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Revise gsk_path_point_get_tangent

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Update the directions enum to allow all four
tangents to be obtained. Add an illustration
to the docs for clarity.

Update all callers.
This commit is contained in:
Matthias Clasen
2023-08-14 14:49:26 -04:00
parent a1d40c5236
commit a85ab3585e
7 changed files with 356 additions and 9 deletions
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2
docs/reference/gsk/gsk4.toml.in
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@@ -36,6 +36,8 @@ content_images = [
"gtk-logo.svg",
"images/caps-dark.png",
"images/caps-light.png",
"images/directions-dark.png",
"images/directions-light.png",
"images/join-dark.png",
"images/join-light.png",
"images/path-dark.png",

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docs/reference/gsk/images/directions.svg Normal file
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9
gsk/gskcontour.c
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@@ -509,7 +509,8 @@ gsk_standard_contour_get_tangent (const GskContour *contour,
idx = point->idx;
t = point->t;
if (t == 0 && direction == GSK_PATH_START)
if (t == 0 && (direction == GSK_PATH_FROM_START ||
direction == GSK_PATH_TO_START))
{
/* Look at the previous segment */
if (idx > 1)
@@ -523,7 +524,8 @@ gsk_standard_contour_get_tangent (const GskContour *contour,
t = 1;
}
}
else if (t == 1 && direction == GSK_PATH_END)
else if (t == 1 && (direction == GSK_PATH_TO_END ||
direction == GSK_PATH_FROM_END))
{
/* Look at the next segment */
if (idx < self->n_ops - 1)
@@ -540,6 +542,9 @@ gsk_standard_contour_get_tangent (const GskContour *contour,
gsk_curve_init (&curve, self->ops[idx]);
gsk_curve_get_tangent (&curve, t, tangent);
if (direction == GSK_PATH_TO_START || direction == GSK_PATH_FROM_END)
graphene_vec2_negate (tangent, tangent);
}
static float

23
gsk/gskenums.h
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@@ -292,17 +292,30 @@ typedef enum {
/**
* GskPathDirection:
* @GSK_PATH_START: The side that leads to the start of the path
* @GSK_PATH_END: The side that leads to the end of the path
* @GSK_PATH_FROM_START: The tangent in path direction of the incoming side
* of the path
* @GSK_PATH_TO_START: The tangent against path direction of the incoming side
* of the path
* @GSK_PATH_TO_END: The tangent in path direction of the outgoing side
* of the path
* @GSK_PATH_FROM_END: The tangent against path direction of the outgoing
* side of the path
*
* The values of the `GskPathDirection` enum are used to pick one
* of the two sides of the path that at a given point on the path.
* of the four tangents at a given point on the path.
*
* <picture>
* <source srcset="directions-dark.png" media="(prefers-color-scheme: dark)">
* <img alt="Path Tangents" src="directions-light.png">
* </picture>
*
* Since: 4.14
*/
typedef enum {
GSK_PATH_START,
GSK_PATH_END
GSK_PATH_FROM_START,
GSK_PATH_TO_START,
GSK_PATH_TO_END,
GSK_PATH_FROM_END,
} GskPathDirection;
/**

4
testsuite/gsk/path-special-cases.c
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@@ -466,8 +466,8 @@ test_path_point (void)
g_assert_true (rp->t == 1);
gsk_path_point_get_position (&point, path, &pos);
gsk_path_point_get_tangent (&point, path, GSK_PATH_START, &t1);
gsk_path_point_get_tangent (&point, path, GSK_PATH_END, &t2);
gsk_path_point_get_tangent (&point, path, GSK_PATH_TO_START, &t1);
gsk_path_point_get_tangent (&point, path, GSK_PATH_TO_END, &t2);
curvature = gsk_path_point_get_curvature (&point, path, &center);
g_assert_true (graphene_point_equal (&pos, &GRAPHENE_POINT_INIT (100, 100)));