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The SCIFreehandDrawingAnnotation

he SCIFreehandDrawingAnnotation allows for freehand drawing directly on the chart surface by capturing a sequence of points that form a continuous brush stroke.

Freehand Drawing Annotation

NOTE: Examples of the Annotations usage can be found in the SciChart iOS Examples Suite as well as on GitHub:

A SCIFreehandDrawingAnnotation is a multi-point annotation that stores a collection of points to represent a freehand path drawn by the user.

The SCIFreehandDrawingAnnotation can be configured using the properties and method listed in the table below:

Field Description
SCIFreehandDrawingAnnotation.stroke Defines the stroke style (color and thickness) of the pen.
SCIFreehandDrawingAnnotation.drawId A unique identifier for the annotation instance.
SCIFreehandDrawingAnnotation.selectionOffset Extra padding applied around the selection bounds.

To learn more about Pens and Brushes and how to utilize them, please refer to the SCIPenStyle, SCIBrushStyle article.

NOTE: To learn more about Annotations in general - please see the [Common Annotation Features](Annotations APIs.html#common-annotations-features) article.

Adding Points

Points for a SCIFreehandDrawingAnnotation are defined sequentially using the [appendPointWithX:y:] method, which appends each new coordinate to the existing path to form a continuous freehand stroke. The clearPoints method can be used to remove all previously added points, resetting the annotation so that it no longer renders until new points are appended.

NOTE: The xAxisId and yAxisId must be supplied if you have axis with non-default Axis Ids, e.g. in multi-axis scenario.

Create a FreehandDrawingAnnotation

A SCIFreehandDrawingAnnotation can be added onto a chart using the following code:

OBJECTIVE-C SWIFT
// Assume a surface has been created and configured somewhere id surface;

SCIFreehandDrawingAnnotation *freehandDrawing = [SCIFreehandDrawingAnnotation new];

// Append points for the path [freehandDrawing appendPointWithX:@(224) y:@(11000)]; [freehandDrawing appendPointWithX:@(250) y:@(12000)]; [freehandDrawing appendPointWithX:@(220) y:@(11400)]; [freehandDrawing appendPointWithX:@(224) y:@(11000)];

// Customize appearance freehandDrawing.stroke = [[SCISolidPenStyle alloc] initWithColorCode:0xFFFF0000 thickness:3];

// Enable interaction freehandDrawing.isEditable = YES;

// Add to chart surface [surface.annotations add: freehandDrawing];

// Assume a surface has been created and configured somewhere let surface: ISCIChartSurface

let freehandDrawing = SCIFreehandDrawingAnnotation()

// Append points for the path freehandDrawing.appendPointWith(x: NSNumber(value: 224), y: NSNumber(value: 11000)) freehandDrawing.appendPointWith(x: NSNumber(value: 250), y: NSNumber(value: 12000)) freehandDrawing.appendPointWith(x: NSNumber(value: 220), y: NSNumber(value: 11400)) freehandDrawing.appendPointWith(x: NSNumber(value: 224), y: NSNumber(value: 11000))

// Customize appearance freehandDrawing.stroke = SCISolidPenStyle(color: SCIColor.red, thickness: 3)

// Enable interaction freehandDrawing.isEditable = true

// Add to chart surface surface.annotations.add(freehandDrawing)

NOTE: For interactive creation of SCIFreehandDrawingAnnotation, use the corresponding annotation creation modifier SCIFreehandDrawingModifier available in SciChart iOS.

NOTE: To learn more about other Annotation Types, available out of the box in SciChart, please find the comprehensive list in the [Annotation APIs](Annotations APIs.html) article.