iOS自定義UIImagePickerController相機裁剪到廣場

Question

我想創建一個像Instagram一樣的相機，用戶可以看到一個盒子並且圖像會裁剪到該盒子。出於某種原因，相機不會一直走到屏幕底部，並在接近尾聲時切斷。我也想知道如何才能將該圖像裁剪成320x320正好在該廣場內？

Answer 1

這裏做到這一點（沒有重新實現UIImagePickerController）最簡單的方法。首先，使用覆蓋圖使相機區域呈現正方形。這裏有一個例子3.5" 屏幕（你需要更新它爲iPhone 5的工作）：

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]; 

然後，你會得到一張圖片後，從UIImagePickerController回來，這作物的方形像這樣的東西：

//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(); 
} 

大功告成

Answer 2

@Anders答案是非常接近的糾正我的iPhone 5，我做了以下修改添加硬編碼爲iPhone 5的疊加：

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];` 

我希望這可以幫助別人。