[pygtk] Questions about GtkDrawingArea
Hi, I have been using GtkDrawingArea by following the example simple/scribble.py in the pygtk distribution. Basically, the only thing drawn into the window is a pixmap the size of the window. All drawing happens onto the pixmap, and the relevant parts of the pixmap are drawn onto the GtkDrawingArea through an expose_event callback. Is this the right way to do things if you just want to be able to use the gdk drawing functions and catch, for instance, mouse button signals? This is what the example seems to be doing, but I am wondering because 1) GtkDrawingArea has other methods when it seems that this use will always only involve displaying a pixmap 2) This produces a window which is very slow to redraw, for instance after a workspace or virtual screen is changed. Whenever this happens, I see the whole window being covered with the default gtk metal theme (which seems to happen quickly), and then the pixmap is redrawn on top of it. Is there a way not to have the metal stuff drawn underneath, or perhaps to put the pixmap where the metal stuff is so it doesn't need to be redrawn all the time? -- Ben Escoto ___ pygtk mailing list [EMAIL PROTECTED] http://www.daa.com.au/mailman/listinfo/pygtk
[pygtk] Re: Questions about GtkDrawingArea
[Ben Escoto]
This produces a window which is very slow to redraw, for instance after
a workspace or virtual screen is changed. Whenever this happens, I see
the whole window being covered with the default gtk metal theme (which
seems to happen quickly), and then the pixmap is redrawn on top of it.
Is there a way not to have the metal stuff drawn underneath, or perhaps
to put the pixmap where the metal stuff is so it doesn't need to be
redrawn all the time?
I'm not fully sure I'm replying to your question, but a good way to update
a display is to draw it into a memory pixmap instead of in the real drawing
area, and once done in memory, fastly transfer the memory to the window.
The following lines are taken from an exercise I gave to myself:
In the initialisation section:
[...]
drawing_area = GtkDrawingArea()
drawing_area.size(400, 400)
frame.add(drawing_area)
drawing_area.show()
self.area = drawing_area.get_window()
self.cyan_gc = self.area.new_gc()
self.cyan_gc.foreground = drawing_area.get_colormap().alloc('cyan')
self.black_gc = drawing_area.get_style().black_gc
self.white_gc = drawing_area.get_style().white_gc
[...]
Within the update function:
[...]
# Redraw everything.
pixmap = create_pixmap(self.area, xmax+1, ymax+1)
draw_rectangle(pixmap, self.white_gc, TRUE, 0,0, xmax+1,ymax+1)
draw_lines(pixmap, self.black_gc, points)
draw_pixmap(self.area, self.white_gc, pixmap, 0,0, 0,0, xmax+1,ymax+1)
--
François Pinard http://www.iro.umontreal.ca/~pinard
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Re: [pygtk] Questions about GtkDrawingArea
If you look at the GtkDrawingArea widget, you'll see that it exposes a bunch of drawing methods: draw_point draw_line draw_rectangle draw_arc draw_polygon draw_string draw_pixmap draw_points draw_segments draw_lines The scribble example is choosing to paint into a pixmap and then present that pixmap on a drawingarea. Your application can draw directly onto the drawing area without using a pixmap, if that is preferred. Pixmaps are just amoung the things you can draw onto a drawingarea. DrawingArea's are good for prototyping new widgets. Good luck! --S ___ pygtk mailing list [EMAIL PROTECTED] http://www.daa.com.au/mailman/listinfo/pygtk
