/*

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

 See LICENSE.txt for this sample’s licensing information

 Abstract:

 Demonstrates using Quartz for drawing images.

 */

import UIKit

class QuartzImageView: QuartzView {

    static let image: CGImage = {

        let u = Bundle.main.url(forResource: "Demo", withExtension: "png")!

        let i = UIImage(contentsOfFile: u.path)!

        return i.cgImage!

    }()

    override func drawInContext(_ context: CGContext) {

        // spare out the width and height of the view for less typing below

        let w = bounds.size.width

        let h = bounds.size.height

        let img = QuartzImageView.image

        // Note: The images are actually drawn upside down because Quartz image drawing expects

        // the coordinate system to have the origin in the lower-left corner, but a UIView

        // puts the origin in the upper-left corner. For the sake of brevity (and because

        // it likely would go unnoticed for the image used) this is not addressed here.

        // For the demonstration of PDF drawing however, it is addressed, as it would definitely

        // be noticed, and one method of addressing it is shown there.

        // draw the image centered in the top part of the view

        var imageRect = CGRect(x: (w-CGFloat(img.width))/2.0, y: ((80.0+h*0.20)-CGFloat(img.height))/2.0, width: CGFloat(img.width), height: CGFloat(img.height))

        context.draw(img, in: imageRect)

        // Tile the same image in the bottom part of the view

        // CGContextDrawTiledImage() will fill the entire clipping area with the image, so to avoid

        // filling the entire view, we'll clip the view to the rect below inset by 20%. This rect extends

        // past the region of the view, but since the view's rectangle has already been applied as a clip

        // to our drawing area, it will be intersected with this rect to form the final clipping area

        context.clip(to: CGRect(x: 0.0, y: 80.0, width: w, height: h).insetBy(dx: w*0.20, dy: h*0.20))

        // The origin of the image rect works similarly to the phase parameter for SetLineDash and

        // SetPatternPhase and specifies where in the coordinate system the "first" image is drawn.

        // The size (previously set to 64x64) specifies the size the image is scaled to before being tiled.

        imageRect.origin = CGPoint(x: 32.0, y: 112.0)

        context.draw(img, in: imageRect, byTiling: true)

        // Drawing lines with a white stroke color

        // Draw them with a 2.0 stroke width so they are a bit more visible.

        context.setLineWidth(2.0)

        // Highlight the "first" image from the DrawTiledImage call.

        context.setFillColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 0.5)

        context.fill(imageRect)

        // And stroke the clipped area

        context.setLineWidth(3.0)

        context.setStrokeColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0)

        context.stroke(context.boundingBoxOfClipPath)

    }

}