Xamarin.iOS应用程序中的手指绘图（C＃）

我做了一个应用程序，用户可以用手指画出一些东西……我不知道我怎么能做到这一点……

经过研究，我找到了下面的代码。

但是使用这段代码我只能画一行。 如果我触摸结束并且新触摸事件开始，则该线继续此点…旧线路自动连接到新线路。

所以我想在每次触摸时创建一个新的线。

有人知道这是如何工作的吗？

码

CGPath path; CGPoint initialPoint; CGPoint latestPoint; public DrawView (IntPtr handle) : base (handle) { BackgroundColor = UIColor.White; path = new CGPath(); } public override void TouchesBegan(NSSet touches, UIEvent evt) { base.TouchesBegan(touches, evt); UITouch touch = touches.AnyObject as UITouch; if (touch != null) { initialPoint = touch.LocationInView(this); } } public override void TouchesMoved(NSSet touches, UIEvent evt) { base.TouchesMoved(touches, evt); UITouch touch = touches.AnyObject as UITouch; if (touch != null) { latestPoint = touch.LocationInView(this); SetNeedsDisplay(); } } public override void Draw(CGRect rect) { base.Draw(rect); if (!initialPoint.IsEmpty) { //get graphics context using (CGContext g = UIGraphics.GetCurrentContext()) { //set up drawing attributes g.SetLineWidth(2); UIColor.Black.SetStroke(); //add lines to the touch points if (path.IsEmpty) { path.AddLines(new CGPoint[] { initialPoint, latestPoint }); } else { path.AddLineToPoint(latestPoint); } //add geometry to graphics context and draw it g.AddPath(path); g.DrawPath(CGPathDrawingMode.Stroke); } } } 

Answer 1

您可以创建一个额外的CGPath来记录路径并使用CGContext绘制它们

代码：

 public partial class DrawLine : UIView { CGPath pathtotal; CGPath path; CGPoint initialPoint; CGPoint latestPoint; public DrawLine(IntPtr handle) : base(handle) { BackgroundColor = UIColor.White; pathtotal = new CGPath(); } public override void TouchesBegan(NSSet touches, UIEvent evt) { base.TouchesBegan(touches, evt); path = new CGPath(); UITouch touch = touches.AnyObject as UITouch; if (touch != null) { initialPoint = touch.LocationInView(this); } } public override void TouchesMoved(NSSet touches, UIEvent evt) { base.TouchesMoved(touches, evt); UITouch touch = touches.AnyObject as UITouch; if (touch != null) { latestPoint = touch.LocationInView(this); SetNeedsDisplay(); } } public override void Draw(CGRect rect) { base.Draw(rect); if (!initialPoint.IsEmpty) { //get graphics context using (CGContext g = UIGraphics.GetCurrentContext()) { //set up drawing attributes g.SetLineWidth(2); UIColor.Black.SetStroke(); //add lines to the touch points if (path.IsEmpty) { path.AddLines(new CGPoint[] { initialPoint, latestPoint }); } else { path.AddLineToPoint(latestPoint); } //add geometry to graphics context and draw it pathtotal.AddPath(path); g.AddPath(pathtotal); g.DrawPath(CGPathDrawingMode.Stroke); } } } } 

测试结果：