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pixels: Add function to extract alpha mask

pull/63/head
Andri Yngvason 2022-02-06 15:01:33 +00:00
parent 613761cf5f
commit 0cc6be091c
2 changed files with 58 additions and 0 deletions
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3
include/pixels.h
View File

@ -35,3 +35,6 @@ uint32_t rfb_pixfmt_to_fourcc(const struct rfb_pixel_format* fmt);
int pixel_size_from_fourcc(uint32_t fourcc); int pixel_size_from_fourcc(uint32_t fourcc);
bool fourcc_to_pixman_fmt(pixman_format_code_t* dst, uint32_t src); bool fourcc_to_pixman_fmt(pixman_format_code_t* dst, uint32_t src);
bool extract_alpha_mask(uint8_t* dst, const void* src, uint32_t format,
size_t len);

55
src/pixels.c
View File

@ -21,6 +21,7 @@
#include <libdrm/drm_fourcc.h> #include <libdrm/drm_fourcc.h>
#define POPCOUNT(x) __builtin_popcount(x) #define POPCOUNT(x) __builtin_popcount(x)
#define UDIV_UP(a, b) (((a) + (b) - 1) / (b))
void pixel32_to_cpixel(uint8_t* restrict dst, void pixel32_to_cpixel(uint8_t* restrict dst,
const struct rfb_pixel_format* dst_fmt, const struct rfb_pixel_format* dst_fmt,
@ -358,3 +359,57 @@ bool fourcc_to_pixman_fmt(pixman_format_code_t* dst, uint32_t src)
return true; return true;
} }
static bool extract_alpha_mask_rgba32(uint8_t* dst, const uint32_t* src,
size_t len, int alpha_shift, uint32_t alpha_max)
{
for (size_t i = 0; i < len; i++) {
uint8_t alpha = (src[i] >> alpha_shift) & alpha_max;
uint8_t binary = !!(alpha > alpha_max / 2);
dst[i / 8] |= binary << (7 - (i % 8));
}
return true;
}
static bool extract_alpha_mask_rgba16(uint8_t* dst, const uint16_t* src,
size_t len, int alpha_shift)
{
for (size_t i = 0; i < len; i++) {
uint8_t alpha = (src[i] >> alpha_shift) & 0xf;
uint8_t binary = !!(alpha > 0xf / 2);
dst[i / 8] |= binary << (7 - (i % 8));
}
return true;
}
// Note: The destination buffer must be at least UDIV_UP(len, 8) long.
bool extract_alpha_mask(uint8_t* dst, const void* src, uint32_t format,
size_t len)
{
memset(dst, 0, UDIV_UP(len, 8));
switch (format & ~DRM_FORMAT_BIG_ENDIAN) {
case DRM_FORMAT_RGBA1010102:
case DRM_FORMAT_BGRA1010102:
return extract_alpha_mask_rgba32(dst, src, len, 0, 3);
case DRM_FORMAT_ARGB2101010:
case DRM_FORMAT_ABGR2101010:
return extract_alpha_mask_rgba32(dst, src, len, 30, 3);
case DRM_FORMAT_RGBA8888:
case DRM_FORMAT_BGRA8888:
return extract_alpha_mask_rgba32(dst, src, len, 0, 0xff);
case DRM_FORMAT_ARGB8888:
case DRM_FORMAT_ABGR8888:
return extract_alpha_mask_rgba32(dst, src, len, 24, 0xff);
case DRM_FORMAT_RGBA4444:
case DRM_FORMAT_BGRA4444:
return extract_alpha_mask_rgba16(dst, src, len, 0);
case DRM_FORMAT_ARGB4444:
case DRM_FORMAT_ABGR4444:
return extract_alpha_mask_rgba16(dst, src, len, 12);
}
return false;
}