处理设备照片时，iOS imageview 裁剪不起作用

Question

我计划创建一个图像编辑应用程序。第一步，我将触摸的图像位置显示到与原始图像视图不同的图像视图中。

使用 默认图片（从 xcode storyboard 属性检查器设置）测试时效果很好。

但当我从设备“照片”导入照片时，它不会裁剪精确的图像。

我真的很困惑并坚持在那里。请有人指导我完成这项任务。

我尝试了下面的代码

提前致谢。

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{

    UIImage *image = [info valueForKey:UIImagePickerControllerEditedImage];
    imgVw.image = image;

//    croperImgvw.image = [self cropImage : image];

    [self dismissViewControllerAnimated:YES completion:NULL];
}


- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    [self dismissViewControllerAnimated:YES completion:NULL];
}



- (UIImage *)cropImage:(UIImage *)image : (CGPoint)point
{

    CGRect clippedRect =CGRectMake(point.x, point.y, 50, 50);
    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], clippedRect);
    UIImage * croppedImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    return croppedImage;


}



-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{

    UITouch *touch = [touches anyObject];

    CGPoint touch_point = [touch locationInView:self.view];


    NSLog(@"X location: %f", touch_point.x);
    NSLog(@"Y Location: %f",touch_point.y);

    CGPoint point = [touch locationInView:self.view];

    croperImgvw.image = [self cropImage:[imgVw image] :point];


}

Answer 1

您似乎正在传递 视图 中的坐标，以便裁剪成 图像。图像视图和它的图像很少有相同的尺寸，尤其是当您从照片中挑选图像时。

在发送要裁剪的图像之前，尝试将第一个视图渲染为图像。您可以通过向 UIView 添加一个类别来做到这一点，如下所示：

@implementation UIView (Image)

- (UIImage *)image {
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0);
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

@end

编辑：或者如果您只是想让它在没有类别的情况下工作，请将此方法添加到您的代码中：

- (UIImage *)imageOfView:(UIImageView *)imageView {
    UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, NO, 0.0);
    [imageView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

然后修改你现有的代码为：

croperImgvw.image = [self cropImage:[self imageOfView:imgVw] :point];

Answer 2

增加订单的答案 分辨率不同，加个scale参数就好了。

TakeSnapshot.h

#import <Foundation/Foundation.h>

@interface TakeSnapshot : NSObject


+(UIImage *)takeSnapshotFromScreenWithSize:(UIView *)view Area:(CGPoint)screenPoint; 

@end

TakeSnapshot.m

#import "TakeSnapshot.h"

@implementation TakeSnapshot
+(UIImage *)takeSnapshotFromScreenWithSize:(UIView *)view Area:(CGPoint)screenPoint{
    {
        if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]){
            UIGraphicsBeginImageContextWithOptions(view.bounds.size, NO, [UIScreen mainScreen].scale);
        }
        else
            UIGraphicsBeginImageContext(view.bounds.size);
        [view.layer renderInContext:UIGraphicsGetCurrentContext()];
        UIImage *screenImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        //    
        if([[UIScreen mainScreen] respondsToSelector:@selector(scale)])  UIGraphicsBeginImageContextWithOptions(CGSizeMake(view.bounds.size.width, view.bounds.size.width),NO,[UIScreen mainScreen].scale);
        else
            UIGraphicsBeginImageContext(view.bounds.size);
        [screenImage drawAtPoint:screenPoint];
        UIImage *shareImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();

        return shareImage;

    }

}
@end

Answer 3

据我了解，您传递给 cropImage:image: 方法的 point 参数来自 UIImageView 坐标系 - CGImageCreateWithImageInRect 中的 rect 参数必须来自 UIImage ，而不是来自 UIImageView。

以下是您如何解决此问题的几个答案：

https://stackoverflow.com/a/10865552/4495995

https://stackoverflow.com/a/21693491/4495995