[gtk/transform-work: 4/4] Add gsk_transform_to_2d_components
- From: Matthias Clasen <matthiasc src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [gtk/transform-work: 4/4] Add gsk_transform_to_2d_components
- Date: Sat, 18 Sep 2021 06:08:58 +0000 (UTC)
commit 41b810da7f36366ca7bbda7630453faed54fa016
Author: Matthias Clasen <mclasen redhat com>
Date: Sat Sep 18 02:06:00 2021 -0400
Add gsk_transform_to_2d_components
This function decomposes a general 2D transform
into skew, scale, rotation and translation.
Tests included.
gsk/gsktransform.c | 118 +++++++++++++++++++++++++++++++++++++++++-----
gsk/gsktransform.h | 9 ++++
testsuite/gsk/transform.c | 80 +++++++++++++++++++++++++++++++
3 files changed, 194 insertions(+), 13 deletions(-)
---
diff --git a/gsk/gsktransform.c b/gsk/gsktransform.c
index cc30f567d9..9eeab2d66a 100644
--- a/gsk/gsktransform.c
+++ b/gsk/gsktransform.c
@@ -121,6 +121,14 @@ gsk_transform_alloc (const GskTransformClass *transform_class,
return self;
}
+static void
+gsk_transform_finalize (GskTransform *self)
+{
+ self->transform_class->finalize (self);
+
+ gsk_transform_unref (self->next);
+}
+
/* }}} */
/* {{{ IDENTITY */
@@ -1022,6 +1030,9 @@ gsk_skew_transform_finalize (GskTransform *self)
{
}
+#define DEG_TO_RAD(x) ((x) / 180.f * G_PI)
+#define RAD_TO_DEG(x) ((x) * 180.f / G_PI)
+
static void
gsk_skew_transform_to_matrix (GskTransform *transform,
graphene_matrix_t *out_matrix)
@@ -1029,8 +1040,8 @@ gsk_skew_transform_to_matrix (GskTransform *transform,
GskSkewTransform *self = (GskSkewTransform *) transform;
graphene_matrix_init_skew (out_matrix,
- self->skew_x / 180.0 * G_PI,
- self->skew_y / 180.0 * G_PI);
+ DEG_TO_RAD (self->skew_x),
+ DEG_TO_RAD (self->skew_y));
}
static void
@@ -1104,8 +1115,8 @@ gsk_skew_transform_invert (GskTransform *transform,
float tx, ty;
graphene_matrix_t matrix;
- tx = tanf (self->skew_x / 180.0 * G_PI);
- ty = tanf (self->skew_y / 180.0 * G_PI);
+ tx = tanf (DEG_TO_RAD (self->skew_x));
+ ty = tanf (DEG_TO_RAD (self->skew_y));
graphene_matrix_init_from_2d (&matrix,
1 / (1 - tx * ty),
@@ -1506,14 +1517,6 @@ gsk_transform_perspective (GskTransform *next,
/* }}} */
/* {{{ PUBLIC API */
-static void
-gsk_transform_finalize (GskTransform *self)
-{
- self->transform_class->finalize (self);
-
- gsk_transform_unref (self->next);
-}
-
/**
* gsk_transform_ref:
* @self: (nullable): a `GskTransform`
@@ -1697,6 +1700,95 @@ gsk_transform_to_2d (GskTransform *self,
out_dx, out_dy);
}
+/**
+ * gsk_transform_to_2d_components:
+ * @self: a `GskTransform`
+ * @out_skew_x: (out): return location for the skew factor
+ * in the x direction
+ * @out_skew_y: (out): return location for the skew factor
+ * in the y direction
+ * @out_scale_x: (out): return location for the scale
+ * factor in the x direction
+ * @out_scale_y: (out): return location for the scale
+ * factor in the y direction
+ * @out_angle: (out): return location for the rotation angle
+ * @out_dx: (out): return location for the translation
+ * in the x direction
+ * @out_dy: (out): return location for the translation
+ * in the y direction
+ *
+ * Converts a `GskTransform` to 2D transformation factors.
