From 9c10527c8c975851b602d1c2379adc4af9146520 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Kristian=20H=C3=B8gsberg?= <krh@bitplanet.net>
Date: Wed, 29 Jan 2014 15:55:09 +0900
Subject: [PATCH] This vfunc lets us read out a rectangle of pixels from the
 currently attached surface buffer.

Change-Id: Ia12d01fd0d157654602a2c46dd5874218252dd2f
---
 src/compositor.h  |  3 +++
 src/gl-renderer.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/src/compositor.h b/src/compositor.h
index 451ca5d..22ab9e1 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -573,6 +573,9 @@ 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 d18e124..4285910 100644
--- a/src/gl-renderer.c
+++ b/src/gl-renderer.c
@@ -128,6 +128,8 @@ struct gl_renderer {
 	EGLContext egl_context;
 	EGLConfig egl_config;
 
+	GLuint fbo;
+
 	struct wl_array vertices;
 	struct wl_array vtxcnt;
 
@@ -693,6 +695,54 @@ out:
 	pixman_region32_fini(&repaint);
 }
 
+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 weston_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;
+	struct wl_shm_buffer *shm_buffer = NULL;
+
+	switch (format) {
+	case PIXMAN_a8r8g8b8:
+		gl_format = GL_BGRA_EXT;
+		break;
+	case PIXMAN_a8b8g8r8:
+		gl_format = GL_RGBA;
+		break;
+	default:
+		return -1;
+	}
+
+        if (buffer) {
+		shm_buffer = wl_shm_buffer_get(buffer->resource);
+	}
+	if (shm_buffer) {
+		size = buffer->width * 4 * buffer->height;
+		memcpy(pixels, wl_shm_buffer_get_data(shm_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
 repaint_views(struct weston_output *output, pixman_region32_t *damage)
 {
@@ -2100,6 +2150,9 @@ gl_renderer_destroy(struct weston_compositor *ec)
 
 	wl_signal_emit(&gr->destroy_signal, gr);
 
+	if (gr->fbo)
+		glDeleteFramebuffers(1, &gr->fbo);
+
 	if (gr->has_bind_display)
 		gr->unbind_display(gr->egl_display, ec->wl_display);
 
@@ -2314,6 +2367,7 @@ gl_renderer_create(struct weston_compositor *ec, EGLenum platform,
 		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;
-- 
2.7.4