使用UIIImagePicker的CGAffineTransform缩放UIImage并保存到Parse SDK [英] Scaling UIImage with a UIIImagePicker's CGAffineTransform and Saving to Parse SDK
问题描述
我使用以下代码缩放UIImagePickerController
.
CGAffineTransform translate = CGAffineTransformMakeTranslation(0.0, 71.0); //This slots the preview exactly in the middle of the screen by moving it down 71 points
self.imagePicker.cameraViewTransform = translate;
CGAffineTransform scale = CGAffineTransformScale(translate, 1.333333, 1.333333);
self.imagePicker.cameraViewTransform = scale;
然后我拍照并将其显示在UIImageView
Then I take the picture and present it in a UIImageView
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {
[picker dismissViewControllerAnimated:NO completion:NULL];
_imageTaken = nil;
_imageTaken = [info objectForKey:UIImagePickerControllerEditedImage];
if(_imageTaken==nil)
{
_imageTaken = [info objectForKey:UIImagePickerControllerOriginalImage];
}
if(_imageTaken==nil)
{
_imageTaken = [info objectForKey:UIImagePickerControllerCropRect];
}
[_imageTakenView setContentMode:UIViewContentModeScaleAspectFill];
if (_selfie) {
UIImage * flippedImage = [UIImage imageWithCGImage:_imageTaken.CGImage scale:_imageTaken.scale orientation:UIImageOrientationLeftMirrored];
_imageTaken = flippedImage;
}
_imageTakenView.image = _imageTaken;
}
到目前为止一切都很好.然后,通过将图像转换为NSData
Everything is good so far. Then I send the image up to my database by converting it to NSData
_imageData = [[NSData alloc] init];
_imageData = UIImageJPEGRepresentation(_image, .1);
当我从服务器加载数据并将其呈现在另一个相同大小的UIImageView
中时,我确实设置了相同的纵横比:
When I load the data back from the server and present it in another UIImageView
of the same size I do set the same aspect ratio:
[_imageViewToShow setContentMode:UIViewContentModeScaleAspectFill];
,但是图像看起来失真(水平压缩).关于为什么会这样的任何想法?
but the image looks distored (squished horizontally). Any ideas as to why this might be?
将UIImage转换为NSData&保存
_imageData = UIImageJPEGRepresentation(_image, .1);
PFFile *imageFile = [PFFile fileWithName:@"image.png" data:_imageData];
newMessage[@"image"] = imageFile;
问题:
当我重新下载数据时,UIImage看上去被压缩了.当我查看数据库中的图像时,看起来还不错.不知道为什么会这样...
When I redownload the data, the UIImage appears squished. When I look at the image on my database, it seems fine. Not sure why this is happening...
图像前后:
推荐答案
在上传之前尝试标准化图像的方向.即使元数据丢失,也可以使图像正常工作
Try normalizing the image's orientation before uploading.This will allow the image to work properly even if the metadata is lost
这里是执行此操作的类别:
Here is a category to do that:
UIImage+OrientationFix.h
@interface UIImage (OrientationFix)
- (UIImage*)imageByNormalizingOrientation;
@end
UIImage+OrientationFix.m
@implementation UIImage (OrientationFix)
- (UIImage*)imageByNormalizingOrientation {
if (self.imageOrientation == UIImageOrientationUp)
return self;
CGSize size = self.size;
UIGraphicsBeginImageContextWithOptions(size, NO, self.scale);
[self drawInRect:(CGRect){{0, 0}, size}];
UIImage* normalizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return normalizedImage;
}
@end
您只需致电:
_imageTaken = [flippedImage normalizedImage];
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