如何调整正在打印的图像的大小？

Question

我正在尝试打印 Swift 生成的 QR 码，当我打印它时它占用了整张纸我想调整图像大小并使其更小。大约 200 像素 x 200 像素

我尝试过使用不同的 UIImage 调整大小功能，但结果仍然相同。我还尝试使用 printController 调整图像大小

func printImage(img:UIImage) {
    let printController = UIPrintInteractionController.shared

    let printInfo = UIPrintInfo(dictionary:nil)
    printInfo.jobName = "Printing \(myTextField.text) 's QR code"
    printInfo.outputType = .photoGrayscale
    self.resizeImage(img, targetSize: CGSizeMake(200.0, 200.0))

    printController.printInfo = printInfo



    printController.printingItem = img

    printController.present(animated: true) { (_, isPrinted, error) in
        if error == nil {
            if isPrinted {
                print("QR Code Has Been Printed :)")
            } else {
                print("QR Code Not Printed")
            }

        }
    }
} 

func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size

let widthRatio  = targetSize.width  / size.width
let heightRatio = targetSize.height / size.height

// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
    newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio)
} else {
    newSize = CGSizeMake(size.width * widthRatio,  size.height * widthRatio)
}

// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRectMake(0, 0, newSize.width, newSize.height)

// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.drawInRect(rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

return newImage
}

我期待一个小的 QR 码 Aprox 200 像素 x 200 像素。我目前正在获取 A4 尺寸的二维码

Answer 1

由于方法resizeImage 返回新的UIImage，您需要存储结果

self.resizeImage(img, targetSize: CGSizeMake(200.0, 200.0))

在另一个对象中，例如：

let resizedImage = self.resizeImage(img, targetSize: CGSizeMake(200.0, 200.0))

现在您可以使用此resizedImage 图像进行打印，例如：

printController.printingItem = resizedImage

希望这会有所帮助。

编辑：

以下是更新代码：

func printImage(img:UIImage) {

    let printController = UIPrintInteractionController.shared

    let printInfo = UIPrintInfo(dictionary:nil)
    printInfo.jobName = "Printing 's QR code"
    printInfo.outputType = .photoGrayscale

    if let resizedImage = self.resizeImage(image: img, targetSize: CGSize(width: 200, height: 200)) {

        printController.printInfo = printInfo
        printController.printingItem = resizedImage

        printController.present(animated: true) { (_, isPrinted, error) in
            if error == nil {
                if isPrinted {
                    print("QR Code Has Been Printed :)")
                } else {
                    print("QR Code Not Printed")
                }
            }
        }
    }
}

func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage? {

    let size = image.size
    let widthRatio  = targetSize.width  / size.width
    let heightRatio = targetSize.height / size.height

    // Figure out what our orientation is, and use that to form the rectangle
    var newSize: CGSize
    if(widthRatio > heightRatio) {
        newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
    } else {
        newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
    }

    // This is the rect that we've calculated out and this is what is actually used below
    let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)

    // Actually do the resizing to the rect using the ImageContext stuff
    UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
    image.draw(in: rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return newImage
}