裁剪 UIImagePicker 并输出到 CollectionView 单元格

Posted 2023-03-08

【中文标题】裁剪 UIImagePicker 并输出到 CollectionView 单元格

【英文标题】：Crop UIImagePicker and output to CollectionView cell

【发布时间】：2013-12-29 19:22:27

【问题描述】：

我正在尝试创建一个相机按钮，该按钮拍摄一张方形图片，然后填充 CollectionViewController 单元格。现在，我在裁剪图片并将其输出到单元格时遇到了一些问题。在注释的代码行中“将图像裁剪为正方形：我收到一条错误消息，指出“图像”是未声明的标识符。如何裁剪图像并将其设置为单元格？

- (IBAction)cameraButtonClicked:(id)sender 
    if (![UIImagePickerController isSourceTypeAvailable:(UIImagePickerControllerSourceTypeCamera)]) 
        UIAlertView *cameraAlertView = [[UIAlertView alloc] initWithTitle:@"Camera Not Available" message:@"There is no camera on this device which really defeats the purpose of this game. We suggest you get an iDevice with a camera." delegate:nil cancelButtonTitle:@"Okay" otherButtonTitles:nil];
        [cameraAlertView show];
    else
        UIImagePickerController *ipc = [[UIImagePickerController alloc] init];
        ipc.sourceType = UIImagePickerControllerSourceTypeCamera;

        if (ipc.sourceType == UIImagePickerControllerSourceTypeCamera) 
            //Create camera overlay
            CGRect f = ipc.view.bounds;
            f.size.height -= ipc.navigationBar.bounds.size.height;
            CGFloat barHeight = (f.size.height - f.size.width) / 2;
            UIGraphicsBeginImageContext(f.size);
            [[UIColor colorWithWhite:0 alpha:.5] set];
            UIRectFillUsingBlendMode(CGRectMake(0, 0, f.size.width, barHeight), kCGBlendModeNormal);
            UIRectFillUsingBlendMode(CGRectMake(0, f.size.height - barHeight, f.size.width, barHeight), kCGBlendModeNormal);
            UIImage *overlayImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();

            UIImageView *overlayIV = [[UIImageView alloc] initWithFrame:f];
            overlayIV.image = overlayImage;
            [ipc.cameraOverlayView addSubview:overlayIV];
        

        ipc.delegate = self;
        [self presentViewController:ipc animated:YES completion:nil];

        //Crop the image to a square
        CGSize imageSize = image.size;
        CGFloat width = imageSize.width;
        CGFloat height = imageSize.height;
        if (width != height) 
            CGFloat newDimension = MIN(width, height);
            CGFloat widthOffset = (width - newDimension) / 2;
            CGFloat heightOffset = (height - newDimension) / 2;
            UIGraphicsBeginImageContextWithOptions(CGSizeMake(newDimension, newDimension), NO, 0.);
            [image drawAtPoint:CGPointMake(-widthOffset, -heightOffset)
                     blendMode:kCGBlendModeCopy
                         alpha:1.];
            image = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
        
    


#pragma mark ImagePicker Delegate
-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

    [self dismissViewControllerAnimated:YES completion:nil];

    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];

    self.imageView.image = image;


-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker

    [self dismissViewControllerAnimated:YES completion:nil];

@end

【参考方案1】：

将您的“作物”代码移到此行下方：

UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage]; 在 didFinishPickingMediaWithInfo

您需要使用新裁剪的图像更新您的数据源。然后，您可以在 UICollectionView 上调用 reloadData 或 insertItemsAtIndexPaths: 以使其反映新添加的图像。我会支持调用后一种方法，因为它比使用reloadData 重新加载整个集合更有效（当集合中有很多图像时）。

UICollectionView 引用是here。

【讨论】：

这有助于解决裁剪问题，但是将图像设置为 CollectionView 单元格呢？

我修改了答案，希望对您有所帮助。