[boilerplate] Implement a reference xlib surface

Create an xlib target that uses a separate display, specified by
CAIRO_REFERENCE_DISPLAY, that can be used as a reference implementation
for the normal display. So this can be used by cairo-trace-test to create
a reference surface that mimics exactly the true surface, but if it
targets an Xvfb display will be entirely rendered in software. If
CAIRO_REFERENCE_DISPLAY is not set, the reference surface degrades into an
xlib-fallback surface which is a close approximation (but still has
behavioural differences).

3 files changed, 74 insertions, 2 deletions

diff --git a/boilerplate/cairo-boilerplate-xlib-private.h b/boilerplate/cairo-boilerplate-xlib-private.h
index 0bd911dd..265ee97c 100644
--- a/boilerplate/cairo-boilerplate-xlib-private.h
+++ b/boilerplate/cairo-boilerplate-xlib-private.h
@@ -41,6 +41,17 @@ _cairo_boilerplate_xlib_create_surface (const char		  *name,
 #endif
 
 cairo_surface_t *
+_cairo_boilerplate_xlib_reference_create_surface (const char			 *name,
+						 cairo_content_t		  content,
+						 int				  width,
+						 int				  height,
+						 int				  max_width,
+						 int				  max_height,
+						 cairo_boilerplate_mode_t	  mode,
+						 int				  id,
+						 void				**closure);
+
+cairo_surface_t *
 _cairo_boilerplate_xlib_fallback_create_surface (const char			 *name,
 						 cairo_content_t		  content,
 						 int				  width,
diff --git a/boilerplate/cairo-boilerplate-xlib.c b/boilerplate/cairo-boilerplate-xlib.c
index a4deeb7b..03febe90 100644
--- a/boilerplate/cairo-boilerplate-xlib.c
+++ b/boilerplate/cairo-boilerplate-xlib.c
@@ -224,6 +224,57 @@ _cairo_boilerplate_xlib_create_surface (const char			 *name,
 
     return surface;
 }
+
+cairo_surface_t *
+_cairo_boilerplate_xlib_reference_create_surface (const char			 *name,
+						  cairo_content_t			  content,
+						  int				  width,
+						  int				  height,
+						  int				  max_width,
+						  int				  max_height,
+						  cairo_boilerplate_mode_t	  mode,
+						  int                               id,
+						  void				**closure)
+{
+    xlib_target_closure_t *xtc;
+    Display *dpy;
+    cairo_surface_t *surface;
+    const char *display;
+
+    display = getenv ("CAIRO_REFERENCE_DISPLAY");
+    if (display == NULL) {
+	return _cairo_boilerplate_xlib_fallback_create_surface (name, content,
+								width, height,
+								max_width,
+								max_height,
+								mode, id,
+								closure);
+    }
+
+    *closure = xtc = xcalloc (1, sizeof (xlib_target_closure_t));
+
+    if (width == 0)
+	width = 1;
+    if (height == 0)
+	height = 1;
+
+    xtc->dpy = dpy = XOpenDisplay (display);
+    if (xtc->dpy == NULL) {
+	free (xtc);
+	CAIRO_BOILERPLATE_DEBUG (("Failed to open display: %s\n", display));
+	return NULL;
+    }
+
+    if (mode == CAIRO_BOILERPLATE_MODE_TEST)
+	surface = _cairo_boilerplate_xlib_test_create_surface (dpy, content, width, height, xtc);
+    else /* mode == CAIRO_BOILERPLATE_MODE_PERF */
+	surface = _cairo_boilerplate_xlib_perf_create_surface (dpy, content, width, height, xtc);
+
+    if (surface == NULL || cairo_surface_status (surface))
+	_cairo_boilerplate_xlib_cleanup (xtc);
+
+    return surface;
+}
 #endif
 
 /* The xlib-fallback target differs from the xlib target in two ways:
diff --git a/boilerplate/cairo-boilerplate.c b/boilerplate/cairo-boilerplate.c
index 50a28f89..39a1a4a9 100644
--- a/boilerplate/cairo-boilerplate.c
+++ b/boilerplate/cairo-boilerplate.c
@@ -552,7 +552,7 @@ static const cairo_boilerplate_target_t targets[] =
     /* Acceleration architectures may make the results differ by a
      * bit, so we set the error tolerance to 1. */
     {
-	"xlib", "xlib", NULL, "xlib-fallback",
+	"xlib", "xlib", NULL, "xlib-reference",
 	CAIRO_SURFACE_TYPE_XLIB, CAIRO_CONTENT_COLOR_ALPHA, 1,
 	_cairo_boilerplate_xlib_create_surface,
 	NULL, NULL,
@@ -562,7 +562,7 @@ static const cairo_boilerplate_target_t targets[] =
 	_cairo_boilerplate_xlib_synchronize
     },
     {
-	"xlib", "xlib", NULL, "xlib-fallback",
+	"xlib", "xlib", NULL, "xlib-reference",
 	CAIRO_SURFACE_TYPE_XLIB, CAIRO_CONTENT_COLOR, 1,
 	_cairo_boilerplate_xlib_create_surface,
 	NULL, NULL,
@@ -571,6 +571,16 @@ static const cairo_boilerplate_target_t targets[] =
 	_cairo_boilerplate_xlib_cleanup,
 	_cairo_boilerplate_xlib_synchronize
     },
+    {
+	"xlib-reference", "xlib", NULL, NULL,
+	CAIRO_SURFACE_TYPE_XLIB, CAIRO_CONTENT_COLOR, 1,
+	_cairo_boilerplate_xlib_reference_create_surface,
+	NULL, NULL,
+	NULL, /* get_image */
+	cairo_surface_write_to_png,
+	_cairo_boilerplate_xlib_cleanup,
+	_cairo_boilerplate_xlib_synchronize
+    },
 #endif
 #if CAIRO_HAS_XLIB_SURFACE
     /* This is a fallback surface which uses xlib fallbacks instead of