Low-Level DigitalPaint: Initializing and Freeing a Paint Handle

Take the following steps to create a new paint handle:

  1. Run Microsoft Visual Studio 2005, select File New Project, and do the following:
    • Expand Visual C++ tree, if it is not already expanded.
    • Select Win32 from the sub tree.
    • Select Win32 Project from the right window.
    • In the Project name text box, specify Tutorial.
    • In the Location text box, specify the path of the project.
    • Click the OK button.
  2. In the overview window, click Next.
  3. In the Application Type step dialog box, do the following:
    • Select Windows application.
    • Be sure to un-check the Empty project checkbox.
    • Click the Finish button.
  4. Add the following Menu to the tutorial.rc:
    • In File menu:
      • &Open
      • with ID = IDM_FILE_OPEN
  5. In Tutorial.cpp replace the WndProc procedure with the following code:
    static LRESULT WINAPI WndProc ( HWND hWnd, L_UINT uMessage, WPARAM wParam, LPARAM lParam ) 
    { 
       static BITMAPHANDLE hBitmap ; 
       static RECT rcView ; 
       static L_INT nVScroll = 0 ; 
       static L_INT nHScroll = 0 ; 
       static L_INT nZoomFactor = 100 ; 
       static pPAINTHANDLE pPaint ; 
        
       switch( uMessage ) 
       { 
          case WM_CREATE: 
          if ( SUCCESS == L_PntInit ( &pPaint ) ) 
          { 
             return 0L ; 
          } 
          else 
          { 
             return -1L ; 
          } 
           
           
          case WM_DESTROY: 
          if ( hBitmap.Flags.Allocated ) 
          { 
             L_FreeBitmap( &hBitmap ) ; 
          } 
           
          if ( SUCCESS == L_PntIsValid ( pPaint ) ) 
          { 
             L_PntFree ( pPaint ) ; 
          } 
           
          PostQuitMessage ( 0 ) ; 
           
          return 0L ; 
           
          case WM_SIZE: 
          OnSize ( hWnd, 
          &hBitmap, 
          &rcView, 
          LOWORD ( lParam ), 
          HIWORD ( lParam ), 
          nZoomFactor, 
          &nHScroll, 
          &nVScroll ) ; 
          break ; 
           
          case WM_HSCROLL: 
          OnHScroll ( hWnd, 
          LOWORD ( wParam ), 
          nZoomFactor, 
          &rcView, 
          &nHScroll, 
          &nVScroll ) ; 
          break ; 
           
          case WM_VSCROLL: 
          OnVScroll ( hWnd, 
          LOWORD ( wParam ), 
          nZoomFactor, 
          &rcView, 
          &nHScroll, 
          &nVScroll ) ; 
           
          break ; 
           
          case WM_PAINT: 
          OnPaint ( hWnd, &hBitmap, &rcView) ; 
          break ; 
           
          case WM_COMMAND: 
          switch( LOWORD( wParam ) ) 
          { 
             case IDM_FILE_OPEN: 
             { 
                BITMAPHANDLE hTempBitmap ; 
                HDC hDC ; 
                 
                 
                if ( OnOpen ( hWnd, &hTempBitmap ) ) 
                { 
                   if ( hBitmap.Flags.Allocated ) 
                   { 
                      L_FreeBitmap( &hBitmap ) ; 
                   } 
                    
                   L_CopyBitmapHandle( &hBitmap, &hTempBitmap, sizeof(BITMAPHANDLE)) ; 
                    
                   hDC = GetDC ( hWnd ) ; 
                    
                    
                   ReleaseDC ( hWnd, hDC ) ; 
                    
                   {//ADJUST WINDOW SIZE 
                       
                      RECT  rcWindow ; 
                      L_INT nWidth, nHeight ; 
                       
                       
                      SystemParametersInfo ( SPI_GETWORKAREA, 0, &rcWindow, 0 ) ; 
                       
                      nWidth = min ( MulDiv ( BITMAPWIDTH ( &hBitmap ), nZoomFactor, 100 ), 
                      ( rcWindow.right  - rcWindow.left ) ) ; 
                       
                      nHeight = min ( MulDiv ( BITMAPHEIGHT ( &hBitmap ), nZoomFactor, 100 ), 
                      ( rcWindow.bottom - rcWindow.top  ) ) ; 
                       
                      MoveWindow ( hWnd, 
                      0, 
                      0, 
                      nWidth, 
                      nHeight, 
                      TRUE ) ; 
                       
