Shoutbox

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Originally posted by http://en.wikipedia.org/wiki/Desktop_Window_Manager

With DWM running, applications do not draw directly to the video memory, but to an off-screen buffers in system memory that are then composited together by DWM to render the final screen, a number of times per second. In that sense, it is similar to the Quartz compositor in Mac OS X. Because the compositor has access to the graphics of all applications, it easily allows effects that string together visuals from multiple applications, such as transparency. DWM uses DirectX to perform the function of compositing and rendering in the GPU, freeing the CPU of the task of managing the rendering from the off-screen buffers to the display. However, it does not affect applications painting to the off-screen buffers; depending on the technologies used for that, it might still be CPU bound. DWM-agnostic rendering techniques like GDI are redirected to the buffers by rendering the UI as bitmaps. DWM-aware rendering technologies like WPF-directly make the internal data structures available in a DWM-compatible format. The window contents in the buffers are then converted to DirectX textures.

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