renderer: Add new read_surface_pixels vfunc

This vfunc lets us read out a rectangle of pixels from the currently
attached surface buffer.

2 files changed, 53 insertions, 0 deletions

diff --git a/src/compositor.h b/src/compositor.h
index c32ced1b..ee516265 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -474,6 +474,9 @@ struct weston_renderer {
 			       pixman_format_code_t format, void *pixels,
 			       uint32_t x, uint32_t y,
 			       uint32_t width, uint32_t height);
+	int (*read_surface_pixels)(struct weston_surface *es,
+				   pixman_format_code_t format, void *pixels,
+				   int x, int y, int width, int height);
 	void (*repaint_output)(struct weston_output *output,
 			       pixman_region32_t *output_damage);
 	void (*flush_damage)(struct weston_surface *surface);
diff --git a/src/gl-renderer.c b/src/gl-renderer.c
index be74eba3..4734ee40 100644
--- a/src/gl-renderer.c
+++ b/src/gl-renderer.c
@@ -89,6 +89,8 @@ struct gl_renderer {
 	struct wl_array indices; /* only used in compositor-wayland */
 	struct wl_array vtxcnt;
 
+	GLuint fbo;
+
 	PFNGLEGLIMAGETARGETTEXTURE2DOESPROC image_target_texture_2d;
 	PFNEGLCREATEIMAGEKHRPROC create_image;
 	PFNEGLDESTROYIMAGEKHRPROC destroy_image;
@@ -1104,6 +1106,50 @@ gl_renderer_read_pixels(struct weston_output *output,
 	return 0;
 }
 
+static int
+gl_renderer_read_surface_pixels(struct weston_surface *es,
+				pixman_format_code_t format, void *pixels,
+				int x, int y, int width, int height)
+{
+	struct wl_buffer *buffer = es->buffer_ref.buffer;
+	struct weston_compositor *ec = es->compositor;
+	struct gl_renderer *gr = get_renderer(ec);
+	struct gl_surface_state *gs = get_surface_state(es);
+	GLenum gl_format;
+	int size;
+
+	switch (format) {
+	case PIXMAN_a8r8g8b8:
+		gl_format = GL_BGRA_EXT;
+		break;
+	case PIXMAN_a8b8g8r8:
+		gl_format = GL_RGBA;
+		break;
+	default:
+		return -1;
+	}
+
+	if (buffer && wl_buffer_is_shm(buffer)) {
+		size = buffer->width * 4 * buffer->height;
+		memcpy(pixels, wl_shm_buffer_get_data(buffer), size);
+	} else {
+		if (gr->fbo == 0)
+			glGenFramebuffers(1, &gr->fbo);
+		glBindFramebuffer(GL_FRAMEBUFFER, gr->fbo);
+		glFramebufferTexture2D(GL_FRAMEBUFFER,
+				       GL_COLOR_ATTACHMENT0,
+				       GL_TEXTURE_2D,
+				       gs->textures[0], 0);
+
+		glReadPixels(x, y, width, height,
+			     gl_format, GL_UNSIGNED_BYTE, pixels);
+
+		glBindFramebuffer(GL_FRAMEBUFFER, 0);
+	}
+
+	return 0;
+}
+
 static void
 gl_renderer_flush_damage(struct weston_surface *surface)
 {
@@ -1328,6 +1374,9 @@ gl_renderer_destroy_surface(struct weston_surface *surface)
 	struct gl_renderer *gr = get_renderer(surface->compositor);
 	int i;
 
+	if (gr->fbo)
+		glDeleteFramebuffers(1, &gr->fbo);
+
 	glDeleteTextures(gs->num_textures, gs->textures);
 
 	for (i = 0; i < gs->num_images; i++)
@@ -1812,6 +1861,7 @@ gl_renderer_create(struct weston_compositor *ec, EGLNativeDisplayType display,
 		return -1;
 
 	gr->base.read_pixels = gl_renderer_read_pixels;
+	gr->base.read_surface_pixels = gl_renderer_read_surface_pixels;
 	gr->base.repaint_output = gl_renderer_repaint_output;
 	gr->base.flush_damage = gl_renderer_flush_damage;
 	gr->base.attach = gl_renderer_attach;