在xamarin.forms中进行屏幕捕获

问题描述

是否有一个可以在xamarin.forms中进行屏幕捕获的软件包?

Is there a package that does screen capture in xamarin.forms ?

我还需要捕获Google地图的屏幕截图

I need also to capture google maps screen shots

推荐答案

查看博客文章.

Check out this blog post by Daniel Hindrikes.

我将假设您使用PCL作为共享代码.

I'm going to assume that you use a PCL for your shared code.

您将需要在PCL中创建一个接口.他称其为IScreenshotManager.声明看起来像这样:

You will need to create an interface in your PCL. He calls it IScreenshotManager. The declaration looks like this:

public interface IScreenshotManager
{
   Task<byte[]> CaptureAsync();
}

现在所有平台都将有自己的实现.对于iOS；

Now all platforms will have their own implementation for it.For iOS;

public class ScreenshotManager : IScreenshotManager
{
    public async System.Threading.Tasks.Task<byte[]> CaptureAsync()
    {
        var view = UIApplication.SharedApplication.KeyWindow.RootViewController.View;

        UIGraphics.BeginImageContext(view.Frame.Size);
        view.DrawViewHierarchy(view.Frame, true);
        var image = UIGraphics.GetImageFromCurrentImageContext();
        UIGraphics.EndImageContext();

        using(var imageData = image.AsPNG())
        {
            var bytes = new byte[imageData.Length];
            System.Runtime.InteropServices.Marshal.Copy(imageData.Bytes, bytes, 0, Convert.ToInt32(imageData.Length));
            return bytes;
        }

    }
}

对于Android:

public class ScreenshotManager : IScreenshotManager
{
    public static Activity Activity { get; set; }

    public async System.Threading.Tasks.Task<byte[]> CaptureAsync()
    {
        if(Activity == null)
        {
            throw new Exception("You have to set ScreenshotManager.Activity in your Android project");
        }

        var view = Activity.Window.DecorView;
        view.DrawingCacheEnabled = true;

        Bitmap bitmap = view.GetDrawingCache(true);

        byte[] bitmapData;

        using (var stream = new MemoryStream())
        {
            bitmap.Compress(Bitmap.CompressFormat.Png, 0, stream);
            bitmapData = stream.ToArray();
        }

        return bitmapData;
    }
}

对于Windows Phone:

And for Windows Phone:

public class ScreenshotManager : IScreenshotManager
{
    public async Task<byte[]> CaptureAsync()
    {
        var rootFrame = Application.Current.RootVisual as PhoneApplicationFrame;

        var screenImage = new WriteableBitmap((int)rootFrame.ActualWidth, (int)rootFrame.ActualHeight);
        screenImage.Render(rootFrame, new MatrixTransform());
        screenImage.Invalidate();

        using (var stream = new MemoryStream())
        {
            screenImage.SaveJpeg(stream, screenImage.PixelWidth, screenImage.PixelHeight, 0, 100);
            var bytes = stream.ToArray();
            return bytes;
        }
    }
}

不要忘记使用依赖性服务，如下所示:

Don't forget to register your platform specific implementations with the attribute which registers it with the Dependency Service, like this:

[assembly: Xamarin.Forms.Dependency (typeof (ScreenshotManager))]

它超出了名称空间声明.

It goes above the namespace declaration.

现在，从您的共享代码中，您可以通过如下调用获得屏幕截图的byte[]:

Now from your shared code you would be able to get the byte[] of a screenshot with a call like this:

var screenshotBytes = DependencyService.Get<IScreenshotManager>().CaptureAsync();

您可能想在使用DependencyService.Get<IScreenshotManager>()之前不是null.

You probably want to check if DependencyService.Get<IScreenshotManager>() isn't null before using it.

之后，您可以将byte[]转换为图像，并随便使用它！

After that you can turn your byte[] into an image and do whatever you like with it!

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