#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;//这种窗口类别样式告诉windows，如果水平或者垂直大小发生改变，则强制更新显示区域。
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);//设置滚动条行数
SetScrollPos(hwnd, SB_VERT, iVscrollPos, TRUE);//设置滚动条的其实位置
return 0;
case WM_SIZE:
/*
当窗口大小改变时，windows给窗口消息处理程序发送了一个WM_SIZE消息。WM_SIZE消息必然跟着一个WM_PAINT消息。因为定义窗口类别的时候
指定窗口类别的样式：CS_HREDRAW | CS_VERDRAW
窗口消息处理程序的LParam参数的低字组中包含显示区域的宽度，高字组中包含显示区域的高度
case WM_SIZE:
cxClient = LOWORD(IParam);
cyClient = HIWORD(IParam);
return 0;
LOWORD和HIWORD宏在Windows表头文件WINDEF.H中 定义。这些宏的定义看起来像这样：
#define LOWORD(I)((WORD)(I))
#define HIWORD(I)((WORD)(((DWORD)(I) >> 16 & 0xFFFF))
*/
cyClient = HIWORD(IParam);
return 0;
case WM_VSCROLL:
/*windows对滚动条的处理：
处理所有滚动条鼠标事件
当使用者在滚动条内单击鼠标时，提供一种「反相显示」的闪烁
当使用者在滚动条内拖动卷动方块时，移动卷动方块
为包含滚动条窗口的窗口消息处理程序发送滚动消息
*/
/*
和所有的消息一样，WM_VSCROLL 和WM_HSCROLL也带有wParam和IParam消息淡出，对于来自作为窗口的一部分额建立的滚动条消息
可以忽略IParam，它只用于作为子窗口而建立的滚动条（通常在对话框内）
wParam低字组指出鼠标对滚动条进行的操作。这个数值被看成一个通知码，以SB开头代表scroll bar的标志符。在WINUSER.H中定义
#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获取先前滚动条的位置
{
SetScrollPos(hwnd, SB_VERT, iVscrollPos, TRUE);//重设滚动条位置
InvalidateRect(hwnd, NULL, TRUE);//使整个窗口无效，InvalidateRect呼叫产生一个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);
}