Basicly I'm developing a GtkDrawingArea based application. As far as I understand, a GdkPixbuf is stored on the client, and a Pixmap on the server.
Of course there are many more differences, but technically that's all I need to know. What I did first in this application was to load pictures onto GdkPixbuf with gdk_pixbuf_new_from_file, and call gdk_draw_pixbuf to draw this to the GtkPixmap target area. (pixbuf to pixmap) Of course, though it worked good enough at first, I was intrigated and I tested this through XDMCP to connect to a distant Xserver to see how it would be reacting. The results were pretty slow. Good looking[1], but slow. I suppose this is caused by the the client->server traffic for the pixbuf to be drawn each frame. >From the GDK Reference Manual, gdk_draw_pixbuf: «On older X servers, rendering pixbufs with an alpha channel involves round trips to the X server, and may be somewhat slow.» What I did then was to store the Pixbuf as a pixmap with gdk_pixbuf_render_pixmap_and_mask, just after having load it with gdk_pixbuf_new_from_file (no change on the loading process) The blit then would be done with gdk_draw_drawable (pixmap to pixmap) And the result is pretty good enough through XDMCP. So I suppose this solve my speed issue. But of course it's not perfect. In fact the GtkPixmap resulting from the gdk_pixbuf_render_pixmap_and_mask lose the alpha channel informations. Or maybe I do something wrong. Though gdk_pixbuf_render_pixmap_and_mask takes an alpha_threshold parameter representing a «treshold value for opacity values» it doesn't look the same when using the resulting pixmap with gdk_draw_drawable[2] I tried with multiple alpha_threshold values but I'm not satisfied at all. What am I missing ? Is there a way to transform a pixbuf to a pixmap without losing the alpha channel? gdk_pixbuf_render_pixmap_and_mask returns a GdkPixmap and a GdkBitmap; the mask; from a GdkPixbuf. I don't need any pixbuf at all, but that's the only convenient way I found to load any picture format (png, svg, etc.) easily from a filename (gdk_pixbuf_new_from_file) [1] Good, but slow: http://boby.joe.free.fr/files/pixbuf-to-drawable.png [2] Fast, but ugly: http://boby.joe.free.fr/files/pixbuf-to-pixmap-to-drawable.png PS: I think it's not necessary to send links to the program itself, because it's big, messy, not well documented, etc. but feel free to request it. It's open-source so there's no problem to get it. _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