                   }//ADJUST WINDOW SIZE 
                    
                   InvalidateRect ( hWnd, NULL, TRUE ) ; 
                } 
             } 
              
             return 0L ; 
              
             case IDM_EXIT: 
             PostMessage ( hWnd, WM_CLOSE, 0, 0 ) ; 
             return 0L ; 
          } 
           
          break ; 
       } 
        
       return DefWindowProc ( hWnd, uMessage, wParam, lParam ) ; 
    } 
  6. Add the following code right before WndProc procedure:
    static L_VOID OnSize 
    ( 
    HWND hWnd, 
    pBITMAPHANDLE pBitmap, 
    LPRECT prcView, 
    L_INT cx, 
    L_INT cy, 
    L_INT nZoom, 
    L_INT *pnHScroll, 
    L_INT *pnVScroll 
    ) 
    { 
       SCROLLINFO si ; 
       L_INT      nXOffset, nYOffset ; 
        
       if ( NULL != pBitmap && pBitmap->Flags.Allocated ) 
       { 
          si.cbSize = sizeof ( SCROLLINFO ) ; 
          si.fMask  = SIF_ALL ; 
           
          // vertical scroll. 
          GetScrollInfo ( hWnd, SB_VERT, &si ) ; 
          si.nMin  = 0 ; 
          si.nMax  = BITMAPHEIGHT ( pBitmap ) ; 
          si.nPage = MulDiv ( cy, 100, nZoom ) ; 
           
          SetScrollInfo ( hWnd, SB_VERT, &si, TRUE ) ; 
           
          GetScrollInfo ( hWnd, SB_VERT, &si ) ; 
           
          *pnVScroll = si.nPos ; 
           
          // horizontal scroll 
          GetScrollInfo ( hWnd, SB_HORZ, &si ) ; 
          si.nMin  = 0 ; 
          si.nMax  = BITMAPWIDTH ( pBitmap ) ; 
          si.nPage = MulDiv ( cx, 100, nZoom ) ; 
           
          SetScrollInfo ( hWnd, SB_HORZ, &si, TRUE ) ; 
           
          GetScrollInfo ( hWnd, SB_HORZ, &si ) ; 
           
          *pnHScroll = si.nPos ; 
       } 
       else 
       { 
          si.cbSize = sizeof ( SCROLLINFO ) ; 
          si.fMask  = SIF_RANGE ; 
          si.nMin   = 0 ; 
          si.nMax   = 0 ; 
           
          SetScrollInfo ( hWnd, SB_VERT, &si, TRUE ) ; 
          SetScrollInfo ( hWnd, SB_HORZ, &si, TRUE ) ; 
           
          *pnHScroll = 0 ; 
          *pnVScroll = 0 ; 
       } 
        
       // set the painting rectangel. 
       SetRect ( prcView, 0, 0, BITMAPWIDTH ( pBitmap ), BITMAPHEIGHT ( pBitmap ) ) ; 
        
       if ( nZoom < 100 ) 
       { 
          nXOffset = MulDiv ( *pnHScroll, 100, nZoom ) ; 
          nYOffset = MulDiv ( *pnVScroll, 100, nZoom ) ; 
       } 
       else 
       { 
          nXOffset = *pnHScroll ; 
          nYOffset = *pnVScroll ; 
       } 
        
       OffsetRect ( prcView, - nXOffset, - nYOffset ) ; 
        
       prcView->left   = MulDiv ( prcView->left,   nZoom, 100 ) ; 
       prcView->top    = MulDiv ( prcView->top,    nZoom, 100 ) ; 
       prcView->right  = MulDiv ( prcView->right,  nZoom, 100 ) ; 
       prcView->bottom = MulDiv ( prcView->bottom, nZoom, 100 ) ; 
    } 
     
    L_VOID OnHScroll 
    ( 
    HWND hWnd, 
    L_UINT code, 
    L_INT nZoom, 
    LPRECT prcView, 
    L_INT *pnHScroll, 
    L_INT *pnVScroll 
    ) 
    { 
       SCROLLINFO si ; 
        
        
       si.cbSize = sizeof (SCROLLINFO) ; 
       si.fMask  = SIF_ALL ; 
       GetScrollInfo (hWnd, SB_HORZ, &si) ; 
        
       *pnHScroll = si.nPos ; 
        
       switch ( code ) 
       { 
          case SB_LINELEFT: 
          si.nPos -= 1 ; 
          break ; 
           
          case SB_LINERIGHT: 
          si.nPos += 1 ; 
          break ; 
           
          case SB_PAGELEFT: 
          si.nPos -= si.nPage ; 
          break ; 
           
          case SB_PAGERIGHT: 
          si.nPos += si.nPage ; 
          break ; 
           
          case SB_THUMBTRACK: 
          si.nPos = si.nTrackPos ; 
          break ; 
           
    default: 
          break ; 
       } 
        
       si.fMask = SIF_POS ; 
       SetScrollInfo (hWnd, SB_HORZ, &si, TRUE) ; 
       GetScrollInfo (hWnd, SB_HORZ, &si) ; 
        
       if ( si.nPos != *pnHScroll ) 
       { 
          L_INT dxUpdate ; 
           
