CODEWITHSUNDEEP
swiftmacosdrawingnsviewnsbezierpath
l30c0d35
l30c0d35

Reputation: 807

Swift: NSBezier

This is the code inside my custom view class:

func drawTestingPoint(_ point: CGPoint, target: Int, output: Int) {
    let path = NSBezierPath()
    path.appendArc(withCenter: point, radius: 5, startAngle: 0, endAngle: 360)
    NSColor.black.setStroke()
    if target == output {
        NSColor.green.setFill()
    } else {
        NSColor.red.setFill()
    }
    path.lineWidth = 3
    path.fill()
    path.stroke()
}

override func draw(_ dirtyRect: NSRect) {
    //If I call the drawTestingPoint function here it works
}

Inside my viewDidLoad method in my NSViewController class I set up the custom view and try to draw the testing point:

let size = getDataViewSize()
let origin = CGPoint(x: view.frame.width/2-size.width/2, y: view.frame.height/2-size.height/2)
dataView = DataView(frame: CGRect(origin: origin, size: size))
view.addSubview(dataView)
dataView.drawTestingPoint(CGPoint(x: view.frame.width/2 y: view.frame.height/2), target: target, output: output)
dataView.needsDisplay = true

My problem is that no point is getting drawn. I think there can't be anything wrong with my drawTestingPoint function because when I call it inside my draw(_ dirtyRect: NSRect) function in my custom NSView class, it works. What can I do so I can call this function inside my viewDidLoad function how you can see in the codes snippets above so my point gets drawn

Upvotes: 0

Views: 212

Answers (1)

Duncan C
Duncan C

Reputation: 131398

You can't just draw any time you want. Normally you set up a view and implement draw(_:) as you've done. The system calls the draw method when it needs the view to draw its contents. Before calling your draw(_:) method it sets up the drawing context correctly to draw inside your view and clip if you draw outside of the view. That's the bit you're missing.

As a general rule you should NOT draw outside of the view's draw(_:) method. I've done drawing outside of the draw(_:) method so infrequently that I don't remember what you'd need to do to set up the drawing context correctly. (To be fair I do mostly iOS development these days and my MacOS is getting rusty.)

So the short answer is "Don't do that."

EDIT:

Instead, set up your custom view to save the information it needs to draw itself. As others have suggested, when you make changes to the view, set needsDisplay=true on the view. That will cause the system to call the view's draw(_:) method on the next pass through the event loop

Upvotes: 1

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