c# - 如何在非UI線程中編輯WriteableBitmap.BackBuffer？

MSDN suggests在後臺線程中寫入backbuffer。只需要在ui線程上執行某些更新前和更新後操作。因此，當後臺線程執行實際更新時，ui線程可以自由地執行其他操作： 

 //Put this code in a method that is called from the background thread
        long pBackBuffer = 0, backBufferStride = 0;
        Application.Current.Dispatcher.Invoke(() =>
        {//lock bitmap in ui thread
            _bitmap.Lock();
            pBackBuffer = (long)_bitmap.BackBuffer;//Make pointer available to background thread
            backBufferStride = Bitmap.BackBufferStride;
        });
        //Back to the worker thread
        unsafe
        {
            //Carry out updates to the backbuffer here
            foreach (var update in updates)
            {
                long bufferWithOffset = pBackBuffer + GetBufferOffset(update.X, update.Y, backBufferStride);
                *((int*)bufferWithOffset) = update.Color;
            }
        }
        Application.Current.Dispatcher.Invoke(() =>
        {//UI thread does post update operations
            _bitmap.AddDirtyRect(new System.Windows.Int32Rect(0, 0, width, height));
            _bitmap.Unlock();
        });