2 hustis1403 HUSTIS1403 于 2016.02.26 13:04 提问

为什么我的程序一开始窗口空白,需要改变大小或者最小化,谁能解释这个和一般的程序的不同

#include
#include

#define NUM 1000
#define TWOPI (2 * 3.14159)

LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);

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

wndclass.style = CS_HREDRAW | CS_VREDRAW;
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("Program requires Windows NT!"),
        szAppName, MB_ICONERROR);
    return 0;
}

hwnd = CreateWindow(szAppName, TEXT("Sine Wave Using Polyline"),
    WS_OVERLAPPEDWINDOW,
    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 lParam)
{
static int cxClient, cyClient;
HDC hdc;
int i;
PAINTSTRUCT ps;
POINT apt[NUM];

switch (message)
{
case WM_SIZE:
    cxClient = LOWORD(lParam);
    cyClient = HIWORD(lParam);
    return 0;

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

    MoveToEx(hdc, 0, cyClient / 2, NULL);
    LineTo(hdc, cxClient, cyClient / 2);

    for (i = 0; i < NUM; i++)
    {
        apt[i].x = i * cxClient / NUM;
        apt[i].y = (int)(cyClient / 2 * (1 - sin(TWOPI * i / NUM)));
    }

    Polyline(hdc, apt, NUM);
    return 0;

case WM_DESTROY:
    PostQuitMessage(0);
    return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);

}

1个回答

caozhy
caozhy   Ds   Rxr 2016.03.08 12:06

调用InvalidateRect强制刷新下客户区

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准确详细的回答,更有利于被提问者采纳,从而获得C币。复制、灌水、广告等回答会被删除,是时候展现真正的技术了!