reactos操作系统实现(167)

co_UserRedrawWindow函数是用来实现窗口重画的功能，实现代码如下：

#001  BOOL FASTCALL

#002  co_UserRedrawWindow(PWINDOW_OBJECT Window, const RECT* UpdateRect, HRGN UpdateRgn,

#003                      ULONG Flags)

#004  {

#005     HRGN hRgn = NULL;

#006 

#007     /*

#008      * Step 1.

#009      * Validation of passed parameters.

#010      */

#011 

 

检验是否合适的参数。

#012     if (!IntIsWindowDrawable(Window) ||

#013           (Flags & (RDW_VALIDATE | RDW_INVALIDATE)) ==

#014           (RDW_VALIDATE | RDW_INVALIDATE))

#015     {

#016        return FALSE;

#017     }

#018 

#019     /*

#020      * Step 2.

#021      * Transform the parameters UpdateRgn and UpdateRect into

#022      * a region hRgn specified in screen coordinates.

#023      */

#024 

 

创建更新的区域。

#025     if (Flags & (RDW_INVALIDATE | RDW_VALIDATE))

#026     {

 

根据用户指定的区域进行更新。

#027        if (UpdateRgn != NULL)

#028        {

#029           hRgn = NtGdiCreateRectRgn(0, 0, 0, 0);

#030           if (NtGdiCombineRgn(hRgn, UpdateRgn, NULL, RGN_COPY) == NULLREGION)

#031           {

#032              NtGdiDeleteObject(hRgn);

#033              hRgn = NULL;

#034           }

 

否则更新整个窗口。

#035           else

#036              NtGdiOffsetRgn(hRgn, Window->Wnd->ClientRect.left, Window->Wnd->ClientRect.top);

#037        }

#038        else if (UpdateRect != NULL)

#039        {

#040           if (!IntGdiIsEmptyRect(UpdateRect))

#041           {

#042              hRgn = UnsafeIntCreateRectRgnIndirect((RECT *)UpdateRect);

#043              NtGdiOffsetRgn(hRgn, Window->Wnd->ClientRect.left, Window->Wnd->ClientRect.top);

#044           }

#045        }

#046        else if ((Flags & (RDW_INVALIDATE | RDW_FRAME)) == (RDW_INVALIDATE | RDW_FRAME) ||

#047                 (Flags & (RDW_VALIDATE | RDW_NOFRAME)) == (RDW_VALIDATE | RDW_NOFRAME))

#048        {

#049           if (!IntGdiIsEmptyRect(&Window->Wnd->WindowRect))

#050              hRgn = UnsafeIntCreateRectRgnIndirect(&Window->Wnd->WindowRect);

#051        }

#052        else

#053        {

 

创建客户区窗口区域更新。

#054           if (!IntGdiIsEmptyRect(&Window->Wnd->ClientRect))

#055              hRgn = UnsafeIntCreateRectRgnIndirect(&Window->Wnd->ClientRect);

#056        }

#057     }

#058 

#059     /*

#060      * Step 3.

#061      * Adjust the window update region depending on hRgn and flags.

#062      */

#063 

 

根据指定的区域进行更新。

#064     if (Flags & (RDW_INVALIDATE | RDW_VALIDATE | RDW_INTERNALPAINT | RDW_NOINTERNALPAINT) &&

#065         hRgn != NULL)

#066     {

#067        IntInvalidateWindows(Window, hRgn, Flags);

#068     }

#069 

#070     /*

#071      * Step 4.

#072      * Repaint and erase windows if needed.

#073      */

#074 

 

重新画窗口。

#075     if (Flags & (RDW_ERASENOW | RDW_UPDATENOW))

#076     {

#077        co_IntPaintWindows(Window, Flags, FALSE);

#078     }

#079 

#080     /*

#081      * Step 5.

#082      * Cleanup ;-)

#083      */

#084 

#085     if (hRgn != NULL)

#086     {

#087        NtGdiDeleteObject(hRgn);

#088     }

#089 

#090     return TRUE;

#091  }