一直试图解决这个问题,但无济于事。
差不多,我正在截取视图的截图,然后尝试裁剪出第一个50px和一个页脚。问题是,当我这样做时,结果有点爆炸,质量会丢失。这是我写的,我认为符合视网膜。
-(UIImage *)takeSnapShotAndReturn{
//Take screenshot of whole view
if([[UIScreen mainScreen] respondsToSelector:@selector(scale)]){
UIGraphicsBeginImageContextWithOptions(self.view.bounds.size,NO,[UIScreen mainScreen].scale);
}
else{
UIGraphicsBeginImageContext(self.view.window.bounds.size);
}
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
combinedImage = [self cropOutArea:image withRectangle:CGRectMake(0, 50, 320, 467)];
UIImageWriteToSavedPhotosAlbum(combinedImage, nil, nil, nil);
UIGraphicsEndImageContext();
return image;
}
-(UIImage *)cropOutArea:(UIImage*)image withRectangle:(CGRect)rectangle{
if(image.scale > 1){
rectangle = CGRectMake(rectangle.origin.x * image.scale,
rectangle.origin.y * image.scale,
rectangle.size.width * image.scale,
rectangle.size.height * image.scale);
}
CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, rectangle);
UIImage *result = [UIImage imageWithCGImage:imageRef scale:image.scale orientation:image.imageOrientation];
CGImageRelease(imageRef);
return result;
}
答案 0 :(得分:2)
我觉得裁剪非常混乱!
我不确定你要做什么,但这可能就是.....
-(UIImage *)simplishTopCropAndTo640:(UIImage *)fromImage
// moderately optimised!
{
float shortDimension = fminf(fromImage.size.width, fromImage.size.height);
// 1.use CGImageCreateWithImageInRect to take only the top square...
// 2. use drawInRect (or CGContextDrawImage, same) to scale...
CGRect topSquareOfOriginalRect =
CGRectMake(0,0, shortDimension,shortDimension);
// NOT fromImage.size.width,fromImage.size.width);
CGImageRef topSquareIR = CGImageCreateWithImageInRect(
fromImage.CGImage, topSquareOfOriginalRect);
CGSize size = CGSizeMake( 640,640 );
CGRect sized = CGRectMake(0.0f, 0.0f, size.width, size.height);
UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);
CGContextRef cc = UIGraphicsGetCurrentContext();
CGContextSetInterpolationQuality(cc, kCGInterpolationLow);
CGContextTranslateCTM(cc, 0, size.height);
CGContextScaleCTM(cc, 1.0, -1.0);
CGContextDrawImage(cc, sized, topSquareIR );
// arguably, those three lines more simply...
//[[UIImage imageWithCGImage:topSquareIR] drawInRect:sized];
CGImageRelease(topSquareIR);
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
result =
[UIImage imageWithCGImage:result.CGImage
scale:result.scale
orientation: fromImage.imageOrientation];
//consider...something like...
//[UIImage imageWithCGImage:cgimg
// scale:3 orientation:fromImage.imageOrientation];
return result;
}
还要考虑这个有价值的类别......
-(UIImage *)ordinaryCrop:(CGRect)toRect
{
// crops any image, to any rect. you can't beat that
CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], toRect);
UIImage *cropped = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return cropped;
}
如果您使用相机“宇宙中最有用的代码!”,请不要忘记这一点。 iOS UIImagePickerController result image orientation after upload
希望它有所帮助
答案 1 :(得分:0)
尝试在result
中发布cropOutArea
之前设置此BOOL属性。
result.layer.masksToBounds = YES