绘制采用核芯显卡
2023-04-18 12:52:46 时间
我想让用户绘制一个矩形上UIImageView
我加了两个变量为先的最后触摸位置 我添加了这个功能上的UIImageView矩形: -绘制采用核芯显卡
func draw(from: CGPoint, to: CGPoint) {
UIGraphicsBeginImageContext(imageView.frame.size)
context = UIGraphicsGetCurrentContext()
context?.setStrokeColor(UIColor(red: 0, green: 0, blue: 0, alpha: 1.0).cgColor)
context?.setLineWidth(5.0)
let currentRect = CGRect(x: from.x,
y: from.y,
width: to.x - from.x,
height: to.y - from.y)
context?.addRect(currentRect)
context?.drawPath(using: .stroke)
context?.strokePath()
imageView.image?.draw(in: self.imageView.frame)
imageView.image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
}
我添加该方法(touchMoved
)它吸引许多矩形
我的方法添加到(touchEnded
)它绘制一个,但是当用户移动触摸它不会出现
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
firstTouchLocation = touch.location(in: self.view)
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
lastTouchLocation = touch.location(in: self.view)
draw(from: firstTouchLocation, to: lastTouchLocation)
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
if let touch = touches.first {
lastTouchLocation = touch.location(in: self.view)
draw(from: firstTouchLocation, to: lastTouchLocation)
}
}
我希望让用户扩展矩形时touchMoved
并绘制touchEnded
时。
Mohmed Showekh
回答
您正在用以前的image
加上一个矩形绘制的新图像替换您的image
。不是从图像视图中绘制图像,而是绘制原始图像。
或者,可以使矩形的形状图层,只是更新形状图层的路径:
class ViewController: UIViewController {
@IBOutlet weak var imageView: UIImageView!
private let shapeLayer: CAShapeLayer = {
let _shapeLayer = CAShapeLayer()
_shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
_shapeLayer.strokeColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1).cgColor
_shapeLayer.lineWidth = 3
return _shapeLayer
}()
private var startPoint: CGPoint!
override func viewDidLoad() {
super.viewDidLoad()
imageView.layer.addSublayer(shapeLayer)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
startPoint = touches.first?.location(in: imageView)
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
guard let startPoint = startPoint, let touch = touches.first else { return }
let point: CGPoint
if let predictedTouch = event?.predictedTouches(for: touch)?.last {
point = predictedTouch.location(in: imageView)
} else {
point = touch.location(in: imageView)
}
updatePath(from: startPoint, to: point)
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
guard let startPoint = startPoint, let touch = touches.first else { return }
let point = touch.location(in: imageView)
updatePath(from: startPoint, to: point)
imageView.image = imageView.snapshot(afterScreenUpdates: true)
shapeLayer.path = nil
}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
shapeLayer.path = nil
}
private func updatePath(from startPoint: CGPoint, to point: CGPoint) {
let size = CGSize(width: point.x - startPoint.x, height: point.y - startPoint.y)
let rect = CGRect(origin: startPoint, size: size)
shapeLayer.path = UIBezierPath(rect: rect).cgPath
}
}
绘制采用核芯显卡
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