recording: optionally disable optimise away clears

The observer wants to get an accurate recording of all operations,
including clears.

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

4 files changed, 28 insertions, 12 deletions

diff --git a/src/cairo-composite-rectangles.c b/src/cairo-composite-rectangles.c
index 6083973f..a25e6d34 100644
--- a/src/cairo-composite-rectangles.c
+++ b/src/cairo-composite-rectangles.c
@@ -224,9 +224,7 @@ _cairo_composite_rectangles_init_for_glyphs (cairo_composite_rectangles_t *exten
 
     if (! _cairo_composite_rectangles_init (extents, unbounded,
 					    op, source, clip))
-    {
 	return CAIRO_INT_STATUS_NOTHING_TO_DO;
-    }
 
     /* Computing the exact bbox and the overlap is expensive.
      * First perform a cheap test to see if the glyphs are all clipped out.
diff --git a/src/cairo-recording-surface-private.h b/src/cairo-recording-surface-private.h
index b7843e6c..ea38c198 100644
--- a/src/cairo-recording-surface-private.h
+++ b/src/cairo-recording-surface-private.h
@@ -134,6 +134,7 @@ typedef struct _cairo_recording_surface {
     cairo_array_t commands;
     int *indices;
     int num_indices;
+    cairo_bool_t optimize_clears;
 
     struct bbtree {
 	cairo_box_t extents;
diff --git a/src/cairo-recording-surface.c b/src/cairo-recording-surface.c
index beafb785..6d4cb379 100644
--- a/src/cairo-recording-surface.c
+++ b/src/cairo-recording-surface.c
@@ -413,6 +413,7 @@ cairo_recording_surface_create (cairo_content_t		 content,
 
     surface->indices = NULL;
     surface->num_indices = 0;
+    surface->optimize_clears = TRUE;
 
     return &surface->base;
 }
@@ -714,13 +715,12 @@ _cairo_recording_surface_paint (void			  *abstract_surface,
     cairo_composite_rectangles_t composite;
     const cairo_rectangle_int_t *extents;
 
-    /* An optimisation that takes care to not replay what was done
-     * before surface is cleared. We don't erase recorded commands
-     * since we may have earlier snapshots of this surface. */
     if (op == CAIRO_OPERATOR_CLEAR && clip == NULL) {
-	_cairo_recording_surface_destroy_bbtree (surface);
-	surface->commands.num_elements = 0;
-	return CAIRO_STATUS_SUCCESS;
+	if (surface->optimize_clears) {
+	    _cairo_recording_surface_destroy_bbtree (surface);
+	    surface->commands.num_elements = 0;
+	    return CAIRO_STATUS_SUCCESS;
+	}
     }
 
     extents = _cairo_recording_surface_extents (surface);
diff --git a/src/cairo-surface-observer.c b/src/cairo-surface-observer.c
index abb00e7e..370b05b9 100644
--- a/src/cairo-surface-observer.c
+++ b/src/cairo-surface-observer.c
@@ -113,7 +113,7 @@ static void init_glyphs (struct glyphs *g)
     init_clip (&g->clip);
 }
 
-static void
+static cairo_status_t
 log_init (cairo_observation_t *log)
 {
     memset (log, 0, sizeof(*log));
@@ -125,8 +125,15 @@ log_init (cairo_observation_t *log)
     init_glyphs (&log->glyphs);
 
     _cairo_array_init (&log->timings, sizeof (cairo_observation_record_t));
+
     log->record = (cairo_recording_surface_t *)
 	    cairo_recording_surface_create (CAIRO_CONTENT_COLOR_ALPHA, NULL);
+    if (unlikely (log->record->base.status))
+	return log->record->base.status;
+
+    log->record->optimize_clears = FALSE;
+
+    return CAIRO_STATUS_SUCCESS;
 }
 
 static void
@@ -323,15 +330,20 @@ static cairo_device_t *
 _cairo_device_create_observer_internal (cairo_device_t *target)
 {
     cairo_device_observer_t *device;
+    cairo_status_t status;
 
     device = malloc (sizeof (cairo_device_observer_t));
     if (unlikely (device == NULL))
 	return _cairo_device_create_in_error (_cairo_error (CAIRO_STATUS_NO_MEMORY));
 
     _cairo_device_init (&device->base, &_cairo_device_observer_backend);
-    device->target = cairo_device_reference (target);
+    status = log_init (&device->log);
+    if (unlikely (status)) {
+	free (device);
+	return _cairo_device_create_in_error (status);
+    }
 
-    log_init (&device->log);
+    device->target = cairo_device_reference (target);
 
     return &device->base;
 }
@@ -349,6 +361,7 @@ _cairo_surface_create_observer_internal (cairo_device_t *device,
 					 cairo_surface_t *target)
 {
     cairo_surface_observer_t *surface;
+    cairo_status_t status;
 
     surface = malloc (sizeof (cairo_surface_observer_t));
     if (unlikely (surface == NULL))
@@ -358,7 +371,11 @@ _cairo_surface_create_observer_internal (cairo_device_t *device,
 			 &_cairo_surface_observer_backend, device,
 			 target->content);
 
-    log_init (&surface->log);
+    status = log_init (&surface->log);
+    if (unlikely (status)) {
+	free (surface);
+	return _cairo_surface_create_in_error (status);
+    }
 
     surface->target = cairo_surface_reference (target);
     surface->base.type = surface->target->type;