From c0a553163b5e82cb70e956e802d7f9b61bb13948 Mon Sep 17 00:00:00 2001 From: Neil Roberts Date: Mon, 1 Mar 2010 18:08:41 +0000 Subject: [PATCH] cogl: Support any format in cogl_read_pixels cogl_read_pixels() no longer asserts that the format passed in is RGBA_8888 but instead accepts any format. The appropriate GL enums for the format are passed to glReadPixels so OpenGL should be perform a conversion if neccessary. It currently assumes glReadPixels will always give us premultiplied data. This will usually be correct because the result of the default blending operations for Cogl ends up with premultiplied data in the framebuffer. However it is possible for the framebuffer to be in whatever format depending on what CoglMaterial is used to render to it. Eventually we may want to add a way for an application to inform Cogl that the framebuffer is not premultiplied in case it is being used for some special purpose. If the requested format is not premultiplied then Cogl will convert it. The tests have been changed to read the data as premultiplied so that they won't be affected by the conversion. Picking in Clutter has been changed to use COGL_PIXEL_FORMAT_RGB_888 because it doesn't need the alpha component. clutter_stage_read_pixels is left unchanged because the application can't specify a format for that so it seems to make most sense to store unpremultiplied values. http://bugzilla.openedhand.com/show_bug.cgi?id=1959 --- clutter/clutter-main.c | 10 +-- clutter/cogl/cogl/cogl.c | 86 +++++++++++++------ clutter/cogl/cogl/cogl.h | 8 +- tests/conform/test-cogl-backface-culling.c | 2 +- tests/conform/test-cogl-blend-strings.c | 4 +- tests/conform/test-cogl-materials.c | 2 +- tests/conform/test-cogl-multitexture.c | 2 +- tests/conform/test-cogl-offscreen.c | 8 +- tests/conform/test-cogl-premult.c | 2 +- tests/conform/test-cogl-readpixels.c | 26 +++++- tests/conform/test-cogl-texture-mipmaps.c | 2 +- .../test-cogl-vertex-buffer-contiguous.c | 10 +-- .../test-cogl-vertex-buffer-interleved.c | 2 +- .../test-cogl-vertex-buffer-mutability.c | 4 +- tests/conform/test-cogl-viewport.c | 2 +- 15 files changed, 114 insertions(+), 56 deletions(-) diff --git a/clutter/clutter-main.c b/clutter/clutter-main.c index a21dfc52f..97bc661e3 100644 --- a/clutter/clutter-main.c +++ b/clutter/clutter-main.c @@ -499,15 +499,15 @@ read_pixels_to_file (char *filename_stem, data = g_malloc (4 * width * height); cogl_read_pixels (x, y, width, height, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGB_888, data); pixbuf = gdk_pixbuf_new_from_data (data, GDK_COLORSPACE_RGB, - TRUE, /* has alpha */ + FALSE, /* has alpha */ 8, /* bits per sample */ width, /* width */ height, /* height */ - width * 4, /* rowstride */ + width * 3, /* rowstride */ pixbuf_free, /* callback to free data */ NULL); /* callback data */ if (pixbuf) @@ -549,7 +549,7 @@ _clutter_do_pick (ClutterStage *stage, ClutterPickMode mode) { ClutterMainContext *context; - guchar pixel[4] = { 0xff, 0xff, 0xff, 0xff }; + guchar pixel[3] = { 0xff, 0xff, 0xff }; CoglColor stage_pick_id; guint32 id; GLboolean dither_was_on; @@ -634,7 +634,7 @@ _clutter_do_pick (ClutterStage *stage, CLUTTER_TIMER_START (_clutter_uprof_context, pick_read); cogl_read_pixels (x, y, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGB_888, pixel); CLUTTER_TIMER_STOP (_clutter_uprof_context, pick_read); diff --git a/clutter/cogl/cogl/cogl.c b/clutter/cogl/cogl/cogl.c