C++中窗口(句柄)的截图

HWND 在Windows上使用C++。以下代码适用于 Notepad 但不是在另一个特定的过程中。相反,代码会为另一个进程返回完全不同的屏幕截图:

#include <Windows.h>

HBITMAP dump_client_window(const HWND window_handle)
{
    RECT window_handle_rectangle;
    GetClientRect(window_handle, &window_handle_rectangle);

    const HDC hdc_screen = GetDC(nullptr);
    const HDC hdc = CreateCompatibleDC(hdc_screen);
    const auto cx = window_handle_rectangle.right - window_handle_rectangle.left;
    const auto cy = window_handle_rectangle.bottom - window_handle_rectangle.top;
    const HBITMAP bitmap = CreateCompatibleBitmap(hdc_screen, cx, cy);
    SelectObject(hdc, bitmap);
    const auto old_bitmap = SelectObject(hdc, bitmap);

    PrintWindow(window_handle, hdc, PW_CLIENTONLY);

    // Cleanup
    SelectObject(hdc, old_bitmap);
    DeleteDC(hdc);
    ReleaseDC(nullptr, hdc_screen);

    return bitmap;
}

原因可能是什么?如果我使用 DirectX11

#include <dxgi.h>
#include <inspectable.h>
#include <dxgi1_2.h>
#include <d3d11.h>
#include <winrt/Windows.System.h>
#include <winrt/Windows.Graphics.Capture.h>
#include <Windows.Graphics.Capture.Interop.h>
#include <windows.graphics.directx.direct3d11.interop.h>
#include <roerrorapi.h>
#include <ShlObj_core.h>
#include <dwmapi.h>
#include <filesystem>

#include "ImageFormatConversion.hpp"

#pragma comment(lib, "Dwmapi.lib")
#pragma comment(lib, "windowsapp.lib")

void capture_window(HWND window_handle, const std::wstring& output_file_path)
{
    // Init COM
    init_apartment(winrt::apartment_type::multi_threaded);

    // Create Direct 3D Device
    winrt::com_ptr<ID3D11Device> d3d_device;

    winrt::check_hresult(D3D11CreateDevice(nullptr, D3D_DRIVER_TYPE_HARDWARE, nullptr, D3D11_CREATE_DEVICE_BGRA_SUPPORT,
        nullptr, 0, D3D11_SDK_VERSION, d3d_device.put(), nullptr, nullptr));

    winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice device;
    const auto dxgiDevice = d3d_device.as<IDXGIDevice>();
    {
        winrt::com_ptr<IInspectable> inspectable;
        winrt::check_hresult(CreateDirect3D11DeviceFromDXGIDevice(dxgiDevice.get(), inspectable.put()));
        device = inspectable.as<winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice>();
    }

    auto idxgi_device2 = dxgiDevice.as<IDXGIDevice2>();
    winrt::com_ptr<IDXGIAdapter> adapter;
    winrt::check_hresult(idxgi_device2->GetParent(winrt::guid_of<IDXGIAdapter>(), adapter.put_void()));
    winrt::com_ptr<IDXGIFactory2> factory;
    winrt::check_hresult(adapter->GetParent(winrt::guid_of<IDXGIFactory2>(), factory.put_void()));

    ID3D11DeviceContext* d3d_context = nullptr;
    d3d_device->GetImmediateContext(&d3d_context);

    RECT rect{};
    DwmGetWindowAttribute(window_handle, DWMWA_EXTENDED_FRAME_BOUNDS, &rect, sizeof(RECT));
    const auto size = winrt::Windows::Graphics::SizeInt32{ rect.right - rect.left, rect.bottom - rect.top };

    winrt::Windows::Graphics::Capture::Direct3D11CaptureFramePool m_frame_pool =
        winrt::Windows::Graphics::Capture::Direct3D11CaptureFramePool::Create(
            device,
            winrt::Windows::Graphics::DirectX::DirectXPixelFormat::B8G8R8A8UIntNormalized,
            2,
            size);

    const auto activation_factory = winrt::get_activation_factory<
        winrt::Windows::Graphics::Capture::GraphicsCaptureItem>();
    auto interop_factory = activation_factory.as<IGraphicsCaptureItemInterop>();
    winrt::Windows::Graphics::Capture::GraphicsCaptureItem capture_item = { nullptr };
    interop_factory->CreateForWindow(window_handle, winrt::guid_of<ABI::Windows::Graphics::Capture::IGraphicsCaptureItem>(),
        winrt::put_abi(capture_item));

    auto is_frame_arrived = false;
    winrt::com_ptr<ID3D11Texture2D> texture;
    const auto session = m_frame_pool.CreateCaptureSession(capture_item);
    m_frame_pool.FrameArrived([&](auto& frame_pool, auto&)
        {
            if (is_frame_arrived)
            {
                return;
            }
            auto frame = frame_pool.TryGetNextFrame();

            struct __declspec(uuid("A9B3D012-3DF2-4EE3-B8D1-8695F457D3C1"))
                IDirect3DDxgiInterfaceAccess : ::IUnknown
            {
                virtual HRESULT __stdcall GetInterface(GUID const& id, void** object) = 0;
            };

            auto access = frame.Surface().as<IDirect3DDxgiInterfaceAccess>();
            access->GetInterface(winrt::guid_of<ID3D11Texture2D>(), texture.put_void());
            is_frame_arrived = true;
            return;
        });

    session.StartCapture();

