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libweston: Add function to find the output transform of a matrix

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When we build up a matrix from a series of operations, it's very useful
to know if the combined operations still result in something that matches
a wl_output_transform.

This adds a function to test if a matrix leads to a standard output
transform, and returns the transform if it does.

Tests are provided that check if complex series of operations return
expected results - the weston_matrix_needs_filtering function is tested
at the same time.

Signed-off-by: Derek Foreman <derek.foreman@collabora.com>
This commit is contained in:
Derek Foreman 2022-01-27 11:20:34 -06:00
parent 0e2136df7b
commit 92a9860e1d
4 changed files with 417 additions and 0 deletions
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6
include/libweston/matrix.h
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@ -29,6 +29,8 @@
#include <stdbool.h>
#include <wayland-server-protocol.h>
#ifdef __cplusplus
extern "C" {
#endif
@ -71,6 +73,10 @@ weston_matrix_invert(struct weston_matrix *inverse,
bool
weston_matrix_needs_filtering(const struct weston_matrix *matrix);
bool
weston_matrix_to_transform(const struct weston_matrix *mat,
enum wl_output_transform *transform);
#ifdef __cplusplus
}
#endif

121
shared/matrix.c
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@ -296,6 +296,12 @@ near_zero_at(const struct weston_matrix *matrix, int row, int col)
return near_zero(get_el(matrix, row, col));
}
static bool
near_one_at(const struct weston_matrix *matrix, int row, int col)
{
return near_zero(get_el(matrix, row, col) - 1.0);
}
static bool
near_pm_one_at(const struct weston_matrix *matrix, int row, int col)
{
@ -395,3 +401,118 @@ weston_matrix_needs_filtering(const struct weston_matrix *matrix)
* heuristics, so recommend filtering */
return true;
}
/** Examine a matrix to see if it applies a standard output transform.
*
* \param mat matrix to examine
* \param[out] transform the transform, if applicable
* \return true if a standard transform is present
* Note that the check only considers rotations and flips.
* If any other scale or translation is present, those may have to
* be dealt with by the caller in some way.
*/
WL_EXPORT bool
weston_matrix_to_transform(const struct weston_matrix *mat,
enum wl_output_transform *transform)
{
/* As a first pass we can eliminate any matrix that doesn't have
* zeroes in these positions:
* [ ? ? 0 ? ]
* [ ? ? 0 ? ]
* [ 0 0 ? ? ]
* [ 0 0 0 ? ]
* As they will be non-affine, or rotations about axes
* other than Z.
*/
if (!near_zero_at(mat, 2, 0) ||
!near_zero_at(mat, 3, 0) ||
!near_zero_at(mat, 2, 1) ||
!near_zero_at(mat, 3, 1) ||
!near_zero_at(mat, 0, 2) ||
!near_zero_at(mat, 1, 2) ||
!near_zero_at(mat, 3, 2))
return false;
/* Enforce the form:
* [ ? ? 0 ? ]
* [ ? ? 0 ? ]
* [ 0 0 ? ? ]
* [ 0 0 0 1 ]
* While we could scale all the elements by a constant to make
* 3,3 == 1, we choose to be lazy and not bother. A matrix
* that doesn't fit this form seems likely to be too complicated
* to pass the other checks.
*/
if (!near_one_at(mat, 3, 3))
return false;
if (near_zero_at(mat, 0, 0)) {
if (!near_zero_at(mat, 1, 1))
return false;
/* We now have a matrix like:
* [ 0 A 0 ? ]
* [ B 0 0 ? ]
* [ 0 0 ? ? ]
* [ 0 0 0 1 ]
* When transforming a vector with a matrix of this form, the X
* and Y coordinates are effectively exchanged, so we have a
* 90 or 270 degree rotation (not 0 or 180), and could have
* a flip depending on the signs of A and B.
*
* We don't require A and B to have the same absolute value,
* so there may be independent scales in the X or Y dimensions.
*/
if (get_el(mat, 0, 1) > 0) {
/* A is positive */
if (get_el(mat, 1, 0) > 0)
*transform = WL_OUTPUT_TRANSFORM_FLIPPED_90;
else
*transform = WL_OUTPUT_TRANSFORM_90;
} else {
/* A is negative */
if (get_el(mat, 1, 0) > 0)
*transform = WL_OUTPUT_TRANSFORM_270;
else
*transform = WL_OUTPUT_TRANSFORM_FLIPPED_270;
}
} else if (near_zero_at(mat, 1, 0)) {
if (!near_zero_at(mat, 0, 1))
return false;
/* We now have a matrix like:
* [ A 0 0 ? ]
* [ 0 B 0 ? ]
* [ 0 0 ? ? ]
* [ 0 0 0 1 ]
* This case won't exchange the X and Y inputs, so the
* transform is 0 or 180 degrees. We could have a flip
* depending on the signs of A and B.
*
* We don't require A and B to have the same absolute value,
* so there may be independent scales in the X or Y dimensions.
*/
if (get_el(mat, 0, 0) > 0) {
/* A is positive */
if (get_el(mat, 1, 1) > 0)
*transform = WL_OUTPUT_TRANSFORM_NORMAL;
else
*transform = WL_OUTPUT_TRANSFORM_FLIPPED_180;
} else {
/* A is negative */
if (get_el(mat, 1, 1) > 0)
*transform = WL_OUTPUT_TRANSFORM_FLIPPED;
else
*transform = WL_OUTPUT_TRANSFORM_180;
}
} else {
return false;
}
return true;
}