index 69e76cfa1..af30f2f43 100644 --- a/clutter/cogl/cogl/cogl.c +++ b/clutter/cogl/cogl/cogl.c @@ -41,6 +41,9 @@ #include "cogl-framebuffer-private.h" #include "cogl-matrix-private.h" #include "cogl-journal-private.h" +#include "cogl-bitmap-private.h" +#include "cogl-texture-private.h" +#include "cogl-texture-driver.h" #if defined (HAVE_COGL_GLES2) || defined (HAVE_COGL_GLES) #include "cogl-gles2-wrapper.h" @@ -630,20 +633,20 @@ cogl_read_pixels (int x, { CoglHandle framebuffer; int framebuffer_height; - int rowstride = width * 4; - guint8 *temprow; + int bpp; + CoglBitmap bmp; + GLenum gl_intformat; + GLenum gl_format; + GLenum gl_type; _COGL_GET_CONTEXT (ctx, NO_RETVAL); - g_return_if_fail (format == COGL_PIXEL_FORMAT_RGBA_8888); g_return_if_fail (source == COGL_READ_PIXELS_COLOR_BUFFER); /* make sure any batched primitives get emitted to the GL driver before * issuing our read pixels... */ cogl_flush (); - temprow = g_alloca (rowstride * sizeof (guint8)); - framebuffer = _cogl_get_framebuffer (); _cogl_framebuffer_flush_state (framebuffer, 0); @@ -659,37 +662,64 @@ cogl_read_pixels (int x, if (!cogl_is_offscreen (framebuffer)) y = framebuffer_height - y - height; + /* Initialise the CoglBitmap */ + bpp = _cogl_get_format_bpp (format); + bmp.format = format; + bmp.data = pixels; + bmp.width = width; + bmp.height = height; + bmp.rowstride = bpp * width; + + if ((format & COGL_A_BIT)) + { + /* FIXME: We are assuming glReadPixels will always give us + premultiplied data so we'll set the premult flag on the + bitmap format. This will usually be correct because the + result of the default blending operations for Cogl ends up + with premultiplied data in the framebuffer. However it is + possible for the framebuffer to be in whatever format + depending on what CoglMaterial is used to render to + it. Eventually we may want to add a way for an application to + inform Cogl that the framebuffer is not premultiplied in case + it is being used for some special purpose. */ + bmp.format |= COGL_PREMULT_BIT; + } + /* Setup the pixel store parameters that may have been changed by Cogl */ - GE (glPixelStorei (GL_PACK_ALIGNMENT, 1)); -#ifdef HAVE_COGL_GL - GE (glPixelStorei (GL_PACK_ROW_LENGTH, 0)); - GE (glPixelStorei (GL_PACK_SKIP_PIXELS, 0)); - GE (glPixelStorei (GL_PACK_SKIP_ROWS, 0)); -#endif /* HAVE_COGL_GL */ + _cogl_texture_driver_prep_gl_for_pixels_download (bmp.rowstride, bpp); - GE (glReadPixels (x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels)); + _cogl_pixel_format_to_gl (format, &gl_intformat, &gl_format, &gl_type); + + GE (glReadPixels (x, y, width, height, gl_format, gl_type, pixels)); + + /* Convert to the premult format specified by the caller + in-place. This will do nothing if the premult status is already + correct. */ + _cogl_bitmap_convert_premult_status (&bmp, format); /* NB: All offscreen rendering is done upside down so there is no need * to flip in this case... */ - if (cogl_is_offscreen (framebuffer)) - return; - - /* TODO: consider using the GL_MESA_pack_invert extension in the future - * to avoid this flip... */ - - /* vertically flip the buffer in-place */ - for (y = 0; y < height / 2; y++) + if (!cogl_is_offscreen (framebuffer)) { - if (y != height - y - 1) /* skip center row */ + guint8 *temprow = g_alloca (bmp.rowstride * sizeof (guint8)); + + /* TODO: consider using the GL_MESA_pack_invert extension in the future + * to avoid this