Question

我正在尝试创建一个带有方形图片的相机按钮，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麻烦。在代码行中注释“将图像裁剪为正方形：我收到一条错误，说”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

Answer 1

将您的“裁剪”编码移到此行下方：

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

您需要使用新裁剪的图像更新dataSource。然后，您可以在UICollectionView上调用reloadData或insertItemsAtIndexPaths:，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（当集合中有大量图像时）。

UICollectionView引用为here。

裁剪UIImagePicker并输出到CollectionView单元格

1 个答案: