Adds a _cogl_util_pixel_format_from_masks API

This adds a utility function for inferring a CoglPixelFormat from a
set of channel masks, a bits-per-pixel value, a pixel-depth value and
pixel byte order.

This plan is to use this to improve how we map X visuals to Cogl pixel
formats.

This patch was based on some ideas from Damien Leone <dleone@nvidia.com>

https://bugzilla.gnome.org/show_bug.cgi?id=660188

Reviewed-by: Neil Roberts <neil@linux.intel.com>
This commit is contained in:
Robert Bragg 2012-02-17 20:44:28 +00:00
parent fcb8b18d39
commit e3c4522a86
3 changed files with 144 additions and 0 deletions

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@ -26,6 +26,7 @@
#endif
#include "cogl-util.h"
#include "cogl-private.h"
/*
* cogl_util_next_p2:
@ -120,3 +121,130 @@ _cogl_util_popcount_table[256] =
};
#endif /* COGL_UTIL_HAVE_BUILTIN_POPCOUNTL */
/* tests/conform/test-bitmask.c tests some cogl internals and includes this
* file directly but since these functions depend on other internal Cogl
* symbols we hide them from test-bitmask.c
*
* XXX: maybe there's a better way for us to handle internal testing
* to avoid needing hacks like this.
*/
#ifndef _COGL_IN_TEST_BITMASK
/* Given a set of red, green and blue component masks, a depth and
* bits per pixel this function tries to determine a corresponding
* CoglPixelFormat.
*
* The depth is measured in bits not including padding for un-used
* alpha. The bits per pixel (bpp) does include padding for un-used
* alpha.
*
* This function firstly aims to match formats with RGB ordered
* components and only considers alpha coming first, in the most
* significant bits. If the function fails to match then it recurses
* by either switching the r and b masks around to check for BGR
* ordered formats or it recurses with the masks shifted to check for
* formats where the alpha component is the least significant bits.
*/
static CoglPixelFormat
_cogl_util_pixel_format_from_masks_real (unsigned long r_mask,
unsigned long g_mask,
unsigned long b_mask,
int depth, int bpp,
gboolean check_bgr,
gboolean check_afirst,
int recursion_depth)
{
CoglPixelFormat image_format;
if (depth == 24 && bpp == 24 &&
r_mask == 0xff0000 && g_mask == 0xff00 && b_mask == 0xff)
{
return COGL_PIXEL_FORMAT_RGB_888;
}
else if ((depth == 24 || depth == 32) && bpp == 32 &&
r_mask == 0xff0000 && g_mask == 0xff00 && b_mask == 0xff)
{
return COGL_PIXEL_FORMAT_ARGB_8888_PRE;
}
else if (depth == 16 && bpp == 16 &&
r_mask == 0xf800 && g_mask == 0x7e0 && b_mask == 0x1f)
{
return COGL_PIXEL_FORMAT_RGB_565;
}
if (recursion_depth == 2)
return 0;
/* Check for BGR ordering if we didn't find a match */
if (check_bgr)
{
image_format =
_cogl_util_pixel_format_from_masks_real (b_mask, g_mask, r_mask,
depth, bpp,
FALSE,
TRUE,
recursion_depth + 1);
if (image_format)
return image_format ^ COGL_BGR_BIT;
}
/* Check for alpha in the least significant bits if we still
* haven't found a match... */
if (check_afirst && depth != bpp)
{
int shift = bpp - depth;
image_format =
_cogl_util_pixel_format_from_masks_real (r_mask >> shift,
g_mask >> shift,
b_mask >> shift,
depth, bpp,
TRUE,
FALSE,
recursion_depth + 1);
if (image_format)
return image_format ^ COGL_AFIRST_BIT;
}
return 0;
}
CoglPixelFormat
_cogl_util_pixel_format_from_masks (unsigned long r_mask,
unsigned long g_mask,
unsigned long b_mask,
int depth, int bpp,
gboolean byte_order_is_lsb_first)
{
CoglPixelFormat image_format =
_cogl_util_pixel_format_from_masks_real (r_mask, g_mask, b_mask,
depth, bpp,
TRUE,
TRUE,
0);
if (!image_format)
{
const char *byte_order[] = { "MSB first", "LSB first" };
g_warning ("Could not find a matching pixel format for red mask=0x%lx,"
"green mask=0x%lx, blue mask=0x%lx at depth=%d, bpp=%d "
"and byte order=%s\n", r_mask, g_mask, b_mask, depth, bpp,
byte_order[!!byte_order_is_lsb_first]);
return 0;
}
/* If the image is in little-endian then the order in memory is
reversed */
if (byte_order_is_lsb_first &&
_cogl_pixel_format_is_endian_dependant (image_format))
{
image_format ^= COGL_BGR_BIT;
if (image_format & COGL_A_BIT)
image_format ^= COGL_AFIRST_BIT;
}
return image_format;
}
#endif /* _COGL_IN_TEST_BITMASK */

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@ -27,6 +27,7 @@
#include <glib.h>
#include <math.h>
#include "cogl-defines.h"
#include "cogl-types.h"
#ifndef COGL_HAS_GLIB_SUPPORT
#include <stdio.h>
@ -190,4 +191,18 @@ _cogl_util_popcountl (unsigned long num)
} while(0)
#endif /* COGL_HAS_GLIB_SUPPORT */
/* Match a CoglPixelFormat according to channel masks, color depth,
* bits per pixel and byte order. These information are provided by
* the Visual and XImage structures.
*
* If no specific pixel format could be found, COGL_PIXEL_FORMAT_ANY
* is returned.
*/
CoglPixelFormat
_cogl_util_pixel_format_from_masks (unsigned long r_mask,
unsigned long g_mask,
unsigned long b_mask,
int depth, int bpp,
int byte_order);
#endif /* __COGL_UTIL_H */

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@ -11,6 +11,7 @@
#include <cogl/cogl-bitmask.h>
#include <cogl/cogl-bitmask.c>
#define _COGL_IN_TEST_BITMASK
#include <cogl/cogl-util.c>
typedef struct