Render control into image in WinRT metro

Question

I'm creating an application for windows 8 metro, I need to render a framework control into an image and save it to hard disk but do not know how. Can I use SharpDX for this? How can I do? Thanks in advance for the help

Answer 1

If you follow through this thread the limitations of Metro and the reasons why it won't work are explained. The essence of it is:

Sorry, but rendering Xaml to an element or capturing a screenshot of your own app did not make it into the release version. It is by design that an app cannot capturing a screenshot of another app.

A workaround mentioned is:

What I meant was - you can draw shapes, text and images using Direct2D. The same shapes that you would otherwise draw with XAML UI. I did not mean to imply that you can render XAML controls - just that you can use Direct2D as an alternative to achieve same results albeit with somewhat more effort.

Answer 2

justin.m.chase's approach certainly works if you do not mind adding dependencies to SharpDX assemblies. The RenderTargetBitmap class might be a good fit for what you are trying to accomplish.

// Render XAML to bitmap
var bitmap = new  RenderTargetBitmap();
await bitmap.RenderAsync(elementToRender);

// get the pixels
IBuffer pixelBuffer = await bitmap.GetPixelsAsync();
byte[] pixels = pixelBuffer.ToArray();

// write the pixels to a InMemoryRandomAccessStream
var stream = new  InMemoryRandomAccessStream();
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.BmpEncoderId, stream);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Straight, (uint)bitmap.PixelWidth, (uint)bitmap.PixelHeight, 96, 96, pixels);

await encoder.FlushAsync();
stream.Seek(0);

Answer 3

I apologize that this is not possible. The WritableBitmap class' Render() method is current insufficient to accomplish what you are wanting. For the same reason a screenshot cannot be created at this time. But these are the things that are on the backlog! But, now you know.

Answer 4

Because I think this is a more correct answer I would like to reiterate the comment that Zeeshan made in the original question.

There is a extension method for that in winrt xaml toolkit. http://winrtxamltoolkit.codeplex.com/.../WriteableBitmapRenderExtensions.cs

Install via nuget:

> Install-Package WinRTXamlToolkit.Composition

Add the using:

using WinRTXamlToolkit.Composition;

Render your xaml:

var bitmap = await element.Render();