Add 'flight-data-recorder' utility.

This is a simple variation on cairo-trace that wraps records the last 16
contexts by wrapping the target surface inside a tee surface, along with a
meta/recording surface. Then on receipt of a SIGUSR1, those last 16
contexts are played via a script-surface into /tmp/fdr.trace.

Mostly proof-of-concept, it seems to be causing a number of rendering
glitches whilst testing with firefox -- otherwise, it seems to works.

configure.ac

@@ -667,6 +667,7 @@ test/Makefile
 test/pdiff/Makefile
 perf/Makefile
 util/Makefile
+util/cairo-fdr/Makefile
 util/cairo-script/Makefile
 util/cairo-script/examples/Makefile
 util/cairo-trace/Makefile

src/cairo-scaled-font-private.h

@@ -123,4 +123,7 @@ struct _cairo_scaled_font {
     const cairo_scaled_font_backend_t *backend;
 };
 
+cairo_private void
+_cairo_scaled_font_revoke_ownership (cairo_scaled_font_t *scaled_font);
+
 #endif /* CAIRO_SCALED_FONT_PRIVATE_H */

src/cairo-scaled-font.c

@@ -838,6 +838,22 @@ _cairo_scaled_font_fini_internal (cairo_scaled_font_t *scaled_font)
     _cairo_user_data_array_fini (&scaled_font->user_data);
 }
 
+/* XXX: allow multiple backends to share the font */
+void
+_cairo_scaled_font_revoke_ownership (cairo_scaled_font_t *scaled_font)
+{
+    if (scaled_font->surface_backend == NULL)
+	return;
+
+    _cairo_scaled_font_reset_cache (scaled_font);
+
+    if (scaled_font->surface_backend->scaled_font_fini != NULL)
+	scaled_font->surface_backend->scaled_font_fini (scaled_font);
+
+    scaled_font->surface_backend = NULL;
+    scaled_font->surface_private = NULL;
+}
+
 void
 _cairo_scaled_font_fini (cairo_scaled_font_t *scaled_font)
 {

src/cairo-script-surface.c

@@ -51,6 +51,7 @@
 #include "cairo-list-private.h"
 #include "cairo-meta-surface-private.h"
 #include "cairo-output-stream-private.h"
+#include "cairo-scaled-font-private.h"
 #include "cairo-surface-clipper-private.h"
 #include "cairo-surface-wrapper-private.h"
 
@@ -445,10 +446,14 @@ static cairo_status_t
 _emit_surface (cairo_script_surface_t *surface)
 {
     _cairo_output_stream_printf (surface->ctx->stream,
-				 "<< /content %s /width %f /height %f",
-				 _content_to_string (surface->base.content),
-				 surface->width,
-				 surface->height);
+				 "<< /content //%s",
+				 _content_to_string (surface->base.content));
+    if (surface->width != -1 && surface->height != -1) {
+	_cairo_output_stream_printf (surface->ctx->stream,
+				     " /width %f /height %f",
+				     surface->width,
+				     surface->height);
+    }
 
     if (surface->base.x_fallback_resolution !=
 	CAIRO_SURFACE_FALLBACK_RESOLUTION_DEFAULT ||
@@ -2573,8 +2578,11 @@ _emit_scaled_font (cairo_script_surface_t *surface,
 
     surface->cr.current_scaled_font = scaled_font;
 
-    assert (scaled_font->surface_backend == NULL ||
-	    scaled_font->surface_backend == &_cairo_script_surface_backend);
+    if (! (scaled_font->surface_backend == NULL ||
+	   scaled_font->surface_backend == &_cairo_script_surface_backend))
+    {
+	_cairo_scaled_font_revoke_ownership (scaled_font);
+    }
 
     font_private = scaled_font->surface_private;
     if (font_private == NULL) {
@@ -3384,6 +3392,44 @@ cairo_script_surface_create_for_target (cairo_script_context_t *context,
 						   target)->base;
 }
 
