DisplayFlow/demo/windows_driver

DisplayFlow IDD Driver Integration Guide

Overview

To achieve a true "Virtual Display" (where Windows thinks a monitor is connected but it's just software), we need to compile and install a User-Mode Driver Framework (UMDF) Indirect Display Driver (IDD).

We will use the Microsoft Indirect Display Driver Sample as a base and modify it to send frames to our shared memory.

Prerequisites

1. Visual Studio 2019/2022 with "Desktop development with C++".
2. Windows Driver Kit (WDK) compatible with your VS version.
   • Download: https://learn.microsoft.com/en-us/windows-hardware/drivers/download-the-wdk

Steps

1. Download the Sample

Clone the Windows Driver Samples repository:

git clone https://github.com/microsoft/Windows-driver-samples.git
cd video/IndirectDisplay/IddCxMonitorDriver

2. Integrate DisplayFlow Code

Copy the following files from demo/windows_driver/src/ to the driver project folder (IddCxMonitorDriver):

• IddProducer.h
• IddProducer.cpp

3. Modify Project Settings

1. Open the solution IddCxMonitorDriver.sln in Visual Studio.
2. Right-click project -> Add -> Existing Item -> Select IddProducer.h and IddProducer.cpp.
3. Ensure IddProducer.cpp is not using precompiled headers (Right-click file -> Properties -> C/C++ -> Precompiled Headers -> Not Using Precompiled Headers).

4. Modify IndirectDevice.cpp (or SwapChainProcessor.cpp)

Find the logic where the driver processes frames. In the sample, this is typically in the SwapChainProcessor class (or inside IndirectDevice::Run).

1. Include Header:

   #include "IddProducer.h"
   

2. Add Member: Add IddProducer m_Producer; to the class that handles the swap chain.

3. Initialize: In the initialization phase (before the loop):

   m_Producer.Initialize();
   

4. Process Frame: Inside the frame loop, after acquiring the ID3D11Texture2D* (Surface), map it and submit it.

   • Note: The surface from IddCx is usually not CPU readable. You must copy it to a Staging Texture first.
   • Refer to demo/windows_driver/src/SwapChainProcessor_Example.cpp for the logic.

5. Build and Install

1. Build the solution (Platform: x64, Configuration: Release).
2. Locate the output files (.dll, .inf, .cat).
3. Install Certificate: The driver is self-signed. You must install the test certificate to Trusted Root Certification Authorities and Trusted Publishers.
4. Install Driver:
   • Open Device Manager.
   • Action -> Add legacy hardware.
   • Install from Disk -> Point to .inf file.
   • Select "IddCx Monitor Driver".

6. Verification

Once installed, Windows should show a new display. DisplayFlow sender (Consumer) should automatically pick up the frames from the Shared Memory (if running with --source=idd).