GI.Gsk.Structs.PathPoint

GskPathPoint is an opaque type representing a point on a path.

It can be queried for properties of the path at that point, such as its tangent or its curvature.

To obtain a GskPathPoint, use pathGetClosestPoint, pathGetStartPoint, pathGetEndPoint or pathMeasureGetPoint.

Note that GskPathPoint structs are meant to be stack-allocated, and don't hold a reference to the path object they are obtained from. It is the callers responsibility to keep a reference to the path as long as the GskPathPoint is used.

Since: 4.14

Exported types

newtype PathPoint

Memory-managed wrapper type.

Constructors

PathPoint (ManagedPtr PathPoint)

Instances

Eq PathPoint

Defined in GI.Gsk.Structs.PathPoint

Methods

(==) :: PathPoint -> PathPoint -> Bool

(/=) :: PathPoint -> PathPoint -> Bool

GBoxed PathPoint

Defined in GI.Gsk.Structs.PathPoint

ManagedPtrNewtype PathPoint

Defined in GI.Gsk.Structs.PathPoint

Methods

toManagedPtr :: PathPoint -> ManagedPtr PathPoint

TypedObject PathPoint

Defined in GI.Gsk.Structs.PathPoint

Methods

glibType :: IO GType

HasParentTypes PathPoint

Defined in GI.Gsk.Structs.PathPoint

IsGValue (Maybe PathPoint)

Convert PathPoint to and from GValue. See toGValue and fromGValue.

Defined in GI.Gsk.Structs.PathPoint

Methods

gvalueGType_ :: IO GType

gvalueSet_ :: Ptr GValue -> Maybe PathPoint -> IO ()

gvalueGet_ :: Ptr GValue -> IO (Maybe PathPoint)

type ParentTypes PathPoint

Defined in GI.Gsk.Structs.PathPoint

type ParentTypes PathPoint = '[] :: [Type]

Methods

Click to display all available methods, including inherited ones

Methods

compare, copy, equal, free.

Getters

getCurvature, getDistance, getPosition, getRotation, getTangent.

Setters

None.

compare

pathPointCompare

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point1: a GskPathPoint

-> PathPoint

point2: another GskPathPoint

-> m Int32

Returns: -1 if point1 is before point2, 1 if point1 is after point2, 0 if they are equal

Returns whether point1 is before or after point2.

Since: 4.14

copy

pathPointCopy :: (HasCallStack, MonadIO m) => PathPoint -> m PathPoint

No description available in the introspection data.

equal

pathPointEqual

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point1: a GskPathPoint

-> PathPoint

point2: another GskPathPoint

-> m Bool

Returns: TRUE if point1 and point2 are equal

Returns whether the two path points refer to the same location on all paths.

Note that the start- and endpoint of a closed contour will compare nonequal according to this definition. Use pathIsClosed to find out if the start- and endpoint of a concrete path refer to the same location.

Since: 4.14

free

pathPointFree :: (HasCallStack, MonadIO m) => PathPoint -> m ()

No description available in the introspection data.

getCurvature

pathPointGetCurvature

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point: a GskPathPoint

-> Path

path: the path that point is on

-> PathDirection

direction: the direction for which to return the curvature

-> m (Float, Maybe Point)

Returns: The curvature of the path at the given point

Calculates the curvature of the path at the point.

Optionally, returns the center of the osculating circle as well. The curvature is the inverse of the radius of the osculating circle.

Lines have a curvature of zero (indicating an osculating circle of infinite radius. In this case, the center is not modified.

Circles with a radius of zero have INFINITY as curvature

Note that certain points on a path may not have a single curvature, such as sharp turns. At such points, there are two curvatures -- the (limit of) the curvature of the path going into the point, and the (limit of) the curvature of the path coming out of it. The direction argument lets you choose which one to get.

<picture> <source srcset="curvature-dark.png" media="(prefers-color-scheme: dark)"> <img alt="Osculating circle" src="curvature-light.png"> </picture>

Since: 4.14

getDistance

pathPointGetDistance

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point: a `GskPathPoint on the path

-> PathMeasure

measure: a GskPathMeasure for the path

-> m Float

Returns: the distance of point

Returns the distance from the beginning of the path to point.

Since: 4.14

getPosition

pathPointGetPosition

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point: a GskPathPoint

-> Path

path: the path that point is on

-> m Point

Gets the position of the point.

Since: 4.14

getRotation

pathPointGetRotation

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point: a GskPathPoint

-> Path

path: the path that point is on

-> PathDirection

direction: the direction for which to return the rotation

-> m Float

Returns: the angle between the tangent and the X axis, in degrees

Gets the direction of the tangent at a given point.

This is a convenience variant of pathPointGetTangent that returns the angle between the tangent and the X axis. The angle can e.g. be used in gtk_snapshot_rotate().

Since: 4.14

getTangent

pathPointGetTangent

Arguments

:: (HasCallStack, MonadIO m)

=> PathPoint

point: a GskPathPoint

-> Path

path: the path that point is on

-> PathDirection

direction: the direction for which to return the tangent

-> m Vec2

Gets the tangent of the path at the point.

Note that certain points on a path may not have a single tangent, such as sharp turns. At such points, there are two tangents -- the direction of the path going into the point, and the direction coming out of it. The direction argument lets you choose which one to get.

If the path is just a single point (e.g. a circle with radius zero), then tangent is set to 0, 0.

If you want to orient something in the direction of the path, pathPointGetRotation may be more convenient to use.

Since: 4.14