为什么我无法通过DirectInput获取键盘？

Question

我今天刚开始使用DirectInput，在Windows7旗舰版N上使用DirectInput8和MinGW。我从一个简单的程序开始，它可以每秒报告哪些键按下了(只是代码，而不是可读的键)。但是，在键盘出错之前，我甚至无法获取键盘：

#define _WIN32_WINNT 0x0601
#include <dinput.h>
//link to dinput8.lib and dxguid.lib

int main() {
    IDirectInput8 *dinput;
    DirectInput8Create(GetModuleHandle(nullptr), DIRECTINPUT_VERSION, IID_IDirectInput8, (void **)&dinput, nullptr);

    IDirectInputDevice8 *kb;
    dinput->CreateDevice(GUID_SysKeyboard, &kb, nullptr);

    kb->SetDataFormat(&c_dfDIKeyboard);
    kb->SetCooperativeLevel(GetConsoleWindow(), DISCL_FOREGROUND | DISCL_NONEXCLUSIVE);
    kb->Acquire(); //fails with DIERR_INVALIDPARAM
}

我省略了错误检查，但是发生的情况是，直到Acquire()，每个调用都会成功(通过对FAILED宏的判断)。该调用失败，并显示错误DIERR_INVALIDPARAM。我看了看MSDN页面和整个网络，但我找不到任何理由它会失败，基于它之前的一切和工作。

另外，我还尝试对Acquire()调用进行循环，直到它成功，然后在它运行时尝试使用windows和键盘，但在它运行的所有时间里，该程序从未成功获取键盘。如何成功获取键盘？

Answer 1

在键盘和操纵杆的控制台程序中进行直接输入的实验

要使用直接输入，不需要有窗口的句柄。您可以只在窗口句柄的参数中使用null。

而不是：

kb->SetCooperativeLevel(GetConsoleWindow(), DISCL_FOREGROUND | DISCL_NONEXCLUSIVE);

使用：

kb->SetCooperativeLevel(NULL, DISCL_FOREGROUND | DISCL_NONEXCLUSIVE);

这是一个示例程序，当按下“a”和“d”键时，它使用直接输入来显示这些键。当按住这些键300毫秒时，它会重复这些键。该示例程序也是高分辨率计数器的一个很好的示例。不需要在Visual Studio中添加属性来添加库dinput8.lib和dxguid.lib。程序顶部的#杂注注释代码行为您做了这件事。

 #include <dinput.h>
#include <iostream>
#include <Windows.h>

#pragma comment(lib,"dinput8.lib")
#pragma comment(lib,"dxguid.lib")

using std::cout;
using std::endl;

LPDIRECTINPUT8 di;
LPDIRECTINPUTDEVICE8 keyboard;

class CTimer
{
public:
    CTimer() {
        QueryPerformanceFrequency(&mqFreq);
    }
    ~CTimer() {}

    void Start() {
        QueryPerformanceCounter(&mqStart);
    }
    void End() {
        QueryPerformanceCounter(&mqEnd);
    }
    double GetTimeInSeconds() {
        return (mqEnd.QuadPart - mqStart.QuadPart)/(double)mqFreq.QuadPart;
    }
    double GetTimeInMilliseconds() {
        return (1.0e3*(mqEnd.QuadPart - mqStart.QuadPart))/mqFreq.QuadPart;
    }
    double GetTimeInMicroseconds() {
        return (1.0e6*(mqEnd.QuadPart - mqStart.QuadPart))/mqFreq.QuadPart;
    }
    double GetTimeInNanoseconds() {
        return (1.0e9*(mqEnd.QuadPart - mqStart.QuadPart))/mqFreq.QuadPart;
    }

private:
    LARGE_INTEGER mqStart;
    LARGE_INTEGER mqEnd;
    LARGE_INTEGER mqFreq;
};


HRESULT initializedirectinput8() {
    HRESULT hr;
    // Create a DirectInput device
if (FAILED(hr = DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION, 
                                   IID_IDirectInput8, (VOID**)&di, NULL))) {
    return hr;
}
}

void createdikeyboard() {
    di->CreateDevice(GUID_SysKeyboard, &keyboard, NULL);
    keyboard->SetDataFormat(&c_dfDIKeyboard);
    keyboard->SetCooperativeLevel(NULL,DISCL_FOREGROUND | DISCL_EXCLUSIVE);
    keyboard->Acquire();
}

void destroydikeyboard() {
    keyboard->Unacquire();
    keyboard->Release();
}

#define keydown(name,key) (name[key] & 0x80)

void main() {
    HRESULT hr;
    BYTE dikeys[256];
    CTimer timeint;
    CTimer timekeywaspressedclass;
    double gettime;
    double lastkeywasa=false;
    double timekeywaspressed=0;
    bool lasttimetherewasakeypress=false;
    bool akeywaspressed=false;
    initializedirectinput8();
    createdikeyboard();
    hr=keyboard->GetDeviceState(256,dikeys);
    timeint.Start();
    while (!keydown(dikeys,DIK_ESCAPE)) {
        timeint.End();
        gettime=timeint.GetTimeInMilliseconds();
        if (gettime >=5) {
            hr=keyboard->GetDeviceState(256,dikeys);
            akeywaspressed=false;
            if (keydown(dikeys,DIK_A)) {
                akeywaspressed=true;
                if (timekeywaspressed >=300) {
                    cout << "a";
                    lasttimetherewasakeypress=false;
                }

