compositor-wayland: Add pixman/SHM fallback mode

This also adds a --use-pixman command-line option to enable the pixman renderer explicitly. Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>
11 years ago · ff2fd46e9c
parent 310382fb2f
commit ff2fd46e9c
2 changed files with 374 additions and 95 deletions
--- a/src/compositor-wayland.c
+++ b/src/compositor-wayland.c
@ -1,5 +1,6 @@
 /*
 * Copyright © 2010-2011 Benjamin Franzke
+ * Copyright © 2013 Jason Ekstrand
 *
 * Permission to use, copy, modify, distribute, and sell this software and
 * its documentation for any purpose is hereby granted without fee, provided
@ -36,6 +37,7 @@

 #include "compositor.h"
 #include "gl-renderer.h"
+#include "pixman-renderer.h"
 #include "../shared/image-loader.h"
 #include "../shared/os-compatibility.h"
 #include "../shared/cairo-util.h"
@ -59,6 +61,8 @@ struct wayland_compositor {
 		uint32_t event_mask;
 	} parent;

+	int use_pixman;
+
 	struct theme *theme;
 	cairo_device_t *frame_device;
 	struct wl_cursor_theme *cursor_theme;
@ -74,22 +78,45 @@ struct wayland_output {
 		int draw_initial_frame;
 		struct wl_surface *surface;
 		struct wl_shell_surface *shell_surface;
-		struct wl_egl_window *egl_window;
 	} parent;

 	int keyboard_count;

 	struct frame *frame;
+
+	struct {
+		struct wl_egl_window *egl_window;
 		struct {
 			cairo_surface_t *top;
 			cairo_surface_t *left;
 			cairo_surface_t *right;
 			cairo_surface_t *bottom;
 		} border;
+	} gl;
+
+	struct {
+		struct wl_list buffers;
+		struct wl_list free_buffers;
+	} shm;

 	struct weston_mode mode;
 };

+struct wayland_shm_buffer {
+	struct wayland_output *output;
+	struct wl_list link;
+	struct wl_list free_link;
+
+	struct wl_buffer *buffer;
+	void *data;
+	size_t size;
+	pixman_region32_t damage;
+	int frame_damaged;
+
+	pixman_image_t *pm_image;
+	cairo_surface_t *c_surface;
+};
+
 struct wayland_input {
 	struct weston_seat base;
 	struct wayland_compositor *compositor;
@ -117,42 +144,59 @@ struct wayland_input {
 struct gl_renderer_interface *gl_renderer;

 static void
-frame_done(void *data, struct wl_callback *callback, uint32_t time)
+wayland_shm_buffer_destroy(struct wayland_shm_buffer *buffer)
 {
-	struct weston_output *output = data;
+	cairo_surface_destroy(buffer->c_surface);
+	pixman_image_unref(buffer->pm_image);

-	wl_callback_destroy(callback);
-	weston_output_finish_frame(output, time);
-}
+	wl_buffer_destroy(buffer->buffer);
+	munmap(buffer->data, buffer->size);

-static const struct wl_callback_listener frame_listener = {
-	frame_done
-};
+	pixman_region32_fini(&buffer->damage);
+
+	wl_list_remove(&buffer->link);
+	wl_list_remove(&buffer->free_link);
+	free(buffer);
+}

 static void
 buffer_release(void *data, struct wl_buffer *buffer)
 {
-	wl_buffer_destroy(buffer);
+	struct wayland_shm_buffer *sb = data;
+
+	if (sb->output) {
+		wl_list_insert(&sb->output->shm.free_buffers, &sb->free_link);
+	} else {
+		wayland_shm_buffer_destroy(sb);
+	}
 }

 static const struct wl_buffer_listener buffer_listener = {
 	buffer_release
 };

-static void
-draw_initial_frame(struct wayland_output *output)
+static struct wayland_shm_buffer *
+wayland_output_get_shm_buffer(struct wayland_output *output)
 {
 	struct wayland_compositor *c =
 		(struct wayland_compositor *) output->base.compositor;
 	struct wl_shm *shm = c->parent.shm;
-	struct wl_surface *surface = output->parent.surface;
-	struct wl_shm_pool *pool;
-	struct wl_buffer *buffer;
+	struct wayland_shm_buffer *sb;

