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截屏专用 Window

[英]Screen Capture Specific Window

 原文  2012-07-01 14:59:54  4   4    c++/ windows/ winapi/ gdi

问题描述

是否可以截屏特定的 window（也可能是另一个进程）？

目前我正在捕获特定显示器的整个桌面，但我真正想要的是捕获特定 window 的内容（无论其位置如何）。

4 个解决方案

解决方案1
 12 已采纳  2012-07-01 15:05:43

是的。 您所需要的只是获取要捕获的窗口的句柄并使用 WinAPI 函数 PrintWindow 例如：

// Get the window handle of calculator application.
HWND hWnd = ::FindWindow( 0, _T( "Calculator" ));

// Take screenshot.
PrintWindow( hWnd, getDC(hWnd), 0 );

这里有 PrintWindow 文档。

解决方案2
 9  2012-07-02 09:50:34

是的，就像捕获全屏一样简单。 您只需在所需窗口上使用GetWindowDC()而不是GetDesktopWindow() ，然后使用BitBlt()从该窗口到您的目标 DC。 您还可以使用GetWindowRect()获得正确的大小。

请注意，此方法还允许您从隐藏/覆盖的窗口中捕获带有边界矩形的完整屏幕截图。

有关更多详细信息，请参阅此问题。

解决方案3
 1  2021-04-30 07:17:12

Windows 10 中有一个新的 API，在winrt/Windows.Graphics.Capture.h微软这里有一个非常复杂的例子： https : //github.com/microsoft/Windows.UI.Composition-Win32-Samples/tree/ master/cpp/Scr​​eenCaptureforHWND

我想创建一些脏示例（非常脏），在我的示例中，您有一个简单的函数可以获取窗口的HWND并捕获它，并将其保存为ScreenShot.bmp

请注意，此函数中的错误处理很糟糕。 欢迎您改进此答案！

笔记：

代码：

#include <iostream>
#include <Windows.h>
#include <dxgi.h>
#include <inspectable.h>
#include <dxgi1_2.h>
#include <d3d11.h>
#include <winrt/Windows.Foundation.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>
#pragma comment(lib,"Dwmapi.lib")
#pragma comment(lib,"windowsapp.lib")


void CaptureWindow(HWND hwndTarget)
{
    // Init COM
    winrt::init_apartment(winrt::apartment_type::multi_threaded);
    
    // Create Direct 3D Device
    winrt::com_ptr<ID3D11Device> d3dDevice;

    winrt::check_hresult(D3D11CreateDevice(nullptr, D3D_DRIVER_TYPE_HARDWARE, nullptr, D3D11_CREATE_DEVICE_BGRA_SUPPORT,
                                           nullptr, 0,D3D11_SDK_VERSION, d3dDevice.put(), nullptr, nullptr));


    winrt::Windows::Graphics::DirectX::Direct3D11::IDirect3DDevice device;
    const auto dxgiDevice = d3dDevice.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 idxgiDevice2 = dxgiDevice.as<IDXGIDevice2>();
    winrt::com_ptr<IDXGIAdapter> adapter;
    winrt::check_hresult(idxgiDevice2->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* d3dContext = nullptr;
    d3dDevice->GetImmediateContext(&d3dContext);

    RECT rect{};
    DwmGetWindowAttribute(hwndTarget, 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_framePool =
        winrt::Windows::Graphics::Capture::Direct3D11CaptureFramePool::Create(
            device,
            winrt::Windows::Graphics::DirectX::DirectXPixelFormat::B8G8R8A8UIntNormalized,
            2,
            size);

    const auto activationFactory = winrt::get_activation_factory<
        winrt::Windows::Graphics::Capture::GraphicsCaptureItem>();
    auto interopFactory = activationFactory.as<IGraphicsCaptureItemInterop>();
    winrt::Windows::Graphics::Capture::GraphicsCaptureItem captureItem = {nullptr};
    interopFactory->CreateForWindow(hwndTarget, winrt::guid_of<ABI::Windows::Graphics::Capture::IGraphicsCaptureItem>(),
                                    reinterpret_cast<void**>(winrt::put_abi(captureItem)));

    auto isFrameArrived = false;
    winrt::com_ptr<ID3D11Texture2D> texture;
    const auto session = m_framePool.CreateCaptureSession(captureItem);
    m_framePool.FrameArrived([&](auto& framePool, auto&)
    {
        if (isFrameArrived) return;
        auto frame = framePool.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());
        isFrameArrived = true;
        return;
    });


    session.IsCursorCaptureEnabled(false);
    session.StartCapture();


    // Message pump
    MSG msg;
    clock_t timer = clock();
    while (!isFrameArrived)
    {
        if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) > 0)
            DispatchMessage(&msg);

        if (clock() - timer > 20000)
        {
            // TODO: try to make here a better error handling
            return;
        }
    }

    session.Close();

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

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

    winrt::com_ptr<ID3D11Texture2D> userTexture = nullptr;
    winrt::check_hresult(d3dDevice->CreateTexture2D(&capturedTextureDesc, NULL, userTexture.put()));

    d3dContext->CopyResource(userTexture.get(), texture.get());


