![]() ![]() Create a FingerPaintPolyline, set the initial point, and store itįingerPaintPolyline polyline = new FingerPaintPolyline This FingerPaintPolyline object is added to the InProgressPolylines dictionary using the Handle property of the UITouch object as a dictionary key: public override void TouchesBegan(NSSet touches, UIEvent evt)įoreach (UITouch touch in touches.Cast()) For each UITouch object, the method creates and initializes a new FingerPaintPolyline object, including storing the initial location of the finger obtained from the LocationInView method. The TouchesBegan overrides loop through these objects. Using (CGContext context = UIGraphics.GetCurrentContext())įoreach (FingerPaintPolyline polyline in completedPolylines)Ĭontext.SetLineWidth(polyline.StrokeWidth) Ĭontext.DrawPath(CGPathDrawingMode.Stroke) įoreach (FingerPaintPolyline polyline in inProgressPolylines.Values)Įach of the Touches overrides potentially reports the actions of multiple fingers, indicated by one or more UITouch objects stored in the touches argument to the method. The override draws the completed polylines and then the in-progress polylines: public override void Draw(CGRect rect) The various Touches overrides accumulate the points that make up the polylines. The objects in this List are in the same order that they were drawn.įingerPaintCanvasView overrides five methods defined by View: The FingerPaintCanvasView class also maintains a List object for the polylines that have been completed: List completedPolylines = new List() This dictionary allows the view to quickly obtain the FingerPaintPolyline information associated with each finger based on the Handle property of the UITouch object. That class maintains a dictionary of objects of type FingerPaintPolyline during the time that they are actively being drawn by one or more fingers: Dictionary inProgressPolylines = new Dictionary() The program defines a small FingerPaintPolyline class for this purpose: class FingerPaintPolylineĮach polyline has a color, a stroke width, and an iOS graphics CGPath object to accumulate and render multiple points of the line as it's being drawn.Īll the rest of the code shown below is contained in a UIView derivative named FingerPaintCanvasView. In the FingerPaint program, each finger stroke (from touch to release) is associated with an object that contains all the information necessary to render the line drawn with that finger. The dictionary value depends on the application. For an iOS program, the dictionary key is the Handle value that identifies a particular finger. Instead, it can use the Handle property of type IntPtr to uniquely identify these UITouch objects.Īlmost always, a program that tracks individual fingers maintains a dictionary for touch tracking. ![]() To keep track of fingers, a program should avoid storing this UITouch object directly. This object remains the same as the finger moves on the screen and then lifts from the screen, at which point the object is disposed. When a finger first touches the screen, iOS creates a UITouch object for that finger. As your program processes multiple touch events, it needs to distinguish between these fingers. You want the user to be able to draw with a single finger, but also to draw with multiple fingers at once. One typical application is a finger-paint program. There are times when a multi-touch application needs to track individual fingers as they move simultaneously on the screen. More coming soon! Please note touch is not supported on iPhone model 4S or older.This document demonstrates how to track touch events from multiple fingers Apple Pencil: Apple Pencil pressure & tilt control All Duet Display base app's gestures included Duet Pro (in-app subscriptions – $60.00 USD) – compatible with iPads only Remote Desktop Protocol (RDP) Toolbar – RDP extended only: 3-finger slide up/down to show/hide the RDP toolbar Hover: Long press with one finger + drag with other finger or Apple Pencil Here are the current supported interactions: Duet Air (in-app subscriptions – $48.00 USD) – compatible with iPads/iPhones only ![]() Duet is more powerful than a regular external monitor because it comes with touch support, so you can interact with OS X or Windows directly with your fingers. ![]()
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