UIImage调整大小不正常
所以我一直试图弄清楚我现在做错了一段时间，我无法理解。我想要完成的是：
- 使用
UIImagePickerController拍摄照片
- 拍摄照片并从顶部和底部裁剪，使其变成正方形（类似于Instagram）
- 在
UIButton中显示该图片
出于某种原因，每次拍摄照片时，它都会在UIButton内失真，看起来裁剪效果不正常。这就是我的工作。在didFinishPickingMediaWithInfo方法中，我有以下代码：
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
//Copy the image to the userImage variable
[picker dismissModalViewControllerAnimated:YES];
userImage = nil;
//Rotate & resize image
userImage = [self resizeAndRotatePhoto:(UIImage *)[info objectForKey:UIImagePickerControllerOriginalImage]];
NSLog(@"Userimage size, width: %f , height: %f", userImage.size.width , userImage.size.height);
//Update the image form field with the image and set the image in the controller
NSLog(@"Button size is height: %f , width: %f" , userImageAvatarButton.frame.size.height , userImageAvatarButton.frame.size.width);
[userImageAvatarButton.layer setMasksToBounds:YES];
[userImageAvatarButton.layer setCornerRadius:3.0];
[userImageAvatarButton setImage:userImage forState:UIControlStateNormal];
}
我会暂时包含resizeAndRotatePhoto方法，但结果如下。此外，在上面的代码中，@property (strong) (UIImage *)userImage;在ViewController的头文件中定义。日志输出也会导致：
2012-05-07 17:38:07.995 NewApp[10666:707] Userimage size, width: 1936.000000 , height: 1936.000000
2012-05-07 17:38:08.000 NewApp[10666:707] Button size is height: 60.000000 , width: 60.000000
如下图所示，它最终失真
至于resizeAndRotate方法，这里是：
- (UIImage *)resizeAndRotatePhoto:(UIImage *)source
{
if( source.imageOrientation == UIImageOrientationRight )
{
source = [self rotateImage:source byDegrees:90];
}
if( userImage.imageOrientation == UIImageOrientationLeft)
{
source = [self rotateImage:source byDegrees:-90];
}
CGFloat x,y;
CGFloat size;
if( source.size.width > source.size.height ){
size = source.size.height;
x = (source.size.width - source.size.height)/2;
y = 0;
}
else {
size = source.size.width;
x = 0;
y = (source.size.height - source.size.width)/2;
}
CGImageRef imageRef = CGImageCreateWithImageInRect([source CGImage], CGRectMake(x,y,size,size) );
return [UIImage imageWithCGImage:imageRef];
}
此时我不知道如何让这张图片显示不失真。尽管系统说图像确实是一个正方形，但它似乎正在裁剪错误并显示错误。
1 个答案:
答案 0 :(得分：9)
由于其他原因，我放弃了vocaro.com解决方案（当使用非典型图像格式时，解决方案会崩溃，例如CMYK）。
无论如何，我现在使用以下imageByScalingAspectFillSize类别的UIImage方法来制作方形缩略图。
顺便说一下，这会自动应用设备主屏幕的比例（例如UIButton按钮，即Retina设备上的60x60点，这将适用2x（或3x）的比例，即120x120或180x180图像）。
的UIImage + SimpleResize.h：
/* UIImage+SimpleResize.h
*
* Modified by Robert Ryan on 5/19/11.
*/
@import UIKit;
/** Image resizing category.
*
* Modified by Robert Ryan on 5/19/11.
*
* Inspired by http://ofcodeandmen.poltras.com/2008/10/30/undocumented-uiimage-resizing/
* but adjusted to support AspectFill and AspectFit modes.
*/
@interface UIImage (SimpleResize)
/** Resize the image to be the required size, stretching it as needed.
*
* @param size The new size of the image.
* @param contentMode The `UIViewContentMode` to be applied when resizing image.
* Either `UIViewContentModeScaleToFill`, `UIViewContentModeScaleAspectFill`, or
* `UIViewContentModeScaleAspectFit`.
*
* @return Return `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode;
/** Resize the image to be the required size, stretching it as needed.
*
* @param size The new size of the image.
* @param contentMode The `UIViewContentMode` to be applied when resizing image.
* Either `UIViewContentModeScaleToFill`, `UIViewContentModeScaleAspectFill`, or
* `UIViewContentModeScaleAspectFit`.
* @param scale The scale factor to apply to the bitmap. If you specify a value of 0.0, the scale factor is set to the scale factor of the device’s main screen.
*
* @return Return `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode scale:(CGFloat)scale;
/** Crop the image to be the required size.
*
* @param bounds The bounds to which the new image should be cropped.
*
* @return Cropped `UIImage`.
*/
- (UIImage * _Nullable)imageByCroppingToBounds:(CGRect)bounds;
/** Crop the image to be the required size.
*
* @param bounds The bounds to which the new image should be cropped.
* @param scale The scale factor to apply to the bitmap. If you specify a value of 0.0, the scale factor is set to the scale factor of the device’s main screen.
*
* @return Cropped `UIImage`.
