xlib,xcb: Force strict adherence to the Render specification when testing

Introduce cairo_xlib_device_debug_set_precision() to override the
automatic selection of rendering precision and force the Xorg/DDX to
strictly adhere to the precise rendering mode of the Render
specification. This allows us to test drivers without worrying, too
much, about minor discrepancies in antialiasing.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/cairo-xlib-display.c b/src/cairo-xlib-display.c
index bef9c839..0dab5586 100644
--- a/src/cairo-xlib-display.c
+++ b/src/cairo-xlib-display.c
@@ -350,6 +350,8 @@ _cairo_xlib_device_create (Display *dpy)
     memset (display->cached_xrender_formats, 0,
 	    sizeof (display->cached_xrender_formats));
 
+    display->force_precision = -1;
+
     /* Prior to Render 0.10, there is no protocol support for gradients and
      * we call function stubs instead, which would silently consume the drawing.
      */
@@ -642,3 +644,22 @@ _cairo_xlib_display_has_gradients (cairo_device_t *device)
 {
     return ! ((cairo_xlib_display_t *) device)->buggy_gradients;
 }
+
+void
+cairo_xlib_device_debug_set_precision (cairo_device_t *device,
+				       int precision)
+{
+    if (device->status)
+	    return;
+
+    ((cairo_xlib_display_t *) device)->force_precision = precision;
+}
+
+int
+cairo_xlib_device_debug_get_precision (cairo_device_t *device)
+{
+    if (device->status)
+	    return -1;
+
+    return ((cairo_xlib_display_t *) device)->force_precision;
+}