/*

 Copyright (C) 2017 Apple Inc. All Rights Reserved.

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Demonstrates Quartz line drawing facilities including stroke width, line cap and line join.

 */

import UIKit

class QuartzDashView: QuartzView {

    var dashPhase: CGFloat = 0.0 {

        didSet(prevPhaseValue) {

            if prevPhaseValue != dashPhase {

                setNeedsDisplay()

            }

        }

    }

    var dashPattern: [CGFloat] = [] {

        didSet(prevdashPattern) {

           // redraw if the contents of the array has changed

            if prevdashPattern.count != dashPattern.count {

                setNeedsDisplay()

            } else {

                for (index, value) in dashPattern.enumerated() {

                    if prevdashPattern[index] != value {

                        setNeedsDisplay()

                        break

                    }

                }

            }

        }

    }

    override func drawInContext(_ context: CGContext) {

        centerDrawing(inContext: context,  drawingExtent: CGRect(x:0.0, y:0.0, width:320.0, height:140.0))

        // Drawing lines with a white stroke color

        context.setStrokeColor(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

        // Each dash entry is a run-length in the current coordinate system

        // The concept is first you determine how many points in the current system you need to fill.

        // Then you start consuming that many pixels in the dash pattern for each element of the pattern.

        // So for example, if you have a dash pattern of {10, 10}, then you will draw 10 points, then skip 10 points, and repeat.

        // As another example if your dash pattern is {10, 20, 30}, then you draw 10 points, skip 20 points, draw 30 points,

        // skip 10 points, draw 20 points, skip 30 points, and repeat.

        // The dash phase factors into this by stating how many points into the dash pattern to skip.

        // So given a dash pattern of {10, 10} with a phase of 5, you would draw 5 points (since phase plus 5 yields 10 points),

        // then skip 10, draw 10, skip 10, draw 10, etc.

        context.setLineDash(phase: dashPhase, lengths: dashPattern)

        // Draw a horizontal line, vertical line, rectangle and circle for comparison

        context.move(to: CGPoint(x: 10.0, y: 30.0))

        context.addLine(to: CGPoint(x: 310.0, y: 20.0))

        context.move(to: CGPoint(x: 160.0, y: 30.0))

        context.addLine(to: CGPoint(x: 160.0, y: 130.0))

        context.addRect(CGRect(x:10.0, y:30.0, width:100.0, height:100.0))

        context.addEllipse(in: CGRect(x:210.0, y:30.0, width:100.0, height:100.0))

        // And width 2.0 so they are a bit more visible

        context.setLineWidth(2.0)

        context.strokePath()

    }

}