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zrle: Implement Palette RLE

tight-png
Andri Yngvason 2019-09-01 22:56:59 +00:00 committed by Andri Yngvason
parent ff67e2fed3
commit 80e1093e71
1 changed files with 125 additions and 0 deletions
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125
src/zrle.c
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@ -146,6 +146,116 @@ void pixel32_to_cpixel(uint8_t *restrict dst,
#undef CONVERT_PIXELS
}
static inline int find_colour_in_palette(uint32_t *palette, int len,
uint32_t colour)
{
for (int i = 0; i < len; ++i)
if (palette[i] == colour)
return i;
return -1;
}
int zrle_get_tile_palette(uint32_t *palette, const uint32_t *src, int stride,
int width, int height)
{
int n = 0;
/* TODO: Maybe ignore the alpha channel */
palette[n++] = src[0];
for (int y = 0; y < height; ++y)
for (int x = 0; x < width; ++x) {
uint32_t colour = src[x + y * stride];
if (find_colour_in_palette(palette, n, colour) < 0) {
if (n >= 16)
return -1;
palette[n++] = colour;
}
}
return n;
}
void zrle_encode_unichrome_tile(struct vec *dst,
const struct rfb_pixel_format *dst_fmt,
uint32_t colour,
const struct rfb_pixel_format *src_fmt)
{
int bytes_per_cpixel = dst_fmt->depth / 8;
vec_fast_append_8(dst, 1);
pixel32_to_cpixel(((uint8_t*)dst->data) + 1, dst_fmt, &colour, src_fmt,
bytes_per_cpixel, 1);
dst->len += bytes_per_cpixel;
}
void encode_run_length(struct vec *dst, int index, int run_length)
{
if (run_length == 1) {
vec_fast_append_8(dst, index);
return;
}
vec_fast_append_8(dst, index | 128);
while (run_length > 255) {
vec_fast_append_8(dst, 255);
run_length -= 255;
}
vec_fast_append_8(dst, run_length - 1);
}
void zrle_encode_packed_tile(struct vec *dst,
const struct rfb_pixel_format *dst_fmt,
const uint32_t *src,
const struct rfb_pixel_format *src_fmt,
int stride, int width, int height,
uint32_t *palette, int palette_size)
{
int bytes_per_cpixel = dst_fmt->depth / 8;
uint8_t cpalette[16 * 3];
pixel32_to_cpixel((uint8_t*)cpalette, dst_fmt, palette,
src_fmt, bytes_per_cpixel, palette_size);
vec_fast_append_8(dst, 128 + palette_size);
vec_append(dst, cpalette, palette_size * bytes_per_cpixel);
int index;
int run_length = -1;
uint32_t old_colour = src[0];
for (int y = 0; y < height; ++y)
for (int x = 0; x < width; ++x) {
uint32_t colour = src[x + y * stride];
run_length++;
if (colour == old_colour)
continue;
index = find_colour_in_palette(palette, palette_size,
old_colour);
encode_run_length(dst, index, run_length);
old_colour = colour;
run_length = 0;
}
if (run_length > 0) {
index = find_colour_in_palette(palette, palette_size,
old_colour);
encode_run_length(dst, index, run_length);
}
}
void zrle_encode_tile(struct vec *dst, const struct rfb_pixel_format *dst_fmt,
const uint32_t *src,
const struct rfb_pixel_format *src_fmt,
@ -155,6 +265,21 @@ void zrle_encode_tile(struct vec *dst, const struct rfb_pixel_format *dst_fmt,
vec_clear(dst);
uint32_t palette[16];
int palette_size = zrle_get_tile_palette(palette, src, stride,
width, height);
if (palette_size == 1) {
zrle_encode_unichrome_tile(dst, dst_fmt, palette[0], src_fmt);
return;
}
if (palette_size > 1) {
zrle_encode_packed_tile(dst, dst_fmt, src, src_fmt, stride,
width, height, palette, palette_size);
return;
}
vec_fast_append_8(dst, 0);
for (int y = 0; y < height; ++y)