How to fill the right bottom corner of NSScrollView?

Question

I want to change its color, but I'm not sure wether to subclass NSScrollView or NSClipView. Or if the corner can be inserted as a regular NSView.

_{(source: flickr.com)}

I don't need code. Just a hint at how to do it.

Answer 1

Already answered elsewhere on stackoverflow by mekentosj. The class to subclass is NSScrollView.

@interface MyScrollView : NSScrollView {
}
@end


@implementation MyScrollView

- (void)drawRect:(NSRect)rect{
    [super drawRect: rect];

    if([self hasVerticalScroller] && [self hasHorizontalScroller]){
        NSRect vframe = [[self verticalScroller]frame];
        NSRect hframe = [[self horizontalScroller]frame];
        NSRect corner;
        corner.origin.x = NSMaxX(hframe);
        corner.origin.y = NSMinY(hframe);
        corner.size.width = NSWidth(vframe);
        corner.size.height = NSHeight(hframe);

        // your custom drawing in the corner rect here
        [[NSColor redColor] set];
        NSRectFill(corner);
    }
}
@end

Answer 2

Kind of odd but just subclassing NSScrollView and overriding draw with super.drawRect() made my NSScrollView (not) fill in that corner with white. I tested it 2x to make sure, since it doesn't make much sense.

import Cocoa

class ThemedScrollView: NSScrollView {
    override func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)
    }
}

Here's a Swift variation of the original answer as well:

import Cocoa

class ThemedScrollView: NSScrollView {

    override func drawRect(dirtyRect: NSRect) {
        super.drawRect(dirtyRect)

        if hasVerticalScroller && hasHorizontalScroller {
            guard verticalScroller != nil && horizontalScroller != nil else { return }

            let vFrame = verticalScroller!.frame
            let hFrame = horizontalScroller!.frame
            let square = NSRect(origin: CGPoint(x: hFrame.maxX, y: vFrame.maxY), size: CGSize(width: vFrame.width, height: hFrame.height))

            let path = NSBezierPath(rect: square)
            let fillColor = NSColor.redColor()
            fillColor.set()
            path.fill()
        }
    }
}

Answer 3

Updated Swift 5.2 version of Austin's answer

class Themed: NSScrollView {

    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)

        if hasVerticalScroller && hasHorizontalScroller {
            guard verticalScroller != nil && horizontalScroller != nil else { return }

            let vFrame = verticalScroller!.frame
            let hFrame = horizontalScroller!.frame
            let square = NSRect(origin: CGPoint(x: hFrame.maxX, y: vFrame.maxY), size: CGSize(width: vFrame.width, height: hFrame.height))

            let path = NSBezierPath(rect: square)
            let fillColor = NSColor.red
            fillColor.set()
            path.fill()
        }
    }
}