Windows上实现截屏并保存为jpg

#include <Windows.h>
#include <stdint.h>
#include <d3d9.h>
//#include <D3dx9tex.h>

extern "C" {
#include "libswscale/swscale.h"
#include "libavutil/pixdesc.h"
#include "libavutil/imgutils.h"
#include "libavformat/avformat.h"
}

#pragma comment(lib, "D3d9.lib")
//#pragma comment(lib, "D3dx9.lib")
#pragma comment(lib, "winmm.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "swscale.lib")

void SaveFrameToJpg(AVFrame *frame)
{
    AVFormatContext *ofmtCtx = NULL;
    AVCodec *codec = NULL;
    AVCodecContext *codecCtx = NULL;
    AVStream *stream = NULL;
    int ret;

    /* allocate the output media context */
    avformat_alloc_output_context2(&ofmtCtx, NULL, NULL, "aa.jpg");
    if (!ofmtCtx) {
        return;
    }

    codec = avcodec_find_encoder(AV_CODEC_ID_MJPEG);
    if (!codec) {
        return;
    }

    stream = avformat_new_stream(ofmtCtx, NULL);
    if (!stream) {
        return;
    }

    codecCtx = avcodec_alloc_context3(codec);
    if (!codecCtx) {
        return;
    }

    codecCtx->pix_fmt = AV_PIX_FMT_YUVJ420P;
    codecCtx->bit_rate = 400000;
    codecCtx->width = frame->width;
    codecCtx->height = frame->height;
    codecCtx->time_base.num = 1;
    codecCtx->time_base.den = 25;

    /* open the codec */
    ret = avcodec_open2(codecCtx, codec, NULL);
    if (ret < 0) {
        return;
    }

    /* open the output file, if needed */
    ret = avio_open(&ofmtCtx->pb, "aa.jpg", AVIO_FLAG_WRITE);
    if (ret < 0) {
        return;
    }

    /* Write the stream header, if any. */
    ret = avformat_write_header(ofmtCtx, NULL);
    if (ret < 0) {
        return;
    }

    AVPacket avpkt = { 0 };
    int got_packet = 0;

    av_init_packet(&avpkt);

    /* encode the image */
    ret = avcodec_send_frame(codecCtx, frame);
    if (ret < 0) {
        return;
    }

    ret = avcodec_receive_packet(codecCtx, &avpkt);
    if (ret < 0) {
        return;
    }

    av_write_frame(ofmtCtx, &avpkt);

    /* Write the trailer, if any. The trailer must be written before you
    * close the CodecContexts open when you wrote the header; otherwise
    * av_write_trailer() may try to use memory that was freed on
    * av_codec_close(). */
    av_write_trailer(ofmtCtx);

    /* Close the output file. */
    avio_closep(&ofmtCtx->pb);

    avcodec_free_context(&codecCtx);

    /* free the stream */
    avformat_free_context(ofmtCtx);

    return;
}

HRESULT capture(IDirect3DDevice9* d3ddev9)
{
    IDirect3DSurface9 *destTarget = NULL;
    HRESULT hr;
    
    int screenWidth = GetSystemMetrics(SM_CXSCREEN);
    int screenHeight = GetSystemMetrics(SM_CYSCREEN);

    hr = d3ddev9->CreateOffscreenPlainSurface(screenWidth, screenHeight, D3DFMT_A8R8G8B8,
        D3DPOOL_SCRATCH, &destTarget, NULL);
    if (FAILED(hr))
    {
        //printf("Failed  CreateOffscreenPlainSurface!");
    }
    hr = d3ddev9->GetFrontBufferData(0, destTarget);

    //D3DXSaveSurfaceToFile(L"Desktop.jpg", D3DXIFF_JPG, destTarget, NULL, NULL);

