.
[ There are 8 animations steps ( each step has 32 X 32 pixels )
[ 
[ Now I want to do the animation routine like this:
[ 
[ void DrawActor(GdkPixmap *drawing_buffer, GtkWidget *drawing_area_widget,
[ typActor *actor)
[ {
[   GdkGC *gc;
[   gint  x, y;
[   
[   gc = drawing_area_widget->style->fg_gc[GTK_STATE_NORMAL];
[ 
[   x = actor->posx;
[   y = actor->posy;
[ 
[   gdk_gc_set_clip_mask(gc, sprite32_mask);
[   gdk_gc_set_clip_origin(gc, x, y);
[ 
[   gdk_draw_pixmap(drawing_buffer, 
[ 		  drawing_area_widget->style->fg_gc[GTK_STATE_NORMAL], 
[ 		  sprite32_pixmap, 
[ 		  actor->sprites[actor->seq].offsetx, 
[ 		  actor->sprites[actor->seq].offsety, 
[ 		  x, y, 
[ 		  actor->width, 
[ 		  actor->height);
[ 
[   gdk_gc_set_clip_mask(gc, NULL);
[ 
[   actor->seq++;
[   
[   if (actor->seq >= actor->nseq) { actor->seq = 0; } 
[ 
[ }
[ 
[ The actor struct handles all animation settings like position, width, height
[ and offsets on the pixmap.
[ 
[ The lines :
[         ...actor->sprites[actor->seq].offsetx, 
[            actor->sprites[actor->seq].offsety,...
[ 
[ I want to use to say which animation step is the current step (an offset in
[ the big picture) !
[ 
[ THE PROBLEM IS: Only the first animation step has the correct mask.
[                 All other steps are masked by the mask of the first
[ animation step (the first 32 X 32 pixels) !!!
[ 
[ I guess, that the offsets into source work only with the pixmap and not with
[ its mask !!
[ Is this right or am I a lamer ??? THIS SUCKS, because I dont want to use
[ many xpms for only one animation.
[ I have to do 100 or more animations and I want to use only one big animation
[ pixmap !!!
[ 
[ Has anyone any idea how I can handle this ??? Is this a bug or not ???
[ Please help me, because its my dissertation !!! Please !!
[ 
[ Many thanx and greetinx
[ Arndt 
[ 
[ 
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