xamarin.ios - 如何在 Xamarin IOS Live Camera 中添加 OverlayView

Question

• 我正在访问实时摄像头，但我想在其上方添加一个叠加层，以拍摄特定照片并将图片保存在叠加层中。
• 我的目标如下图所示

Answer 1

你可以使用UIImagePickerController来做到这一点。

首先制作一个覆盖视图，就像您的问题中显示的那样。

• 我相信您可以使用视图的Alpha属性获得灰色效果。
• 您可以使用UIBezierPath制作线条

完成覆盖视图后，将其分配给UIImagePickerController的CameraOverlayView属性

这是一个粗略的例子。

    imagePicker = new UIImagePickerController();

    // set our source to the camera
    imagePicker.SourceType = UIImagePickerControllerSourceType.Camera;

    // set
    imagePicker.MediaTypes = new string[] { "public.image" };

    // show the camera controls
    imagePicker.ShowsCameraControls = true;

    // This is where you assign the view that you want to overlay   
    imagePicker.CameraOverlayView = new CameraOverlayView();

---

更新：

使用CGImageCreateWithImageInRect类获取图像的裁剪版本。传递相机叠加层的矩形和相机拍摄的图片的图像参考，该类将返回相机叠加层覆盖的裁剪图像。

这是来自 Objective C 的示例，我相信您可以在 Xamarin.iOS 中执行类似的操作

CGImageRef imageRef = CGImageCreateWithImageInRect([largeImage CGImage], cropRect);
// or use the UIImage wherever you like
[UIImageView setImage:[UIImage imageWithCGImage:imageRef]]; 
CGImageRelease(imageRef);

Answer 2

我设法添加了 CameraOverlayView，“以允许用户在给定的矩形内拍照”

private UIImagePickerController _imagePicker;

private void OpenCameraAndTakePhoto() { 
    _imagePicker = new UIImagePickerController();
    _imagePicker.SourceType = UIImagePickerControllerSourceType.Camera;
    _imagePicker.MediaTypes = UIImagePickerController.AvailableMediaTypes(UIImagePickerControllerSourceType.Camera);
    _imagePicker.FinishedPickingMedia += Handle_FinishedPickingMedia;
    _imagePicker.Canceled += Handle_Canceled;
    _imagePicker.ShowsCameraControls = true;
    UIView view = new UIView(new CGRect(30, 200, 250, 120));
    view.Layer.BorderColor = UIColor.Blue.CGColor;
    view.Layer.BorderWidth = 3.0f;
    _imagePicker.CameraOverlayView = view;

    PresentModalViewController(_imagePicker, true);
}