《windows程序设计》滚动条Ⅰ（07）

代码如下：

program Project2;

{$APPTYPE CONSOLE}

{$R *.res}

uses
  System.SysUtils,
  windows,
  Winapi.Messages,
  Vcl.Dialogs;

var
  swndClass: tagWNDCLASS;
  message: MSG;
  mHwnd: hwnd;
  cxChar, cyChar: Integer;
  cxClient, cyClient: Integer;

function WindowProc(hwnd: hwnd; uMsg: UINT; wParam: wParam; lParam: lParam): LRESULT; stdcall;
var
  i: integer;
  uHdc: HDC;
  ps: tagPAINTSTRUCT;
  tm: tagTEXTMETRIC;
  str: string;
begin
  case uMsg of
    WM_CREATE:
      begin
        {获取窗口尺寸}
        cxclient := GetSystemMetrics(SM_CXSCREEN);
        cyclient := GetSystemMetrics(SM_CYSCREEN);
        {获取文本尺寸}
        uHdc := GetDC(hwnd);
        GetTextMetrics(uHdc, tm);
        ReleaseDC(hwnd, uHdc);
        cxChar := tm.tmAveCharWidth;
        cyChar := tm.tmHeight + tm.tmExternalLeading;
      end;
    WM_PAINT:
      begin
        uHdc := BeginPaint(hwnd, ps);
//        for i := 0 to 100 do
//        begin
//          str:='Hello world num:' + i.ToString;
//          TextOut(uHdc,0,i*cychar,PWideChar(str),Length(str));
//        end;
        EndPaint(hwnd, ps);
      end;
    WM_VSCROLL:
      begin
        case LOWORD(wParam) of
          SB_BOTTOM:
            begin
              {滚动到底部}
              uHdc := GetDC(hwnd);
              str := '滚动到底部';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_ENDSCROLL:
            begin
             {完成滚动，松开鼠标}
              uHdc := GetDC(hwnd);
              str := '完成滚动，松开鼠标';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_LINEDOWN:
            begin
              {向下滚动一行}
              uHdc := GetDC(hwnd);
              str := '向下滚动一行';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_LINEUP:
            begin
             {向上滚动一行}
              uHdc := GetDC(hwnd);
              str := '向上滚动一行';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_PAGEDOWN:
            begin
              {向下滚动一页}
              uHdc := GetDC(hwnd);
              str := '向下滚动一页';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_PAGEUP:
            begin
             {向上滚动一页}
              uHdc := GetDC(hwnd);
              str := '向上滚动一页';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_THUMBPOSITION:
            begin
             {用户拖动滚动条，且松开鼠标}
              uHdc := GetDC(hwnd);
              str := '用户拖动滚动条，且松开鼠标';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          SB_THUMBTRACK:
            begin
             {用户正在拖动滚动条}
              uHdc := GetDC(hwnd);
              str := '用户正在拖动滚动条';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
          sb_top:
            begin
              {滚动条到顶端}
              uHdc := GetDC(hwnd);
              str := '滚动条到顶端';
              TextOut(uHdc, 0, 0, PWideChar(str), Length(str));
              ReleaseDC(hwnd, uHdc);
            end;
        end;
      end;

  end;
  result := DefWindowProc(hwnd, uMsg, wParam, lParam);
end;

begin
  swndClass.cbClsExtra := 0; //窗口类扩展，无
  swndClass.cbWndExtra := 0; //窗口实例扩展
  swndClass.hbrBackground := COLOR_BACKGROUND; //窗口背景颜色黑色
  //LoadCursor()
  swndClass.hCursor := LoadCursor(0, IDC_ARROW); //窗口采用箭头光标
  swndClass.hIcon := LoadIcon(0, IDI_APPLICATION); //窗口最小化图标：采用缺省图标
  swndClass.hInstance := hInstance; //窗口实例句柄
  swndClass.lpfnWndProc := @WindowProc; //窗口处理函数
  swndClass.lpszClassName := 'myWnd'; //窗口类名
  swndClass.lpszMenuName := nil; //窗口菜单
  swndClass.style := CS_DBLCLKS; //窗口样式
  if RegisterClass(swndClass) = 0 then
  begin
    Writeln('windows class register error!');
    Exit;
  end;

  mHwnd := CreateWindowEx(0, 'myWnd', 'Delphi Windows', WS_OVERLAPPEDWINDOW or WS_VSCROLL or WS_HSCROLL,  {滚动条添加}
    CW_USEDEFAULT, CW_USEDEFAULT, 544, 375, HWND_DESKTOP, 0, hInstance, 0);

  ShowWindow(mHwnd, SW_SHOW);
  UpdateWindow(mHwnd);
  while GetMessage(message, 0, 0, 0) do
  begin
    TranslateMessage(message);
    DispatchMessage(message);
  end;

  Readln;
end.