Direct: -Direct Screen Access example

Description

Direct demonstrates -the window server's direct screen area (CDirectScreenAccess) -interface.

The example has an engine, CLifeEngine, -for the famous "Game of Life" algorithm, which generates grids of cells, each -update being derived by simple rules from the previous generation. The initial -configuration of the cells is random.

The UI simply has little user -interaction. It simply draws the current grid using CDirectScreenAccess, -and requests the engine to generate the next update. The UI classes are:

CDirectDisplayLife: -the object that draws the grid through a CDirectScreenAccess, -and which implements the API's MDirectScreenAccess callback -interface, so that the window server can indicate when conditions (e.g. overlaying -windows) change
CExampleAppView: -the application's window, which owns the CDirectDisplayLife object
CExampleAppUi: -handles commands and calls the view appropriately

Download

Click -on the following link to download the example: Direct.zip

Click: browse to view the example code.

Class Summary

CDirectScreenAccess

MDirectScreenAccess

RNotifier

Usage

Commands -are given to the example through its Lifemenu. The commands are:

Start: starts or restarts -the life display
Test overlay: simulates -a window from another program being placed partially over the display area. -The display area is then clipped appropriately, so that the upper window is -not overwritten

Note -for developers

While the DSA is in operation, the client should -not make any call to the Window Server (WSERV) that will affect the visible -area of the window in which the DSA is taking place. If this happens, it will -cause a temporary deadlock (since the client will be waiting for WSERV to -make the requested window rearrangement, and WSERV will be waiting for the -client to acknowledge that the DSA has aborted).

+ + + + + +Direct: +Direct Screen Access example +

Description

Direct demonstrates +the window server's direct screen area (CDirectScreenAccess) +interface.

The example has an engine, CLifeEngine, +for the famous "Game of Life" algorithm, which generates grids of cells, each +update being derived by simple rules from the previous generation. The initial +configuration of the cells is random.

The UI simply has little user +interaction. It simply draws the current grid using CDirectScreenAccess, +and requests the engine to generate the next update. The UI classes are:

CDirectDisplayLife: +the object that draws the grid through a CDirectScreenAccess, +and which implements the API's MDirectScreenAccess callback +interface, so that the window server can indicate when conditions (e.g. overlaying +windows) change
CExampleAppView: +the application's window, which owns the CDirectDisplayLife object
CExampleAppUi: +handles commands and calls the view appropriately

Download

Click +on the following link to download the example: Direct.zip

Click: browse to view the example code.

Class Summary

CDirectScreenAccess

MDirectScreenAccess

RNotifier

Usage

Commands +are given to the example through its Lifemenu. The commands are:

Start: starts or restarts +the life display
Test overlay: simulates +a window from another program being placed partially over the display area. +The display area is then clipped appropriately, so that the upper window is +not overwritten

Note +for developers

While the DSA is in operation, the client should +not make any call to the Window Server (WSERV) that will affect the visible +area of the window in which the DSA is taking place. If this happens, it will +cause a temporary deadlock (since the client will be waiting for WSERV to +make the requested window rearrangement, and WSERV will be waiting for the +client to acknowledge that the DSA has aborted).

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