NSWindow scaled drawing in contentView - swift

Question

I'm creating a bare-bones window programmatically and I just need to draw some lines in its content view. The size of the area the lines fall in (worldBounds) needs to be scaled down and I assume I need the contentView bounds origin to be the same as worldBounds origin so it can draw everything. The approach is to set the frame to 1/8 the size, then use setBoundsOrigin and setBoundsSize on the contentView, which I understand scales the coordinate system.
The problem is no drawing appears. The window appears with the correct size. I have a function drawTestLines set up just to test it. If I remove the calls to setBounds, everything draws fine, but of course then the bounds don't match worldBounds. Any help is much appreciated!
var worldBounds = NSRect()
let scale: CGFloat = 0.125
func drawMap() {
boundLineStore(lineStore, &worldBounds)
worldBounds.origin.x -= 8
worldBounds.origin.y -= 8
worldBounds.size.width += 16
worldBounds.size.height += 16
if !draw {
return
}
let scaled = NSRect(x: 300.0, // to set the window size/position
y: 80,
width: worldBounds.size.width*scale, // 575
height: worldBounds.size.height*scale) // 355
window = NSWindow(contentRect: scaled,
styleMask: .titled,
backing: .buffered,
defer: false)
window.display()
window.orderFront(nil)
window.contentView!.setBoundsSize(worldBounds.size) // (4593, 2833)
window.contentView!.setBoundsOrigin(worldBounds.origin) // (-776, -4872)
// Draw map lines
window.contentView!.lockFocus()
drawTestLines(in: window.contentView!)
window.contentView!.unlockFocus()
}
// for testing
func drawTestLines(in view: NSView) {
let bottom = view.bounds.minY
let top = view.bounds.maxY
let left = view.bounds.minX
let right = view.bounds.maxX
NSColor.black.setStroke()
for i in Int(left)..<Int(right) { // draw vertical lines across the view just to see if it works!
if i%64 == 0 {
NSBezierPath.strokeLine(from: NSPoint(x: CGFloat(i), y: bottom), to: NSPoint(x: CGFloat(i), y: top))
}
}
NSBezierPath.strokeLine(from: NSPoint(x: left, y: bottom), to: NSPoint(x: right, y: top))
NSBezierPath.strokeLine(from: NSPoint.zero, to: NSPoint(x: 50.0, y: 50.0))
}

Answer 1

Experiment: Create a new Xcode project. Change applicationDidFinishLaunching:
func applicationDidFinishLaunching(_ aNotification: Notification) {
if let contentBounds = window.contentView?.bounds {
let scale: CGFloat = 0.5
let worldBounds = CGRect(x: 0.0, y: 0.0, width: contentBounds.size.width * scale, height: contentBounds.size.height * scale)
window.contentView!.bounds = worldBounds
}
}
Change the class of the content view of the window in IB to MyView. Add a new class MyView, subclass of NSView. Change draw to:
override func draw(_ dirtyRect: NSRect) {
super.draw(dirtyRect)
let bottom = self.bounds.minY
let top = self.bounds.maxY
let left = self.bounds.minX
let right = self.bounds.maxX
NSColor.black.setStroke()
for i in Int(left)..<Int(right) { // draw vertical lines across the view just to see if it works!
if i%64 == 0 {
NSBezierPath.strokeLine(from: NSPoint(x: CGFloat(i), y: bottom), to: NSPoint(x: CGFloat(i), y: top))
}
}
NSBezierPath.strokeLine(from: NSPoint(x: left, y: bottom), to: NSPoint(x: right, y: top))
NSBezierPath.strokeLine(from: NSPoint.zero, to: NSPoint(x: 50.0, y: 50.0))
}
See what happens when you change scale or the origin of worldBounds.