video-pc/AvRecorder/test/capturer/gdi_capturer.cpp

#include "gdi_capturer.h"
#include "basic/basic.h"

bool GdiCapturer::Open(HWND hwnd, int width, int height)
{
    Close();
    m_width = width;
    m_height = height;
    _srcHdc = GetWindowDC(hwnd);
    _dstHdc = CreateCompatibleDC(_srcHdc);
    _bitmap = CreateCompatibleBitmap(_srcHdc, width, height);
    SelectObject(_dstHdc, _bitmap);

    _bitmapInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    _bitmapInfo.bmiHeader.biPlanes = 1;
    _bitmapInfo.bmiHeader.biBitCount = 24;
    _bitmapInfo.bmiHeader.biWidth = width;
    _bitmapInfo.bmiHeader.biHeight = height;
    _bitmapInfo.bmiHeader.biCompression = BI_RGB;
    _bitmapInfo.bmiHeader.biSizeImage = width * height;

    // 创建缓存帧
    _frame = Frame<MediaType::VIDEO>::Alloc(AV_PIX_FMT_BGR24, width, height);
    return true;
}

HDC GdiCapturer::GetHdc(int borderWidth, int borderHeight)
{
    __CheckNullptr(
        BitBlt(_dstHdc, 0, 0, m_width, m_height,
            _srcHdc, borderWidth / 2, borderHeight - borderWidth / 2, SRCCOPY));

    return _dstHdc;
}

AVFrame* GdiCapturer::GetFrame()
{
    auto linesize = _frame->linesize[0];
    for (int row = 0; row < m_height; ++row) {
        __CheckNullptr(GetDIBits(_dstHdc, _bitmap, m_height - 1 - row, 1, _frame->data[0] + row * linesize, &_bitmapInfo, DIB_RGB_COLORS));
    }
    return _frame;
}

void GdiCapturer::Close()
{
    Free(_frame, [this] { av_frame_free(&_frame); });
    Free(_dstHdc, [this] { DeleteObject(_dstHdc); });
    Free(_bitmap, [this] { DeleteObject(_bitmap); });
}

GdiCapturer::~GdiCapturer()
{
    Close();
}