color color用于核心图像颜色

Question

我正在使用CIAztecCodeGenerator生成一个阿兹特克代码。

我正在尝试设置一个图案而不是纯色作为它的前景色，但是它呈现为空白/白色，我想知道是否有人知道我做错了什么。

[colorFilter setValue:[CIColor colorWithCGColor:[[UIColor colorWithPatternImage:image] CGColor]] forKey:@"inputColor0"];

Answer 1

这有点复杂，但您可以通过以某种方式组合和混合图像来使用自定义模式：

import CoreImage.CIFilterBuiltins // needed for using the type-safe filter interface

// ...

let patternImage = UIImage(named: "<image_name>")!
var patternInput = CIImage(cgImage: patternImage.cgImage!)

// potentially scale the pattern image
patternInput = patternInput.transformed(by: CGAffineTransform(scaleX: 0.5, y: 0.5))

let codeFilter = CIFilter.aztecCodeGenerator()
codeFilter.message = "<message>".data(using: .utf8)!
var codeImage = codeFilter.outputImage!

// invert code so the actual code part is white
let colorInvertFilter = CIFilter.colorInvert()
colorInvertFilter.inputImage = codeImage
codeImage = colorInvertFilter.outputImage!

// potentially scale the barcode (using nearest sampling to retain sharp edges)
codeImage = codeImage.samplingNearest().transformed(by: CGAffineTransform(scaleX: 50, y: 50))

let blendFilter = CIFilter.blendWithMask()
blendFilter.inputImage = patternInput
// using white color as background here, but can be any (or transparent when alpha = 0)
blendFilter.backgroundImage = CIImage(color: CIColor.white).cropped(to: codeImage.extent)
blendFilter.maskImage = codeImage

let output = blendFilter.outputImage!

Objective-C版本：

// the image containing the pattern you want to show over the aztec code
CIImage *patternImage = [CIImage imageWithData:imageData];

// potentially scale the pattern image, if necessary
patternImage = [patternImage imageByApplyingTransform:CGAffineTransformMakeScale(0.5, 0.5)];

// generate aztec code image
CIFilter *qrFilter = [CIFilter filterWithName:@"CIAztecCodeGenerator"];
[qrFilter setValue:stringData forKey:@"inputMessage"];
CIImage *codeImage = qrFilter.outputImage;

// invert code so the actual code part is white (used for masking below)
codeImage = [codeImage imageByApplyingFilter: @"CIColorInvert"];

// potentially scale the aztec code (using nearest sampling to retain sharp edges)
codeImage = [[codeImage imageBySamplingNearest] imageByApplyingTransform:CGAffineTransformMakeScale(50, 50)];

// the background color for your aztec code; basically a solid color image of the same size of the code
CIImage *background = [[CIImage imageWithColor:[CIColor whiteColor]] imageByCroppingToRect:codeImage.extent];

//
CIFilter *blendFilter = [CIFilter filterWithName:@"CIBlendWithMask"];
[blendFilter setValue:patternImage forKey:@"inputImage"]; // the pattern image is in the foreground
[blendFilter setValue:background forKey:@"backgroundImage"]; // solid color in the aztec code, but could be any color or image
[blendFilter setValue:codeImage forKey:@"maskImage"]; // use the aztec code as a mask for the pattern image over the background

CIImage *output = blendFilter.outputImage

请注意，两个缩放步骤中的数字取决于您希望显示代码的大小，以及模式图像应如何缩放到代码上方。