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D3DImage.Lock Method

Locks the D3DImage and enables operations on the back buffer.

Namespace:  System.Windows.Interop
Assembly:  PresentationCore (in PresentationCore.dll)

public void Lock()


The lock count equals MaxValue.

Call the Lock method to change the back buffer by calling the AddDirtyRect and SetBackBuffer methods. While the D3DImage is locked, your application can also render to the Direct3D surface assigned to the back buffer.


The Lock method blocks when the rendering system is reading the back buffer to update the front buffer. Use the TryLock method to avoid blocking indefinitely.

The following code example shows how to call the Lock method to enable updates to the back buffer. For more information, see Walkthrough: Hosting Direct3D9 Content in WPF.

// Repeatedly calling SetBackBuffer with the same IntPtr is 
// a no-op. There is no performance penalty.
d3dimg.SetBackBuffer(D3DResourceType.IDirect3DSurface9, pSurface);
d3dimg.AddDirtyRect(new Int32Rect(0, 0, d3dimg.PixelWidth, d3dimg.PixelHeight));

.NET Framework

Supported in: 4, 3.5 SP1, 3.0 SP2

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.