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description of HDC_SCREEN, HDC_SCREEN_SYS under compositing schema

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Vincent Wei
2020-01-10 19:04:36 +08:00
parent e75144e069
commit e9db07e428
1 changed files with 47 additions and 9 deletions
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56
include/gdi.h
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@@ -1111,23 +1111,61 @@ MG_EXPORT BOOL GUIAPI InitPolygonRegion (PCLIPRGN dst,
/**
* \def HDC_SCREEN
* \brief Handle to the device context of the whole screen.
* \brief Handle to the device context of the whole screen or the fake screen
* when MiniGUI is running under MiniGUI-Processes with compositing schema.
*
* This DC is a special one. MiniGUI uses it to draw popup menus and
* other global objects. You can also use this DC to draw lines or text on
* the screen directly, and there is no need to get or release it.
* This DC is a special one. Under MiniGUI-Standalone runmode, MiniGUI-Threads
* runmode, and MiniGUI-Processes runmode with shared frame buffer schema,
* MiniGUI uses it to draw popup menus and other global objects. You can also
* use this DC to draw lines or text on the screen directly, and there is no
* need to get or release it.
*
* If you do not want to create any main window, but you want to draw on
* the screen, you can use this DC.
* the screen, you can use this DC. Note that MiniGUI does not do any
* clipping operation for this DC, so drawing something on this DC may
* make a mess of other windows.
*
* \note MiniGUI does not do any clipping operation for this DC,
* so use this DC may make a mess of other windows.
* However, under MiniGUI-Processes with compositing schema, HDC_SCREEN
* stands for a global surface for wallpaper. This surface is the ONLY
* surface that can be accessed by all processess (including the server
* and all clients) under compositing schema.
*
* This surface will have the same pixel format as the real screen.
* Therefore, one app can still use HDC_SCREEN to create a compatible
* memory DC, load bitmaps, or draw something to the surface. However,
* the content in the wallpaper surface may not be reflected to
* the whole screen; the compositor decides how to display its content.
*
* On the other hand, you can configure MiniGUI to create a smaller
* surface than the whole screen as the underlaying surface of HDC_SCREEN,
* and the compositor may use it as a pattern to tile the content
* to the whole wallpaer. You can use the key
* `compositing_schema.wallpaper_pattern_size` to specify the pattern size,
* i.e., the size of HDC_SCREEN.
*
* Because of the change of HDC_SCREEN's connotation, you should avoid
* to use \a GetGDCapability to determine the screen resolution. Instead,
* you use the global variable \a g_rcScr.
*
* \sa HDC_SCREEN_SYS
*/
#define HDC_SCREEN ((HDC)0)
/*
* This is a system screen DC create for MiniGUI internal usage, for example,
* menu and z-order operations
* \def HDC_SCREEN_SYS
* \brief This is a system screen DC created for internal use.
*
* Under compositing schema, this DC stands for the surface of the
* real screen surface. The compositor running in the server will
* use this DC to compositing the surfaces created and rendered by
* the server and the clients to the screen. For clients, this DC
* essentially is HDC_SCREEN.
*
* Under MiniGUI-Standalone runmode, MiniGUI-Threads
* runmode, and MiniGUI-Processes runmode with shared frame buffer schema,
* MiniGUI uses it to draw popup menus and other global objects.
*
* \sa HDC_SCREEN
*/
#define HDC_SCREEN_SYS ((HDC)1)