pdf (debug API): Export the ability to force fallbacks

We need to occasionally force fallbacks whilst testing the PDF
output, so export a debug interface to do so in order to avoid poking
around inside cairo internals.

References: https://bugs.freedesktop.org/show_bug.cgi?id=48577
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

boilerplate/cairo-boilerplate-pdf.c

@@ -29,8 +29,6 @@
 #if CAIRO_CAN_TEST_PDF_SURFACE
 
 #include <cairo-pdf.h>
-#include <cairo-pdf-surface-private.h>
-#include <cairo-paginated-surface-private.h>
 
 #if HAVE_SIGNAL_H
 #include <signal.h>
@@ -221,23 +219,18 @@ _cairo_boilerplate_pdf_cleanup (void *closure)
 }
 
 static void
-_cairo_boilerplate_pdf_force_fallbacks (cairo_surface_t *abstract_surface,
+_cairo_boilerplate_pdf_force_fallbacks (cairo_surface_t *surface,
 				       double		 x_pixels_per_inch,
 				       double		 y_pixels_per_inch)
 {
-    pdf_target_closure_t *ptc = cairo_surface_get_user_data (abstract_surface,
-							     &pdf_closure_key);
-
-    cairo_paginated_surface_t *paginated;
-    cairo_pdf_surface_t *surface;
+    pdf_target_closure_t *ptc =
+	cairo_surface_get_user_data (surface, &pdf_closure_key);
 
     if (ptc->target)
-	abstract_surface = ptc->target;
+	surface = ptc->target;
 
-    paginated = (cairo_paginated_surface_t*) abstract_surface;
-    surface = (cairo_pdf_surface_t*) paginated->target;
-    surface->force_fallbacks = TRUE;
-    cairo_surface_set_fallback_resolution (&paginated->base,
+    cairo_pdf_surface_debug_force_fallbacks (surface);
+    cairo_surface_set_fallback_resolution (surface,
 					   x_pixels_per_inch,
 					   y_pixels_per_inch);
 }

src/cairo-pdf-surface.c

@@ -683,6 +683,27 @@ cairo_pdf_surface_set_size (cairo_surface_t	*surface,
 	status = _cairo_surface_set_error (surface, status);
 }
 
+/**
+ * cairo_pdf_surface_debug_force_fallbacks:
+ * @surface: a PDF #cairo_surface_t
+ *
+ * This is purely a debugging interface, intended only to be used in
+ * conformation testing, to force the surface to contain only rasterised
+ * graphics and no native PDF drawing.
+ *
+ * Since: 1.12.2
+ **/
+void
+cairo_pdf_surface_debug_force_fallbacks (cairo_surface_t *abstract_surface)
+{
+    cairo_pdf_surface_t *surface = NULL;
+
+    if (! _extract_pdf_surface (abstract_surface, &surface))
+	return;
+
+    surface->force_fallbacks = TRUE;
+}
+
 static void
 _cairo_pdf_surface_clear (cairo_pdf_surface_t *surface)
 {

src/cairo-pdf.h

@@ -85,6 +85,11 @@ cairo_pdf_surface_set_size (cairo_surface_t	*surface,
 			    double		 width_in_points,
 			    double		 height_in_points);
 
+/* debug interface */
+
+cairo_public void
+cairo_pdf_surface_debug_force_fallbacks (cairo_surface_t *abstract_surface);
+
 CAIRO_END_DECLS
 
 #else  /* CAIRO_HAS_PDF_SURFACE */