iOS Custom UIImagePickerController Camera Crop to Square

Question

我正在尝试创建一个像Instagram这样的相机,用户可以看到一个盒子,图像会裁剪到那个盒子.由于某些原因,相机不会一直到达屏幕底部并在末端附近切断.我也想知道如何在正方形内将图像裁剪为320x320？

Answer 1

这是最简单的方法(没有重新实现UIImagePickerController).首先,使用叠加使相机字段看起来是方形的.以下是3.5英寸屏幕的示例(您需要将其更新为适用于iPhone 5):

UIImagePickerController *imagePickerController = [[UIImagePickerController alloc] init];
imagePickerController.sourceType = source;

if (source == UIImagePickerControllerSourceTypeCamera) {
    //Create camera overlay
    CGRect f = imagePickerController.view.bounds;
    f.size.height -= imagePickerController.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;
    [imagePickerController.cameraOverlayView addSubview:overlayIV];
}

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

然后,在您从中获取图片后,将其UIImagePickerController裁剪为方形,如下所示:

//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();
}

而且你已经完成了.