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[cogl] Adds cogl_read_pixels to replace direct use of glReadPixels

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To allow for flushing of batched geometry within Cogl we can't support users
directly calling glReadPixels.  glReadPixels is also awkward, not least
because it returns upside down image data.

All the unit tests have been swithed over and clutter_stage_read_pixels now
sits on top of this too.
This commit is contained in:
Robert Bragg 2009-06-17 14:30:44 +01:00
parent 27fff12a6a
commit 24ca92951f
9 changed files with 151 additions and 66 deletions
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44
clutter/clutter-stage.c
View File

@ -1366,10 +1366,9 @@ clutter_stage_read_pixels (ClutterStage *stage,
gint height)
{
guchar *pixels;
guchar *temprow;
GLint viewport[4];
gint rowstride;
gint stage_x, stage_y, stage_width, stage_height;
gint stage_width, stage_height;
g_return_val_if_fail (CLUTTER_IS_STAGE (stage), NULL);
@ -1383,8 +1382,6 @@ clutter_stage_read_pixels (ClutterStage *stage,
clutter_actor_paint (CLUTTER_ACTOR (stage));
glGetIntegerv (GL_VIEWPORT, viewport);
stage_x = viewport[0];
stage_y = viewport[1];
stage_width = viewport[2];
stage_height = viewport[3];
@ -1397,42 +1394,11 @@ clutter_stage_read_pixels (ClutterStage *stage,
rowstride = width * 4;
pixels = g_malloc (height * rowstride);
temprow = g_malloc (rowstride);
/* Setup the pixel store parameters that may have been changed by
Cogl */
glPixelStorei (GL_PACK_ALIGNMENT, 4);
#ifdef HAVE_COGL_GL
glPixelStorei (GL_PACK_ROW_LENGTH, 0);
glPixelStorei (GL_PACK_SKIP_PIXELS, 0);
glPixelStorei (GL_PACK_SKIP_ROWS, 0);
#endif /* HAVE_COGL_GL */
/* The y co-ordinate should be given in OpenGL's coordinate system
so 0 is the bottom row */
y = stage_height - y - height;
glFinish ();
/* check whether we need to read into a smaller temporary buffer */
glReadPixels (x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
/* vertically flip the buffer in-place */
for (y = 0; y < height / 2; y++)
{
if (y != height - y - 1) /* skip center row */
{
memcpy (temprow,
pixels + y * rowstride, rowstride);
memcpy (pixels + y * rowstride,
pixels + (height - y - 1) * rowstride, rowstride);
memcpy (pixels + (height - y - 1) * rowstride,
temprow,
rowstride);
}
}
g_free (temprow);
cogl_read_pixels (x, y, width, height,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixels);
return pixels;
}

33
clutter/cogl/cogl.h.in
View File

@ -691,6 +691,39 @@ void cogl_push_draw_buffer (void);
*/
void cogl_pop_draw_buffer (void);
/**
* CoglReadPixelsFlags:
* @COGL_READ_PIXELS_COLOR_BUFFER: Read from the color buffer
*/
typedef enum _CoglReadPixelsFlags
{
COGL_READ_PIXELS_COLOR_BUFFER = 1L<<0
} CoglReadPixelsFlags;
/**
* cogl_read_pixels:
* @x: The window x position to start reading from
* @y: The window y position to start reading from
* @width: The width of the rectangle you want to read
* @height: The height of the rectangle you want to read
* @source: Identifies which auxillary buffer you want to read
* (only COGL_READ_PIXELS_COLOR_BUFFER supported currently)
* @format: The pixel format you want the result in
* (only COGL_PIXEL_FORMAT_RGBA_8888 supported currently)
* @pixels: The location to write the pixel data.
*
* This reads a rectangle of pixels from the current draw buffer 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)
*/
void cogl_read_pixels (int x,
int y,
int width,
int height,
CoglReadPixelsFlags source,
CoglPixelFormat format,
guint8 *pixels);
/*
* Internal API available only to Clutter.