+	struct wl_shm_pool *pool;
 	int width, height, stride;
-	int size;
+	int32_t fx, fy;
 	int fd;
-	void *data;
+	unsigned char *data;
+
+	if (!wl_list_empty(&output->shm.free_buffers)) {
+		sb = container_of(output->shm.free_buffers.next,
+				  struct wayland_shm_buffer, free_link);
+		wl_list_remove(&sb->free_link);
+		wl_list_init(&sb->free_link);
+
+		return sb;
+	}

 	if (output->frame) {
 		width = frame_width(output->frame);
@ -162,39 +206,92 @@ draw_initial_frame(struct wayland_output *output)
 		height = output->mode.height;
 	}

-	stride = width * 4;
-	size = height * stride;
+	stride = cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, width);

-	fd = os_create_anonymous_file(size);
+	fd = os_create_anonymous_file(height * stride);
 	if (fd < 0) {
 		perror("os_create_anonymous_file");
-		return;
+		return NULL;
 	}

-	data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	data = mmap(NULL, height * stride, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 	if (data == MAP_FAILED) {
 		perror("mmap");
 		close(fd);
-		return;
+		return NULL;
 	}

-	pool = wl_shm_create_pool(shm, fd, size);
+	sb = zalloc(sizeof *sb);
+
+	sb->output = output;
+	wl_list_init(&sb->free_link);
+	wl_list_insert(&output->shm.buffers, &sb->link);

-	buffer = wl_shm_pool_create_buffer(pool, 0,
+	pixman_region32_init_rect(&sb->damage, 0, 0,
+				  output->base.width, output->base.height);
+	sb->frame_damaged = 1;
+
+	sb->data = data;
+	sb->size = height * stride;
+
+	pool = wl_shm_create_pool(shm, fd, sb->size);
+
+	sb->buffer = wl_shm_pool_create_buffer(pool, 0,
 					       width, height,
 					       stride,
 					       WL_SHM_FORMAT_ARGB8888);
-	wl_buffer_add_listener(buffer, &buffer_listener, buffer);
+	wl_buffer_add_listener(sb->buffer, &buffer_listener, sb);
 	wl_shm_pool_destroy(pool);
 	close(fd);

-	memset(data, 0, size);
+	memset(data, 0, sb->size);
+
+	sb->c_surface =
+		cairo_image_surface_create_for_data(data, CAIRO_FORMAT_ARGB32,
+						    width, height, stride);
+
+	fx = 0;
+	fy = 0;
+	if (output->frame)
+		frame_interior(output->frame, &fx, &fy, 0, 0);
+	sb->pm_image =
+		pixman_image_create_bits(PIXMAN_a8r8g8b8, width, height,
+					 (uint32_t *)(data + fy * stride) + fx,
+					 stride);
+
+	return sb;
+}
+
+static void
+frame_done(void *data, struct wl_callback *callback, uint32_t time)
+{
+	struct weston_output *output = data;
+
+	wl_callback_destroy(callback);
+	weston_output_finish_frame(output, time);
+}
+
+static const struct wl_callback_listener frame_listener = {
+	frame_done
+};
+
+static void
+draw_initial_frame(struct wayland_output *output)
+{
+	struct wayland_shm_buffer *sb;
+
+	sb = wayland_output_get_shm_buffer(output);

-	wl_surface_attach(surface, buffer, 0, 0);
+	/* If we are rendering with GL, then orphan it so that it gets
+	 * destroyed immediately */
+	if (output->gl.egl_window)
+		sb->output = NULL;
+
+	wl_surface_attach(output->parent.surface, sb->buffer, 0, 0);

 	/* We only need to damage some part, as its only transparant
 	 * pixels anyway. */
-	wl_surface_damage(surface, 0, 0, 1, 1);
+	wl_surface_damage(output->parent.surface, 0, 0, 1, 1);
 }

 static void
@ -212,59 +309,59 @@ wayland_output_update_gl_border(struct wayland_output *output)
 	fheight = frame_height(output->frame);
 	frame_interior(output->frame, &ix, &iy, &iwidth, &iheight);

