/*

    Copyright (C) 2015 Apple Inc. All Rights Reserved.

    See LICENSE.txt for this sample’s licensing information

    Abstract:

    `UIPrintPageRenderer` subclass for drawing an image for print.

*/

import UIKit

/// A `UIPrintPageRenderer` subclass to print an image.

class CustomAssetPrintPageRenderer: UIPrintPageRenderer {

    // MARK: Properties

    var image: UIImage

    // MARK: Initilization

    init(image: UIImage) {

        self.image = image

    }

    // MARK: UIPrintPageRenderer Overrides

    override func numberOfPages() -> Int {

        return 1

    }

    override func drawPageAtIndex(pageIndex: Int, inRect printableRect: CGRect) {

        /*

            When `drawPageAtIndex(_:inRect:)` is invoked, `paperRect` reflects the

            size of the paper we are printing on and `printableRect` reflects the

            rectangle describing the imageable area of the page, that is the portion

            of the page that the printer can mark without clipping.

        */

        let paperSize = paperRect.size

        let imageableAreaSize = printableRect.size

        /*

            If `paperRect` and `printableRect` are the same size, the sheet is

            borderless and we will use the fill algorithm. Otherwise we will uniformly

            scale the image to fit the imageable area as close as is possible without

            clipping.

        */

        let fillsSheet = paperSize == imageableAreaSize

        let imageSize = image.size

        let destinationRect: CGRect

        if fillsSheet {

            destinationRect = CGRect(origin: .zero, size: paperSize)

        }

        else {

            destinationRect = printableRect

        }

        /*

            Calculate the ratios of the destination rectangle width and height to

            the image width and height.

        */

        let widthScale = destinationRect.width / imageSize.width

        let heightScale = destinationRect.height / imageSize.height

        // Scale the image to have some padding within the page.

        let scale: CGFloat

        if fillsSheet {

            // Produce a fill to the entire sheet and clips content.

            scale = (widthScale > heightScale ? widthScale : heightScale)

        }

        else {

            // Show all the content at the expense of additional white space.

            scale = (widthScale < heightScale ? widthScale : heightScale)

        }

        /*

            Compute the coordinates for `centeredDestinationRect` so that the scaled

            image is centered on the sheet.

        */

        let printOriginX = (paperSize.width - imageSize.width * scale) / 2

        let printOriginY = (paperSize.height - imageSize.height * scale) / 2

        let printWidth = imageSize.width * scale

        let printHeight = imageSize.height * scale

        let printRect = CGRect(x: printOriginX, y: printOriginY, width: printWidth, height: printHeight)

        // Inset the printed image by 10% of the size of the image.

        let inset = max(printRect.width, printRect.height) * 0.1

        let insettedPrintRect = printRect.insetBy(dx: inset, dy: inset)

        // Create the vignette clipping.

        let context = UIGraphicsGetCurrentContext()!

        CGContextAddEllipseInRect(context, insettedPrintRect)

        CGContextClip(context)

        image.drawInRect(insettedPrintRect)

    }

}