Custom NSTextView Insertion Point

TextView.md

Custom NSTextView Insertion Point

While making the default insertion caret pop a little wider for better accessibility, I ran into an issue where the insertion point ghosted on arrow key presses. Christian Tietze observed the same issue.

My culprit was settings an x offset for the rect inside drawInsertionPoint. While Christian's blog code doesn't include an offset, there's otherwise no difference in our approach.

Below draws wider insertion caret with rounded corners.

class FatRoundInsertionCaretTextView: NSTextView {

    var caretWidth: CGFloat = 3
    var caretColor = NSColor.systemOrange
    
    private lazy var radius = caretWidth / 2
    private lazy var displayAdjustment = caretWidth - 1

        open override func drawInsertionPoint(in rect: NSRect, color: NSColor, turnedOn flag: Bool) {
            
            var rect = rect
            rect.size.width = caretWidth

            let path = NSBezierPath(roundedRect: rect,
                                    xRadius: radius,
                                    yRadius: radius)
            path.setClip()

            super.drawInsertionPoint(in: rect,
                                     color: caretColor,
                                     turnedOn: flag)
        }

        open override func setNeedsDisplay(_ rect: NSRect, avoidAdditionalLayout flag: Bool) {
            var rect = rect
            rect.size.width += displayAdjustment
            super.setNeedsDisplay(rect, avoidAdditionalLayout: flag)
        }
}

thank you very much! This helped me with my small note taking app project :)

Thank you 🙏