#include <windows.h>
#include "SYSMETS.h"
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPreInstance, PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT("SysMets2");
HWND hwnd;
MSG msg;
WNDCLASS wndclass;
wndclass.style = CS_HREDRAW | CS_VREDRAW;//這種窗口類別樣式告訴windows，如果水平或者垂直大小發生改變，則強制更新顯示區域。
wndclass.lpfnWndProc = WndProc;
wndclass.cbClsExtra = 0;
wndclass.cbWndExtra = 0;
wndclass.hInstance = hInstance;
wndclass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
wndclass.lpszMenuName = NULL;
wndclass.lpszClassName = szAppName;
if (!RegisterClass(&wndclass))
{
MessageBox(NULL, TEXT("Thi program requires Windows NT!"), szAppName, MB_ICONERROR);
return 0;
}
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);
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return msg.wParam;
}
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM IParam)
{
static int cxChar, cxCaps, cyChar, cyClient, iVscrollPos;
HDC hdc;
int i, y;
PAINTSTRUCT ps;
TCHAR szBuffer[10];
TEXTMETRIC tm;
switch (message)
{
case WM_CREATE:
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);
SetScrollRange(hwnd, SB_VERT, 0, NUMLINES - 1, FALSE);//設置滾動條行數
SetScrollPos(hwnd, SB_VERT, iVscrollPos, TRUE);//設置滾動條的其實位置
return 0;
case WM_SIZE:
/*
當窗口大小改變時，windows給窗口消息處理程序發送了一個WM_SIZE消息。WM_SIZE消息必然跟著一個WM_PAINT消息。因為定義窗口類別的時候
指定窗口類別的樣式：CS_HREDRAW | CS_VERDRAW
窗口消息處理程序的LParam參數的低字組中包含顯示區域的寬度，高字組中包含顯示區域的高度
case WM_SIZE:
cxClient = LOWORD(IParam);
cyClient = HIWORD(IParam);
return 0;
LOWORD和HIWORD宏在Windows表頭文件WINDEF.H中 定義。這些宏的定義看起來像這樣：
#define LOWORD(I)((WORD)(I))
#define HIWORD(I)((WORD)(((DWORD)(I) >> 16 & 0xFFFF))
*/
cyClient = HIWORD(IParam);
return 0;
case WM_VSCROLL:
/*windows對滾動條的處理：
處理所有滾動條鼠標事件
當使用者在滾動條內單擊鼠標時，提供一種「反相顯示」的閃爍
當使用者在滾動條內拖動卷動方塊時，移動卷動方塊
為包含滾動條窗口的窗口消息處理程序發送滾動消息
*/
/*
和所有的消息一樣，WM_VSCROLL 和WM_HSCROLL也帶有wParam和IParam消息淡出，對于來自作為窗口的一部分額建立的滾動條消息
可以忽略IParam，它只用于作為子窗口而建立的滾動條（通常在對話框內）
wParam低字組指出鼠標對滾動條進行的操作。這個數值被看成一個通知碼，以SB開頭代表scroll bar的標志符。在WINUSER.H中定義
#define SB_LINEUP 0
#define SB_LINELEFT 0
#define SB_LINEDOWN 1
#define SB_LINERIGHT 1
#define SB_PAGEUP 2
#define SB_PAGELEFT 2
#define SB_PAGEDOWN 3
#define SB_PAGERIGHT 3
#define SB_THUMBPOSITION 4
#define SB_THUMBTRACK 5
#define SB_TOP 6
#define SB_LEFT 6
#define SB_BOTTOM 7
#define SB_RIGHT 7
#define SB_ENDSCROLL 8
*/
switch(LOWORD(wParam))
{
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);
break;
default:
break;
}
iVscrollPos = max (0, min(iVscrollPos, NUMLINES - 1));
if (iVscrollPos != GetScrollPos(hwnd, SB_VERT))//GetScrollPos獲取先前滾動條的位置
{
SetScrollPos(hwnd, SB_VERT, iVscrollPos, TRUE);//重設滾動條位置
InvalidateRect(hwnd, NULL, TRUE);//使整個窗口無效，InvalidateRect呼叫產生一個WM_PAINT消息，
}
return 0;
case WM_PAINT:
hdc = BeginPaint(hwnd, &ps);
for (i = 0; i < NUMLINES; i++)
{
y = cyChar * (i - iVscrollPos);
TextOut(hdc, 0, y, sysmetrics[i].szLabel, lstrlen(sysmetrics[i].szLabel));
TextOut(hdc, 22 * cxCaps, y, sysmetrics[i].szDesc, lstrlen(sysmetrics[i].szDesc));
SetTextAlign(hdc, TA_RIGHT | TA_TOP);
TextOut(hdc, 22 * cxCaps + 40 * cxChar, y, szBuffer,
wsprintf(szBuffer, TEXT("%5d"),
GetSystemMetrics (sysmetrics[i].Index)));
SetTextAlign(hdc, TA_LEFT | TA_TOP);
}
EndPaint(hwnd, &ps);
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, IParam);
}