BitmapDataExtensionsDrawQuadraticCurves(IReadWriteBitmapData, IAsyncContext, Pen, IEnumerablePoint, DrawingOptions) Method

public static bool DrawQuadraticCurves(
	this IReadWriteBitmapData bitmapData,
	IAsyncContext? context,
	Pen pen,
	IEnumerable<Point> points,
	DrawingOptions? drawingOptions = null
)

<ExtensionAttribute>
Public Shared Function DrawQuadraticCurves ( 
	bitmapData As IReadWriteBitmapData,
	context As IAsyncContext,
	pen As Pen,
	points As IEnumerable(Of Point),
	Optional drawingOptions As DrawingOptions = Nothing
) As Boolean

public:
[ExtensionAttribute]
static bool DrawQuadraticCurves(
	IReadWriteBitmapData^ bitmapData, 
	IAsyncContext^ context, 
	Pen^ pen, 
	IEnumerable<Point>^ points, 
	DrawingOptions^ drawingOptions = nullptr
)

[<ExtensionAttribute>]
static member DrawQuadraticCurves : 
        bitmapData : IReadWriteBitmapData * 
        context : IAsyncContext * 
        pen : Pen * 
        points : IEnumerable<Point> * 
        ?drawingOptions : DrawingOptions 
(* Defaults:
        let _drawingOptions = defaultArg drawingOptions null
*)
-> bool 

Parameters

bitmapData  IReadWriteBitmapData

The IReadWriteBitmapData instance to draw on.

context  IAsyncContext

An IAsyncContext instance that contains information for asynchronous processing about the current operation.

pen  Pen

The Pen that determines the characteristics of the curves.

points  IEnumerablePoint

The points of the curves to draw.

drawingOptions  DrawingOptions  (Optional)

A DrawingOptions instance that specifies the drawing options to use. If , then the default options are used. This parameter is optional.
Default value: .

Return Value

Usage Note

In the points parameter 0 or odd number of points are expected.

When points has at least three items, the first three points define the first quadratic curve. Each additional two points define a new quadratic curve, where the last point of the previous curve is the starting point of the next curve.

This method draws quadratic Bézier curves. A quadratic Bézier curve is defined by three points: the starting point, the control point, and the end point. To draw cubic Bézier curves, you can use the DrawBeziers methods. In fact, this method transforms the quadratic curves into cubic Bézier curves internally.

This method tries to use a shortcut to draw the curves directly, which is faster than creating a Path and adding the curves to it. A shortcut is possible when the specified pen has a width between 0.25 and 1, it uses a solid Brush with an opaque color, and if drawingOptions is either , or its FastThinLines is enabled in drawingOptions, it specifies that no anti-aliasing and no alpha blending is required, the transformation is the identity matrix, and neither Quantizer nor Ditherer is specified.

When no shortcut can be used and the same curves are drawn repeatedly, creating a Path with PreferCaching enabled can provide a better performance.

This method blocks the caller thread, but if context belongs to an async top level method, then the execution may already run on a pool thread. Degree of parallelism, the ability of cancellation and reporting progress depend on how these were configured at the top level method. To reconfigure the degree of parallelism of an existing context, you can use the AsyncContextWrapper class.

Alternatively, you can use this method to specify the degree of parallelism for synchronous execution. For example, by passing AsyncHelper.SingleThreadContext to the context parameter the method will be forced to use a single thread only.

When reporting progress, this library always passes a DrawingOperation instance to the generic methods of the IAsyncProgress interface.

Reference