           
          // update screen. 
          if ( nZoom >= 100 ) 
          { 
             dxUpdate = MulDiv ( ( *pnHScroll - si.nPos ), nZoom, 100 ) ; 
          } 
          else 
          { 
             dxUpdate = *pnHScroll - si.nPos ; 
          } 
           
          // update screen. 
          OffsetRect ( prcView, dxUpdate, 0 ) ; 
           
          ScrollWindow ( hWnd, dxUpdate, 0, NULL, NULL ) ; 
           
          *pnHScroll = si.nPos ; 
           
          UpdateWindow ( hWnd ) ; 
       } 
    } 
     
    L_VOID OnVScroll 
    ( 
    HWND hWnd, 
    L_UINT code, 
    L_INT nZoom, 
    LPRECT prcView, 
    L_INT *pnHScroll, 
    L_INT *pnVScroll 
    ) 
    { 
       SCROLLINFO si ; 
        
        
       si.cbSize = sizeof ( SCROLLINFO ) ; 
       si.fMask  = SIF_ALL ; 
       GetScrollInfo (hWnd, SB_VERT, &si) ; 
        
       *pnVScroll = si.nPos ; 
        
       switch ( code ) 
       { 
          case SB_LINEUP: 
          si.nPos -= 1 ; 
          break ; 
           
          case SB_LINEDOWN: 
          si.nPos += 1 ; 
          break ; 
           
          case SB_PAGEUP: 
          si.nPos -= si.nPage ; 
          break ; 
           
          case SB_PAGEDOWN: 
          si.nPos += si.nPage ; 
          break ; 
           
          case SB_THUMBTRACK: 
          si.nPos = si.nTrackPos ; 
          break ; 
           
    default: 
          break ; 
       } 
        
       si.fMask = SIF_POS ; 
       SetScrollInfo ( hWnd, SB_VERT, &si, TRUE ) ; 
       GetScrollInfo ( hWnd, SB_VERT, &si ) ; 
        
       if ( si.nPos != *pnVScroll ) 
       { 
          L_INT dyUpdate ; 
           
           
          // update screen. 
          if ( nZoom >= 100 ) 
          { 
             dyUpdate = MulDiv ( ( *pnVScroll - si.nPos ), nZoom, 100 ) ; 
          } 
          else 
          { 
             dyUpdate = *pnVScroll - si.nPos ; 
          } 
           
          // update screen. 
          OffsetRect ( prcView, 0, dyUpdate ) ; 
           
          ScrollWindow ( hWnd, 0, dyUpdate, NULL, NULL ) ; 
           
          *pnVScroll = si.nPos ; 
           
          UpdateWindow ( hWnd ) ; 
       } 
    } 
     
    L_VOID OnPaint 
    ( 
    HWND hWnd, 
    pBITMAPHANDLE pBitmap, 
    LPRECT prcView 
    ) 
    { 
       HDC hDC ; 
       PAINTSTRUCT ps ; 
       HPALETTE hOldPal = NULL; 
       HPALETTE hPalette; 
        
       hDC = BeginPaint (hWnd, &ps) ; 
        
       if ( pBitmap->Flags.Allocated ) 
       { 
          hPalette = L_CreatePaintPalette( hDC, pBitmap ) ; 
          if ( hPalette ) 
          { 
             hOldPal = SelectPalette ( hDC, hPalette, TRUE ) ; 
             RealizePalette ( hDC ) ; 
          } 
           
          L_PaintDC( hDC, pBitmap, NULL, NULL, prcView, &ps.rcPaint, SRCCOPY ) ; 
           
          if ( NULL != hOldPal ) 
          { 
             SelectPalette ( hDC, hOldPal, TRUE ) ; 
             DeleteObject(hPalette); 
          } 
       } 
        
       EndPaint (hWnd, &ps) ; 
    } 
     
     
    static L_BOOL OnOpen ( HWND hWnd, pBITMAPHANDLE pBitmap ) 
    { 
       static L_INT  nOpenIndex = 0 ; 
       OPENFILENAME  OpenFileName ; 
       L_TCHAR        szFile [ MAX_PATH ] = TEXT("\0") ; 
       L_TCHAR        szFileTitle [ MAX_PATH ] = TEXT("\0") ; 
       L_TCHAR        szOpenFileFilter [ ] = {TEXT("ALL\0")TEXT("*.*\0")} ; 
       OPENDLGPARAMS  FileOpenParams ; 
       BITMAPHANDLE   hThumb ; 
        
        
        
       memset ( &FileOpenParams, 0, sizeof ( OPENDLGPARAMS ) ) ; 
        
       lstrcpy ( szFile, TEXT("") ) ; 
        
       L_InitBitmap( pBitmap, sizeof(BITMAPHANDLE), 0, 0, 0 ) ; 
        