-	if (!output->border.top)
-		output->border.top =
+	if (!output->gl.border.top)
+		output->gl.border.top =
 			cairo_image_surface_create(CAIRO_FORMAT_ARGB32,
 						   fwidth, iy);
-	cr = cairo_create(output->border.top);
+	cr = cairo_create(output->gl.border.top);
 	frame_repaint(output->frame, cr);
 	cairo_destroy(cr);
 	gl_renderer->output_set_border(&output->base, GL_RENDERER_BORDER_TOP,
 				       fwidth, iy,
-				       cairo_image_surface_get_stride(output->border.top) / 4,
-				       cairo_image_surface_get_data(output->border.top));
+				       cairo_image_surface_get_stride(output->gl.border.top) / 4,
+				       cairo_image_surface_get_data(output->gl.border.top));


-	if (!output->border.left)
-		output->border.left =
+	if (!output->gl.border.left)
+		output->gl.border.left =
 			cairo_image_surface_create(CAIRO_FORMAT_ARGB32,
 						   ix, 1);
-	cr = cairo_create(output->border.left);
+	cr = cairo_create(output->gl.border.left);
 	cairo_translate(cr, 0, -iy);
 	frame_repaint(output->frame, cr);
 	cairo_destroy(cr);
 	gl_renderer->output_set_border(&output->base, GL_RENDERER_BORDER_LEFT,
 				       ix, 1,
-				       cairo_image_surface_get_stride(output->border.left) / 4,
-				       cairo_image_surface_get_data(output->border.left));
+				       cairo_image_surface_get_stride(output->gl.border.left) / 4,
+				       cairo_image_surface_get_data(output->gl.border.left));


-	if (!output->border.right)
-		output->border.right =
+	if (!output->gl.border.right)
+		output->gl.border.right =
 			cairo_image_surface_create(CAIRO_FORMAT_ARGB32,
 						   fwidth - (ix + iwidth), 1);
-	cr = cairo_create(output->border.right);
+	cr = cairo_create(output->gl.border.right);
 	cairo_translate(cr, -(iwidth + ix), -iy);
 	frame_repaint(output->frame, cr);
 	cairo_destroy(cr);
 	gl_renderer->output_set_border(&output->base, GL_RENDERER_BORDER_RIGHT,
 				       fwidth - (ix + iwidth), 1,
-				       cairo_image_surface_get_stride(output->border.right) / 4,
-				       cairo_image_surface_get_data(output->border.right));
+				       cairo_image_surface_get_stride(output->gl.border.right) / 4,
+				       cairo_image_surface_get_data(output->gl.border.right));


-	if (!output->border.bottom)
-		output->border.bottom =
+	if (!output->gl.border.bottom)
+		output->gl.border.bottom =
 			cairo_image_surface_create(CAIRO_FORMAT_ARGB32,
 						   fwidth, fheight - (iy + iheight));
-	cr = cairo_create(output->border.bottom);
+	cr = cairo_create(output->gl.border.bottom);
 	cairo_translate(cr, 0, -(iy + iheight));
 	frame_repaint(output->frame, cr);
 	cairo_destroy(cr);
 	gl_renderer->output_set_border(&output->base, GL_RENDERER_BORDER_BOTTOM,
 				       fwidth, fheight - (iy + iheight),
-				       cairo_image_surface_get_stride(output->border.bottom) / 4,
-				       cairo_image_surface_get_data(output->border.bottom));
+				       cairo_image_surface_get_stride(output->gl.border.bottom) / 4,
+				       cairo_image_surface_get_data(output->gl.border.bottom));
 }

 static void
@ -293,7 +390,7 @@ wayland_output_start_repaint_loop(struct weston_output *output_base)
 }

 static int
-wayland_output_repaint(struct weston_output *output_base,
+wayland_output_repaint_gl(struct weston_output *output_base,
 			  pixman_region32_t *damage)
 {
 	struct wayland_output *output = (struct wayland_output *) output_base;
@ -312,23 +409,154 @@ wayland_output_repaint(struct weston_output *output_base,
 	return 0;
 }

