MTMR/MTMR/CustomSlider.swift

//
//  CustomSlider.swift
//  MTMR
//
//  Created by Anton Palgunov on 15/04/2018.
//  Copyright © 2018 Anton Palgunov. All rights reserved.
//

import Foundation

class CustomSliderCell: NSSliderCell {
    var knobImage: NSImage!
    private var _currentKnobRect: NSRect!
    private var _barRect: NSRect!

    required init(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    override init() {
        super.init()
    }

    init(knob: NSImage?) {
        knobImage = knob
        super.init()
    }

    override func drawKnob(_ knobRect: NSRect) {
        if knobImage == nil {
            super.drawKnob(knobRect)
            return
        }

        _currentKnobRect = knobRect
        drawBar(inside: _barRect, flipped: true)

        let x = (knobRect.origin.x * (_barRect.size.width - (knobImage.size.width - knobRect.size.width)) / _barRect.size.width) + 1
        let y = knobRect.origin.y + 3

        knobImage.draw(
            at: NSPoint(x: x, y: y),
            from: NSZeroRect,
            operation: NSCompositingOperation.sourceOver,
            fraction: 1
        )
    }

    override func drawBar(inside aRect: NSRect, flipped _: Bool) {
        _barRect = aRect

        let barRadius = CGFloat(2)

        var bgRect = aRect
        bgRect.size.height = CGFloat(4)

        let bg = NSBezierPath(roundedRect: bgRect, xRadius: barRadius, yRadius: barRadius)
        NSColor.lightGray.setFill()
        bg.fill()

        var activeRect = bgRect

        activeRect.size.width = CGFloat((Double(bgRect.size.width) / (maxValue - minValue)) * doubleValue)
        let active = NSBezierPath(roundedRect: activeRect, xRadius: barRadius, yRadius: barRadius)
        NSColor.darkGray.setFill()
        active.fill()
    }
}

class CustomSlider: NSSlider {
    var currentValue: CGFloat = 0

    override func setNeedsDisplay(_ invalidRect: NSRect) {
        super.setNeedsDisplay(invalidRect)
    }

    override func awakeFromNib() {
        super.awakeFromNib()
        if (cell?.isKind(of: CustomSliderCell.self)) == false {
            let cell: CustomSliderCell = CustomSliderCell()
            self.cell = cell
        }
    }

    convenience init(knob: NSImage) {
        self.init()
        cell = CustomSliderCell(knob: knob)
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }

    override init(frame frameRect: NSRect) {
        super.init(frame: frameRect)
    }

    func knobImage() -> NSImage {
        let cell = self.cell as! CustomSliderCell
        return cell.knobImage
    }

    func setKnobImage(image: NSImage) {
        let cell = self.cell as! CustomSliderCell
        cell.knobImage = image
    }
}