iOS 7 Core Image QR Code 生成太模糊

Question

这是我生成二维码图片的代码

+ (UIImage *)generateQRCodeWithString:(NSString *)string {
    NSData *stringData = [string dataUsingEncoding:NSUTF8StringEncoding];
    CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [filter setValue:stringData forKey:@"inputMessage"];
    [filter setValue:@"M" forKey:@"inputCorrectionLevel"];
    return [UIImage imageWithCIImage:filter.outputImage];
}

结果太模糊了。是否可以设置生成的二维码的大小？

Answer 1

我正要开始悬赏这个问题，但我找到了答案。

您需要的是一个比例过滤器。要使用 CoreImage 实现这一点，您需要执行以下操作：

CIImage *input = [CIImage imageWithCGImage: ImageView.Image.CGImage]; // input image is 100 X 100
CGAffineTransform transform = CGAffineTransformMakeScale(5.0f, 5.0f); // Scale by 5 times along both dimensions
CIImage *output = [input imageByApplyingTransform: transform];
// output image is now 500 X 500

来自这个答案： https://stackoverflow.com/a/16316701/2859764

Answer 2

此方法将使用 CoreImage 将 QR 码生成为 CIImage。不幸的是，没有简单的方法来禁用插值，因此缩放图像会产生模糊的代码。解决方法是使用位创建临时 CGImageRef 并将其绘制到灰度位图 CGContextRef 中。

在 OSX 上测试，但应该可以在 iOS 上运行。

- (CGImageRef)createQRImageForString:(NSString *)string size:(CGSize)size {
  // Setup the QR filter with our string
  CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
  [filter setDefaults];

  NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
  [filter setValue:data forKey:@"inputMessage"];
  CIImage *image = [filter valueForKey:@"outputImage"];

  // Calculate the size of the generated image and the scale for the desired image size
  CGRect extent = CGRectIntegral(image.extent);
  CGFloat scale = MIN(size.width / CGRectGetWidth(extent), size.height / CGRectGetHeight(extent));

  // Since CoreImage nicely interpolates, we need to create a bitmap image that we'll draw into
  // a bitmap context at the desired size;
  size_t width = CGRectGetWidth(extent) * scale;
  size_t height = CGRectGetHeight(extent) * scale;
  CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();
  CGContextRef bitmapRef = CGBitmapContextCreate(nil, width, height, 8, 0, cs, (CGBitmapInfo)kCGImageAlphaNone);

#if TARGET_OS_IPHONE
  CIContext *context = [CIContext contextWithOptions:nil];
#else
  CIContext *context = [CIContext contextWithCGContext:bitmapRef options:nil];
#endif

  CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];

  CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
  CGContextScaleCTM(bitmapRef, scale, scale);
  CGContextDrawImage(bitmapRef, extent, bitmapImage);

  // Create an image with the contents of our bitmap
  CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);

  // Cleanup
  CGContextRelease(bitmapRef);
  CGImageRelease(bitmapImage);

  return scaledImage;
}

Answer 3

我遇到了同样的问题，基于这个tutorial这是我解决它的方法：

-(UIImage *) generateQRCodeWithString:(NSString *)string scale:(CGFloat) scale{
NSData *stringData = [string dataUsingEncoding:NSUTF8StringEncoding ];

CIFilter *filter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
[filter setValue:stringData forKey:@"inputMessage"];
[filter setValue:@"M" forKey:@"inputCorrectionLevel"];

// Render the image into a CoreGraphics image
CGImageRef cgImage = [[CIContext contextWithOptions:nil] createCGImage:[filter outputImage] fromRect:[[filter outputImage] extent]];

//Scale the image usign CoreGraphics
UIGraphicsBeginImageContext(CGSizeMake([[filter outputImage] extent].size.width * scale, [filter outputImage].extent.size.width * scale));
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(context, kCGInterpolationNone);
CGContextDrawImage(context, CGContextGetClipBoundingBox(context), cgImage);
UIImage *preImage = UIGraphicsGetImageFromCurrentImageContext();

//Cleaning up .
UIGraphicsEndImageContext();
CGImageRelease(cgImage);

// Rotate the image
UIImage *qrImage = [UIImage imageWithCGImage:[preImage CGImage]
                                            scale:[preImage scale]
                                      orientation:UIImageOrientationDownMirrored];
return qrImage;
}

Answer 4

我必须改编@cromanelli 的答案才能达到完美的清晰度：

func convertTextToQRCode(text: String, withSize size: CGSize) -> UIImage {

    let data = text.dataUsingEncoding(NSISOLatin1StringEncoding, allowLossyConversion: false)

    let filter = CIFilter(name: "CIQRCodeGenerator")!

    filter.setValue(data, forKey: "inputMessage")
    filter.setValue("L", forKey: "inputCorrectionLevel")

    var qrcodeCIImage = filter.outputImage!

    let cgImage = CIContext(options:nil).createCGImage(qrcodeCIImage, fromRect: qrcodeCIImage.extent)
    UIGraphicsBeginImageContext(CGSizeMake(size.width * UIScreen.mainScreen().scale, size.height * UIScreen.mainScreen().scale))
    let context = UIGraphicsGetCurrentContext()
    CGContextSetInterpolationQuality(context, .None)
    CGContextDrawImage(context, CGContextGetClipBoundingBox(context), cgImage)
    let preImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    let qrCodeImage = UIImage(CGImage: preImage.CGImage!, scale: 1.0/UIScreen.mainScreen().scale, orientation: .DownMirrored)

    return qrCodeImage
}

Answer 5

也许你应该试试这个。 Here 是一个快速教程。

+ (UIImage *)generateQRCodeImageBySize:(CGFloat)size andString:(NSString *)string {

    CIImage *qrCodeImage = [[CIImage alloc] init];

    NSData *stringData = [string dataUsingEncoding:NSISOLatin1StringEncoding allowLossyConversion:NO];

    CIFilter *ciFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];

    [ciFilter setValue:stringData forKey:@"inputMessage"];
    [ciFilter setValue:@"Q" forKey:@"inputCorrectionLevel"];

    qrCodeImage = ciFilter.outputImage;

    CGFloat scaleX = size / qrCodeImage.extent.size.width;
    CGFloat scaleY = size / qrCodeImage.extent.size.height;
    CIImage *transformedQRImage = [qrCodeImage imageByApplyingTransform:CGAffineTransformMakeScale(scaleX, scaleY)];

    return [UIImage imageWithCIImage:transformedQRImage];
}

Answer 6

在 Swift 3.1 中重写 @Benoît Caron 的答案：

func convertTextToQRCode(text: String, withSize size: CGSize) -> UIImage {

    let data = text.data(using: String.Encoding.isoLatin1, allowLossyConversion: false)

    let filter = CIFilter(name: "CIQRCodeGenerator")!

    filter.setValue(data, forKey: "inputMessage")
    filter.setValue("L", forKey: "inputCorrectionLevel")

    let qrcodeCIImage = filter.outputImage!

    let cgImage = CIContext(options:nil).createCGImage(qrcodeCIImage, from: qrcodeCIImage.extent)
    UIGraphicsBeginImageContext(CGSize(width: size.width * UIScreen.main.scale, height:size.height * UIScreen.main.scale))
    let context = UIGraphicsGetCurrentContext()
    context!.interpolationQuality = .none

    context?.draw(cgImage!, in: CGRect(x: 0.0,y: 0.0,width: context!.boundingBoxOfClipPath.width,height: context!.boundingBoxOfClipPath.height))

    let preImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    let qrCodeImage = UIImage(cgImage: (preImage?.cgImage!)!, scale: 1.0/UIScreen.main.scale, orientation: .downMirrored)

    return qrCodeImage
}

Answer 7

修复使用 CIFilter 生成的 QR 码中的模糊外观： 放大 QR 码图像而不使其模糊的基本思想是更改其变换属性。但是，由于放大图像并同时将其添加到图像视图中是不可行的，因此我们将创建另一个将被放大的 CIImage，然后将其分配给图像视图。

目标 C：

- (void)createQRForData:(id)qrData forImageView:(UIImageView *)imageView {

    NSData *data = [NSJSONSerialization dataWithJSONObject:qrData options:NSJSONWritingPrettyPrinted error:nil];

    CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
    [qrFilter setValue:data forKey:@"inputMessage"];
    [qrFilter setValue:@"Q" forKey: @"inputCorrectionLevel"];

    //Scaling the CIFilter image as per the UIImageView frame. 
    CGFloat scaleX = imageView.frame.size.width / qrFilter.outputImage.extent.size.width;
    CGFloat scaleY = imageView.frame.size.height / qrFilter.outputImage.extent.size.height;
    CIImage *transformedImage = [qrFilter.outputImage imageByApplyingTransform:CGAffineTransformMakeScale(scaleX, scaleY)];

    UIImage *QRImage = [UIImage imageWithCIImage:transformedImage];

    imageView.image = QRImage;
}

这帮助我解决了 QR 码中的模糊外观。

Answer 8

最简单的解决方案是将以下内容添加到您的图像视图中：

imgViewQR.layer.magnificationFilter = kCAFilterNearest

这将使用nearest 自动将您生成的二维码图像放大到 imageview 的大小，从而生成清晰的像素化图像。这通常不是您在调整图标/照片大小时想要的，但对于 QR 码来说是完美

（它似乎在模拟器上不起作用，但在真实设备上效果很好

Answer 9

这是一个 SwiftUI 版本。

import SwiftUI
import CoreImage.CIFilterBuiltins

struct QRCodeView: View {
    let message: Data

    var body: some View {
        GeometryReader { reader in
            generate(size: reader.size)
        }
    }

    func generate(size: CGSize) -> Image {
        let filter = CIFilter.qrCodeGenerator()
        filter.message = message
        filter.correctionLevel = "Q"

        if let output = filter.outputImage {
            let x = size.width / output.extent.size.width
            let y = size.height / output.extent.size.height

            let scaled = output.transformed(by: CGAffineTransform(scaleX: x, y: y))
            if let cg = CIContext().createCGImage(scaled, from: scaled.extent) {
                return Image(uiImage: UIImage(cgImage: cg))
            }
        }

        return Image(systemName: "xmark.circle")
    }
}

struct QRCodeView_Previews: PreviewProvider {
    static var previews: some View {
        QRCodeView(message: Data("Hi mom".utf8))
            .frame(width: 200, height: 200)
    }
}

Answer 10

Swift 5.5

// 在 5.5 中更改

imgViewQR.layer.magnificationFilter = CALayerContentsFilter.nearest