56
clutter/cogl/common/cogl.c
View File

@ -572,6 +572,8 @@ void
cogl_get_viewport (float v[4])
{
/* FIXME: cogl_get_viewport should return a gint vec */
/* FIXME: cogl_get_viewport should only return a width + height
* (I don't think we need to support offset viewports) */
#if defined (HAVE_COGL_GLES2) || defined (HAVE_COGL_GLES)
GLint viewport[4];
int i;
@ -676,3 +678,57 @@ cogl_flush_gl_state (int flags)
}
#endif
void
cogl_read_pixels (int x,
int y,
int width,
int height,
CoglReadPixelsFlags source,
CoglPixelFormat format,
guint8 *pixels)
{
GLint viewport[4];
GLint viewport_height;
int rowstride = width * 4;
guint8 temprow[rowstride];
g_return_if_fail (format == COGL_PIXEL_FORMAT_RGBA_8888);
g_return_if_fail (source == COGL_READ_PIXELS_COLOR_BUFFER);
glGetIntegerv (GL_VIEWPORT, viewport);
viewport_height = viewport[3];
/* The y co-ordinate should be given in OpenGL's coordinate system
so 0 is the bottom row */
y = viewport_height - y - height;
/* Setup the pixel store parameters that may have been changed by
Cogl */
glPixelStorei (GL_PACK_ALIGNMENT, 4);
#ifdef HAVE_COGL_GL
glPixelStorei (GL_PACK_ROW_LENGTH, 0);
glPixelStorei (GL_PACK_SKIP_PIXELS, 0);
glPixelStorei (GL_PACK_SKIP_ROWS, 0);
#endif /* HAVE_COGL_GL */
glReadPixels (x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
/* 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 (y != height - y - 1) /* skip center row */
{
memcpy (temprow,
pixels + y * rowstride, rowstride);
memcpy (pixels + y * rowstride,
pixels + (height - y - 1) * rowstride, rowstride);
memcpy (pixels + (height - y - 1) * rowstride,
temprow,
rowstride);
}
}
}

4
doc/reference/cogl/cogl-sections.txt
View File

@ -68,6 +68,10 @@ cogl_set_source_color4ub
cogl_set_source_color4f
cogl_set_source_texture
<SUBSECTION>
CoglReadPixelsFlags
cogl_read_pixels
<SUBSECTION Standard>
COGL_TYPE_ATTRIBUTE_TYPE
COGL_TYPE_BUFFER_BIT

16
tests/conform/test-blend-strings.c
View File

@ -124,8 +124,7 @@ test_blend (TestState *state,
/* See what we got... */
/* NB: glReadPixels is done in GL screen space so y = 0 is at the bottom */
y_off = state->stage_geom.height - y * QUAD_WIDTH - (QUAD_WIDTH / 2);
y_off = y * QUAD_WIDTH + (QUAD_WIDTH / 2);
x_off = x * QUAD_WIDTH + (QUAD_WIDTH / 2);
/* XXX:
@ -134,7 +133,10 @@ test_blend (TestState *state,
if (state->frame <= 2)
return;
glReadPixels (x_off, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (x_off, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
{
g_print ("test_blend (%d, %d):\n%s\n", x, y, blend_string);
@ -252,8 +254,7 @@ test_tex_combine (TestState *state,
/* See what we got... */
/* NB: glReadPixels is done in GL screen space so y = 0 is at the bottom */
y_off = state->stage_geom.height - y * QUAD_WIDTH - (QUAD_WIDTH / 2);
y_off = y * QUAD_WIDTH + (QUAD_WIDTH / 2);
x_off = x * QUAD_WIDTH + (QUAD_WIDTH / 2);
/* XXX:
@ -262,7 +263,10 @@ test_tex_combine (TestState *state,
if (state->frame <= 2)
return;
glReadPixels (x_off, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (x_off, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
{
g_print ("test_tex_combine (%d, %d):\n%s\n", x, y, combine_string);

