util: add a couple of 3x3 matrix helper functions

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

diff --git a/src/libinput-util.h b/src/libinput-util.h
index 5d366b0..f807210 100644 (file)
--- a/src/libinput-util.h
+++ b/src/libinput-util.h
@@ -25,6 +25,7 @@
 
 #include <unistd.h>
 #include <math.h>
+#include <string.h>
 
 #include "libinput.h"
 
@@ -179,4 +180,103 @@ long_set_bit_state(unsigned long *array, int bit, int state)
                long_clear_bit(array, bit);
 }
 
+struct matrix {
+       float val[3][3]; /* [row][col] */
+};
+
+static inline void
+matrix_init_identity(struct matrix *m)
+{
+       memset(m, 0, sizeof(*m));
+       m->val[0][0] = 1;
+       m->val[1][1] = 1;
+       m->val[2][2] = 1;
+}
+
+static inline void
+matrix_from_farray6(struct matrix *m, const float values[6])
+{
+       matrix_init_identity(m);
+       m->val[0][0] = values[0];
+       m->val[0][1] = values[1];
+       m->val[0][2] = values[2];
+       m->val[1][0] = values[3];
+       m->val[1][1] = values[4];
+       m->val[1][2] = values[5];
+}
+
+static inline void
+matrix_init_scale(struct matrix *m, float sx, float sy)
+{
+       matrix_init_identity(m);
+       m->val[0][0] = sx;
+       m->val[1][1] = sy;
+}
+
+static inline void
+matrix_init_translate(struct matrix *m, float x, float y)
+{
+       matrix_init_identity(m);
+       m->val[0][2] = x;
+       m->val[1][2] = y;
+}
+
+static inline int
+matrix_is_identity(struct matrix *m)
+{
+       return (m->val[0][0] == 1 &&
+               m->val[0][1] == 0 &&
+               m->val[0][2] == 0 &&
+               m->val[1][0] == 0 &&
+               m->val[1][1] == 1 &&
+               m->val[1][2] == 0 &&
+               m->val[2][0] == 0 &&
+               m->val[2][1] == 0 &&
+               m->val[2][2] == 1);
+}
+
+static inline void
+matrix_mult(struct matrix *dest,
+           const struct matrix *m1,
+           const struct matrix *m2)
+{
+       struct matrix m; /* allow for dest == m1 or dest == m2 */
+       int row, col, i;
+
+       for (row = 0; row < 3; row++) {
+               for (col = 0; col < 3; col++) {
+                       double v = 0;
+                       for (i = 0; i < 3; i++) {
+                               v += m1->val[row][i] * m2->val[i][col];
+                       }
+                       m.val[row][col] = v;
+               }
+       }
+
+       memcpy(dest, &m, sizeof(m));
+}
+
+static inline void
+matrix_mult_vec(struct matrix *m, int *x, int *y)
+{
+       int tx, ty;
+
+       tx = *x * m->val[0][0] + *y * m->val[0][1] + m->val[0][2];
+       ty = *x * m->val[1][0] + *y * m->val[1][1] + m->val[1][2];
+
+       *x = tx;
+       *y = ty;
+}
+
+static inline void
+matrix_to_farray6(const struct matrix *m, float out[6])
+{
+       out[0] = m->val[0][0];
+       out[1] = m->val[0][1];
+       out[2] = m->val[0][2];
+       out[3] = m->val[1][0];
+       out[4] = m->val[1][1];
+       out[5] = m->val[1][2];
+}
+
 #endif /* LIBINPUT_UTIL_H */

diff --git a/test/misc.c b/test/misc.c
index 983c3f9..1512180 100644 (file)
--- a/test/misc.c
+++ b/test/misc.c
@@ -431,6 +431,83 @@ START_TEST(config_status_string)
 }
 END_TEST
 
