touch-bar-simulator/Touch Bar Simulator/ToolbarSlider.swift

import Cocoa
import Defaults

private final class ToolbarSliderCell: NSSliderCell {
	var fillColor: NSColor
	var borderColor: NSColor
	var shadow: NSShadow?

	init(fillColor: NSColor, borderColor: NSColor, shadow: NSShadow? = nil) {
		self.fillColor = fillColor
		self.borderColor = borderColor
		self.shadow = shadow
		super.init()
	}

	@available(*, unavailable)
	required init(coder: NSCoder) {
		fatalError("init(coder:) has not been implemented")
	}

	override func drawKnob(_ knobRect: CGRect) {
		var frame = knobRect.insetBy(dx: 0, dy: 6.5)
		if let shadow = self.shadow {
			// Make room on either side of the view for the shadow to spill into,
			// rather than clip on the edges.
			frame.origin.x *= ((barRect.width - shadow.shadowBlurRadius * 2) / barRect.width)
			frame.origin.x += shadow.shadowBlurRadius
		}

		// Make the slider grey.
		var greySliderFrame = barRect
		greySliderFrame.origin.x -= 1
		greySliderFrame.origin.y = barRect.origin.y + 1
		greySliderFrame.size.width = frame.origin.x
		greySliderFrame.size.height = 3
		let greySliderPath = NSBezierPath(roundedRect: greySliderFrame, xRadius: 1.5, yRadius: 1.5)
		NSColor.lightGray.setFill()
		greySliderPath.fill()

		NSGraphicsContext.saveGraphicsState()

		shadow?.set()

		// Circle
		let path = NSBezierPath(roundedRect: frame, xRadius: 4, yRadius: 12)
		fillColor.set()
		path.fill()

		// Border should not draw a shadow.
		NSShadow().set()

		// Border
		borderColor.set()
		path.lineWidth = 0.8
		path.stroke()

		NSGraphicsContext.restoreGraphicsState()
	}

	private var barRect = CGRect.zero

	override func drawBar(inside rect: CGRect, flipped: Bool) {
		barRect = rect

		// A knob shadow requires a small skew in the origin of the knob (see above),
		// which causes the knob to not go all the way to the ends of the bar.
		// Fix this by shortening the bar.
		if let shadow = self.shadow {
			barRect = barRect.insetBy(dx: shadow.shadowBlurRadius * 2, dy: 0)
		}

		super.drawBar(inside: barRect, flipped: flipped)
	}
}

extension NSSlider {
	// Redisplaying the slider prevents shadow artifacts that result
	// from moving a knob that draws a shadow
	// However, only do so if its value has changed, because if a
	// redisplay is attempted without a change, then the slider draws
	// itself brighter for some reason.
	func alwaysRedisplayOnValueChanged() -> Self {
		addAction { sender in
			if (Defaults[.windowTransparency] - sender.doubleValue) != 0 {
				sender.needsDisplay = true
			}
		}

		return self
	}
}

final class ToolbarSlider: NSSlider {
	override init(frame: CGRect) {
		super.init(frame: frame)

		let knobShadow = NSShadow()
		knobShadow.shadowColor = NSColor.black.withAlphaComponent(0.7)
		knobShadow.shadowOffset = CGSize(width: 0.8, height: -0.8)
		knobShadow.shadowBlurRadius = 5

		self.cell = ToolbarSliderCell(fillColor: .lightGray, borderColor: .black, shadow: knobShadow)
	}

	@available(*, unavailable)
	required init?(coder: NSCoder) {
		fatalError("init(coder:) has not been implemented")
	}
}

final class MenubarSlider: NSSlider {
	override init(frame: CGRect) {
		super.init(frame: frame)

		let knobShadow = NSShadow()
		knobShadow.shadowColor = NSColor.black.withAlphaComponent(0.6)
		knobShadow.shadowOffset = CGSize(width: 0.8, height: -0.8)
		knobShadow.shadowBlurRadius = 4

		self.cell = ToolbarSliderCell(fillColor: .controlTextColor, borderColor: .clear, shadow: knobShadow)
	}

	@available(*, unavailable)
	required init?(coder: NSCoder) {
		fatalError("init(coder:) has not been implemented")
	}
}