+cairo_status_t
+cairo_script_from_meta_surface (cairo_script_context_t *context,
+				cairo_surface_t *meta)
+{
+    cairo_box_t bbox;
+    cairo_rectangle_int_t extents;
+    cairo_surface_t *surface;
+    cairo_status_t status;
+
+    if (unlikely (context->status))
+	return context->status;
+
+    if (unlikely (meta->status))
+	return meta->status;
+
+    if (unlikely (! _cairo_surface_is_meta (meta)))
+	return _cairo_error (CAIRO_STATUS_SURFACE_TYPE_MISMATCH);
+
+    status = _cairo_meta_surface_get_bbox ((cairo_meta_surface_t *) meta,
+					   &bbox, NULL);
+    if (unlikely (status))
+	return status;
+
+    _cairo_box_round_to_rectangle (&bbox, &extents);
+    surface = &_cairo_script_surface_create_internal (context,
+						      meta->content,
+						      extents.width,
+						      extents.height,
+						      NULL)->base;
+    if (unlikely (surface->status))
+	return surface->status;
+
+    status = cairo_meta_surface_replay (meta, surface);
+    cairo_surface_destroy (surface);
+
+    return status;
+}
+
 void
 cairo_script_context_destroy (cairo_script_context_t *context)
 {

src/cairo-script.h

@@ -81,6 +81,10 @@ cairo_public cairo_surface_t *
 cairo_script_surface_create_for_target (cairo_script_context_t *context,
 					cairo_surface_t *target);
 
+cairo_public cairo_status_t
+cairo_script_from_meta_surface (cairo_script_context_t *context,
+				cairo_surface_t *meta);
+
 CAIRO_END_DECLS
 
 #else  /*CAIRO_HAS_SCRIPT_SURFACE*/

src/cairo.h

@@ -2198,6 +2198,10 @@ cairo_public void
 cairo_tee_surface_append (cairo_surface_t *surface,
 			  cairo_surface_t *target);
 
+cairo_public cairo_surface_t *
+cairo_tee_surface_index (cairo_surface_t *abstract_surface,
+			 int index);
+
 /* Pattern creation functions */
 
 cairo_public cairo_pattern_t *

util/Makefile.am

@@ -4,6 +4,9 @@ SUBDIRS = . cairo-script
 
 if BUILD_TRACE
 SUBDIRS += cairo-trace
+if CAIRO_HAS_SCRIPT_SURFACE
+SUBDIRS += cairo-fdr
+endif
 endif
 
 AM_CPPFLAGS = -I$(top_srcdir)/src

util/cairo-fdr/Makefile.am

@@ -0,0 +1,13 @@
+cairolibdir = $(libdir)/cairo
+
+#bin_SCRIPTS = cairo-fdr
+cairolib_LTLIBRARIES = cairo-fdr.la
+
+AM_CPPFLAGS = -I$(top_srcdir)/src \
+	      -I$(top_builddir)/src
+
+cairo_fdr_la_SOURCES = fdr.c
+cairo_fdr_la_CPPFLAGS = $(AM_CPPFLAGS)
+cairo_fdr_la_CFLAGS = $(CAIRO_CFLAGS)
+cairo_fdr_la_LDFLAGS = -module -no-undefined
+cairo_fdr_la_LIBADD = -ldl

