实现一个简单的屏幕截图程序

试了一下，对win API还是不熟悉啊，代码如下，不多说了，还是得多练练项目

#include <windows.h>
#include <stdlib.h>
#include <malloc.h>
#include <memory.h>
#include <tchar.h>
#define MAX_LOADSTRING 100

// 全局变量: 
HINSTANCE hInst;                                // 当前实例
WCHAR szTitle[MAX_LOADSTRING];                  // 标题栏文本
WCHAR szWindowClass[MAX_LOADSTRING];            // 主窗口类名

RECT rect;
HDC g_srcMemDc;
int screenW;
int screenH;

BOOL isSelect = FALSE;
BOOL isDown = FALSE;

// 此代码模块中包含的函数的前向声明: 
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);
void ScreenCapture();
void CopyBitmapToCipBoard();

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
    _In_opt_ HINSTANCE hPrevInstance,
    _In_ LPWSTR    lpCmdLine,
    _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: 在此放置代码。

    // 初始化全局字符串
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_SCREENCAPTURE, szWindowClass, MAX_LOADSTRING);
    MyRegisterClass(hInstance);

    // 执行应用程序初始化: 
    if (!InitInstance(hInstance, nCmdShow))
    {
        return FALSE;
    }

    HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_SCREENCAPTURE));

    MSG msg;

    // 主消息循环: 
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return (int)msg.wParam;
}



//
//  函数: MyRegisterClass()
//
//  目的: 注册窗口类。
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style = CS_HREDRAW | CS_VREDRAW | CS_DBLCLKS;
    wcex.lpfnWndProc = WndProc;
    wcex.cbClsExtra = 0;
    wcex.cbWndExtra = 0;
    wcex.hInstance = hInstance;
    wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_SCREENCAPTURE));
    wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1);
    wcex.lpszMenuName = 0;//MAKEINTRESOURCEW(IDC_SCREENCAPTURE);
    wcex.lpszClassName = szWindowClass;
    wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

//
//   函数: InitInstance(HINSTANCE, int)
//
//   目的: 保存实例句柄并创建主窗口
//
//   注释: 
//
//        在此函数中，我们在全局变量中保存实例句柄并
//        创建和显示主程序窗口。
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    hInst = hInstance; // 将实例句柄存储在全局变量中

    HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_POPUP,
        CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, nullptr, nullptr, hInstance, nullptr);

    if (!hWnd)
    {
        return FALSE;
    }

    ShowWindow(hWnd, SW_MAXIMIZE);
    UpdateWindow(hWnd);

    return TRUE;
}

//
//  函数: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  目的:    处理主窗口的消息。
//
//  WM_COMMAND  - 处理应用程序菜单
//  WM_PAINT    - 绘制主窗口
//  WM_DESTROY  - 发送退出消息并返回
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    //透明画刷
    LOGBRUSH brush;
    brush.lbStyle = BS_NULL;
    HBRUSH hBrush = CreateBrushIndirect(&brush);

    //框框颜色
    LOGPEN pen;
    POINT pt;
    pt.x = 2;
    pt.y = 2;
    pen.lopnColor = 0xFF33FF;
    pen.lopnStyle = PS_SOLID;
    pen.lopnWidth = pt;

    HPEN hPen = CreatePenIndirect(&pen);

    switch (message)
    {
    case WM_LBUTTONDOWN:
        //MessageBox(hWnd, L"hh", L"jj", NULL);
    {
        if (!isSelect)
        {
            POINT pt;
            GetCursorPos(&pt);

            rect.left = pt.x;
            rect.top = pt.y;
            rect.right = pt.x;
            rect.bottom = pt.y;
            InvalidateRgn(hWnd, 0, true);

            isDown = TRUE;
        }
    }
    break;
    case WM_LBUTTONUP:
    {
        if (isDown == TRUE && !isSelect)
        {
            POINT pt;
            GetCursorPos(&pt);

            rect.right = pt.x;
            rect.bottom = pt.y;
            InvalidateRgn(hWnd, 0, true);

            isDown = FALSE;
            isSelect = TRUE;
        }
    }
    break;
    case WM_MOUSEMOVE:
        break;
    case WM_LBUTTONDBLCLK:
        if (isSelect)
        {
            CopyBitmapToCipBoard();
            isSelect = FALSE;
        }

        break;

    case WM_CREATE:
        ScreenCapture();
        break;
    case WM_COMMAND:
    {
        int wmId = LOWORD(wParam);
        // 分析菜单选择: 
        switch (wmId)
        {
        case IDM_ABOUT:
            DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
            break;
        case IDM_EXIT:
            DestroyWindow(hWnd);
            break;
        default:
            return DefWindowProc(hWnd, message, wParam, lParam);
        }
    }
    break;
    case WM_PAINT:
    {
        PAINTSTRUCT ps;
        HDC hdc = BeginPaint(hWnd, &ps);
        SelectObject(hdc, hBrush);
        SelectObject(hdc, hPen);
        BitBlt(hdc, 0, 0, screenW, screenH, g_srcMemDc, 0, 0, SRCCOPY);
        Rectangle(hdc, rect.left, rect.top, rect.right, rect.bottom);
        EndPaint(hWnd, &ps);
    }
    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
        {
            EndDialog(hDlg, LOWORD(wParam));
            return (INT_PTR)TRUE;
        }
        break;
    }
    return (INT_PTR)FALSE;
}

void ScreenCapture()
{
    HDC disDc = ::CreateDC(L"display", 0, 0, 0);

    screenW = GetDeviceCaps(disDc, HORZRES);
    screenH = GetDeviceCaps(disDc, VERTRES);

    g_srcMemDc = CreateCompatibleDC(disDc);
    HBITMAP hbitMap = CreateCompatibleBitmap(disDc, screenW, screenH);

    SelectObject(g_srcMemDc, hbitMap);
    BitBlt(g_srcMemDc, 0, 0, screenW, screenH, disDc, 0, 0, SRCCOPY);

}

void CopyBitmapToCipBoard()
{
    int width = rect.right - rect.left;
    int height = rect.bottom - rect.top;

    HDC hSrcDc = CreateDC(L"display", 0, 0, 0);

    HDC memDC = CreateCompatibleDC(hSrcDc);
    HBITMAP  hBitmap = CreateCompatibleBitmap(hSrcDc, width, height);
    HBITMAP oldmap = (HBITMAP)SelectObject(memDC, hBitmap);

    BitBlt(memDC, 0, 0, width, height, hSrcDc, rect.left, rect.top, SRCCOPY);

    HBITMAP newmap = (HBITMAP)SelectObject(memDC, oldmap);

    if (OpenClipboard(0))
    {
        EmptyClipboard();
        SetClipboardData(CF_BITMAP, newmap);
        CloseClipboard();
    }
}

 实现效果如下

呃。。。好吧

就是直接运行，截图之后画框框，然后双击，然后ctrl+c随便粘喽