    D3DLOCKED_RECT lr;
    ZeroMemory(&lr, sizeof(D3DLOCKED_RECT));
    hr = destTarget->LockRect(&lr, 0, D3DLOCK_READONLY);
    if (FAILED(hr))
    {
        //printf("Cannot lock rect!");
    }

    if (lr.pBits)
    {
        uint8_t *dst_data[4] = { 0 };
        int dst_linesize[4];
        uint8_t *src_data[4] = { 0 };
        int src_linesize[4];
        struct SwsContext *sws_ctx = NULL;
        AVFrame *frame = NULL;
        int ret;

        sws_ctx = sws_getContext(screenWidth, screenHeight, AV_PIX_FMT_BGRA,
            screenWidth, screenHeight, AV_PIX_FMT_YUV420P,
            SWS_BILINEAR, NULL, NULL, NULL);

        if ((ret = av_image_alloc(dst_data, dst_linesize,
            screenWidth, screenHeight, AV_PIX_FMT_YUV420P, 1)) < 0)
        {
            fprintf(stderr, "Could not allocate destination image\n");
            return E_FAIL;
        }

        frame = av_frame_alloc();

        frame->format = AV_PIX_FMT_YUVJ420P;
        frame->width = screenWidth;
        frame->height = screenHeight;

        src_data[0] = (uint8_t*)lr.pBits;
        src_linesize[0] = lr.Pitch;

        sws_scale(sws_ctx, src_data,
            src_linesize, 0, screenHeight, dst_data, dst_linesize);

        frame->data[0] = dst_data[0];
        frame->data[1] = dst_data[1];
        frame->data[2] = dst_data[2];
        frame->linesize[0] = dst_linesize[0];
        frame->linesize[1] = dst_linesize[1];
        frame->linesize[2] = dst_linesize[2];

        SaveFrameToJpg(frame);

        av_freep(&dst_data[0]);
        av_frame_free(&frame);
        sws_freeContext(sws_ctx);
    }

    hr = destTarget->UnlockRect();
    if (FAILED(hr))
    {
        //printf("Cannot unlock rect!");
    }
    destTarget->Release();

    return hr;
}

int CaptureLoop(HWND hwnd)
{
    IDirect3D9* d3d9 = NULL;
    IDirect3DDevice9* d3ddev9 = NULL;
    D3DPRESENT_PARAMETERS d3dpp = { 0 };

    d3d9 = Direct3DCreate9(D3D_SDK_VERSION);

    D3DDISPLAYMODE* dispMode = new D3DDISPLAYMODE();
    d3d9->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, dispMode);

    d3dpp.Windowed = true;
    d3dpp.SwapEffect = D3DSWAPEFFECT_DISCARD;
    d3dpp.hDeviceWindow = hwnd;
    d3dpp.BackBufferFormat = dispMode->Format;
    d3d9->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, hwnd, D3DCREATE_SOFTWARE_VERTEXPROCESSING, &d3dpp, &d3ddev9);
    delete dispMode;

    capture(d3ddev9);

    MSG msg;

    memset(&msg, 0, sizeof(msg));
    while (msg.message != WM_QUIT)
    {
        if (PeekMessage(&msg, 0, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    if (d3ddev9) d3ddev9->Release();
    if (d3d9) d3d9->Release();
    return msg.wParam;
}

LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hwnd, message, wParam, lParam);
    }

    return 0;
}

int WINAPI WinMain(HINSTANCE hThisInstance, HINSTANCE hPrevInstance, LPSTR lpszArgument, int nCmdShow)
{
    WNDCLASSEX wincl;
    wincl.hInstance = hThisInstance;
    wincl.lpszClassName = L"D3DWindow";
    wincl.lpfnWndProc = WindowProcedure;
    wincl.style = CS_DBLCLKS;
    wincl.cbSize = sizeof(WNDCLASSEX);
    wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
    wincl.hCursor = LoadCursor(NULL, IDC_ARROW);
    wincl.lpszMenuName = NULL;
    wincl.cbClsExtra = 0;
    wincl.cbWndExtra = 0;
    wincl.hbrBackground = (HBRUSH)COLOR_BACKGROUND;

    if (!RegisterClassEx(&wincl)) return 0;
    HWND hwnd = CreateWindowEx(0, L"D3DWindow", L"D3D9: Window", WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, 544, 375, HWND_DESKTOP, NULL, hThisInstance, NULL);

    av_register_all();

    return CaptureLoop(hwnd);
}

参考
Windows桌面共享中一些常见的抓屏技术
http://www.cppblog.com/weiym/archive/2013/12/01/204536.html

https://www.codeproject.com/Articles/5051/Various-methods-for-capturing-the-screen

DXSDK部分头文件和库文件的直接下载地址
https://github.com/brian9206/docker-dxsdk/tree/master/DXSDK