[cairo] xcb surface example?

[Bryce Harrington]

On Fri, Jun 26, 2015 at 08:09:36PM +0200, Uli Schlachter wrote:
> Am 26.06.2015 um 13:31 schrieb Andreas Lobinger:
> > Hello colleagues,
> 
> Hi,
> 
> > is there a good, known example of the cairo XcbSurface available? On the
> > http://cairographics.org/examples/ page there is a link to
> > git clone git://git.thisnukes4u.net/cairo-xcb-demo.git
> > which seems to be outdated.
> 
> What exactly do you need? There is mostly just a single useful function in
> cairo-xcb. :-)
> 
> Anyway, attached is a quick example that I hacked together. Hopefully it can
> help you.

I've added this as a new link at the end of our cookbook:

    http://cairographics.org/cookbook/

...and removed the linkrot from our examples page.

Uli, would you mind specifying what license should be listed for your
code?  (Fwiw, the blur.c code appears to be using an MIT-ish license.)

Bryce

> Cheers,
> Uli
> -- 
> Homophobia - The fear that another man will treat you the way you treat women.

> #include <xcb/xcb.h>
> #include <cairo-xcb.h>
> #include <stdio.h>
> #include <stdlib.h>
> 
> static xcb_visualtype_t *find_visual(xcb_connection_t *c, xcb_visualid_t visual)
> {
> 	xcb_screen_iterator_t screen_iter = xcb_setup_roots_iterator(xcb_get_setup(c));
> 	
> 	for (; screen_iter.rem; xcb_screen_next(&screen_iter)) {
> 		xcb_depth_iterator_t depth_iter = xcb_screen_allowed_depths_iterator(screen_iter.data);
> 		for (; depth_iter.rem; xcb_depth_next(&depth_iter)) {
> 			xcb_visualtype_iterator_t visual_iter = xcb_depth_visuals_iterator(depth_iter.data);
> 			for (; visual_iter.rem; xcb_visualtype_next(&visual_iter))
> 				if (visual == visual_iter.data->visual_id)
> 					return visual_iter.data;
> 		}
> 	}
> 
> 	return NULL;
> }
> 
> int main()
> {
> 	xcb_connection_t *c;
> 	xcb_screen_t *screen;
> 	xcb_window_t window;
> 	uint32_t mask[2];
> 	xcb_visualtype_t *visual;
> 	xcb_generic_event_t *event;
> 	cairo_surface_t *surface;
> 	cairo_t *cr;
> 
> 	c = xcb_connect(NULL, NULL);
> 	if (xcb_connection_has_error(c)) {
> 		fprintf(stderr, "Could not connect to X11 server");
> 		return 1;
> 	}
> 
> 	mask[0] = 1;
> 	mask[1] = XCB_EVENT_MASK_EXPOSURE;
> 	screen = xcb_setup_roots_iterator(xcb_get_setup(c)).data;
> 	window = xcb_generate_id(c);
> 	xcb_create_window(c, XCB_COPY_FROM_PARENT, window, screen->root,
> 			20, 20, 150, 150, 0,
> 			XCB_WINDOW_CLASS_INPUT_OUTPUT,
> 			screen->root_visual,
> 			XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK,
> 			mask);
> 	xcb_map_window(c, window);
> 
> 	visual = find_visual(c, screen->root_visual);
> 	if (visual == NULL) {
> 		fprintf(stderr, "Some weird internal error...?!");
> 		xcb_disconnect(c);
> 		return 1;
> 	}
> 	surface = cairo_xcb_surface_create(c, window, visual, 150, 150);
> 	cr = cairo_create(surface);
> 
> 	xcb_flush(c);
> 	while ((event = xcb_wait_for_event(c))) {
> 		switch (event->response_type & ~0x80) {
> 		case XCB_EXPOSE:
> 			/* Should check if this is the last expose event in the
> 			 * sequence, but I'm too lazy right now...
> 			 */
> 			cairo_set_source_rgb(cr, 0, 1, 0);
> 			cairo_paint(cr);
> 
> 			cairo_set_source_rgb(cr, 1, 0, 0);
> 			cairo_move_to(cr, 0, 0);
> 			cairo_line_to(cr, 150, 0);
> 			cairo_line_to(cr, 150, 150);
> 			cairo_close_path(cr);
> 			cairo_fill(cr);
> 
> 			cairo_set_source_rgb(cr, 0, 0, 1);
> 			cairo_set_line_width(cr, 20);
> 			cairo_move_to(cr, 0, 150);
> 			cairo_line_to(cr, 150, 0);
> 			cairo_stroke(cr);
> 
> 			cairo_surface_flush(surface);
> 			break;
> 		}
> 		free(event);
> 		xcb_flush(c);
> 	}
> 	cairo_surface_finish(surface);
> 	xcb_disconnect(c);
> 	return 0;
> }

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