*/
- (UIImage * _Nullable)imageByCroppingToBounds:(CGRect)bounds scale:(CGFloat)scale;
/** Resize the image to fill the rectange of the specified size, preserving the aspect ratio, trimming if needed.
*
* @param size The new size of the image.
*
* @return Return `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingAspectFillSize:(CGSize)size;
/** Resize the image to fill the rectange of the specified size, preserving the aspect ratio, trimming if needed.
*
* @param size The new size of the image.
* @param scale The scale factor to apply to the bitmap. If you specify a value of 0.0, the scale factor is set to the scale factor of the device’s main screen.
*
* @return Return `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingAspectFillSize:(CGSize)size scale:(CGFloat)scale;
/** Resize the image to be the required size, stretching it as needed.
*
* @param size The new size of the image.
*
* @return Resized `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingToFillSize:(CGSize)size;
/** Resize the image to be the required size, stretching it as needed.
*
* @param size The new size of the image.
* @param scale The scale factor to apply to the bitmap. If you specify a value of 0.0, the scale factor is set to the scale factor of the device’s main screen.
*
* @return Resized `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingToFillSize:(CGSize)size scale:(CGFloat)scale;
/** Resize the image to fit within the required size, preserving the aspect ratio, with no trimming taking place.
*
* @param size The new size of the image.
*
* @return Return `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingAspectFitSize:(CGSize)size;
/** Resize the image to fit within the required size, preserving the aspect ratio, with no trimming taking place.
*
* @param size The new size of the image.
* @param scale The scale factor to apply to the bitmap. If you specify a value of 0.0, the scale factor is set to the scale factor of the device’s main screen.
*
* @return Return `UIImage` of resized image.
*/
- (UIImage * _Nullable)imageByScalingAspectFitSize:(CGSize)size scale:(CGFloat)scale;
@end
的UIImage + SimpleResize.m：
// UIImage+SimpleResize.m
//
// Created by Robert Ryan on 5/19/11.
#import "UIImage+SimpleResize.h"
@implementation UIImage (SimpleResize)
- (UIImage *)imageByScalingToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode {
return [self imageByScalingToSize:size contentMode:contentMode scale:0];
}
- (UIImage *)imageByScalingToSize:(CGSize)size contentMode:(UIViewContentMode)contentMode scale:(CGFloat)scale {
if (contentMode == UIViewContentModeScaleToFill) {
return [self imageByScalingToFillSize:size];
}
else if ((contentMode == UIViewContentModeScaleAspectFill) ||
(contentMode == UIViewContentModeScaleAspectFit)) {
CGFloat horizontalRatio = self.size.width / size.width;
CGFloat verticalRatio = self.size.height / size.height;
CGFloat ratio;
if (contentMode == UIViewContentModeScaleAspectFill)
ratio = MIN(horizontalRatio, verticalRatio);
else
ratio = MAX(horizontalRatio, verticalRatio);
CGSize sizeForAspectScale = CGSizeMake(self.size.width / ratio, self.size.height / ratio);
UIImage *image = [self imageByScalingToFillSize:sizeForAspectScale scale:scale];
// if we're doing aspect fill, then the image still needs to be cropped
if (contentMode == UIViewContentModeScaleAspectFill) {
CGRect subRect = CGRectMake(floor((sizeForAspectScale.width - size.width) / 2.0),
floor((sizeForAspectScale.height - size.height) / 2.0),
size.width,
size.height);
image = [image imageByCroppingToBounds:subRect];
}
return image;
}
return nil;
}
- (UIImage *)imageByCroppingToBounds:(CGRect)bounds {
return [self imageByCroppingToBounds:bounds scale:0];
}
- (UIImage *)imageByCroppingToBounds:(CGRect)bounds scale:(CGFloat)scale {
if (scale == 0) {
scale = [[UIScreen mainScreen] scale];
}
CGRect rect = CGRectMake(bounds.origin.x * scale, bounds.origin.y * scale, bounds.size.width * scale, bounds.size.height * scale);
CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef scale:scale orientation:self.imageOrientation];
CGImageRelease(imageRef);
return croppedImage;
}
- (UIImage *)imageByScalingToFillSize:(CGSize)size {
return [self imageByScalingToFillSize:size scale:0];
}
- (UIImage *)imageByScalingToFillSize:(CGSize)size scale:(CGFloat)scale {
UIGraphicsBeginImageContextWithOptions(size, false, scale);
[self drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}
- (UIImage *)imageByScalingAspectFillSize:(CGSize)size {
return [self imageByScalingAspectFillSize:size scale:0];
}
- (UIImage *)imageByScalingAspectFillSize:(CGSize)size scale:(CGFloat)scale {
return [self imageByScalingToSize:size contentMode:UIViewContentModeScaleAspectFill scale:scale];
}
- (UIImage *)imageByScalingAspectFitSize:(CGSize)size {
return [self imageByScalingAspectFitSize:size scale:0];
}
- (UIImage *)imageByScalingAspectFitSize:(CGSize)size scale:(CGFloat)scale {
return [self imageByScalingToSize:size contentMode:UIViewContentModeScaleAspectFit scale:scale];
}
@end
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