mirrors/foot
1
0
Fork 0
mirror of https://codeberg.org/dnkl/foot.git synced 2026-03-21 05:33:45 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

render: gamma-correct blending

Browse source 
This implements gamma-correct blending, which mainly affects font
rendering.

The implementation requires compile-time availability of the new
color-management protocol (available in wayland-protocols >= 1.41),
and run-time support for the same in the compositor (specifically, the
EXT_LINEAR TF function and sRGB primaries).

How it works: all colors are decoded from sRGB to linear (using a
lookup table, generated in the exact same way pixman generates it's
internal conversion tables) before being used by pixman. The resulting
image buffer is thus in decoded/linear format. We use the
color-management protocol to inform the compositor of this, by tagging
the wayland surfaces with the 'ext_linear' image attribute.

Sixes: all colors are sRGB internally, and decoded to linear before
being used in any sixels. Thus, the image buffers will contain linear
colors. This is important, since otherwise there would be a
decode/encode penalty every time a sixel is blended to the grid.

Emojis: we require fcft >= 3.2, which adds support for sRGB decoding
color glyphs. Meaning, the emoji pixman surfaces can be blended
directly to the grid, just like sixels.

Gamma-correct blending is enabled by default *when the compositor
supports it*. There's a new option to explicitly enable/disable it:
gamma-correct-blending=no|yes. If set to 'yes', and the compositor
does not implement the required color-management features, warning
logs are emitted.

There's a loss of precision when storing linear pixels in 8-bit
channels. For this reason, this patch also adds supports for 10-bit
surfaces. For now, this is disabled by default since such surfaces
only have 2 bits for alpha. It can be enabled with
tweak.surface-bit-depth=10-bit.

Perhaps, in the future, we can enable it by default if:

* gamma-correct blending is enabled
* the user has not enabled a transparent background
This commit is contained in:
Daniel Eklöf 2025-02-21 11:01:29 +01:00
parent 6d39f66eb7
commit ccf625b991
No known key found for this signature in database
GPG key ID: 5BBD4992C116573F
20 changed files with 746 additions and 101 deletions
Download patch file Download diff file Expand all files Collapse all files

