iOS 自定义 UIImagePickerController 相机裁剪为正方形
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/17712797/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
iOS Custom UIImagePickerController Camera Crop to Square
提问by NSDavidObject
I'm trying to create a camera like Instagram where the user can see a box and the image would crop to that box. For Some reason the camera doesn't go all the way to the bottom of the screen and cuts off near the end. I'm also wondering how would I go about cropping the image to be 320x320 exactly inside that square?
我正在尝试创建一个像 Instagram 这样的相机，用户可以在其中看到一个框，并且图像会裁剪到那个框。出于某种原因，相机没有一直走到屏幕底部并在接近尾声时切断。我还想知道如何将图像裁剪为 320x320 正好在那个正方形内？
回答by Ander
Here's the easiest way to do it (without reimplementing UIImagePickerController). First, use an overlay to make the camera field look square. Here's an example for 3.5" screens (you'd need to update it to work for iPhone 5):
这是最简单的方法（无需重新实现UIImagePickerController）。首先，使用叠加使相机场看起来是方形的。这是 3.5" 屏幕的示例（您需要对其进行更新以适用于 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];
Then, after you get a picture back from the UIImagePickerController, crop it to a square with something like this:
然后，在您从 中取回图片后，将其UIImagePickerController裁剪为具有以下内容的正方形：
//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();
}
And you're done.
你已经完成了。
回答by Tomch
@Anders answer was very close to correct for me on iPhone 5. I made the following modification to add an overlay hardcoded for iPhone 5:
@Anders 的回答非常接近于我在 iPhone 5 上的正确答案。我进行了以下修改，为 iPhone 5 添加了硬编码的叠加层：
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];`
I hope this helps someone.
我希望这可以帮助别人。
