tests: add alpha-blending test

In anticipation of invasive future work on color management, add an
alpha blending test to make sure we don't break alpha blending.

The idea for doing a monotonicity test came from glennk on #dri-devel in
Freenode IRC.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
This commit is contained in:
Pekka Paalanen 2020-11-12 14:15:43 +02:00
parent f8d170c4e7
commit 26258817fc
3 changed files with 254 additions and 0 deletions

253
tests/alpha-blending-test.c Normal file
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@ -0,0 +1,253 @@
/*
* Copyright 2020 Collabora, Ltd.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial
* portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "config.h"
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include "weston-test-client-helper.h"
#include "weston-test-fixture-compositor.h"
struct setup_args {
enum renderer_type renderer;
};
static const int ALPHA_STEPS = 256;
static const int BLOCK_WIDTH = 3;
static const struct setup_args my_setup_args[] = {
{ RENDERER_PIXMAN },
{ RENDERER_GL },
};
static enum test_result_code
fixture_setup(struct weston_test_harness *harness, const struct setup_args *arg)
{
struct compositor_setup setup;
compositor_setup_defaults(&setup);
setup.renderer = arg->renderer;
setup.width = BLOCK_WIDTH * ALPHA_STEPS;
setup.height = 16;
setup.shell = SHELL_TEST_DESKTOP;
return weston_test_harness_execute_as_client(harness, &setup);
}
DECLARE_FIXTURE_SETUP_WITH_ARG(fixture_setup, my_setup_args);
static void
set_opaque_rect(struct client *client,
struct surface *surface,
const struct rectangle *rect)
{
struct wl_region *region;
region = wl_compositor_create_region(client->wl_compositor);
wl_region_add(region, rect->x, rect->y, rect->width, rect->height);
wl_surface_set_opaque_region(surface->wl_surface, region);
wl_region_destroy(region);
}
static uint32_t
premult_color(uint32_t a, uint32_t r, uint32_t g, uint32_t b)
{
uint32_t c = 0;
c |= a << 24;
c |= (a * r / 255) << 16;
c |= (a * g / 255) << 8;
c |= a * b / 255;
return c;
}
static void
fill_alpha_pattern(struct buffer *buf)
{
void *pixels;
int stride_bytes;
int w, h;
int y;
assert(pixman_image_get_format(buf->image) == PIXMAN_a8r8g8b8);
pixels = pixman_image_get_data(buf->image);
stride_bytes = pixman_image_get_stride(buf->image);
w = pixman_image_get_width(buf->image);
h = pixman_image_get_height(buf->image);
assert(w == BLOCK_WIDTH * ALPHA_STEPS);
for (y = 0; y < h; y++) {
uint32_t *row = pixels + y * stride_bytes;
uint32_t step;
for (step = 0; step < (uint32_t)ALPHA_STEPS; step++) {
uint32_t alpha = step * 255 / (ALPHA_STEPS - 1);
uint32_t color;
int i;
color = premult_color(alpha, 0, 255 - alpha, 255);
for (i = 0; i < BLOCK_WIDTH; i++)
*row++ = color;
}
}
}
static uint8_t
red(uint32_t v)
{
return (v >> 16) & 0xff;
}
static uint8_t
blue(uint32_t v)
{
return v & 0xff;
}
static bool
pixels_monotonic(const uint32_t *row, int x)
{
bool ret = true;
if (red(row[x + 1]) > red(row[x])) {
testlog("pixel %d -> next: red value increases\n", x);
ret = false;
}
if (blue(row[x + 1]) < blue(row[x])) {
testlog("pixel %d -> next: blue value decreases\n", x);
ret = false;
}
return ret;
}
static bool
check_blend_pattern(struct buffer *shot)
{
bool ret = true;
const int y = (BLOCK_WIDTH - 1) / 2; /* middle row */
int x;
void *pixels;
int stride_bytes;
uint32_t *row;
assert(pixman_image_get_width(shot->image) >= BLOCK_WIDTH * ALPHA_STEPS);
assert(pixman_image_get_height(shot->image) >= BLOCK_WIDTH);
pixels = pixman_image_get_data(shot->image);
stride_bytes = pixman_image_get_stride(shot->image);
row = pixels + y * stride_bytes;
for (x = 0; x < BLOCK_WIDTH * ALPHA_STEPS - 1; x++)
if (!pixels_monotonic(row, x))
ret = false;
return ret;
}
/*
* Test that alpha blending is roughly correct, and that an alpha ramp
* results in a stricly monotonic color ramp. This should ensure that any
* animation that varies alpha never goes "backwards" as that is easily
* noticeable.
*
* The background is a constant color. On top of that, there is an
* alpha-blended gradient with ramps in both alpha and color. Sub-surface
* ensures the correct positioning and stacking.
*
* The gradient consists of ALPHA_STEPS number of blocks. Block size is
* BLOCK_WIDTH x BLOCK_WIDTH and a block has a uniform color.
*
* In the blending result over x axis:
* - red goes from 1.0 to 0.0, monotonic
* - green is not monotonic
* - blue goes from 0.0 to 1.0, monotonic
*/
TEST(alpha_blend_monotonic)
{
const int width = BLOCK_WIDTH * ALPHA_STEPS;
const int height = BLOCK_WIDTH;
const pixman_color_t background_color = {
.red = 0xffff,
.green = 0x8080,
.blue = 0x0000,
.alpha = 0xffff
};
struct client *client;
struct buffer *buf;
struct wl_subcompositor *subco;
struct wl_surface *surf;
struct wl_subsurface *sub;
struct buffer *shot;
bool match;
client = create_client();
subco = bind_to_singleton_global(client, &wl_subcompositor_interface, 1);
/* background window content */
buf = create_shm_buffer_a8r8g8b8(client, width, height);
fill_image_with_color(buf->image, &background_color);
/* background window, main surface */
client->surface = create_test_surface(client);
client->surface->width = width;
client->surface->height = height;
client->surface->buffer = buf; /* pass ownership */
set_opaque_rect(client, client->surface,
&(struct rectangle){ 0, 0, width, height });
/* foreground blended content */
buf = create_shm_buffer_a8r8g8b8(client, width, height);
fill_alpha_pattern(buf);
/* foreground window, sub-surface */
surf = wl_compositor_create_surface(client->wl_compositor);
sub = wl_subcompositor_get_subsurface(subco, surf, client->surface->wl_surface);
/* sub-surface defaults to position 0, 0, top-most, synchronized */
wl_surface_attach(surf, buf->proxy, 0, 0);
wl_surface_damage(surf, 0, 0, width, height);
wl_surface_commit(surf);
/* attach, damage, commit background window */
move_client(client, 0, 0);
shot = capture_screenshot_of_output(client);
assert(shot);
match = verify_image(shot, "alpha_blend_monotonic", 0, NULL, 0);
assert(match);
assert(check_blend_pattern(shot));
buffer_destroy(shot);
wl_subsurface_destroy(sub);
wl_surface_destroy(surf);
buffer_destroy(buf);
client_destroy(client);
}

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@ -118,6 +118,7 @@ dep_zucmain = declare_dependency(
)
tests = [
{ 'name': 'alpha-blending', },
{ 'name': 'bad-buffer', },
{ 'name': 'buffer-transforms', },
{ 'name': 'devices', },

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