    // Message pump
    MSG message;
    while (!is_frame_arrived)
    {
        if (PeekMessage(&message, nullptr, 0, 0, PM_REMOVE) > 0)
        {
            DispatchMessage(&message);
        }
    }

    session.Close();

    D3D11_TEXTURE2D_DESC captured_texture_desc;
    texture->GetDesc(&captured_texture_desc);

    captured_texture_desc.Usage = D3D11_USAGE_STAGING;
    captured_texture_desc.BindFlags = 0;
    captured_texture_desc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
    captured_texture_desc.MiscFlags = 0;

    winrt::com_ptr<ID3D11Texture2D> user_texture = nullptr;
    winrt::check_hresult(d3d_device->CreateTexture2D(&captured_texture_desc, nullptr, user_texture.put()));

    d3d_context->CopyResource(user_texture.get(), texture.get());

    D3D11_MAPPED_SUBRESOURCE resource;
    winrt::check_hresult(d3d_context->Map(user_texture.get(), NULL, D3D11_MAP_READ, 0, &resource));

    BITMAPINFO l_bmp_info;

    // BMP 32 bpp
    ZeroMemory(&l_bmp_info, sizeof(BITMAPINFO));
    l_bmp_info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    l_bmp_info.bmiHeader.biBitCount = 32;
    l_bmp_info.bmiHeader.biCompression = BI_RGB;
    l_bmp_info.bmiHeader.biWidth = captured_texture_desc.Width;
    l_bmp_info.bmiHeader.biHeight = captured_texture_desc.Height;
    l_bmp_info.bmiHeader.biPlanes = 1;
    l_bmp_info.bmiHeader.biSizeImage = captured_texture_desc.Width * captured_texture_desc.Height * 4;

    std::unique_ptr<BYTE> p_buf(new BYTE[l_bmp_info.bmiHeader.biSizeImage]);
    UINT l_bmp_row_pitch = captured_texture_desc.Width * 4;
    auto sptr = static_cast<BYTE*>(resource.pData);
    auto dptr = p_buf.get() + l_bmp_info.bmiHeader.biSizeImage - l_bmp_row_pitch;

    UINT l_row_pitch = std::min<UINT>(l_bmp_row_pitch, resource.RowPitch);

    for (size_t h = 0; h < captured_texture_desc.Height; ++h)
    {
        memcpy_s(dptr, l_bmp_row_pitch, sptr, l_row_pitch);
        sptr += resource.RowPitch;
        dptr -= l_bmp_row_pitch;
    }

    // Save bitmap buffer into the file
    WCHAR l_my_doc_path[MAX_PATH];

    winrt::check_hresult(SHGetFolderPathW(nullptr, CSIDL_PERSONAL, nullptr, SHGFP_TYPE_CURRENT, l_my_doc_path));

    FILE* lfile = nullptr;

    if (auto lerr = _wfopen_s(&lfile, output_file_path.c_str(), L"wb"); lerr != 0)
    {
        return;
    }

    if (lfile != nullptr)
    {
        BITMAPFILEHEADER bmp_file_header;

        bmp_file_header.bfReserved1 = 0;
        bmp_file_header.bfReserved2 = 0;
        bmp_file_header.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + l_bmp_info.bmiHeader.biSizeImage;
        bmp_file_header.bfType = 'MB';
        bmp_file_header.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

        fwrite(&bmp_file_header, sizeof(BITMAPFILEHEADER), 1, lfile);
        fwrite(&l_bmp_info.bmiHeader, sizeof(BITMAPINFOHEADER), 1, lfile);
        fwrite(p_buf.get(), l_bmp_info.bmiHeader.biSizeImage, 1, lfile);

        fclose(lfile);

        convert_image_encoding(output_file_path, L"png");
    }
}

为什么会这样 DirectX11 代码如此复杂/漫长且缓慢(每次调用约800ms-1s,包括冷启动初始化)?另外,后一个版本会导致捕获的窗口周围出现闪烁的边框,我可能希望消除这些边框。我似乎还不得不采取更低效的方法,将BMP图像存储到磁盘,然后将其重新加载,以便将其转换为PNG,然后再次存储,以在磁盘上生成我喜欢的最终结果。

欢迎提供任何建议或帮助,尤其是为什么第一个截图捕获代码会根据捕获的窗口生成意外的图像。除此之外,我喜欢第一个版本的速度,简洁和简单。