flip... */ + + /* vertically flip the buffer in-place */ + for (y = 0; y < height / 2; y++) { - memcpy (temprow, - pixels + y * rowstride, rowstride); - memcpy (pixels + y * rowstride, - pixels + (height - y - 1) * rowstride, rowstride); - memcpy (pixels + (height - y - 1) * rowstride, - temprow, - rowstride); + if (y != height - y - 1) /* skip center row */ + { + memcpy (temprow, + pixels + y * bmp.rowstride, bmp.rowstride); + memcpy (pixels + y * bmp.rowstride, + pixels + (height - y - 1) * bmp.rowstride, bmp.rowstride); + memcpy (pixels + (height - y - 1) * bmp.rowstride, + temprow, + bmp.rowstride); + } } } } diff --git a/clutter/cogl/cogl/cogl.h b/clutter/cogl/cogl/cogl.h index 053df6d13..53ddec2de 100644 --- a/clutter/cogl/cogl/cogl.h +++ b/clutter/cogl/cogl/cogl.h @@ -936,7 +936,13 @@ typedef enum { /*< prefix=COGL_READ_PIXELS >*/ * * This reads a rectangle of pixels from the current framebuffer where * position (0, 0) is the top left. The pixel at (x, y) is the first - * read, and the data is returned with a rowstride of (width * 4) + * read, and the data is returned with a rowstride of (width * 4). + * + * Currently Cogl assumes that the framebuffer is in a premultiplied + * format so if @format is non-premultiplied it will convert it. To + * read the pixel values without any conversion you should either + * specify a format that doesn't use an alpha channel or use one of + * the formats ending in PRE. */ void cogl_read_pixels (int x, diff --git a/tests/conform/test-cogl-backface-culling.c b/tests/conform/test-cogl-backface-culling.c index 177af6048..c8c3c473d 100644 --- a/tests/conform/test-cogl-backface-culling.c +++ b/tests/conform/test-cogl-backface-culling.c @@ -50,7 +50,7 @@ validate_part (int xnum, int ynum, gboolean shown) TEXTURE_RENDER_SIZE - TEST_INSET * 2, TEXTURE_RENDER_SIZE - TEST_INSET * 2, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixels); /* Make sure every pixels is the appropriate color */ diff --git a/tests/conform/test-cogl-blend-strings.c b/tests/conform/test-cogl-blend-strings.c index 54e16eb02..6c09ed53d 100644 --- a/tests/conform/test-cogl-blend-strings.c +++ b/tests/conform/test-cogl-blend-strings.c @@ -135,7 +135,7 @@ test_blend (TestState *state, cogl_read_pixels (x_off, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) { @@ -265,7 +265,7 @@ test_tex_combine (TestState *state, cogl_read_pixels (x_off, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) { diff --git a/tests/conform/test-cogl-materials.c b/tests/conform/test-cogl-materials.c index 012115131..31837afd5 100644 --- a/tests/conform/test-cogl-materials.c +++ b/tests/conform/test-cogl-materials.c @@ -53,7 +53,7 @@ check_pixel (TestState *state, int x, int y, guint32 color) cogl_read_pixels (x_off, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print (" result = %02x, %02x, %02x, %02x\n", diff --git a/tests/conform/test-cogl-multitexture.c b/tests/conform/test-cogl-multitexture.c index acbc3e820..9466ea6a4 100644 --- a/tests/conform/test-cogl-multitexture.c +++ b/tests/conform/test-cogl-multitexture.c @@ -31,7 +31,7 @@ assert_region_color (int x, guint8 *data = g_malloc0 (width * height * 4); cogl_read_pixels (x, y, width, height, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, data); for (y = 0; y < height; y++) for (x = 0; x < width; x++) diff --git a/tests/conform/test-cogl-offscreen.c b/tests/conform/test-cogl-offscreen.c index 626eb4264..a7f67416c 