A simple demonstration of the ability of various backends

1 files changed, 122 insertions, 0 deletions

diff --git a/xcb.c b/xcb.c
new file mode 100644
index 0000000..a0b9dd3
--- /dev/null
+++ b/xcb.c
@@ -0,0 +1,122 @@
+#include <cairo-xcb.h>
+
+#include "demo.h"
+
+#include <stdlib.h>
+
+struct xcb_device {
+    struct device base;
+
+    xcb_connection_t *connection;
+    xcb_window_t drawable;
+};
+
+struct xcb_framebuffer {
+    struct framebuffer base;
+};
+
+static void
+destroy (struct framebuffer *abstract_framebuffer)
+{
+    struct xcb_framebuffer *fb = (struct xcb_framebuffer *) abstract_framebuffer;
+
+    cairo_surface_destroy (fb->base.surface);
+    free (fb);
+}
+
+static void
+show (struct framebuffer *abstract_framebuffer)
+{
+    struct xcb_framebuffer *fb = (struct xcb_framebuffer *) abstract_framebuffer;
+    struct xcb_device *device = (struct xcb_device *) fb->base.device;
+    cairo_t *cr;
+
+    cr = cairo_create (device->base.scanout);
+    cairo_set_source_surface (cr, fb->base.surface, 0, 0);
+    cairo_paint (cr);
+    cairo_destroy (cr);
+
+    xcb_flush (device->connection);
+}
+
+static struct framebuffer *
+get_fb (struct device *abstract_device)
+{
+    struct xcb_device *device = (struct xcb_device *) abstract_device;
+    struct xcb_framebuffer *fb;
+
+    fb = malloc (sizeof (struct xcb_framebuffer));
+    fb->base.device = &device->base;
+    fb->base.show = show;
+    fb->base.destroy = destroy;
+
+    fb->base.surface = cairo_surface_create_similar (device->base.scanout,
+						     CAIRO_CONTENT_COLOR,
+						     device->base.width,
+						     device->base.height);
+
+    return &fb->base;
+}
+
+static xcb_visualtype_t *
+lookup_visual (xcb_screen_t *s, xcb_visualid_t visual)
+{
+    xcb_depth_iterator_t d;
+
+    d = xcb_screen_allowed_depths_iterator (s);
+    for (; d.rem; xcb_depth_next (&d)) {
+	xcb_visualtype_iterator_t v = xcb_depth_visuals_iterator (d.data);
+	for (; v.rem; xcb_visualtype_next (&v)) {
+	    if (v.data->visual_id == visual)
+		return v.data;
+	}
+    }
+
+    return 0;
+}
+
+struct device *
+xcb_open (int argc, char **argv)
+{
+    struct xcb_device *device;
+    xcb_connection_t *c;
+    xcb_screen_t *s;
+    xcb_visualtype_t *v;
+    uint32_t values[] = { 1 };
+
+    c = xcb_connect (NULL, NULL);
+    if (c == NULL)
+	return NULL;
+
+    device = malloc (sizeof (struct xcb_device));
+    device->base.name = "xcb";
+    device->base.get_framebuffer = get_fb;
+    device->connection = c;
+    device->drawable = xcb_generate_id (c);
+
+    s = xcb_setup_roots_iterator (xcb_get_setup (c)).data;
+    v = lookup_visual (s, s->root_visual);
+
+    device->base.width = s->width_in_pixels;
+    device->base.height = s->height_in_pixels;
+
+    xcb_create_window (c,
+		       s->root_depth,
+		       device->drawable,
+		       s->root,
+		       0, 0, device->base.width, device->base.height, 0,
+		       XCB_WINDOW_CLASS_INPUT_OUTPUT,
+		       s->root_visual,
+		       XCB_CW_OVERRIDE_REDIRECT,
+		       values);
+    xcb_map_window (c, device->drawable);
+
+    device->base.scanout = cairo_xcb_surface_create (c,
+						     device->drawable,
+						     v,
+						     device->base.width,
+						     device->base.height);
+
+    return &device->base;
+}
+