+ *
+ * To recreate an equivalent transform from the factors returned
+ * by this function, use
+ *
+ * gsk_transform_skew (
+ * gsk_transform_scale (
+ * gsk_transform_rotate (
+ * gsk_transform_translate (NULL, &GRAPHENE_POINT_T (dx, dy)),
+ * angle),
+ * scale_x, scale_y),
+ * skew_x, skew_y)
+ *
+ * @self must be a 2D transformation. If you are not sure, use
+ *
+ * gsk_transform_get_category() >= %GSK_TRANSFORM_CATEGORY_2D
+ *
+ * to check.
+ *
+ * Since: 4.6
+ */
+void
+gsk_transform_to_2d_components (GskTransform *self,
+ float *out_skew_x,
+ float *out_skew_y,
+ float *out_scale_x,
+ float *out_scale_y,
+ float *out_angle,
+ float *out_dx,
+ float *out_dy)
+{
+ float a, b, c, d, e, f;
+
+ gsk_transform_to_2d (self, &a, &b, &c, &d, &e, &f);
+
+ *out_dx = e;
+ *out_dy = f;
+
+#define sign(f) ((f) < 0 ? -1 : 1)
+
+ if (a != 0 || b != 0)
+ {
+ float det = a * d - b * c;
+ float r = sqrtf (a*a + b*b);
+
+ *out_angle = RAD_TO_DEG (sign (b) * acosf (a / r));
+ *out_scale_x = r;
+ *out_scale_y = det / r;
+ *out_skew_x = RAD_TO_DEG (atanf ((a*c + b*d) / (r*r)));
+ *out_skew_y = 0;
+ }
+ else if (c != 0 || d != 0)
+ {
+ float det = a * d - b * c;
+ float s = sqrtf (c*c + d*d);
+
+ *out_angle = RAD_TO_DEG (G_PI/2 - sign (d) * acosf (-c / s));
+ *out_scale_x = det / s;
+ *out_scale_y = s;
+ *out_skew_x = 0;
+ *out_skew_y = RAD_TO_DEG (atanf ((a*c + b*d) / (s*s)));
+ }
+ else
+ {
+ *out_angle = 0;
+ *out_scale_x = 0;
+ *out_scale_y = 0;
+ *out_skew_x = 0;
+ *out_skew_y = 0;
+ }
+}
+
/**
* gsk_transform_to_affine:
* @self: a `GskTransform`
@@ -1718,7 +1810,7 @@ gsk_transform_to_2d (GskTransform *self,
* &GRAPHENE_POINT_T (dx, dy)),
* sx, sy)
*
- * @self must be a 2D transformation. If you are not
+ * @self must be a 2D affine transformation. If you are not
* sure, use
*
* gsk_transform_get_category() >= %GSK_TRANSFORM_CATEGORY_2D_AFFINE
diff --git a/gsk/gsktransform.h b/gsk/gsktransform.h
index a580547331..d74d4e197f 100644
--- a/gsk/gsktransform.h
+++ b/gsk/gsktransform.h
@@ -59,6 +59,15 @@ void gsk_transform_to_2d (GskTransform
float *out_yy,
float *out_dx,
float *out_dy);
+GDK_AVAILABLE_IN_4_6
+void gsk_transform_to_2d_components (GskTransform *self,
+ float *out_skew_x,
+ float *out_skew_y,
+ float *out_scale_x,
+ float *out_scale_y,
+ float *out_angle,
+ float *out_dx,
+ float *out_dy);
GDK_AVAILABLE_IN_ALL
void gsk_transform_to_affine (GskTransform *self,
float *out_scale_x,
diff --git a/testsuite/gsk/transform.c b/testsuite/gsk/transform.c
index eba1e05ec0..ec2b138761 100644
--- a/testsuite/gsk/transform.c
+++ b/testsuite/gsk/transform.c
@@ -657,6 +657,84 @@ test_to_2d (void)
g_assert_cmpfloat (dy, ==, 0.0);
}
+static void
+test_to_2d_components (void)
+{
+ GskTransform *transform, *transform2;
