最近實驗室要我們研究，兩隻手機透過wifi傳影像，我想說先試試用電腦跟平板對傳影像，所以就先處理電腦這端WebCam的程式，沒想到還蠻簡單的。主要是要熟悉C語言跟呼叫dll的部分，還有剪貼簿的操作。

程式碼如下：

#include<windows.h>
#define ID_MYTIMER 100
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
ATOM InitApp(HINSTANCE);
BOOL InitInstance(HINSTANCE hInst, int);
BOOL LoadWebCamAPI(void);


TCHAR szClassName[] = TEXT("WebCam");
INT_PTR (*CapturePicture)(LPSTR, int, int, int, int, int, INT_PTR, int);
INT_PTR intDeviceHandle;
LPSTR baDeviceName;

const int WM_CAP_DRIVER_CONNECT = 0x40a;
const int WM_CAP_DRIVER_DISCONNECT = 0x40b;
const int WM_CAP_EDIT_COPY = 0x41e;

const int WM_CAP_GRAB_FRAME = 0x43c;

int WINAPI WinMain(HINSTANCE hCurInst, HINSTANCE hPrevInst, LPSTR lpszCmdLine, int nCmdShow)
{
    MSG msg;
    BOOL bRet;

    if (!InitApp(hCurInst))
        return FALSE;
    if (!InitInstance(hCurInst, nCmdShow))
        return FALSE;

    while ((bRet = GetMessage(&msg, NULL, 0, 0)) != 0)
    {
            if (bRet == -1)
                break;
            else {
                TranslateMessage(&msg);
                DispatchMessage(&msg);
            }

    }
    return 0;
}

ATOM InitApp(HINSTANCE hInst)
{
    WNDCLASSEX wc;

    wc.style = CS_VREDRAW | CS_HREDRAW;

    wc.cbSize = sizeof(WNDCLASSEX);
    wc.cbWndExtra = 0;
    wc.cbClsExtra = 0;

    wc.lpfnWndProc = WndProc;
    wc.lpszClassName = szClassName;
    wc.lpszMenuName = NULL;

    wc.hInstance = hInst;
    wc.hIcon = (HICON)LoadImage(NULL,
                                MAKEINTRESOURCE(IDI_APPLICATION),
                                IMAGE_ICON,
                                0,
                                0,
                                LR_DEFAULTSIZE | LR_SHARED);
    wc.hIconSm = NULL;
    wc.hCursor = (HCURSOR)LoadImage(NULL,
                                    MAKEINTRESOURCE(IDC_ARROW),
                                    IMAGE_CURSOR,
                                    0,
                                    0,
                                    LR_DEFAULTSIZE | LR_SHARED);
    wc.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);

    return (RegisterClassEx(&wc));
}

BOOL InitInstance(HINSTANCE hInst, int nCmdShow)
{
    HWND hWnd = CreateWindow(szClassName,
                             TEXT("WebCam"),
                             WS_OVERLAPPEDWINDOW,
                             CW_USEDEFAULT,
                             CW_USEDEFAULT,
                             CW_USEDEFAULT,
                             CW_USEDEFAULT,
                             NULL,
                             NULL,
                             hInst,
                             NULL);
    if (!hWnd)
        return FALSE;
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);
    return TRUE;
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp)
{
    PAINTSTRUCT ps;
    HDC hdc, mdc;
    HGLOBAL  hmem;
    RECT rc;
    HBITMAP hbmp;
    switch (msg) {
        case WM_CREATE:
        SetTimer(hWnd, ID_MYTIMER, 1, NULL);
        if (!LoadWebCamAPI())
        {
            MessageBox(hWnd, TEXT("Error!"), TEXT("AVIcap32.dll加載失敗!"), MB_YESNO | MB_ICONQUESTION);
            PostQuitMessage(0);
        } else {
            intDeviceHandle = (CapturePicture)(baDeviceName, WS_VISIBLE | WS_CHILD, 0, 0, 0, 0, (INT_PTR)hWnd, 0);
            SendMessage(intDeviceHandle, WM_CAP_DRIVER_CONNECT, 0, 0);
            MessageBox( hWnd, TEXT("Success!"), TEXT("AVIcap32.dll加載成功!"), MB_OK);
        }
        break;
        case WM_TIMER:

            InvalidateRect(hWnd, NULL, FALSE);
            break;
        case WM_PAINT:
            hdc = BeginPaint(hWnd, &ps);
            mdc = CreateCompatibleDC(hdc);
             if (SendMessage(intDeviceHandle, WM_CAP_GRAB_FRAME, 0, 0) > 0) //如果有截取到畫面
            {
                if (SendMessage(intDeviceHandle, WM_CAP_EDIT_COPY, 0, 0) > 0) //如果有Copy到剪貼簿
                {
                   OpenClipboard (hWnd) ;
                   hbmp = GetClipboardData(CF_BITMAP);
                   SelectObject(mdc, hbmp);
                   GetClipBox(mdc, &rc);
                   BitBlt(hdc, 0, 0, rc.right, rc.bottom, mdc,0, 0, SRCCOPY);
                   CloseClipboard();
                }
            }


            EndPaint(hWnd, &ps);
            DeleteObject(hbmp);
            DeleteDC(mdc);
            break;
        case WM_DESTROY:
            KillTimer(hWnd, ID_MYTIMER);
            PostQuitMessage(0);
            break;
        default:
            return DefWindowProc(hWnd, msg, wp, lp);
    }

    return 0;
}

BOOL LoadWebCamAPI(void)
{
    HMODULE hInst;

    hInst = LoadLibrary("AVIcap32.dll");
    if (hInst == NULL)
        return FALSE;
    CapturePicture = GetProcAddress(hInst, "capCreateCaptureWindowA");
    if (CapturePicture == NULL)
        return FALSE;
    return TRUE;
}