My goal is to call methods, which are implemented in the Unity Code, from my UWP DLL. (So I can use them in my HoloLens Project)
I tried this with a bigger project but failed. Therefore I wrote a simple example to make it easier to find the mistake and exclude other influences.
But still, I get the same error.
My Working Environment:
- 64-bit Computer with OS Windows 10
- Micsrosoft Visual Studio Community
2015 Version 14.0.25431.01 Update 3 - HoloLens Emulator 10.0.14393.0
- Unity 5.5.0f3 Personal (64 bit)
Creating the UWP DLL:
To approach this I created a C++ DLL(Windows Universal) in Visual Studio 2015 as followed:
New Project > Visual C++ > Windows > Universal > DLL(Universal Windows)
After the project was auto generated I added my code.
So the code looks like this:
Native Library Code:
SimpleProjectDLL.cpp:
#include "pch.h"
#define DLL_EXPORT __declspec(dllexport)
typedef void(*CB_V)();
typedef void(*CB_V_VI)(const char * a, int b);
CB_V_VI cb_native_log;
CB_V cb_call;
void log()
{
// this method makes problems !
cb_native_log("Call for callback", 1);
}
extern "C" {
DLL_EXPORT void initInterfaceCallbacks(
CB_V_VI native_log,
CB_V call
) {
cb_native_log = native_log;
cb_call = call;
}
DLL_EXPORT void callSmth()
{
cb_call();
}
DLL_EXPORT int getSomeInt()
{
return 42;
}
DLL_EXPORT void initCallback()
{
log();
}
}
SimpleProjectDLL.h is prepearing the delegates:
SimpleProjectDLL.h:
#pragma once
#include <cstdint>
#define DLL_EXPORT __declspec(dllexport)
extern "C"
{
typedef void(*CB_V)();
typedef void(*CB_V_VI)(const char * a, int b);
}
I did not make any changes to the auto generated files dllmain.cpp, pch.cpp, pch.h or targetver.h.
Finally I build the project for “Release” mode and architecture “x86” to generate the DLL-file.
Location of the DLL-file is now: project-root-folder/Release/SimpleProject/SimpleProjectDLL.dll.
---------------------
Next step I created a new Unity Project added the HoloLens-Toolkit and made sure that the new project is running fine on the emulator.
Unity Project Code:
After that I added the SimpleProjectDLL.dll in the Asset-Folder and implemented the following code:
First of all we need to create the connection between the delegates.
Cpp.cs prepears the Delegates:
Cpp.cs
using UnityEngine;
using System;
using System.Runtime.InteropServices;
namespace Cpp
{
delegate void DelegateV();
delegate void DelegateVVi(IntPtr a, int b);
}
SimpleInterfaceCpp.cs initializes the connection:
SimpleInterfaceCpp.cs
using Cpp;
using System.Runtime.InteropServices;
using UnityEngine;
public static class SimpleInterfaceCpp
{
public static void Init()
{
initInterfaceCallbacks(
SimpleInterface.NativeLog,
SimpleInterface.Call
);
}
[DllImport(SimpleInterface.DLL)]
private static extern void initInterfaceCallbacks(
DelegateVVi native_log,
DelegateV call
);
}
Main:
MainController.cs
using UnityEngine;
using System.Collections;
using System.Runtime.InteropServices;
public class MainController : MonoBehaviour
{
void Start ()
{
SimpleInterfaceCpp.Init();
SimpleInterface.TestCalls();
}
}
SimpleInterface.cs is calling the methodes:
SimpleInterface.cs
using System;
using UnityEngine;
using System.Runtime.InteropServices;
using AOT;
using IntPtr = System.IntPtr;
using Cpp;
using StringReturn = System.IntPtr;
public class SimpleInterface
{
public const string DLL = "SimpleProjectDLL";
public static void TestCalls()
{
// This works fine
int number = getSomeInt();
Debug.Log("getSomeInt: " + number);
// This also works fine and outputs "--- A callback ---"
callSmth();
// This call gives the output "call_log: native log" but crashes afterwards !
initCallback();
}
[MonoPInvokeCallback(typeof(DelegateVVi))]
public static void NativeLog(IntPtr logMessage,
int logLevel)
{
string result = StringFromCReturn(logMessage);
UnityEngine.Debug.Log(result); // outputs "call_log: native log"
}
[MonoPInvokeCallback(typeof(DelegateV))]
public static void Call()
{
UnityEngine.Debug.Log("--- A callback---");
}
[DllImport(DLL)]
private static extern void initCallback();
[DllImport(DLL)]
private static extern void callSmth();
[DllImport(DLL)]
private static extern int getSomeInt();
public static string StringFromCReturn(StringReturn someReturnVal)
{
return Marshal.PtrToStringAnsi(someReturnVal);
}
}
Now if I create a SLN, open the project in Visual Studio and start it with the “HoloLens Emulator” I get the following Output:
getSomeInt: 42
(Filename: C:/buildslave/unity/build/artifacts/generated/Metro/runtime/DebugBindings.gen.cpp Line: 51)
--- A callback---
(Filename: C:/buildslave/unity/build/artifacts/generated/Metro/runtime/DebugBindings.gen.cpp Line: 51)
call_log: native log
(Filename: C:/buildslave/unity/build/artifacts/generated/Metro/runtime/DebugBindings.gen.cpp Line: 51)
The program '[1932] SimpleProject.exe' has exited with code -1073740791 (0xc0000409).
After that the App just closes.
So my Question is, does anyone know what the problem could be?
Is this the right way to use callbacks in a HoloLens Project?
Or does someone know how to find an error description for the code “-1073740791 (0xc0000409)” ?
Additional Information:
I also tried it on a real HoloLens device, same issue, so the problem does not lays at the emulator.