+START_TEST(matrix_helpers)
+{
+       struct matrix m1, m2, m3;
+       float f[6] = { 1, 2, 3, 4, 5, 6 };
+       int x, y;
+       int row, col;
+
+       matrix_init_identity(&m1);
+
+       for (row = 0; row < 3; row++) {
+               for (col = 0; col < 3; col++) {
+                       ck_assert_int_eq(m1.val[row][col],
+                                        (row == col) ? 1 : 0);
+               }
+       }
+       ck_assert(matrix_is_identity(&m1));
+
+       matrix_from_farray6(&m2, f);
+       ck_assert_int_eq(m2.val[0][0], 1);
+       ck_assert_int_eq(m2.val[0][1], 2);
+       ck_assert_int_eq(m2.val[0][2], 3);
+       ck_assert_int_eq(m2.val[1][0], 4);
+       ck_assert_int_eq(m2.val[1][1], 5);
+       ck_assert_int_eq(m2.val[1][2], 6);
+       ck_assert_int_eq(m2.val[2][0], 0);
+       ck_assert_int_eq(m2.val[2][1], 0);
+       ck_assert_int_eq(m2.val[2][2], 1);
+
+       x = 100;
+       y = 5;
+       matrix_mult_vec(&m1, &x, &y);
+       ck_assert_int_eq(x, 100);
+       ck_assert_int_eq(y, 5);
+
+       matrix_mult(&m3, &m1, &m1);
+       ck_assert(matrix_is_identity(&m3));
+
+       matrix_init_scale(&m2, 2, 4);
+       ck_assert_int_eq(m2.val[0][0], 2);
+       ck_assert_int_eq(m2.val[0][1], 0);
+       ck_assert_int_eq(m2.val[0][2], 0);
+       ck_assert_int_eq(m2.val[1][0], 0);
+       ck_assert_int_eq(m2.val[1][1], 4);
+       ck_assert_int_eq(m2.val[1][2], 0);
+       ck_assert_int_eq(m2.val[2][0], 0);
+       ck_assert_int_eq(m2.val[2][1], 0);
+       ck_assert_int_eq(m2.val[2][2], 1);
+
+       matrix_mult_vec(&m2, &x, &y);
+       ck_assert_int_eq(x, 200);
+       ck_assert_int_eq(y, 20);
+
+       matrix_init_translate(&m2, 10, 100);
+       ck_assert_int_eq(m2.val[0][0], 1);
+       ck_assert_int_eq(m2.val[0][1], 0);
+       ck_assert_int_eq(m2.val[0][2], 10);
+       ck_assert_int_eq(m2.val[1][0], 0);
+       ck_assert_int_eq(m2.val[1][1], 1);
+       ck_assert_int_eq(m2.val[1][2], 100);
+       ck_assert_int_eq(m2.val[2][0], 0);
+       ck_assert_int_eq(m2.val[2][1], 0);
+       ck_assert_int_eq(m2.val[2][2], 1);
+
+       matrix_mult_vec(&m2, &x, &y);
+       ck_assert_int_eq(x, 210);
+       ck_assert_int_eq(y, 120);
+
+       matrix_to_farray6(&m2, f);
+       ck_assert_int_eq(f[0], 1);
+       ck_assert_int_eq(f[1], 0);
+       ck_assert_int_eq(f[2], 10);
+       ck_assert_int_eq(f[3], 0);
+       ck_assert_int_eq(f[4], 1);
+       ck_assert_int_eq(f[5], 100);
+}
+END_TEST
+
 int main (int argc, char **argv) {
        litest_add_no_device("events:conversion", event_conversion_device_notify);
        litest_add_no_device("events:conversion", event_conversion_pointer);
@@ -441,5 +518,6 @@ int main (int argc, char **argv) {
        litest_add("device:id", device_ids, LITEST_ANY, LITEST_ANY);
        litest_add_no_device("config:status string", config_status_string);
 
+       litest_add_no_device("misc:matrix", matrix_helpers);
        return litest_run(argc, argv);
 }