+ float skew_x, skew_y, scale_x, scale_y, angle, dx, dy;
+ graphene_matrix_t m, m2;
+
+ transform = gsk_transform_scale (
+ gsk_transform_rotate (
+ gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (10, 20)),
+ 22),
+ 3, 3);
+ gsk_transform_to_2d_components (transform,
+ &skew_x, &skew_y,
+ &scale_x, &scale_y,
+ &angle,
+ &dx, &dy);
+ g_assert_cmpfloat_with_epsilon (skew_x, 0, 0.0001);
+ g_assert_cmpfloat_with_epsilon (skew_y, 0, 0.0001);
+ g_assert_cmpfloat_with_epsilon (scale_x, 3, 0.0001);
+ g_assert_cmpfloat_with_epsilon (scale_y, 3, 0.0001);
+ g_assert_cmpfloat_with_epsilon (angle, 22, 0.0001);
+ g_assert_cmpfloat_with_epsilon (dx, 10, 0.0001);
+ g_assert_cmpfloat_with_epsilon (dy, 20, 0.0001);
+
+ gsk_transform_unref (transform);
+
+ transform = gsk_transform_skew (
+ gsk_transform_scale (
+ gsk_transform_rotate (
+ gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (10, 20)),
+ 22),
+ 3, 6),
+ 33, 0);
+
+ g_assert_true (gsk_transform_get_category (transform) >= GSK_TRANSFORM_CATEGORY_2D);
+
+ gsk_transform_to_2d_components (transform,
+ &skew_x, &skew_y,
+ &scale_x, &scale_y,
+ &angle,
+ &dx, &dy);
+
+ transform2 = gsk_transform_skew (
+ gsk_transform_scale (
+ gsk_transform_rotate (
+ gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (dx, dy)),
+ angle),
+ scale_x, scale_y),
+ skew_x, skew_y);
+
+ gsk_transform_to_matrix (transform, &m);
+ gsk_transform_to_matrix (transform2, &m2);
+ g_assert_true (graphene_matrix_near (&m, &m2, 0.001));
+
+ gsk_transform_unref (transform);
+ gsk_transform_unref (transform2);
+}
+
+static void
+test_transform_point (void)
+{
+ GskTransform *t, *t2;
+ graphene_point_t p;
+
+ t = gsk_transform_scale (gsk_transform_translate (NULL, &GRAPHENE_POINT_INIT (1, 2)), 2, 2);
+ t2 = gsk_transform_translate (gsk_transform_scale (NULL, 2, 2), &GRAPHENE_POINT_INIT (1, 2));
+
+ gsk_transform_transform_point (t, &GRAPHENE_POINT_INIT (1,1), &p);
+ g_assert_true (graphene_point_equal (&p, &GRAPHENE_POINT_INIT (3, 4)));
+
+ gsk_transform_transform_point (t2, &GRAPHENE_POINT_INIT (1,1), &p);
+ g_assert_true (graphene_point_equal (&p, &GRAPHENE_POINT_INIT (4, 6)));
+
+ gsk_transform_unref (t);
+ gsk_transform_unref (t2);
+}
+
int
main (int argc,
char *argv[])
@@ -672,7 +750,9 @@ main (int argc,
g_test_add_func ("/transform/check-axis-aligneness", test_axis_aligned);
g_test_add_func ("/transform/to-affine", test_to_affine);
g_test_add_func ("/transform/bounds", test_transform_bounds);
+ g_test_add_func ("/transform/point", test_transform_point);
g_test_add_func ("/transform/to-2d", test_to_2d);
+ g_test_add_func ("/transform/to-2d-components", test_to_2d_components);
return g_test_run ();
}
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