100644 --- a/tests/conform/test-cogl-offscreen.c +++ b/tests/conform/test-cogl-offscreen.c @@ -96,28 +96,28 @@ on_paint (ClutterActor *actor, void *state) /* red, top right */ cogl_read_pixels (FRAMEBUFFER_WIDTH - 1, 0, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); g_assert (pixel[RED] == 0xff && pixel[GREEN] == 0x00 && pixel[BLUE] == 0x00); /* green, top left */ cogl_read_pixels ((FRAMEBUFFER_WIDTH/2), 0, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); g_assert (pixel[RED] == 0x00 && pixel[GREEN] == 0xff && pixel[BLUE] == 0x00); /* blue, bottom right */ cogl_read_pixels (FRAMEBUFFER_WIDTH - 1, (FRAMEBUFFER_HEIGHT/2) - 1, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); g_assert (pixel[RED] == 0x00 && pixel[GREEN] == 0x00 && pixel[BLUE] == 0xff); /* white, bottom left */ cogl_read_pixels ((FRAMEBUFFER_WIDTH/2), (FRAMEBUFFER_HEIGHT/2) - 1, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); g_assert (pixel[RED] == 0xff && pixel[GREEN] == 0xff && pixel[BLUE] == 0xff); diff --git a/tests/conform/test-cogl-premult.c b/tests/conform/test-cogl-premult.c index 83140e4dd..caaa24e5a 100644 --- a/tests/conform/test-cogl-premult.c +++ b/tests/conform/test-cogl-premult.c @@ -126,7 +126,7 @@ check_texture (TestState *state, cogl_read_pixels (x_off, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) { diff --git a/tests/conform/test-cogl-readpixels.c b/tests/conform/test-cogl-readpixels.c index 618c19fa7..167d86570 100644 --- a/tests/conform/test-cogl-readpixels.c +++ b/tests/conform/test-cogl-readpixels.c @@ -25,6 +25,7 @@ on_paint (ClutterActor *actor, void *state) CoglHandle tex; CoglHandle offscreen; guint32 *pixels; + guint8 *pixelsc; /* Save the Clutter viewport/matrices and load identity matrices */ @@ -70,7 +71,7 @@ on_paint (ClutterActor *actor, void *state) pixels = g_malloc0 (FRAMEBUFFER_WIDTH * 4 * FRAMEBUFFER_HEIGHT); cogl_read_pixels (0, 0, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, (guchar *)pixels); g_assert_cmpint (pixels[0], ==, 0xff0000ff); @@ -91,7 +92,7 @@ on_paint (ClutterActor *actor, void *state) pixels = g_malloc0 (FRAMEBUFFER_WIDTH * 4 * FRAMEBUFFER_HEIGHT); cogl_read_pixels (0, 0, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, (guchar *)pixels); g_assert_cmpint (pixels[0], ==, 0xff0000ff); @@ -100,6 +101,27 @@ on_paint (ClutterActor *actor, void *state) g_assert_cmpint (pixels[(FRAMEBUFFER_HEIGHT - 1) * FRAMEBUFFER_WIDTH + FRAMEBUFFER_WIDTH - 1], ==, 0xffffffff); g_free (pixels); + /* Verify using BGR format */ + + cogl_set_source_texture (tex); + cogl_rectangle (-1, 1, 1, -1); + + pixelsc = g_malloc0 (FRAMEBUFFER_WIDTH * 3 * FRAMEBUFFER_HEIGHT); + cogl_read_pixels (0, 0, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT, + COGL_READ_PIXELS_COLOR_BUFFER, + COGL_PIXEL_FORMAT_BGR_888, + (guchar *)pixelsc); + + g_assert_cmpint (pixelsc[0], ==, 0x00); + g_assert_cmpint (pixelsc[1], ==, 0x00); + g_assert_cmpint (pixelsc[2], ==, 0xff); + + g_assert_cmpint (pixelsc[(FRAMEBUFFER_WIDTH - 1) * 3 + 0], ==, 0x00); + g_assert_cmpint (pixelsc[(FRAMEBUFFER_WIDTH - 1) * 3 + 1], ==, 0xff); + g_assert_cmpint (pixelsc[(FRAMEBUFFER_WIDTH - 1) * 3 + 2], ==, 0x00); + + g_free (pixelsc); + cogl_handle_unref (tex); diff --git a/tests/conform/test-cogl-texture-mipmaps.c b/tests/conform/test-cogl-texture-mipmaps.c index e00a2d198..a07e1e69d 100644 --- a/tests/conform/test-cogl-texture-mipmaps.c +++ b/tests/conform/test-cogl-texture-mipmaps.c @@ -82,7 +82,7 @@ on_paint (ClutterActor *actor, TestState *state) /* Read back the two pixels we rendered */ cogl_read_pixels (0, 0, 2, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixels); /* The first pixel should be just one of the colors from the diff --git a/tests/conform/test-cogl-vertex-buffer-contiguous.c b/tests/conform/test-cogl-vertex-buffer-contiguous.c index 925b4f76e..41766f7b1 100644 --- a/tests/conform/test-cogl-vertex-buffer-contiguous.c +++ b/tests/conform/test-cogl-vertex-buffer-contiguous.c @@ -43,7 +43,7 @@ validate_result (TestState *state) /* Should see a blue pixel */ cogl_read_pixels (10, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 0 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); @@ -52,7 +52,7 @@ validate_result (TestState *state) /* Should see a red pixel */ cogl_read_pixels (110, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 1 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); @@ -61,7 +61,7 @@ validate_result (TestState *state) /* Should see a blue pixel */ cogl_read_pixels (210, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 2 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); @@ -70,7 +70,7 @@ validate_result (TestState *state) /* Should see a green pixel, at bottom of 4th triangle */ cogl_read_pixels (310, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 3 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); @@ -79,7 +79,7 @@ validate_result (TestState *state) /* Should see a red pixel, at top of 4th triangle */ cogl_read_pixels (310, y_off - 70, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 4 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); diff --git a/tests/conform/test-cogl-vertex-buffer-interleved.c b/tests/conform/test-cogl-vertex-buffer-interleved.c index 8de563305..46449d7e7 100644 --- a/tests/conform/test-cogl-vertex-buffer-interleved.c +++ b/tests/conform/test-cogl-vertex-buffer-interleved.c @@ -47,7 +47,7 @@ validate_result (TestState *state) /* Should see a blue pixel */ cogl_read_pixels (10, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 0 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); diff --git a/tests/conform/test-cogl-vertex-buffer-mutability.c b/tests/conform/test-cogl-vertex-buffer-mutability.c index 845898345..32a52fe61 100644 --- a/tests/conform/test-cogl-vertex-buffer-mutability.c +++ b/tests/conform/test-cogl-vertex-buffer-mutability.c @@ -34,7 +34,7 @@ validate_result (TestState *state) /* Should see a red pixel */ cogl_read_pixels (110, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 0 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); @@ -43,7 +43,7 @@ validate_result (TestState *state) /* Should see a green pixel */ cogl_read_pixels (210, y_off, 1, 1, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, pixel); if (g_test_verbose ()) g_print ("pixel 1 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]); diff --git a/tests/conform/test-cogl-viewport.c b/tests/conform/test-cogl-viewport.c index 96e3d4777..e983cab97 100644 --- a/tests/conform/test-cogl-viewport.c +++ b/tests/conform/test-cogl-viewport.c @@ -27,7 +27,7 @@ assert_region_color (int x, guint8 *data = g_malloc0 (width * height * 4); cogl_read_pixels (x, y, width, height, COGL_READ_PIXELS_COLOR_BUFFER, - COGL_PIXEL_FORMAT_RGBA_8888, + COGL_PIXEL_FORMAT_RGBA_8888_PRE, data); for (y = 0; y < height; y++) for (x = 0; x < width; x++)