286
tests/matrix-transform-test.c Normal file
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@ -0,0 +1,286 @@
/*
* Copyright © 2022 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 <assert.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <wayland-client.h>
#include "libweston-internal.h"
#include "libweston/matrix.h"
#include "weston-test-client-helper.h"
static void
transform_expect(struct weston_matrix *a, bool valid, enum wl_output_transform ewt)
{
enum wl_output_transform wt;
assert(weston_matrix_to_transform(a, &wt) == valid);
if (valid)
assert(wt == ewt);
}
TEST(transformation_matrix)
{
struct weston_matrix a, b;
int i;
weston_matrix_init(&a);
weston_matrix_init(&b);
weston_matrix_multiply(&a, &b);
assert(a.type == 0);
/* Make b a matrix that rotates a surface on the x,y plane by 90
* degrees counter-clockwise */
weston_matrix_rotate_xy(&b, 0, -1);
assert(b.type == WESTON_MATRIX_TRANSFORM_ROTATE);
for (i = 0; i < 10; i++) {
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_90);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_180);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_270);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
}
weston_matrix_init(&b);
/* Make b a matrix that rotates a surface on the x,y plane by 45
* degrees counter-clockwise. This should alternate between a
* standard transform and a rotation that fails to match any
* known rotations. */
weston_matrix_rotate_xy(&b, cos(-M_PI / 4.0), sin(-M_PI / 4.0));
assert(b.type == WESTON_MATRIX_TRANSFORM_ROTATE);
for (i = 0; i < 10; i++) {
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_90);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_180);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_270);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
assert(a.type == WESTON_MATRIX_TRANSFORM_ROTATE);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
}
weston_matrix_init(&b);
/* Make b a matrix that rotates a surface on the x,y plane by 45
* degrees counter-clockwise. This should alternate between a
* standard transform and a rotation that fails to match any known
* rotations. */
weston_matrix_rotate_xy(&b, cos(-M_PI / 4.0), sin(-M_PI / 4.0));
/* Flip a */
weston_matrix_scale(&a, -1.0, 1.0, 1.0);
for (i = 0; i < 10; i++) {
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
/* Since we're not translated or scaled, any matrix that
* matches a standard wl_output_transform should not need
* filtering when used to transform images - but any
* matrix that fails to match will. */
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_90);
assert(!weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_180);
assert(!weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_270);
assert(!weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED);
assert(!weston_matrix_needs_filtering(&a));
}
weston_matrix_init(&a);
/* Flip a around Y*/
weston_matrix_scale(&a, 1.0, -1.0, 1.0);
for (i = 0; i < 100; i++) {
/* Throw some arbitrary translation in here to make sure it
* doesn't have any impact. */
weston_matrix_translate(&a, 31.0, -25.0, 0.0);
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_270);
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED);
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_90);
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_180);
}
/* Scale shouldn't matter, as long as it's positive */
weston_matrix_scale(&a, 4.0, 3.0, 1.0);
/* Invert b so it rotates the opposite direction, go back the other way. */
weston_matrix_invert(&b, &b);
for (i = 0; i < 100; i++) {
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_90);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_270);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, false, 0);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_FLIPPED_180);
assert(weston_matrix_needs_filtering(&a));
}
/* Flipping Y should return us from here to normal */
weston_matrix_scale(&a, 1.0, -1.0, 1.0);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
weston_matrix_init(&a);
weston_matrix_init(&b);
weston_matrix_translate(&b, 0.5, -0.75, 0);
/* Crawl along with translations, 0.5 and .75 will both hit an integer multiple
* at the same time every 4th step, so assert that only the 4th steps don't need
* filtering */
for (i = 0; i < 100; i++) {
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(weston_matrix_needs_filtering(&a));
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(!weston_matrix_needs_filtering(&a));
}
weston_matrix_init(&b);
weston_matrix_scale(&b, 1.5, 2.0, 1.0);
for (i = 0; i < 10; i++) {
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(weston_matrix_needs_filtering(&a));
}
weston_matrix_invert(&b, &b);
for (i = 0; i < 9; i++) {
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(weston_matrix_needs_filtering(&a));
}
/* Last step should bring us back to a matrix that doesn't need
* a filter */
weston_matrix_multiply(&a, &b);
transform_expect(&a, true, WL_OUTPUT_TRANSFORM_NORMAL);
assert(!weston_matrix_needs_filtering(&a));
}

4
tests/meson.build
View File

@ -176,6 +176,10 @@ tests = [
'name': 'matrix',
'dep_objs': [ dep_libm ]
},
{
'name': 'matrix-transform',
'dep_objs': dep_libm,
},
{ 'name': 'output-damage', },
{ 'name': 'output-transforms', },
{ 'name': 'plugin-registry', },