On Thu, 2006-08-10 at 16:34 +0200, KLEIN Stéphane wrote: > Hello, > > I use Ubuntu system. I've showed gnome and Gimp to one friend. This > friend use MS Windows since always. > > He say : "I dislike Linux, Ubuntu, Gnome, Gimp ... because the GUI > display scintillate. This also for Gimp MS Windows version". > > He say : "First, I see the window draw, next the background draw of > button...". On the contrary, MS Windows application display all widget > in one step." > > I don't know if you understand my subject. > > My question : is there double buffering render in GTK ? If yes, why my > friend think than Windows display is faster than GTK and other widget > toolkit ? If not, why that ? It is a matter of perception. I cannot say whether GTK renders faster than Windows. But GTK is double-buffered. However what your friend is seeing is a result of a couple of things. First is that when you uncover a window, X11 sends expose events to the uncovered window. It is up to the client (the app) to respond to these events and redraw the parts that were exposed. If the window is in motion, these expose events may come faster than the app can deal with. GTK typically "compresses" these events and will wait to do the actual redraw. This reduces the CPU consumption and increases overall speed, but it comes at the expense of visual stuttering. One is that the X windowing system in asynchronous. This means, among other things, that the windowing code accepts requests as they come from various clients (apps). These means that redraws and reconfigures of the various applications aren't necessarily going to happen at the exact same time. Also when you drag a window, for example, the redrawing isn't synchronized to any particular clock, so you get tearing. Windows also often has tearing when you drag a large window around. Mac does not, for reasons I'll describe below. Work is being done to address these perceptions (speed really is fast; it just looks slow). First of all, people are developing X servers that use OpenGL to draw the windows on the screen. What this means is that apps draw to an off-screen bitmap, which OpenGL then pastes on the screen. Since the OpenGL drawing is very quick, this eliminates redraw flicker to a large degree (since the flicker is hidden off-screen where you can't see it). Also when you move a window, the window underneath is intact (it's an opengl texture) so there are *no* expose events needed. This doesn't address the resize stuttering issue, though (even Mac OS X stutters on resizes on slow video cards). This will be addressed through new synchronization events that the X server will use to make sure everything happens smoothly, without any stuttering. If you want to see how fast a Linux desktop can appear, check out the new OpenSuSE with it's Xgl system. It's sweet! Fedora Core 6 will have similar technology, called AIXGL. Besides providing fast rendering (which will definitely quell your friend's complaints), it also enables lots of other cool things like 3-d desktops, OS X-like expose, etc. See http://www.freedesktop.org/~davidr/xgl-demo1.xvid.avi , and also http://kororaa.org/ Michael > > Thanks for your response. > --Stéphane > _______________________________________________ > > gtk-list@xxxxxxxxx > http://mail.gnome.org/mailman/listinfo/gtk-list _______________________________________________ gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