97
sixel.c
View file

@ -10,6 +10,7 @@
#include "grid.h"
#include "hsl.h"
#include "render.h"
#include "srgb.h"
#include "util.h"
#include "xmalloc.h"
#include "xsnprintf.h"
@ -19,6 +20,40 @@ static size_t count;
static void sixel_put_generic(struct terminal *term, uint8_t c);
static void sixel_put_ar_11(struct terminal *term, uint8_t c);
static uint32_t
color_decode_srgb(const struct terminal *term, uint16_t r, uint16_t g, uint16_t b)
{
if (term->sixel.linear_blending) {
if (term->sixel.use_10bit) {
r = srgb_decode_8_to_16(r) >> 6;
g = srgb_decode_8_to_16(g) >> 6;
b = srgb_decode_8_to_16(b) >> 6;
} else {
r = srgb_decode_8_to_8(r);
g = srgb_decode_8_to_8(g);
b = srgb_decode_8_to_8(b);
}
} else {
if (term->sixel.use_10bit) {
r <<= 2;
g <<= 2;
b <<= 2;
}
}
uint32_t color;
if (term->sixel.use_10bit) {
if (PIXMAN_FORMAT_TYPE(term->sixel.pixman_fmt) == PIXMAN_TYPE_ARGB)
color = 0x3u << 30 | r << 20 | g << 10 | b;
else
color = 0x3u << 30 | b << 20 | g << 10 | r;
} else
color = 0xffu << 24 | r << 16 | g << 8 | b;
return color;
}
void
sixel_fini(struct terminal *term)
{
@ -75,6 +110,23 @@ sixel_init(struct terminal *term, int p1, int p2, int p3)
term->sixel.image.height = 0;
term->sixel.image.alloc_height = 0;
term->sixel.image.bottom_pixel = 0;
term->sixel.linear_blending = render_do_linear_blending(term);
term->sixel.pixman_fmt = PIXMAN_a8r8g8b8;
if (term->conf->tweak.surface_bit_depth == SHM_10_BIT) {
if (term->wl->shm_have_argb2101010 && term->wl->shm_have_xrgb2101010) {
term->sixel.use_10bit = true;
term->sixel.pixman_fmt = PIXMAN_a2r10g10b10;
}
else if (term->wl->shm_have_abgr2101010 && term->wl->shm_have_xbgr2101010) {
term->sixel.use_10bit = true;
term->sixel.pixman_fmt = PIXMAN_a2b10g10r10;
}
}
const size_t active_palette_entries = min(
ALEN(term->conf->colors.sixel), term->sixel.palette_size);
if (term->sixel.use_private_palette) {
xassert(term->sixel.private_palette == NULL);
@ -83,11 +135,18 @@ sixel_init(struct terminal *term, int p1, int p2, int p3)
memcpy(
term->sixel.private_palette, term->conf->colors.sixel,
min(sizeof(term->conf->colors.sixel),
term->sixel.palette_size * sizeof(term->sixel.private_palette[0])));
active_palette_entries * sizeof(term->sixel.private_palette[0]));
if (term->sixel.linear_blending || term->sixel.use_10bit) {
for (size_t i = 0; i < active_palette_entries; i++) {
uint8_t r = (term->sixel.private_palette[i] >> 16) & 0xff;
uint8_t g = (term->sixel.private_palette[i] >> 8) & 0xff;
uint8_t b = (term->sixel.private_palette[i] >> 0) & 0xff;
term->sixel.private_palette[i] = color_decode_srgb(term, r, g, b);
}
}
term->sixel.palette = term->sixel.private_palette;
} else {
if (term->sixel.shared_palette == NULL) {
term->sixel.shared_palette = xcalloc(
@ -95,8 +154,16 @@ sixel_init(struct terminal *term, int p1, int p2, int p3)
memcpy(
term->sixel.shared_palette, term->conf->colors.sixel,
min(sizeof(term->conf->colors.sixel),
term->sixel.palette_size * sizeof(term->sixel.shared_palette[0])));
active_palette_entries * sizeof(term->sixel.shared_palette[0]));
if (term->sixel.linear_blending || term->sixel.use_10bit) {
for (size_t i = 0; i < active_palette_entries; i++) {
uint8_t r = (term->sixel.private_palette[i] >> 16) & 0xff;
uint8_t g = (term->sixel.private_palette[i] >> 8) & 0xff;
uint8_t b = (term->sixel.private_palette[i] >> 0) & 0xff;
term->sixel.private_palette[i] = color_decode_srgb(term, r, g, b);
}
}
} else {
/* Shared palette - do *not* reset palette for new sixels */
}
@ -488,7 +555,7 @@ blend_new_image_over_old(const struct terminal *term,
int stride = new_width * sizeof(uint32_t);
uint32_t *new_data = xmalloc(stride * new_height);
pixman_image_t *pix2 = pixman_image_create_bits_no_clear(
PIXMAN_a8r8g8b8, new_width, new_height, new_data, stride);
term->sixel.pixman_fmt, new_width, new_height, new_data, stride);
#if defined(_DEBUG)
/* Fill new image with an easy-to-recognize color (green) */
@ -651,8 +718,7 @@ sixel_overwrite(struct terminal *term, struct sixel *six,
}
pixman_image_t *new_pix = pixman_image_create_bits_no_clear(
PIXMAN_a8r8g8b8,
new_width, new_height, new_data, new_width * sizeof(uint32_t));
term->sixel.pixman_fmt, new_width, new_height, new_data, new_width * sizeof(uint32_t));
struct sixel new_six = {
.pix = NULL,
@ -948,7 +1014,7 @@ sixel_sync_cache(const struct terminal *term, struct sixel *six)
uint8_t *scaled_data = xmalloc(scaled_height * scaled_stride);
pixman_image_t *scaled_pix = pixman_image_create_bits_no_clear(
PIXMAN_a8r8g8b8, scaled_width, scaled_height,
term->sixel.pixman_fmt, scaled_width, scaled_height,
(uint32_t *)scaled_data, scaled_stride);
pixman_image_composite32(
@ -1232,7 +1298,7 @@ sixel_unhook(struct terminal *term)
image.pos.row, image.pos.row + image.rows);
image.original.pix = pixman_image_create_bits_no_clear(
PIXMAN_a8r8g8b8, image.original.width, image.original.height,
term->sixel.pixman_fmt, image.original.width, image.original.height,
img_data, stride);
pixel_row_idx += height;
@ -2006,15 +2072,14 @@ decgci(struct terminal *term, uint8_t c)
}
case 2: { /* RGB */
uint8_t r = 255 * min(c1, 100) / 100;
uint8_t g = 255 * min(c2, 100) / 100;
uint8_t b = 255 * min(c3, 100) / 100;
uint16_t r = 255 * min(c1, 100) / 100;
uint16_t g = 255 * min(c2, 100) / 100;
uint16_t b = 255 * min(c3, 100) / 100;
LOG_DBG("setting palette #%d = RGB %hhu/%hhu/%hhu",
LOG_DBG("setting palette #%d = RGB %hu/%hu/%hu",
term->sixel.color_idx, r, g, b);
term->sixel.palette[term->sixel.color_idx] =
0xffu << 24 | r << 16 | g << 8 | b;
term->sixel.palette[term->sixel.color_idx] = color_decode_srgb(term, r, g, b);
break;
}
}