I'm trying to put together a simple drawing app using PencilKit. However, when I zoom in on the canvas, I'd like the stroke to be thinner (visually the same size on the screen as it was before zooming in, but once I zoom all the way out, the result would be thinner). Moreover, I'd like the strokes to be always uniform, which means not change its size based on speed/timing of stroke, angle, etc. A simple scribbling pad. I have a fully working drawing canvas already, but I can't make those extra requirements work. Here's what I tried:
Conformed to PKCanvasViewDelegate and implemented canvasViewDidEndUsingTool. There, I added my code to customize the strokes, for instance this snippet that transforms everything to have a uniform 5x5 stroke:
func canvasViewDidEndUsingTool(_ canvasView: PKCanvasView) {
dump(canvasView.drawing.strokes.count)
var newDrawingStrokes = [PKStroke]()
for stroke in canvasView.drawing.strokes {
var newPoints = [PKStrokePoint]()
stroke.path.forEach { (point) in
let newPoint = PKStrokePoint(
location: point.location,
timeOffset: point.timeOffset,
size: CGSize(width: 5,height: 5),
opacity: CGFloat(1),
force: point.force,
azimuth: point.azimuth,
altitude: point.altitude
)
newPoints.append(newPoint)
}
let newPath = PKStrokePath(controlPoints: newPoints, creationDate: Date())
newDrawingStrokes.append(PKStroke(ink: PKInk(.pen, color: .white), path: newPath))
}
let newDrawing = PKDrawing(strokes: newDrawingStrokes)
canvasView.drawing = newDrawing
}
This delegate gets called when I finish drawing a stroke on the canvas. However, upon invoking the canvasView.drawing = newDrawing on the last line, I get this log on the console:
[] Drawing count mismatch!
And the stroke I just drew disappears.
I don't know what's wrong with this since my snippet simply iterates over the existing strokes, modify them, and set them again on the drawing. I found no documentation around this and Google earned 0 results for this error/warning message.
Appreciate any help.
