base/applications/taskmgr/proclist.c

   1 /*
   2  *  ReactOS Task Manager
   3  *
   4  *  proclist.c
   5  *
   6  *  Copyright (C) 1999 - 2001  Brian Palmer  <brianp@reactos.org>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  21  */
  22
  23 #include "precomp.h"
  24
  25 INT_PTR CALLBACK    ProcessListWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam);
  26
  27 WNDPROC             OldProcessListWndProc;
  28
  29
  30 INT_PTR CALLBACK
  31 ProcessListWndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
  32 {
  33     HBRUSH  hbrBackground;
  34     RECT    rcItem;
  35     RECT    rcClip;
  36     HDC     hDC;
  37     int     DcSave;
  38
  39     switch (message)
  40     {
  41     case WM_ERASEBKGND:
  42
  43         /*
  44          * The list control produces a nasty flicker
  45          * when the user is resizing the window because
  46          * it erases the background to white, then
  47          * paints the list items over it.
  48          *
  49          * We will clip the drawing so that it only
  50          * erases the parts of the list control that
  51          * show only the background.
  52          */
  53
  54         /*
  55          * Get the device context and save it's state
  56          * to be restored after we're done
  57          */
  58         hDC = (HDC) wParam;
  59         DcSave = SaveDC(hDC);
  60
  61         /*
  62          * Get the background brush
  63          */
  64         hbrBackground = (HBRUSH)(LONG_PTR) GetClassLongPtrW(hWnd, GCL_HBRBACKGROUND);
  65
  66         /*
  67          * Calculate the clip rect by getting the RECT
  68          * of the first and last items and adding them up.
  69          *
  70          * We also have to get the item's icon RECT and
  71          * subtract it from our clip rect because we don't
  72          * use icons in this list control.
  73          */
  74         rcClip.left = LVIR_BOUNDS;
  75         SendMessageW(hWnd, LVM_GETITEMRECT, 0, (LPARAM)&rcClip);
  76         rcItem.left = LVIR_BOUNDS;
  77         SendMessageW(hWnd, LVM_GETITEMRECT, ListView_GetItemCount(hWnd) - 1, (LPARAM)&rcItem);
  78         rcClip.bottom = rcItem.bottom;
  79         rcClip.right = rcItem.right;
  80         rcItem.left = LVIR_ICON;
  81         SendMessageW(hWnd, LVM_GETITEMRECT, 0, (LPARAM)&rcItem);
  82         rcClip.left = rcItem.right;
  83
  84         /*
  85          * Now exclude the clip rect
  86          */
  87         ExcludeClipRect(hDC, rcClip.left, rcClip.top, rcClip.right, rcClip.bottom);
  88
  89         /*
  90          * Now erase the background
  91          *
  92          *
  93          * FIXME: Should I erase it myself or
  94          * pass down the updated HDC and let
  95          * the default handler do it?
  96          */
  97         GetClientRect(hWnd, &rcItem);
  98         FillRect(hDC, &rcItem, hbrBackground);
  99
 100         /*
 101          * Now restore the DC state that we
 102          * saved earlier
 103          */
 104         RestoreDC(hDC, DcSave);
 105
 106         return TRUE;
 107     }
 108
 109     /*
 110      * We pass on all messages except WM_ERASEBKGND
 111      */
 112     return CallWindowProcW(OldProcessListWndProc, hWnd, message, wParam, lParam);
 113 }