    D3D11_MAPPED_SUBRESOURCE resource;
    winrt::check_hresult(d3dContext->Map(userTexture.get(), NULL, D3D11_MAP_READ, 0, &resource));

    BITMAPINFO lBmpInfo;

    // BMP 32 bpp
    ZeroMemory(&lBmpInfo, sizeof(BITMAPINFO));
    lBmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    lBmpInfo.bmiHeader.biBitCount = 32;
    lBmpInfo.bmiHeader.biCompression = BI_RGB;
    lBmpInfo.bmiHeader.biWidth = capturedTextureDesc.Width;
    lBmpInfo.bmiHeader.biHeight = capturedTextureDesc.Height;
    lBmpInfo.bmiHeader.biPlanes = 1;
    lBmpInfo.bmiHeader.biSizeImage = capturedTextureDesc.Width * capturedTextureDesc.Height * 4;
    
    std::unique_ptr<BYTE> pBuf(new BYTE[lBmpInfo.bmiHeader.biSizeImage]);
    UINT lBmpRowPitch = capturedTextureDesc.Width * 4;
    auto sptr = static_cast<BYTE*>(resource.pData);
    auto dptr = pBuf.get() + lBmpInfo.bmiHeader.biSizeImage - lBmpRowPitch;

    UINT lRowPitch = std::min<UINT>(lBmpRowPitch, resource.RowPitch);

    for (size_t h = 0; h < capturedTextureDesc.Height; ++h)
    {
        memcpy_s(dptr, lBmpRowPitch, sptr, lRowPitch);
        sptr += resource.RowPitch;
        dptr -= lBmpRowPitch;
    }

    // Save bitmap buffer into the file ScreenShot.bmp
    WCHAR lMyDocPath[MAX_PATH];

    winrt::check_hresult(SHGetFolderPath(nullptr, CSIDL_PERSONAL, nullptr, SHGFP_TYPE_CURRENT, lMyDocPath));

    std::wstring lFilePath = L"ScreenShot.bmp";

    FILE* lfile = nullptr;

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

    if (lfile != nullptr)
    {
        BITMAPFILEHEADER bmpFileHeader;

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

        fwrite(&bmpFileHeader, sizeof(BITMAPFILEHEADER), 1, lfile);
        fwrite(&lBmpInfo.bmiHeader, sizeof(BITMAPINFOHEADER), 1, lfile);
        fwrite(pBuf.get(), lBmpInfo.bmiHeader.biSizeImage, 1, lfile);

        fclose(lfile);
    }

    return;
}

如何使用：

auto targetHwnd = FindWindow(L"Notepad",NULL); // Or user any other HWND
CaptureWindow(targetHwnd); // If it worked, it will create ScreenShot.bmp file

解决方案4
 0  2022-12-09 08:35:00

当我想在记事本上绘制游戏画面时，使用以下方法只会显示黑屏。

hdcGame := GetDC(hwndGame)
BitBlt(hdcNotpad, 0, 0, rectGame.Width(), rectGame.Height(),
       hdcGame, 0, 0,
       SRCCOPY
)

所以我尝试@Roman R. 的建议来捕获桌面 DC GetDC(GetDesktopWindow())然后计算我们屏幕的目标 position GetWindowRect并仅绘制 position.BitBlt 或StretchBlt

例子

以下代码由go实现

// draw the calculator's screen on the notepad
func Example_captureWindow() {
    user32dll := w32.NewUser32DLL()
    gdi32dll := w32.NewGdi32DLL()

    hwndScreen := user32dll.GetDesktopWindow()
    hdcScreen := user32dll.GetDC(hwndScreen)
    defer user32dll.ReleaseDC(hwndScreen, hdcScreen) // release when exit function

    hwndCalculator := user32dll.FindWindow("ApplicationFrameWindow", "小算盤")
    hwndNotepad := user32dll.FindWindow("Notepad", "")

    hdcNotepad := user32dll.GetWindowDC(hwndNotepad)
    defer user32dll.ReleaseDC(hwndNotepad, hdcNotepad)

    var rectNotepad w32.RECT
    var rectC w32.RECT
    gdi32dll.SetStretchBltMode(hdcNotepad, w32.HALFTONE)
    user32dll.GetWindowRect(hwndNotepad, &rectNotepad)
    user32dll.GetWindowRect(hwndCalculator, &rectC)
    gdi32dll.StretchBlt(
        hdcNotepad, rectNotepad.Width()/4, rectNotepad.Height()/4, rectNotepad.Width()/2, rectNotepad.Height()/2, // draw screen on the center
        hdcScreen, rectC.Left, rectC.Top, rectC.Width(), rectC.Height(), w32.SRCCOPY,
    )
}

其他例子：

  1. 每 0.1 秒捕获一次计算器的屏幕，然后将其绘制在记事本上： 源链接

  2. 按 F9 可以捕获特定设备屏幕并将其显示在记事本上。 源链接

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