util/cairo-fdr/fdr.c

@@ -0,0 +1,304 @@
+/* cairo-fdr - a 'flight data recorder', a black box, for cairo
+ *
+ * Copyright © 2009 Chris Wilson
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define _GNU_SOURCE
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <cairo.h>
+#include <cairo-script.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <signal.h>
+
+#include <dlfcn.h>
+
+static void *_dlhandle = RTLD_NEXT;
+#define DLCALL(name, args...) ({ \
+    static typeof (&name) name##_real; \
+    if (name##_real == NULL) { \
+	name##_real = dlsym (_dlhandle, #name); \
+	if (name##_real == NULL && _dlhandle == RTLD_NEXT) { \
+	    _dlhandle = dlopen ("libcairo.so", RTLD_LAZY); \
+	    name##_real = dlsym (_dlhandle, #name); \
+	    assert (name##_real != NULL); \
+	} \
+    } \
+    (*name##_real) (args);  \
+})
+
+#define RINGBUFFER_SIZE 16
+static cairo_surface_t *fdr_ringbuffer[RINGBUFFER_SIZE];
+static int fdr_position;
+static int fdr_dump;
+
+static const cairo_user_data_key_t fdr_key;
+
+static void
+fdr_replay_to_script (cairo_surface_t *meta, cairo_script_context_t *ctx)
+{
+    if (meta != NULL) {
+	DLCALL (cairo_script_context_write_comment, ctx, "--- fdr ---", -1);
+	DLCALL (cairo_script_from_meta_surface, ctx, meta);
+    }
+}
+
+static void
+fdr_dump_ringbuffer (void)
+{
+    cairo_script_context_t *ctx;
+    int n;
+
+    ctx = DLCALL (cairo_script_context_create, "/tmp/fdr.trace");
+
+    for (n = fdr_position; n < RINGBUFFER_SIZE; n++)
+	fdr_replay_to_script (fdr_ringbuffer[n], ctx);
+
+    for (n = 0; n < fdr_position; n++)
+	fdr_replay_to_script (fdr_ringbuffer[n], ctx);
+
+    DLCALL (cairo_script_context_destroy, ctx);
+}
+
+static void
+fdr_sighandler (int sig)
+{
+    fdr_dump = 1;
+}
+
+static void
+fdr_atexit (void)
+{
+    if (fdr_dump)
+	fdr_dump_ringbuffer ();
+}
+
+static void
+fdr_pending_signals (void)
+{
+    static int initialized;
+
+    if (! initialized) {
+	initialized = 1;
+
+	signal (SIGUSR1, fdr_sighandler);
+	atexit (fdr_atexit);
+    }
+
+    if (fdr_dump) {
+	fdr_dump_ringbuffer ();
+	fdr_dump = 0;
+    }
+}
+
+static void
+fdr_get_extents (cairo_surface_t *surface,
+		 cairo_rectangle_t *extents)
+{
+    cairo_t *cr;
+
+    cr = DLCALL (cairo_create, surface);
+    DLCALL (cairo_clip_extents, cr,
+	    &extents->x, &extents->y, &extents->width, &extents->height);
+    DLCALL (cairo_destroy, cr);
+
+    extents->width -= extents->x;
+    extents->height -= extents->y;
+}
+
+static void
+fdr_surface_destroy (void *surface)
+{
+    DLCALL (cairo_surface_destroy, surface);
+}
+
+static void
+fdr_surface_reference (void *surface)
+{
+    DLCALL (cairo_surface_reference, surface);
+}
+
+static cairo_surface_t *
+fdr_surface_get_tee (cairo_surface_t *surface)
+{
+    return DLCALL (cairo_surface_get_user_data, surface, &fdr_key);
+}
+
+static cairo_surface_t *
+fdr_tee_surface_index (cairo_surface_t *surface, int index)
+{
+    return DLCALL (cairo_tee_surface_index, surface, index);
+}
+
+cairo_t *
+cairo_create (cairo_surface_t *surface)
+{
+    cairo_surface_t *record, *tee;
+
+    fdr_pending_signals ();
+
+    tee = fdr_surface_get_tee (surface);
+    if (tee == NULL) {
+	cairo_rectangle_t extents;
+	cairo_content_t content;
+
+	fdr_get_extents (surface, &extents);
+	content = DLCALL (cairo_surface_get_content, surface);
+
+	tee = DLCALL (cairo_tee_surface_create, surface);
