It seems PKCanvasView overrides the property UIScrollViewDelegate which inherits from the UIScrollView to PKCanvasViewDelegate. And does not provide access to UIScrollViewDelegate.
In order to implement zooming, so I added a PKCanvasView into my own UIScrollView. And implemented delegate method viewForZooming in which return PKCanvasView.
But all drawing in PKCanvasView was blurred when zooming or scale. How to re-render drawing after zoom to make it has reasonable stroke width and clear ?
Some related code:
let canvasView = PKCanvasView()
let scrollView = UIScrollView()
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(scrollView)
scrollView.addSubview(canvasView)
scrollView.delegate = self
scrollView.minimumZoomScale = 0.5
scrollView.maximumZoomScale = 2.5
}
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
return canvasView
}
Some solutions I had tried:
1: Reset PKCanvasView contentScaleFactor
func scrollViewDidEndZooming(_ scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
if let canvas = view {
let contentScale = scale * UIScreen.main.scale
canvas.contentScaleFactor = contentScale
}
}
Not worked!
2: Re-render PKStroke:
func reRender(_ scale: CGFloat) {
let newStrokeWidth = strokeWidth * scale
var newDrawingStrokes: [PKStroke] = []
for stroke in canvasView.drawing.strokes {
canvasView.tool = PKInkingTool(.pen, color: .red, width: newStrokeWidth)
var newPoints = [PKStrokePoint]()
stroke.path.forEach { (point) in
let newPoint = PKStrokePoint(location: point.location,
timeOffset: point.timeOffset,
size: CGSize(width: newStrokeWidth, height: newStrokeWidth),
opacity: CGFloat(1), force: point.force,
azimuth: point.azimuth, altitude: point.altitude)
newPoints.append(newPoint)
}
let newPath = PKStrokePath(controlPoints: newPoints, creationDate: Date())
let newStroke = PKStroke(ink: PKInk(.pen, color: UIColor.red), path: newPath)
newDrawingStrokes.append(newStroke)
}
let newDrawing = PKDrawing(strokes: newDrawingStrokes)
canvasView.drawing = newDrawing
}
Not worked! Still blurred, just changed strokeWidth by multiply scale.
3: I try to reset PKDrawing or PKStroke transform by using scrollView scale. Then PKDrawing position disordered and it was still blurred.
Please help me.
