iOS Custom UIImagePickerController Camera Crop to Square

Question

我正在尝试创建像Instagram这样的相机，用户可以在其中看到一个框，图像​​会裁剪到该框中。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UIImagePickerController获取图片后，将其裁剪为方形，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();
}

你已经完成了。

Answer 2

@Anders在iPhone 5上的回答非常接近正确。我做了以下修改，为iPhone 5添加了一个硬编码的覆盖：

CGRect f = imagePickerController.view.bounds;
f.size.height -= imagePickerController.navigationBar.bounds.size.height;
UIGraphicsBeginImageContext(f.size);
[[UIColor colorWithWhite:0 alpha:.5] set];
UIRectFillUsingBlendMode(CGRectMake(0, 0, f.size.width, 124.0), kCGBlendModeNormal);
UIRectFillUsingBlendMode(CGRectMake(0, 444, f.size.width, 52), kCGBlendModeNormal);
UIImage *overlayImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

UIImageView *overlayIV = [[UIImageView alloc] initWithFrame:f];
overlayIV.image = overlayImage;
overlayIV.alpha = 0.7f;
[imagePickerController setCameraOverlayView:overlayIV];`

我希望这有助于某人。