iOS 创建彩色二维码

桃扇骨 2022-07-14 01:16 200阅读 0赞

**因为系统创建的二维码默认都是黑色的，所以突然想改变一下二维码颜色，具体操作有点复杂，而且其中用到了好多C语言的语法，Swift不好写，所以默认用了OC。只贴了.m文件的代码，.h文件就是几个类函数的声明。**

#import "UIImage+CreateQRCode.h"
    
    @implementation UIImage (CreateQRCode)
    
    + (UIImage *)createQRCode:(NSString *)string andSize:(CGSize)size andColor:(UIColor *)color {
        UIImage *qrcode = [self createNonInterpolatedUIImageFormCIImage:[self createQRForString:string] withSize:size];
        const CGFloat *_components = CGColorGetComponents(color.CGColor);
        CGFloat red = _components[0] * 255.f;
        CGFloat green = _components[1] * 255.f;
        CGFloat blue = _components[2] * 255.f;
        return [self imageBlackToTransparent:qrcode withRed:red andGreen:green andBlue:blue];
    }
    
    + (void)setImageViewShadow:(UIImageView *)view {
        view.layer.shadowOffset = CGSizeMake(0, 2);
        view.layer.shadowRadius = 2;
        view.layer.shadowColor = [UIColor blackColor].CGColor;
        view.layer.shadowOpacity = 0.5;
        view.backgroundColor = [UIColor clearColor];
    }
    
    #pragma mark - 创建灰度图，只有灰度图才能改变颜色
    + (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGSize)size {
        CGRect extent = CGRectIntegral(image.extent);
        CGFloat scale = MIN(size.width/CGRectGetWidth(extent), size.height/CGRectGetHeight(extent));
        
        size_t width = CGRectGetWidth(extent) * scale;
        size_t height = CGRectGetHeight(extent) * scale;
        
    //    iOS不支持设备依赖颜色空间或通用颜色空间。iOS应用程序必须使用设备颜色空间
    //    设备颜色空间主要用于IOS应用程序，因为其它颜色空间无法在IOS上使用。大多数情况下，Mac OS X应用程序应使用通用颜色空间，而不使用设备颜色空间。
    //    CGColorSpaceCreateDeviceGray：创建设备依赖灰度颜色空间
    //    CGColorSpaceCreateDeviceRGB：创建设备依赖RGB颜色空间
    //    CGColorSpaceCreateDeviceCMYK：创建设备依赖CMYK颜色空间
        CGColorSpaceRef cs = CGColorSpaceCreateDeviceGray();//这个是改变二维码颜色的主要属性，必须是灰度空间，作用是将UIImage转变成了灰度图
        
        CGContextRef bitmapRef = CGBitmapContextCreate(NULL, width, height, 8, 0, cs, kCGImageAlphaNone);
        CIContext * context = [CIContext contextWithOptions:NULL];
        CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
        CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationHigh);
        CGContextScaleCTM(bitmapRef, scale, scale);
        CGContextDrawImage(bitmapRef, extent, bitmapImage);
        CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
        
        CGContextRelease(bitmapRef);
        CGImageRelease(bitmapImage);
        
        return [UIImage imageWithCGImage:scaledImage];
    }
    
    #pragma mark - 创建二维码的主要代码
    + (CIImage *)createQRForString:(NSString *)qrString {
        NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];
        CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
        [qrFilter setValue:stringData forKey:@"inputMessage"];
        [qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];
        return qrFilter.outputImage;
    }
    
    #pragma mark - 改变二维码的颜色
    void ProviderReleaseData (void *info, const void *data, size_t size){
        free((void*)data);
    }
    
    + (UIImage*)imageBlackToTransparent:(UIImage*)image withRed:(CGFloat)red andGreen:(CGFloat)green andBlue:(CGFloat)blue{
        const int imageWidth = image.size.width;
        const int imageHeight = image.size.height;
        size_t      bytesPerRow = imageWidth * 4;
        uint32_t* rgbImageBuf = (uint32_t*)malloc(bytesPerRow * imageHeight);
        
        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
        CGContextRef context = CGBitmapContextCreate(rgbImageBuf, imageWidth, imageHeight, 8, bytesPerRow, colorSpace,
                                                     kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
        CGContextDrawImage(context, CGRectMake(0, 0, imageWidth, imageHeight), image.CGImage);
        
        int pixelNum = imageWidth * imageHeight;
        uint32_t* pCurPtr = rgbImageBuf;
        for (int i = 0; i < pixelNum; i++, pCurPtr++){
            if ((*pCurPtr & 0xFFFFFF00) < 0x99999900){
                uint8_t* ptr = (uint8_t*)pCurPtr;
                ptr[3] = red; //0~255
                ptr[2] = green;
                ptr[1] = blue;
            }else{
                uint8_t* ptr = (uint8_t*)pCurPtr;
                ptr[0] = 0;
            }
        }
        
        CGDataProviderRef dataProvider = CGDataProviderCreateWithData(NULL, rgbImageBuf, bytesPerRow * imageHeight, ProviderReleaseData);
        CGImageRef imageRef = CGImageCreate(imageWidth, imageHeight, 8, 32, bytesPerRow, colorSpace,
                                            kCGImageAlphaLast | kCGBitmapByteOrder32Little, dataProvider,
                                            NULL, true, kCGRenderingIntentDefault);
        CGDataProviderRelease(dataProvider);
        UIImage* resultUIImage = [UIImage imageWithCGImage:imageRef];
        
        CGImageRelease(imageRef);
        CGContextRelease(context);
        CGColorSpaceRelease(colorSpace);
        
        return resultUIImage;
    }
    
    @end