Marek H Marek H - 1 year ago 93
Swift Question

What is the difference between NSRectFill and NSBezierPath(rect).fill

I know I can fill a rect using NSRectFill(bounds). However I wanted to preserve transparency for PDF output and I discovered that I can do that only with NSBezierPath(rect: bounds).fill()
What is the difference (behind the scenes) of those two?

func drawBackground() {
if (NSGraphicsContext.currentContextDrawingToScreen()) {
NSColor(patternImage: checkerboardImage).set()
NSRectFillUsingOperation(bounds, NSCompositingOperation.CompositeSourceOver)
//NSRectFill(bounds) //option 1
NSBezierPath(rect: bounds).fill() // option 2

extension NSImage {

static func checkerboardImageWithSize(size : CGFloat) -> NSImage {
let fullRect = NSRect(x: 0, y: 0, width: size, height: size)
let halfSize : CGFloat = size * 0.5;
let upperSquareRect = NSRect(x: 0, y: 0, width: halfSize, height: halfSize);
let bottomSquareRect = NSRect(x: halfSize, y: halfSize, width:halfSize, height: halfSize);
let image = NSImage(size: NSSize(width: size, height: size))
NSColor(deviceWhite: 0.0, alpha:0.1).set()
return image

Answer Source

I'm mostly an iOS programmer and not very fluent these days over on the AppKit side of things, but my guess is that you're getting the wrong NSCompositingOperation. I see from the docs that NSRectFill uses NSCompositeCopy. Perhaps it would work better if you used NSRectFillUsingOperation, where you get to specify the compositing operation.