       L_InitBitmap( &hThumb, sizeof(BITMAPHANDLE), 0, 0, 0 ) ; 
        
       OpenFileName.lStructSize = sizeof(OPENFILENAME); 
       OpenFileName.hwndOwner = hWnd; 
       OpenFileName.lpstrFilter = szOpenFileFilter; 
       OpenFileName.lpstrCustomFilter = NULL; 
       OpenFileName.nMaxCustFilter = 0; 
       OpenFileName.nFilterIndex = nOpenIndex; 
       OpenFileName.nMaxFile = sizeof(szFile); 
       OpenFileName.lpstrFile = szFile; 
       OpenFileName.nMaxFileTitle = sizeof(szFileTitle); 
       OpenFileName.lpstrFileTitle = szFileTitle; 
       OpenFileName.lpstrInitialDir = NULL; 
       OpenFileName.lpstrTitle = TEXT("Open a File"); 
       OpenFileName.nFileOffset = 0; 
       OpenFileName.nFileExtension = 0; 
       OpenFileName.lpstrDefExt = NULL; 
       OpenFileName.lpfnHook = NULL; 
       OpenFileName.Flags = OFN_LONGNAMES; 
        
        
       FileOpenParams.uStructSize = sizeof(OPENDLGPARAMS); 
       FileOpenParams.uDlgFlags =   DLG_OPEN_SHOW_PROGRESSIVE | 
       DLG_OPEN_SHOW_MULTIPAGE | 
       DLG_OPEN_SHOW_LOADROTATED | 
       DLG_OPEN_SHOW_LOADCOMPRESSED | 
       DLG_OPEN_SHOW_FILEINFO | 
       DLG_OPEN_SHOW_PREVIEW | 
       DLG_OPEN_ENABLESIZING | 
       DLG_OPEN_USEFILESTAMP | 
       DLG_OPEN_LOADBITMAP; 
        
       if (L_DlgOpen( hWnd, &OpenFileName, &FileOpenParams) == SUCCESS_DLG_OK) 
       { 
          L_CopyBitmap(pBitmap, FileOpenParams.pFileData[0].pBitmap, sizeof(BITMAPHANDLE)); 
          L_FreeBitmap(FileOpenParams.pFileData[0].pBitmap); 
          nOpenIndex = OpenFileName.nFilterIndex; 
           
          L_FreeBitmap( &hThumb ); 
           
          L_ChangeBitmapViewPerspective(pBitmap, pBitmap, sizeof(BITMAPHANDLE), TOP_LEFT ); 
           
          return TRUE ; 
       } 
       else 
       { 
          return FALSE ; 
       } 
    } 
  7. Add the following lines in _tWinMain after  HACCEL hAccelTable;
    UNLOCKSUPPORT ( ) ; 
    L_DlgInit(DLG_INIT_COLOR); 
  8. In stdafx.h add the following headers: (keep in mind, you may have to change the path to where the header files reside):
    #include <commdlg.h> 
      
    #include "..\..\..\..\..\Include\ltpnt.h" 
    #include "..\..\..\..\..\Include\l_bitmap.h" 
    #include "..\..\..\..\..\Include\ltdlg.h" 
  9. Add the following code before the function "PostQuitMessage" call in the WM_DESTROY message in the WndProc function:

    if ( SUCCESS == L_PntIsValid ( pPaint ) ) 
    { 
       L_PntFree ( pPaint ) ; 
    } 

  10. Create a new file called Imports.cpp in place it beside your project files.

    • In the Project Workspace, click the Solution Explorer tab.
    • Double-click the ToolbarTutorial folder to open it.
    • Right-click the Source files folder and select Add New item.
    • Right-click on the Source file
    • Expand Visual C++ tree, if it is not already expanded.
    • Select Code from the sub tree.
    • Select C++ File (.cpp) from the right window.
    • In the name text box, specify Imports.
    • Click the OK button.
    • Double-click the Imports.cpp in the solution Explorer and add the following lines: (keep in mind, you may have to change the path to where the header files reside)
      #include "StdAfx.h" 
        
      #if defined(FOR_WIN64) 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\x64\\Ltkrn_x.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\x64\\Ltdis_x.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\x64\\Ltdlgkrn_x.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\x64\\Ltdlgfile_x.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\x64\\Ltpnt_x.lib") 
      #elif defined(FOR_WIN32) 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\Win32\\Ltkrn_u.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\Win32\\Ltdis_u.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\Win32\\Ltdlgkrn_u.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\Win32\\Ltdlgfile_u.lib") 
         #pragma comment(lib, "..\\..\\..\\..\\..\\Lib\\CDLLVC10\\Win32\\Ltpnt_u.lib") 
      #endif // #if defined(FOR_WIN64) 
  11. Compile and run the project by selecting Build->Execute tutorial.exe from the menu.
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