Re: selection rectangle

[Patrice St-Gelais <patrice st-gelais oricom ca>]

This is exactly what I did for drawing a selection box in the preview area of a
scanner interface.

I first initialized a "graphic context" this way:

 invert_gc = gdk_gc_new(image_area->window);
 gdk_gc_copy(invert_gc,image_area->style->black_gc);
 gdk_gc_set_function(invert_gc,GDK_INVERT);

... then draw / undraw with something like this:

 gdk_draw_rectangle(pixmap,invert_gc,FALSE,
  last_rect.x, last_rect.y,
  last_rect.width, last_rect.height);

An other option would be to dig in the Gimp code for the "marching ants", but
I'm not sure it's simple.

Hoping this helps.

Regards,

Patrice St-Gelais
____________________________________

Johan Bondeson a écrit :

> I saw an example somewere were the selection rectangle was drawn just by
> inverting the pixels that the rectangle consisted of. To erease the
> rectangle it was only inverted once again and the original colors were back,
> however I think this was a Windows (excuse the bad language) and I have no
> idea how to do this using GTK.

> ----Original Message Follows----
> From: Rok Roskar <rroskar artsci wustl edu>
> To: <gtk-app-devel-list gnome org>
> Subject: selection rectangle
> Date: Sat, 12 Jan 2002 13:43:16 -0600 (CST)
>
> is there an easy way to draw a selection rectangle (one that the user can
> drag) onto a pixmap in drawing_area? The only way I can come up with is
> one where I draw a rectangle each time the user movesthe mouse, but that
> means  that Ihave to erase the one previously drawn and it's becoming
> rather cumbersome.... any ideas?
>
> Rok
>
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