apps/tests/wm_erasebkgnd/wm_erasebkgnd.cpp

   1
   2 // ------------------------------------------------------------------
   3 // Windows 2000 Graphics API Black Book
   4 // Chapter 2 - CD-ROM (WM_ERASEBKGND Demo)
   5 //
   6 // Created by Damon Chandler <dmc27@ee.cornell.edu>
   7 // Updates can be downloaded at: <www.coriolis.com>
   8 //
   9 // Please do not hesistate to e-mail me at dmc27@ee.cornell.edu
  10 // if you have any questions about this code.
  11 // ------------------------------------------------------------------
  12
  13 //*********************************************************//
  14 //                                                         //
  15 // SYNOPSIS:                                               //
  16 //   This sample project demonstrates how to render        //
  17 //   a background image in response to the WM_ERASEBKGND   //
  18 //   message.  It also shows how to create a transparent   //
  19 //   static (text) control by handling the                 //
  20 //   WM_CTLCOLORSTATIC message.                            //
  21 //                                                         //
  22 //*********************************************************//
  23
  24
  25 //>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
  26 #include <windows.h>
  27 //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
  28
  29
  30 HINSTANCE HInst;
  31 const char* WndClassName = "GMainWnd";
  32 LRESULT CALLBACK MainWndProc(HWND HWnd, UINT Msg, WPARAM WParam,
  33    LPARAM LParam);
  34
  35
  36 int APIENTRY WinMain(HINSTANCE HInstance, HINSTANCE HPrevInstance,
  37     LPTSTR lpCmdLine, int nCmdShow)
  38 {
  39    HInst = HInstance;
  40
  41    WNDCLASS wc;
  42    memset(&wc, 0, sizeof(WNDCLASS));
  43
  44    wc.style = CS_VREDRAW | CS_HREDRAW | CS_DBLCLKS;
  45    wc.lpfnWndProc = MainWndProc;
  46    wc.hInstance = HInstance;
  47    wc.hCursor = LoadCursor(NULL, IDC_ARROW);
  48    wc.hbrBackground =
  49       reinterpret_cast<HBRUSH>(COLOR_BTNFACE + 1);
  50    wc.lpszClassName = WndClassName;
  51
  52    if (RegisterClass(&wc))
  53    {
  54       HWND HWnd =
  55          CreateWindow(WndClassName,
  56                       TEXT("WM_ERASEBKGND Demo"),
  57                       WS_OVERLAPPEDWINDOW | WS_CAPTION |
  58                       WS_VISIBLE | WS_CLIPSIBLINGS,
  59                       CW_USEDEFAULT, CW_USEDEFAULT, 205, 85,
  60                       NULL, NULL, HInstance, NULL);
  61
  62       if (HWnd)
  63       {
  64          ShowWindow(HWnd, nCmdShow);
  65          UpdateWindow(HWnd);
  66
  67          MSG msg;
  68          while (GetMessage(&msg, NULL, 0, 0))
  69          {
  70              TranslateMessage(&msg);
  71              DispatchMessage(&msg);
  72          }
  73       }
  74     }
  75     return 0;
  76 }
  77 //------------------------------------------------------------------
  78
  79
  80 // static text and bitmap-related variables
  81 HWND HStatic;
  82 HDC HMemDC;
  83 HBITMAP HBmp, HOldBmp;
  84 const char* filename = "BACKBITMAP.BMP";
  85
  86 LRESULT CALLBACK MainWndProc(HWND HWnd, UINT Msg, WPARAM WParam,
  87    LPARAM LParam)
  88 {
  89    switch (Msg)
  90    {
  91       case WM_CREATE:
  92       {
  93          HStatic =
  94             CreateWindow(TEXT("STATIC"), TEXT("Static Text"),
  95                          WS_CHILD | WS_VISIBLE | SS_CENTER,
  96                          10, 20, 175, 30,
  97                          HWnd, NULL, HInst, NULL);
  98
  99          // create a memory DC compatible with the screen
 100          HMemDC = CreateCompatibleDC(NULL);
 101          if (HMemDC)
 102          {
 103             // load a DDB from file
 104             HBmp = static_cast<HBITMAP>(
 105                LoadImage(HInst, filename, IMAGE_BITMAP,
 106                          0, 0, LR_LOADFROMFILE)
 107                );
 108             if (HBmp)
 109             {
 110                // associate the DDB with the memory DC
 111                HOldBmp = static_cast<HBITMAP>(
 112                   SelectObject(HMemDC, HBmp)
 113                   );
 114             }
 115          }
 116       }
 117       case WM_CTLCOLORSTATIC:
 118       {
 119          if (reinterpret_cast<HWND>(LParam) == HStatic)
 120          {
 121             HDC HStaticDC = reinterpret_cast<HDC>(WParam);
 122             SetBkMode(HStaticDC, TRANSPARENT);
 123
 124             return reinterpret_cast<LRESULT>(
 125                GetStockObject(NULL_BRUSH)
 126                );
 127          }
 128          break;
 129       }
 130       case WM_ERASEBKGND:
 131       {
 132          BITMAP bmp;
 133          if (GetObject(HBmp, sizeof(BITMAP), &bmp))
 134          {
 135             RECT RClient;
 136             GetClientRect(HWnd, &RClient);
 137
 138             HDC Hdc = reinterpret_cast<HDC>(WParam);
 139             SetStretchBltMode(Hdc, COLORONCOLOR);
 140
 141             //
 142             // TODO: add palette handling code for
 143             // palettized displays (see Chapter 9)...
 144             //
 145
 146             // render the background image
 147             StretchBlt(Hdc, 0, 0,
 148                        RClient.right - RClient.left,
 149                        RClient.bottom - RClient.top,
 150                        HMemDC, 0, 0, bmp.bmWidth, bmp.bmHeight,
 151                        SRCCOPY);
 152             return TRUE;
 153          }
 154          break;
 155       }
 156       case WM_DESTROY:
 157       {
 158          if (HBmp)
 159          {
 160             // free the bitmap
 161             DeleteObject(SelectObject(HMemDC, HOldBmp));
 162          }
 163          // free the memory DC
 164          DeleteDC(HMemDC);
 165
 166          PostQuitMessage(0);
 167          return 0;
 168       }
 169    }
 170    return DefWindowProc(HWnd, Msg, WParam, LParam);
 171 }
 172 //------------------------------------------------------------------
 173
 174
 175