Getting a DrawingContext for a wpf WriteableBitmap

I found sixlettervariables' solution the most workable one. However, there's a "drawingContext.Close()" missing. According to MSDN, "A DrawingContext must be closed before its content can be rendered".The result is the following utility function:

public static BitmapSource CreateBitmap(    int width, int height, double dpi, Action<DrawingContext> render){    DrawingVisual drawingVisual = new DrawingVisual();    using (DrawingContext drawingContext = drawingVisual.RenderOpen())    {        render(drawingContext);    }    RenderTargetBitmap bitmap = new RenderTargetBitmap(        width, height, dpi, dpi, PixelFormats.Default);    bitmap.Render(drawingVisual);    return bitmap;}

This can then easily be used like this:

BitmapSource image = ImageTools.CreateBitmap(    320, 240, 96,    drawingContext =>    {        drawingContext.DrawRectangle(            Brushes.Green, null, new Rect(50, 50, 200, 100));        drawingContext.DrawLine(            new Pen(Brushes.White, 2), new Point(0, 0), new Point(320, 240));    });

If you don't mind using System.Drawing you could do something like:

var wb = new WriteableBitmap( width, height, dpi, dpi,                               PixelFormats.Pbgra32, null );wb.Lock();var bmp = new System.Drawing.Bitmap( wb.PixelWidth, wb.PixelHeight,                                     wb.BackBufferStride,                                      PixelFormat.Format32bppPArgb,                                      wb.BackBuffer );Graphics g = System.Drawing.Graphics.FromImage( bmp ); // Good old Graphicsg.DrawLine( ... ); // etc...// ...and finally:g.Dispose(); bmp.Dispose();wb.AddDirtyRect( ... );wb.Unlock();                    

I'm wondering the same thing, as currently I do something like:

DrawingVisual drawingVisual = new DrawingVisual();using (DrawingContext drawingContext = drawingVisual.RenderOpen()){   //   // ... draw on the drawingContext   //   RenderTargetBitmap bmp = new RenderTargetBitmap(width, height, dpi, dpi, PixelFormats.Default);   bmp.Render(drawingVisual);   image.Source = bmp;}

I'm trying to use the WriteableBitmap to allow multithreaded access to the pixel buffer, which is currently not allowed with neither a DrawingContext nor a RenderTargetBitmap. Maybe some sort of WritePixels routine based off of what you've retrieved from the RenderTargetBitmap would work?