Windows學習筆記——SYSMETS2

在SYSMETS1程序的基礎上，爲窗口添加最重要的元素之一 ——滾動條.

代碼註釋，如下：

//SYSMETS2.cpp
#include<windows.h>
#include"sysmets.h"

LRESULT CALLBACK WndProc(HWND hwnd,UINT message,WPARAM wParam,LPARAM lParam);


int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     PSTR     szCmdLine,
                     int       iCmdShow)
{
    static TCHAR szAppName[]=TEXT("SysMets2");
    HWND hWnd;
    MSG msg;
    WNDCLASS wndclass;

    //填充窗口類的10個字段
    wndclass.cbClsExtra=0;
    wndclass.cbWndExtra=0;

    wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH);

    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION);

    wndclass.hInstance=hInstance;

    wndclass.lpfnWndProc=WndProc;                                 //窗口過程處理函數
    wndclass.lpszClassName=szAppName;                             //窗口類名

    wndclass.lpszMenuName=NULL;

    wndclass.style=CS_HREDRAW|CS_VREDRAW;

    //註冊窗口類
    int retVal=RegisterClass(&wndclass); //失敗，返回0；成功，返回非0
    if(retVal == 0)
    {
        MessageBox(NULL,TEXT("This progrom requires Windows NT !"),szAppName,MB_ICONERROR);
        return 0;
    }

    //創建窗口
    hWnd=CreateWindow(szAppName,
                      TEXT("Get System Metrics No.2"),
                      WS_OVERLAPPEDWINDOW | WS_VSCROLL,
                      CW_USEDEFAULT,CW_USEDEFAULT,
                      CW_USEDEFAULT,CW_USEDEFAULT,
                      NULL,NULL,hInstance,NULL);

    ShowWindow(hWnd,iCmdShow);
    UpdateWindow(hWnd);

    //獲取消息
    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }


    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    static int cxChar,cxCaps,cyChar,cyClient,iVscrollPos;
    HDC hdc;
    int i;
    PAINTSTRUCT ps;
    TCHAR szBuffer[10];
    TEXTMETRIC tm;

    //消息處理
    switch(message){

    case WM_CREATE: //CreateWindows函數時，產生該消息(通過調用API產生的消息，均是非隊列消息)
        hdc=GetDC(hWnd);

        GetTextMetrics(hdc,&tm);
        cxChar=tm.tmAveCharWidth;
        cxCaps=(tm.tmPitchAndFamily & 1? 3:2)* cxChar/2;
        cyChar=tm.tmHeight+tm.tmExternalLeading;

        ReleaseDC(hWnd,hdc);

        //設置滾動條的範圍和滑塊的位置
        SetScrollRange(hWnd,SB_VERT,0,NUMLINES-1,FALSE);
        SetScrollPos(hWnd,SB_VERT,iVscrollPos,TRUE);
        return 0;

    case WM_SIZE: //(窗口大小發生變化，產生該消息；緊接着產生WM_PAINT消息)
        cyClient=HIWORD(lParam); //lParam：低字位，表示客戶區的寬度；高字位，是高度.
        return 0;

    case WM_VSCROLL:
        switch(LOWORD(wParam)) //wParam：低字位，表示鼠標在滾動條上的動作
        {
        case SB_LINEUP:
            iVscrollPos-=1;
            break;
        case SB_LINEDOWN:
            iVscrollPos+=1;
            break;
        case SB_PAGEUP:
            iVscrollPos-=cyClient/cyChar;
            break;
        case SB_PAGEDOWN:
            iVscrollPos+=cyClient/cyChar;
            break;

        case SB_THUMBPOSITION:
            iVscrollPos=HIWORD(wParam); //高字位，表示表示(翻閱之後)滑塊的位置
            break;
        default:
            break;
        }

        //如果滑塊位置改變，重設爲iVscrollPos
        iVscrollPos=max(0,min(iVscrollPos,NUMLINES-1));
        if(GetScrollPos(hWnd,SB_VERT) != iVscrollPos)
        {
            SetScrollPos(hWnd,SB_VERT,iVscrollPos,TRUE);
            InvalidateRect(hWnd,NULL,TRUE);
        }
        return 0;


    case WM_PAINT:
        hdc=BeginPaint(hWnd,&ps);


        for(i=0;i<NUMLINES;i++)
        {
            TextOut(hdc,0,cyChar*(i-iVscrollPos),sysmetrics[i].szLabel,lstrlen(sysmetrics[i].szLabel));
            TextOut(hdc,22*cxCaps,cyChar*(i-iVscrollPos),sysmetrics[i].szDesc,lstrlen(sysmetrics[i].szDesc));

            SetTextAlign(hdc,TA_LEFT|TA_TOP);
            TextOut(hdc,
                    22*cxCaps+40*cxChar,cyChar*(i-iVscrollPos),
                    szBuffer,wsprintf(szBuffer,TEXT("%5d"),GetSystemMetrics(sysmetrics[i].iIndex)));
            SetTextAlign(hdc,TA_LEFT|TA_TOP);
        }

        EndPaint(hWnd,&ps);
        return 0;

    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hWnd,message,wParam,lParam);
}

 

 

函數原型：

1.

ATOM RegisterClass(
  const WNDCLASS* lpWndClass
); 

typedef  WORD                ATOM;

typedef  unsigned short      WORD;

2.

BOOL InvalidateRect( 
  HWND hWnd, 
  const RECT* lpRect, 
  BOOL bErase
); 

const RECT* lpRect, //爲NULL,表示整個客戶區爲更新區域

BOOL bErase //如果爲TRUE,擦除背景顏色；否則，不擦除.

3.

BOOL SetScrollRange( 
  HWND hWnd, 
  int nBar, 
  int nMinPos, 
  int nMaxPos, 
  BOOL bRedraw 
); 

int nBar,  //SB_VERT | SB_HORZ
BOOL bRedraw //一般情況下，滾動條的範圍不需要重繪

int SetScrollPos( 
  HWND hWnd, 
  int nBar, 
  int nPos, 
  BOOL bRedraw 
); 

BOOL bRedraw //滑塊的位置，每次更新後必須重繪