Windows Vista desktop window manager (1)

What is the desktop window manager? It isVistaA new component in:Desktop Window Manager(DWM). It is built onWPFBased on the core graphics layer components. Remember when I was in the firstPostAs mentioned inCompositionEngine?DWMDesktop synthesis is built on thisCompositionNew features based on the engine. Its appearance almost changedVistaMedium ApplicationProgramDisplay Mode of the screen pixel.

PassDWMDesktop merging, the display of the application is not directly painted on the screen, but a display of one off-screen in the memorySurface. ThenDWMReplace theseSurfaceMerged to display on the screen.

From the perspective of user experience, enableDWMThe visual effects provided by the rear are frosted glass frames,3DSupports window transform animation, window flip, and high resolution.The most obvious features are:Real-time thumbnails of the taskbar window;Alt-TabAndWin-TabEffect of the key combination. 

 

 

Desktop merging (Composition)

InVistaBefore,WindowsApplications are required to draw their own visible areas, which can be directly painted in the video buffer of the video card. InVista, The system requires the application to draw the entire surface to the off-screenSurface. ThenDWMControl all the off-screen surfaces and combine them to display them on the real screen.

Nowadays, computer graphics chips are developing rapidly and have powerful processing capabilities. They are mainly used in games and other aspects.DWMThe main goal is to use the processing capabilities of graphics chips to bring the best possible experience to non-game users. ThereforeDWMIs based onDirectX, EspeciallyDirect3d. For more information,DWMIs directly built onMilcore.MilcoreIt is also established inDirectX. Eventually useDirect3dTexture to represent the window content and window frame.DWM/milcoreCall appropriateDirect3dFunctionDirect3dTexture Synthesis is the final desktop.VistaThe desktop can be understood as a full screenDirect3dApplication.

From the perspective of Window System display, this can bring us great convenience and help achieve higher quality visual effects, such:

1Access window: All windows are now displayed on the off-screen surface, which can be used elsewhere. For exampleAlt-TabKey combination.

2The background application is no longer involved in window operations:VistaPreviously, if the hidden window becomes visible again, this area only responds after the application wakes up.Wm_paintThis results in a lot of ugly effects. InVistaThe background window does not receiveWm_paintAnd will not be requested to be submitted because their content is already on the off-screen surface and can be directly used for re-merging.

3More dazzling user experience. You can have your own experience.

4High-resolution support: Most applications do not know the resolution of the monitor they are running. With the popularization of high-resolution display, this will make the application look smaller and smaller in physical space, the effect is very poor. BecauseDWMAfter accessing the off-screen surface of the window, the display resolution of the application can be adjusted in a special position to make it better on the high-resolution display.