+static void
+wayland_output_update_shm_border(struct wayland_shm_buffer *buffer)
+{
+	int32_t ix, iy, iwidth, iheight, fwidth, fheight;
+	cairo_t *cr;
+
+	if (!buffer->output->frame || !buffer->frame_damaged)
+		return;
+
+	cr = cairo_create(buffer->c_surface);
+
+	frame_interior(buffer->output->frame, &ix, &iy, &iwidth, &iheight);
+	fwidth = frame_width(buffer->output->frame);
+	fheight = frame_height(buffer->output->frame);
+
+	/* Set the clip so we don't unnecisaraly damage the surface */
+	cairo_move_to(cr, ix, iy);
+	cairo_rel_line_to(cr, iwidth, 0);
+	cairo_rel_line_to(cr, 0, iheight);
+	cairo_rel_line_to(cr, -iwidth, 0);
+	cairo_line_to(cr, ix, iy);
+	cairo_line_to(cr, 0, iy);
+	cairo_line_to(cr, 0, fheight);
+	cairo_line_to(cr, fwidth, fheight);
+	cairo_line_to(cr, fwidth, 0);
+	cairo_line_to(cr, 0, 0);
+	cairo_line_to(cr, 0, iy);
+	cairo_close_path(cr);
+	cairo_clip(cr);
+
+	/* Draw using a pattern so that the final result gets clipped */
+	cairo_push_group(cr);
+	frame_repaint(buffer->output->frame, cr);
+	cairo_pop_group_to_source(cr);
+	cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+	cairo_paint(cr);
+
+	cairo_destroy(cr);
+}
+
+static void
+wayland_shm_buffer_attach(struct wayland_shm_buffer *sb)
+{
+	pixman_region32_t damage;
+	pixman_box32_t *rects;
+	int32_t ix, iy, iwidth, iheight, fwidth, fheight;
+	int i, n;
+
+	if (sb->output->frame) {
+		frame_interior(sb->output->frame, &ix, &iy, &iwidth, &iheight);
+		fwidth = frame_width(sb->output->frame);
+		fheight = frame_height(sb->output->frame);
+
+		pixman_region32_init(&damage);
+		pixman_region32_copy(&damage, &sb->damage);
+		pixman_region32_translate(&damage, ix, iy);
+
+		if (sb->frame_damaged) {
+			pixman_region32_union_rect(&damage, &damage,
+						   0, 0, fwidth, iy);
+			pixman_region32_union_rect(&damage, &damage,
+						   0, iy, ix, iheight);
+			pixman_region32_union_rect(&damage, &damage,
+						   ix + iwidth, iy,
+						   fwidth - (ix + iwidth), iheight);
+			pixman_region32_union_rect(&damage, &damage,
+						   0, iy + iheight,
+						   fwidth, fheight - (iy + iheight));
+		}
+		rects = pixman_region32_rectangles(&damage, &n);
+	} else {
+		rects = pixman_region32_rectangles(&sb->damage, &n);
+	}
+
+	wl_surface_attach(sb->output->parent.surface, sb->buffer, 0, 0);
+	for (i = 0; i < n; ++i)
+		wl_surface_damage(sb->output->parent.surface, rects[i].x1,
+				  rects[i].y1, rects[i].x2 - rects[i].x1,
+				  rects[i].y2 - rects[i].y1);
+
+	if (sb->output->frame)
+		pixman_region32_fini(&damage);
+}
+
+static int
+wayland_output_repaint_pixman(struct weston_output *output_base,
+			      pixman_region32_t *damage)
+{
+	struct wayland_output *output = (struct wayland_output *) output_base;
+	struct wayland_compositor *c =
+		(struct wayland_compositor *)output->base.compositor;
+	struct wl_callback *callback;
+	struct wayland_shm_buffer *sb;
+
+	if (output->frame) {
+		if (frame_status(output->frame) & FRAME_STATUS_REPAINT)
+			wl_list_for_each(sb, &output->shm.buffers, link)
+				sb->frame_damaged = 1;
+	}
+
+	wl_list_for_each(sb, &output->shm.buffers, link)
+		pixman_region32_union(&sb->damage, &sb->damage, damage);
+
+	sb = wayland_output_get_shm_buffer(output);
+
+	wayland_output_update_shm_border(sb);
+	pixman_renderer_output_set_buffer(output_base, sb->pm_image);
+	c->base.renderer->repaint_output(output_base, &sb->damage);
+
+	wayland_shm_buffer_attach(sb);
+
+	callback = wl_surface_frame(output->parent.surface);
+	wl_callback_add_listener(callback, &frame_listener, output);
+	wl_surface_commit(output->parent.surface);
+	wl_display_flush(c->parent.wl_display);
+
+	pixman_region32_fini(&sb->damage);
+	pixman_region32_init(&sb->damage);
+	sb->frame_damaged = 0;
+
+	pixman_region32_subtract(&c->base.primary_plane.damage,
+				 &c->base.primary_plane.damage, damage);
+	return 0;
+}
+
 static void
 wayland_output_destroy(struct weston_output *output_base)
 {
 	struct wayland_output *output = (struct wayland_output *) output_base;
+	struct wayland_compositor *c =
+		(struct wayland_compositor *) output->base.compositor;