14
tests/conform/test-premult.c
View File

@ -101,9 +101,9 @@ check_texture (TestState *state,
CoglHandle tex,
guint32 expected_result)
{
GLubyte pixel[4];
GLint y_off;
GLint x_off;
guchar pixel[4];
int y_off;
int x_off;
cogl_material_set_layer (state->passthrough_material, 0, tex);
@ -115,8 +115,7 @@ check_texture (TestState *state,
/* See what we got... */
/* NB: glReadPixels is done in GL screen space so y = 0 is at the bottom */
y_off = state->stage_geom.height - y * QUAD_WIDTH - (QUAD_WIDTH / 2);
y_off = y * QUAD_WIDTH + (QUAD_WIDTH / 2);
x_off = x * QUAD_WIDTH + (QUAD_WIDTH / 2);
/* XXX:
@ -125,7 +124,10 @@ check_texture (TestState *state,
if (state->frame <= SKIP_FRAMES)
return;
glReadPixels (x_off, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (x_off, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
{
g_print ("check texture (%d, %d):\n", x, y);

28
tests/conform/test-vertex-buffer-contiguous.c
View File

@ -28,9 +28,8 @@ static void
validate_result (TestState *state)
{
GLubyte pixel[4];
GLint y_off = state->stage_geom.height - 90;
GLint y_off = 90;
/* NB: glReadPixels is done in GL screen space so y = 0 is at the bottom */
if (g_test_verbose ())
g_print ("y_off = %d\n", y_off);
@ -42,31 +41,46 @@ validate_result (TestState *state)
#define BLUE 2
/* Should see a blue pixel */
glReadPixels (10, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (10, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 0 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] == 0 && pixel[GREEN] == 0 && pixel[BLUE] != 0);
/* Should see a red pixel */
glReadPixels (110, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (110, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 1 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] != 0 && pixel[GREEN] == 0 && pixel[BLUE] == 0);
/* Should see a blue pixel */
glReadPixels (210, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (210, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 2 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] == 0 && pixel[GREEN] == 0 && pixel[BLUE] != 0);
/* Should see a green pixel, at bottom of 4th triangle */
glReadPixels (310, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (310, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 3 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[GREEN] > pixel[RED] && pixel[GREEN] > pixel[BLUE]);
/* Should see a red pixel, at top of 4th triangle */
glReadPixels (310, y_off + 70 , 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (310, y_off - 70, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 4 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] > pixel[GREEN] && pixel[RED] > pixel[BLUE]);

9
tests/conform/test-vertex-buffer-interleved.c
View File

@ -35,9 +35,7 @@ static void
validate_result (TestState *state)
{
GLubyte pixel[4];
GLint y_off = state->stage_geom.height - 90;
/* NB: glReadPixels is done in GL screen space so y = 0 is at the bottom */
GLint y_off = 90;
/* NB: We ignore the alpha, since we don't know if our render target is
* RGB or RGBA */
@ -47,7 +45,10 @@ validate_result (TestState *state)
#define BLUE 2
/* Should see a blue pixel */
glReadPixels (10, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (10, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 0 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] == 0 && pixel[GREEN] == 0 && pixel[BLUE] != 0);

13
tests/conform/test-vertex-buffer-mutability.c
View File

@ -22,8 +22,7 @@ static void
validate_result (TestState *state)
{
GLubyte pixel[4];
GLint y_off = state->stage_geom.height - 90;
/* NB: glReadPixels is done in GL screen space so y = 0 is at the bottom */
GLint y_off = 90;
/* NB: We ignore the alpha, since we don't know if our render target is
* RGB or RGBA */
@ -33,13 +32,19 @@ validate_result (TestState *state)
#define BLUE 2
/* Should see a red pixel */
glReadPixels (110, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (110, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 0 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] != 0 && pixel[GREEN] == 0 && pixel[BLUE] == 0);
/* Should see a green pixel */
glReadPixels (210, y_off, 1, 1, GL_RGBA, GL_UNSIGNED_BYTE, &pixel);
cogl_read_pixels (210, y_off, 1, 1,
COGL_READ_PIXELS_COLOR_BUFFER,
COGL_PIXEL_FORMAT_RGBA_8888,
pixel);
if (g_test_verbose ())
g_print ("pixel 1 = %x, %x, %x\n", pixel[RED], pixel[GREEN], pixel[BLUE]);
g_assert (pixel[RED] == 0 && pixel[GREEN] != 0 && pixel[BLUE] == 0);