iOS7之后,可以使用原生的CIFilter创建二维码,但是生成的二维码只有黑白,而且大小不好控制,找了一下资料,发现解决的方法,使二维码透明背景,自定义颜色,还能加上阴影效果,方法很简单,直接调用即可,效果如下:
首先是二维码的生成,使用CIFilter很简单,直接传入生成二维码的字符串即可:
- (CIImage *)createQRForString:(NSString *)qrString {
NSData *stringData = [qrString dataUsingEncoding:NSUTF8StringEncoding];
// 创建filter
CIFilter *qrFilter = [CIFilter filterWithName:@"CIQRCodeGenerator"];
// 设置内容和纠错级别
[qrFilter setValue:stringData forKey:@"inputMessage"];
[qrFilter setValue:@"M" forKey:@"inputCorrectionLevel"];
// 返回CIImage
return qrFilter.outputImage;
}
因为生成的二维码是一个CIImage,我们直接转换成UIImage的话大小不好控制,所以使用下面方法返回需要大小的UIImage:
- (UIImage *)createNonInterpolatedUIImageFormCIImage:(CIImage *)image withSize:(CGFloat) size {
CGRect extent = CGRectIntegral(image.extent);
CGFloat scale = MIN(size/CGRectGetWidth(extent), size/CGRectGetHeight(extent));
// 创建bitmap;
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);
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef bitmapImage = [context createCGImage:image fromRect:extent];
CGContextSetInterpolationQuality(bitmapRef, kCGInterpolationNone);
CGContextScaleCTM(bitmapRef, scale, scale);
CGContextDrawImage(bitmapRef, extent, bitmapImage);
// 保存bitmap到图片
CGImageRef scaledImage = CGBitmapContextCreateImage(bitmapRef);
CGContextRelease(bitmapRef);
CGImageRelease(bitmapImage);
return [UIImage imageWithCGImage:scaledImage];
}
因为生成的二维码是黑白的,所以还要对二维码进行颜色填充,并转换为透明背景,使用遍历图片像素来更改图片颜色,因为使用的是CGContext,速度非常快:
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);
// 遍历像素
int pixelNum = imageWidth * imageHeight;
uint32_t* pCurPtr = rgbImageBuf;
for (int i = 0; i < pixelNum; i++, pCurPtr++){
if ((*pCurPtr & 0xFFFFFF00) < 0x99999900) // 将白色变成透明
{
// 改成下面的代码,会将图片转成想要的颜色
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;
}
}
// 输出图片
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];
// 清理空间
CGImageRelease(imageRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
return resultUIImage;
}
经过这样的处理,基本上二维码就成型了,如果还想加上阴影,就在ImageView的Layer上使用下面代码添加阴影:
ImageView.layer.shadowOffset = CGSizeMake(0, 0.5); // 设置阴影的偏移量
ImageView.layer.shadowRadius = 1; // 设置阴影的半径
ImageView.layer.shadowColor = [UIColor blackColor].CGColor; // 设置阴影的颜色为黑色
ImageView.layer.shadowOpacity = 0.3; // 设置阴影的不透明度
原文链接:http://blog.sina.com.cn/s/blog_693de6100102vtjk.html