+	record = DLCALL (cairo_meta_surface_create, content, &extents);
+	DLCALL (cairo_tee_surface_append, tee, record);
+
+	DLCALL (cairo_surface_set_user_data, surface,
+		&fdr_key, tee, fdr_surface_destroy);
+    } else {
+	int n;
+
+	record = fdr_tee_surface_index (tee, 1);
+
+	/* update the position of the recording surface in the ringbuffer */
+	for (n = 0; n < RINGBUFFER_SIZE; n++) {
+	    if (record == fdr_ringbuffer[n]) {
+		fdr_ringbuffer[n] = NULL;
+		break;
+	    }
+	}
+    }
+
+    fdr_surface_destroy (fdr_ringbuffer[fdr_position]);
+    fdr_ringbuffer[fdr_position] = record;
+    fdr_position = (fdr_position + 1) % RINGBUFFER_SIZE;
+
+    return DLCALL (cairo_create, tee);
+}
+
+static void
+fdr_remove_tee (cairo_surface_t *surface)
+{
+    fdr_surface_reference (surface);
+    DLCALL (cairo_surface_set_user_data, surface, &fdr_key, NULL, NULL);
+    fdr_surface_destroy (surface);
+}
+
+void
+cairo_destroy (cairo_t *cr)
+{
+    cairo_surface_t *tee;
+
+    tee = DLCALL (cairo_get_target, cr);
+    DLCALL (cairo_destroy, cr);
+
+    if (DLCALL (cairo_surface_get_reference_count, tee) == 1)
+	fdr_remove_tee (fdr_tee_surface_index (tee, 0));
+}
+
+void
+cairo_pattern_destroy (cairo_pattern_t *pattern)
+{
+    if (DLCALL (cairo_pattern_get_type, pattern) == CAIRO_PATTERN_TYPE_SURFACE) {
+	cairo_surface_t *surface;
+
+	if (DLCALL (cairo_pattern_get_surface, pattern, &surface) == CAIRO_STATUS_SUCCESS &&
+	    DLCALL (cairo_surface_get_type, surface) == CAIRO_SURFACE_TYPE_TEE &&
+	    DLCALL (cairo_surface_get_reference_count, surface) == 2)
+	{
+	    fdr_remove_tee (fdr_tee_surface_index (surface, 0));
+	}
+    }
+
+    DLCALL (cairo_pattern_destroy, pattern);
+}
+
+cairo_surface_t *
+cairo_get_target (cairo_t *cr)
+{
+    cairo_surface_t *tee;
+
+    tee = DLCALL (cairo_get_target, cr);
+    return fdr_tee_surface_index (tee, 0);
+}
+
+cairo_surface_t *
+cairo_get_group_target (cairo_t *cr)
+{
+    cairo_surface_t *tee;
+
+    tee = DLCALL (cairo_get_group_target, cr);
+    return fdr_tee_surface_index (tee, 0);
+}
+
+cairo_pattern_t *
+cairo_pattern_create_for_surface (cairo_surface_t *surface)
+{
+    cairo_surface_t *tee;
+
+    tee = fdr_surface_get_tee (surface);
+    if (tee != NULL)
+	surface = tee;
+
+    return DLCALL (cairo_pattern_create_for_surface, surface);
+}
+
+cairo_status_t
+cairo_pattern_get_surface (cairo_pattern_t *pattern,
+			   cairo_surface_t **surface)
+{
+    cairo_status_t status;
+    cairo_surface_t *tee;
+
+    status = DLCALL (cairo_pattern_get_surface, pattern, surface);
+    if (status != CAIRO_STATUS_SUCCESS)
+	return status;
+
+    tee = fdr_surface_get_tee (*surface);
+    if (tee != NULL)
+	*surface = tee;
+
+    return CAIRO_STATUS_SUCCESS;
+}
+
+void
+cairo_set_source_surface (cairo_t *cr,
+			  cairo_surface_t *surface,
+			  double x, double y)
+{
+    cairo_surface_t *tee;
+
+    tee = fdr_surface_get_tee (surface);
+    if (tee != NULL)
+	surface = tee;
+
+    DLCALL (cairo_set_source_surface, cr, surface, x, y);
+}
+
+cairo_surface_t *
+cairo_surface_create_similar (cairo_surface_t *surface,
+			      cairo_content_t content,
+			      int width, int height)
+{
+    cairo_surface_t *tee;
+
+    tee = fdr_surface_get_tee (surface);
+    if (tee != NULL)
+	surface = tee;
+
+    return DLCALL (cairo_surface_create_similar,
+		   surface, content, width, height);
+}