Chris, thanks for you reply. I clearly understand now the distinction between images and X Drawables. So, to summarise, could you please confirm that my following GTK/Cairo interface functions correctly and always use the XServer: 1. In my expose_event function I do: maincanvas_drawable = GTK_LAYOUT(maincanvas)->bin_window; // drawable layout window // maincanvas_cs = gdk_cairo_create(maincanvas_drawable); // corresponding cairo state// to get the Cairo State maincanvas_cs 2. Next, I draw to maincanvas_cs: ... cairo_paint(maincanvas_cs); ... or 3. I create a similar surface and draw to that, for double-buffering, like this: parent_sf = cairo_get_target(maincanvas_cs); // get parent surface // drawbuffer_sf = cairo_surface_create_similar(parent_sf, CAIRO_CONTENT_COLOR_ALPHA, maincanvasWidth, maincanvasHeight); All of the above exploit the GPU, correct? Thanks for your time and help! Christos. <div class="gmail_quote">On 10 October 2012 12:08, Chris Wilson <<a href="mailto:chris@chris-wilson.co.uk" target="_blank">chris@chris-wilson.co.uk</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">On Wed, 10 Oct 2012 09:20:40 +0300, Christos Sotiriou <<a href="mailto:csotiriou@gmail.com">csotiriou@gmail.com</a>> wrote: > Dear Chris, Dear Cairo Developers/Users, > </div>> I had a few more questions regarding my older post, *i.e.* being able to <div class="im">> draw millions of small rectangles on a Cairo surface provided by GTK/GDK. > > Chris Wilson was kind enough to explain that my Cairo drawing is slow as I > use a non-integer, non-uniform scaling factor, and has improved the Cairo > code for new releases; however, I am stuck with the older Cairo version > which I mention in my older email (for O/S compatibility), so I am back to > probing this issue further, as I really need to speed up zoom-in/zoom-out > for my rectangles. > > My two questions are the following: > </div>> 1. Does Cairo *always use or not use* 2D Hardware Rendering? How can <div class="im">> this be enabled or verified using Cairo code? If not, where can I find a > Cairo code snippet which enables X acceleration? </div>If you pass cairo an X Drawable, it will use XRender to draw to it. If you pass cairo an image buffer, it will render directly to it using the CPU. > 2. As I mention in a prior message I used two methods for <div class="im">> "double-buffering", drawing to an image surface OR drawing to a similar > surface (cairo_surface_create_similar). Funnily enough, the latter was > faster. Is there a reason for this? It seems mysterious... </div>Using image requires doing all the rasterisation locally and transferring the final result using PutImage. Using the similar surface, and you will offload the rasterisation to the X server, which may in turn use the GPU to accelerate the operations. > 3. Related to my first question, I tried to use Cairo/X interaction to > verify if this would improve drawing, *i.e.* if I used an Xlib surface. <div class="im">> I used the following code: > > xdisplay = gdk_x11_drawable_get_xdisplay(maincanvas_drawable); > xid = gdk_x11_drawable_get_xid(maincanvas_drawable); > visual = > gdk_x11_visual_get_xvisual(gtk_widget_get_visual(GTK_WIDGET(maincanvas))); > > maincanvas_sf = cairo_xlib_surface_create(xdisplay, xid, visual, > maincanvasWidth, maincanvasHeight); > maincanvas_cs = cairo_create(maincanvas_sf); > > However, drawing to the Xlib surface did not help either (actually made > matters worse, as GDK/GTK interaction with scrollbars stopped working). So, > coming back to my first question, how can I guarantee 2D acceleration and > why is an Xlib surface not helping? How can an Xlib surface be used > properly? </div>In your expose event, you want to call cr = gdk_cairo_create(gtk_widget_get_window(widget)) to integrate your drawing into the GTK+ model. <div class="HOEnZb"><div class="h5">-Chris -- Chris Wilson, Intel Open Source Technology Centre </div></div></blockquote></div> -- -------------------------------------------------------------------------- Christos P. Sotiriou email: <a href="mailto:csotiriou@gmail.com">csotiriou@gmail.com</a> Cell: +30 697 8984 222