+	if (c->use_pixman) {
+		pixman_renderer_output_destroy(output_base);
+	} else {
 		gl_renderer->output_destroy(output_base);
+	}

-	wl_egl_window_destroy(output->parent.egl_window);
+	wl_egl_window_destroy(output->gl.egl_window);
 	wl_surface_destroy(output->parent.surface);
 	wl_shell_surface_destroy(output->parent.shell_surface);

 	if (output->frame) {
 		frame_destroy(output->frame);
-		cairo_surface_destroy(output->border.top);
-		cairo_surface_destroy(output->border.left);
-		cairo_surface_destroy(output->border.right);
-		cairo_surface_destroy(output->border.bottom);
+		cairo_surface_destroy(output->gl.border.top);
+		cairo_surface_destroy(output->gl.border.left);
+		cairo_surface_destroy(output->gl.border.right);
+		cairo_surface_destroy(output->gl.border.bottom);
 	}

 	weston_output_destroy(&output->base);
@ -339,6 +567,52 @@ wayland_output_destroy(struct weston_output *output_base)

 static const struct wl_shell_surface_listener shell_surface_listener;

+static int
+wayland_output_init_gl_renderer(struct wayland_output *output)
+{
+	int32_t fx, fy, fwidth, fheight;
+
+	if (output->frame) {
+		fwidth = frame_width(output->frame);
+		fheight = frame_height(output->frame);
+	} else {
+		fwidth = output->base.width;
+		fheight = output->base.height;
+	}
+
+	output->gl.egl_window =
+		wl_egl_window_create(output->parent.surface,
+				     fwidth, fheight);
+	if (!output->gl.egl_window) {
+		weston_log("failure to create wl_egl_window\n");
+		return -1;
+	}
+
+	if (gl_renderer->output_create(&output->base,
+			output->gl.egl_window) < 0)
+		goto cleanup_window;
+
+	if (output->frame) {
+		frame_interior(output->frame, &fx, &fy, NULL, NULL);
+		output->base.border.left = fx;
+		output->base.border.top = fy;
+		output->base.border.right = fwidth - output->base.width - fx;
+		output->base.border.bottom = fheight - output->base.height - fy;
+	}
+
+	return 0;
+
+cleanup_window:
+	wl_egl_window_destroy(output->gl.egl_window);
+	return -1;
+}
+
+static int
+wayland_output_init_pixman_renderer(struct wayland_output *output)
+{
+	return pixman_renderer_output_create(&output->base);
+}
+
 static int
 wayland_compositor_create_output(struct wayland_compositor *c,
 				 int width, int height)
@ -368,39 +642,31 @@ wayland_compositor_create_output(struct wayland_compositor *c,

 	weston_output_move(&output->base, 0, 0);

+	wl_list_init(&output->shm.buffers);
+	wl_list_init(&output->shm.free_buffers);
+
 	if (!c->theme)
 		c->theme = theme_create();
 	output->frame = frame_create(c->theme, width, height,
 				     FRAME_BUTTON_CLOSE, "Weston");
 	frame_resize_inside(output->frame, width, height);
-	frame_interior(output->frame, &fx, &fy, NULL, NULL);
-	fwidth = frame_width(output->frame);
-	fheight = frame_height(output->frame);

-	weston_log("Creating %dx%d wayland output (%dx%d actual)\n",
-		   width, height, fwidth, fheight);
+	weston_log("Creating %dx%d wayland output\n", width, height);

 	output->parent.surface =
 		wl_compositor_create_surface(c->parent.compositor);
 	wl_surface_set_user_data(output->parent.surface, output);

