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Add gsk_path_offset

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Add a function that takes a path, and offsets it
by some distance, applying line-join parameters
as needed.

This commit just adds the api, the implementation
will be in the following commit.
This commit is contained in:
Matthias Clasen
2020-12-26 23:59:16 -05:00
parent 645eddf838
commit a7b3a0c472
4 changed files with 95 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

55
gsk/gskcontour.c
View File

@@ -89,6 +89,11 @@ struct _GskContourClass
void (* add_stroke) (const GskContour *contour,
GskPathBuilder *builder,
GskStroke *stroke);
void (* offset) (const GskContour *contour,
GskPathBuilder *builder,
float distance,
GskLineJoin line_join,
float miter_limit);
};
static gsize
@@ -498,8 +503,8 @@ gsk_rect_contour_get_stroke_bounds (const GskContour *contour,
static gboolean
stroke_is_simple (GskStroke *stroke)
{
if (stroke->line_join != GSK_LINE_JOIN_MITER &&
stroke->line_join != GSK_LINE_JOIN_MITER_CLIP)
if (stroke->line_join == GSK_LINE_JOIN_ROUND ||
stroke->line_join == GSK_LINE_JOIN_BEVEL)
return FALSE;
if (stroke->miter_limit < 1.5)
@@ -536,6 +541,15 @@ gsk_rect_contour_add_stroke (const GskContour *contour,
gsk_contour_default_add_stroke (contour, builder, stroke);
}
static void
gsk_rect_contour_offset (const GskContour *contour,
GskPathBuilder *builder,
float distance,
GskLineJoin line_join,
float miter_limit)
{
}
static const GskContourClass GSK_RECT_CONTOUR_CLASS =
{
sizeof (GskRectContour),
@@ -554,7 +568,8 @@ static const GskContourClass GSK_RECT_CONTOUR_CLASS =
gsk_rect_contour_add_segment,
gsk_rect_contour_get_winding,
gsk_rect_contour_get_stroke_bounds,
gsk_rect_contour_add_stroke
gsk_rect_contour_add_stroke,
gsk_rect_contour_offset
};
GskContour *
@@ -911,6 +926,15 @@ gsk_circle_contour_add_stroke (const GskContour *contour,
gsk_contour_default_add_stroke (contour, builder, stroke);
}
static void
gsk_circle_contour_offset (const GskContour *contour,
GskPathBuilder *builder,
float distance,
GskLineJoin line_join,
float miter_limit)
{
}
static const GskContourClass GSK_CIRCLE_CONTOUR_CLASS =
{
sizeof (GskCircleContour),
@@ -929,7 +953,8 @@ static const GskContourClass GSK_CIRCLE_CONTOUR_CLASS =
gsk_circle_contour_add_segment,
gsk_circle_contour_get_winding,
gsk_circle_contour_get_stroke_bounds,
gsk_circle_contour_add_stroke
gsk_circle_contour_add_stroke,
gsk_circle_contour_offset
};
GskContour *
@@ -1625,6 +1650,15 @@ gsk_standard_contour_add_stroke (const GskContour *contour,
gsk_contour_default_add_stroke (contour, builder, stroke);
}
static void
gsk_standard_contour_offset (const GskContour *contour,
GskPathBuilder *builder,
float distance,
GskLineJoin line_join,
float miter_limit)
{
}
static const GskContourClass GSK_STANDARD_CONTOUR_CLASS =
{
sizeof (GskStandardContour),
@@ -1643,7 +1677,8 @@ static const GskContourClass GSK_STANDARD_CONTOUR_CLASS =
gsk_standard_contour_add_segment,
gsk_standard_contour_get_winding,
gsk_standard_contour_get_stroke_bounds,
gsk_standard_contour_add_stroke
gsk_standard_contour_add_stroke,
gsk_standard_contour_offset
};
/* You must ensure the contour has enough size allocated,
@@ -1823,6 +1858,16 @@ gsk_contour_add_stroke (const GskContour *self,
self->klass->add_stroke (self, builder, stroke);
}
void
gsk_contour_offset (const GskContour *self,
GskPathBuilder *builder,
float distance,
GskLineJoin line_join,
float miter_limit)
{
self->klass->offset (self, builder, distance, line_join, miter_limit);
}
void
gsk_contour_copy (GskContour *dest,
const GskContour *src)

6
gsk/gskcontourprivate.h
View File

@@ -103,6 +103,12 @@ void gsk_contour_default_add_stroke (const GskContou
GskPathBuilder *builder,
GskStroke *stroke);
void gsk_contour_offset (const GskContour *contour,
GskPathBuilder *builder,
float distance,
GskLineJoin line_join,
float miter_limit);
G_END_DECLS
#endif /* __GSK_CONTOUR_PRIVATE_H__ */

33
gsk/gskpath.c
View File

@@ -1264,3 +1264,36 @@ gsk_path_stroke (GskPath *self,
return gsk_path_builder_free_to_path (builder);
}
/**
* gsk_path_offset:
* @self: a `GskPath`
* @distance: the distance to offset the path by
* @line_join: how joins are supposed to be drawn
* @miter_limit: miter limit for joins
*
* Create a new path that is offset from @self by @distance.
*
* The offset can be positive (to the right) or negative.
* The @line_join and @miter_limit arguments influence how
* joins between the offset path segments are made.
*
* Returns: a new `GskPath`
*/
GskPath *
gsk_path_offset (GskPath *self,
float distance,
GskLineJoin line_join,
float miter_limit)
{
GskPathBuilder *builder;
builder = gsk_path_builder_new ();
for (int i = 0; i < self->n_contours; i++)
gsk_contour_offset (gsk_path_get_contour (self, i), builder, distance, line_join, miter_limit);
return gsk_path_builder_free_to_path (builder);
}

6
gsk/gskpath.h
View File

@@ -113,6 +113,12 @@ GDK_AVAILABLE_IN_ALL
GskPath * gsk_path_stroke (GskPath *self,
GskStroke *stroke);
GDK_AVAILABLE_IN_ALL
GskPath * gsk_path_offset (GskPath *self,
float distance,
GskLineJoin line_join,
float miter_limit);
G_END_DECLS