我有一个UIImage
,当我的iPad以纵向方式显示时,它看起来是正确的方式,但当我得到CGImageRef
与之关联时,CGImageRef
被旋转90度逆时针。经过一些谷歌搜索,我得知这是因为CGImageRef
没有与UIImage
不同的方向数据。我需要查看和修改CGImageRef
中的一些像素,我现在通过直接访问rawData变量(图像是UIImage *)来实现这一点:
CGImageRef imageRef = [image CGImage];
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB(); //maybe make ...Gray();
unsigned char *rawData = (unsigned char*) calloc(height * width * 4, sizeof(unsigned char));
CGContextRef context = CGBitmapContextCreate(rawData, width, height, bitsPerComponent, bytesPerRow, colorSpaceRef, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
但是,为了让我正确修改存储在rawData中的像素数据,我需要CGImageRef处于正确的方向。如何顺时针旋转CGImageRef
90度然后访问rawData(像素信息)?
答案 0 :(得分:0)
试试这个:
CGImageRef imageRef = [sourceImage CGImage];
CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);
CGContextRef bitmap;
if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
} else {
bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
}
if (sourceImage.imageOrientation == UIImageOrientationLeft) {
CGContextRotateCTM (bitmap, radians(90));
CGContextTranslateCTM (bitmap, 0, -targetHeight);
} else if (sourceImage.imageOrientation == UIImageOrientationRight) {
CGContextRotateCTM (bitmap, radians(-90));
CGContextTranslateCTM (bitmap, -targetWidth, 0);
} else if (sourceImage.imageOrientation == UIImageOrientationUp) {
// NOTHING
} else if (sourceImage.imageOrientation == UIImageOrientationDown) {
CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
CGContextRotateCTM (bitmap, radians(-180.));
}
CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef);
CGImageRef ref = CGBitmapContextCreateImage(bitmap);