-	output->parent.egl_window =
-		wl_egl_window_create(output->parent.surface,
-				     fwidth, fheight);
-	if (!output->parent.egl_window) {
-		weston_log("failure to create wl_egl_window\n");
+	if (c->use_pixman) {
+		if (wayland_output_init_pixman_renderer(output) < 0)
 			goto cleanup_output;
+		output->base.repaint = wayland_output_repaint_pixman;
+	} else {
+		if (wayland_output_init_gl_renderer(output) < 0)
+			goto cleanup_output;
+		output->base.repaint = wayland_output_repaint_gl;
 	}

-	if (gl_renderer->output_create(&output->base,
-			output->parent.egl_window) < 0)
-		goto cleanup_window;
-
-	output->base.border.left = fx;
-	output->base.border.top = fy;
-	output->base.border.right = fwidth - width - fx;
-	output->base.border.bottom = fheight - height - fy;
-
 	frame_input_rect(output->frame, &fx, &fy, &fwidth, &fheight);
 	region = wl_compositor_create_region(c->parent.compositor);
 	wl_region_add(region, fx, fy, fwidth, fheight);
@ -422,7 +688,6 @@ wayland_compositor_create_output(struct wayland_compositor *c,
 	wl_shell_surface_set_toplevel(output->parent.shell_surface);

 	output->base.start_repaint_loop = wayland_output_start_repaint_loop;
-	output->base.repaint = wayland_output_repaint;
 	output->base.destroy = wayland_output_destroy;
 	output->base.assign_planes = NULL;
 	output->base.set_backlight = NULL;
@ -433,8 +698,6 @@ wayland_compositor_create_output(struct wayland_compositor *c,

 	return 0;

-cleanup_window:
-	wl_egl_window_destroy(output->parent.egl_window);
 cleanup_output:
 	/* FIXME: cleanup weston_output */
 	free(output);
@ -1001,7 +1264,7 @@ create_cursor(struct wayland_compositor *c, struct weston_config *config)
 }

 static struct weston_compositor *
-wayland_compositor_create(struct wl_display *display,
+wayland_compositor_create(struct wl_display *display, int use_pixman,
 			  int width, int height, const char *display_name,
 			  int *argc, char *argv[],
 			  struct weston_config *config)
@ -1039,10 +1302,23 @@ wayland_compositor_create(struct wl_display *display,
 	if (!gl_renderer)
 		goto err_display;

+	c->use_pixman = use_pixman;
+	if (!use_pixman) {
 		if (gl_renderer->create(&c->base, c->parent.wl_display,
 				gl_renderer->alpha_attribs,
-			NULL) < 0)
+				NULL) < 0) {
+			weston_log("Failed to initialize the GL renderer; "
+				   "falling back to pixman.\n");
+			c->use_pixman = 1;
+		}
+	}
+
+	if (c->use_pixman) {
+		if (pixman_renderer_init(&c->base) < 0) {
+			weston_log("Failed to initialize pixman renderer\n");
 			goto err_display;
+		}
+	}

 	c->base.destroy = wayland_destroy;
 	c->base.restore = wayland_restore;
@ -1081,16 +1357,18 @@ backend_init(struct wl_display *display, int *argc, char *argv[],
 {
 	int width = 1024, height = 640;
 	char *display_name = NULL;
+	int use_pixman = 0;

 	const struct weston_option wayland_options[] = {
 		{ WESTON_OPTION_INTEGER, "width", 0, &width },
 		{ WESTON_OPTION_INTEGER, "height", 0, &height },
 		{ WESTON_OPTION_STRING, "display", 0, &display_name },
+		{ WESTON_OPTION_BOOLEAN, "use-pixman", 0, &use_pixman },
 	};

 	parse_options(wayland_options,
 		      ARRAY_LENGTH(wayland_options), argc, argv);

-	return wayland_compositor_create(display, width, height, display_name,
-					 argc, argv, config);
+	return wayland_compositor_create(display, use_pixman, width, height,
+					 display_name, argc, argv, config);
 }
--- a/src/compositor.c
+++ b/src/compositor.c
@ -3611,6 +3611,7 @@ usage(int error_code)
 		"Options for wayland-backend.so:\n\n"
 		"  --width=WIDTH\t\tWidth of Wayland surface\n"
 		"  --height=HEIGHT\tHeight of Wayland surface\n"
+		"  --use-pixman\t\tUse the pixman (CPU) renderer\n"
 		"  --display=DISPLAY\tWayland display to connect to\n\n");

 #if defined(BUILD_RPI_COMPOSITOR) && defined(HAVE_BCM_HOST)