            }
            if (keydown(dikeys,DIK_D)) {
                akeywaspressed=true;
                if (timekeywaspressed >=300) {
                    cout << "d";
                    lasttimetherewasakeypress=false;
                }
            }
            if (lasttimetherewasakeypress==false && akeywaspressed==true) {
                timekeywaspressedclass.Start();
                timekeywaspressed=0;
                lasttimetherewasakeypress=true;
            }
            if (lasttimetherewasakeypress==true && akeywaspressed==true) {
                timekeywaspressedclass.End();
                gettime=timekeywaspressedclass.GetTimeInMilliseconds();
                timekeywaspressed+=gettime;
                timekeywaspressedclass.Start();
            }
            if (akeywaspressed==false) {
                lasttimetherewasakeypress=false;
                timekeywaspressed=0;
            }


        } // end if (gettime >=5)

        } // end while
destroydikeyboard();

} // end main

以下是操纵杆的示例控制台程序。

#include <dinput.h>
#include <iostream>
#include <Windows.h>

#pragma comment(lib,"dinput8.lib")
#pragma comment(lib,"dxguid.lib")

using std::cout;
using std::endl;


LPDIRECTINPUT8 di;
LPDIRECTINPUTDEVICE8 joystick;
LPDIRECTINPUTDEVICE8 keyboard;
DIJOYSTATE2 js;
BOOL CALLBACK enumCallback(const DIDEVICEINSTANCE* instance, VOID* context);
BOOL CALLBACK enumAxesCallback(const DIDEVICEOBJECTINSTANCE* instance, VOID* context);

HRESULT selectjoystick() {
    HRESULT hr;
    // Look for the first simple joystick we can find.
if (FAILED(hr = di->EnumDevices(DI8DEVCLASS_GAMECTRL, enumCallback,
                                NULL, DIEDFL_ATTACHEDONLY))) {
    return hr;
}

// Make sure we got a joystick
if (joystick == NULL) {
  //  printf("Joystick not found.\n");
    return E_FAIL;
}
}

DIDEVCAPS capabilities;

HRESULT setjoystickproperties() {
    HRESULT hr;
    // Set the data format to "simple joystick" - a predefined data format 
//
// A data format specifies which controls on a device we are interested in,
// and how they should be reported. This tells DInput that we will be
// passing a DIJOYSTATE2 structure to IDirectInputDevice::GetDeviceState().
if (FAILED(hr = joystick->SetDataFormat(&c_dfDIJoystick2))) {
    return hr;
}

// Set the cooperative level to let DInput know how this device should
// interact with the system and with other DInput applications.
if (FAILED(hr = joystick->SetCooperativeLevel(NULL, DISCL_EXCLUSIVE |
                                              DISCL_FOREGROUND))) {
    return hr;
}

// Determine how many axis the joystick has (so we don't error out setting
// properties for unavailable axis)

capabilities.dwSize = sizeof(DIDEVCAPS);
if (FAILED(hr = joystick->GetCapabilities(&capabilities))) {
    return hr;
}
}

BOOL CALLBACK enumCallback(const DIDEVICEINSTANCE* instance, VOID* context)
{
    HRESULT hr;

    // Obtain an interface to the enumerated joystick.
    hr = di->CreateDevice(instance->guidInstance, &joystick, NULL);

    // If it failed, then we can't use this joystick. (Maybe the user unplugged
    // it while we were in the middle of enumerating it.)
    if (FAILED(hr)) { 
        return DIENUM_CONTINUE;
    }

    // Stop enumeration. Note: we're just taking the first joystick we get. You
    // could store all the enumerated joysticks and let the user pick.
    return DIENUM_STOP;
}

HRESULT enumaxes() {
    HRESULT hr;
// Enumerate the axes of the joyctick and set the range of each axis. Note:
// we could just use the defaults, but we're just trying to show an example
// of enumerating device objects (axes, buttons, etc.).
if (FAILED(hr = joystick->EnumObjects(enumAxesCallback, NULL, DIDFT_AXIS))) {
    return hr;
}
}

BOOL CALLBACK enumAxesCallback(const DIDEVICEOBJECTINSTANCE* instance, VOID* context)
{
    HWND hDlg = (HWND)context;

    DIPROPRANGE propRange; 
    propRange.diph.dwSize       = sizeof(DIPROPRANGE); 
    propRange.diph.dwHeaderSize = sizeof(DIPROPHEADER); 
    propRange.diph.dwHow        = DIPH_BYID; 
    propRange.diph.dwObj        = instance->dwType;
    propRange.lMin              = -1000; 
    propRange.lMax              = +1000; 

    // Set the range for the axis
    if (FAILED(joystick->SetProperty(DIPROP_RANGE, &propRange.diph))) {
        return DIENUM_STOP;
    }

    return DIENUM_CONTINUE;
}

HRESULT polljoy() {
    HRESULT     hr;

    if (joystick == NULL) {
        return S_OK;
    }


    // Poll the device to read the current state
    hr = joystick->Poll(); 
    if (FAILED(hr)) {
        // DInput is telling us that the input stream has been
        // interrupted. We aren't tracking any state between polls, so
        // we don't have any special reset that needs to be done. We
        // just re-acquire and try again.
        hr = joystick->Acquire();
        while (hr == DIERR_INPUTLOST) {
            hr = joystick->Acquire();
        }

        // If we encounter a fatal error, return failure.
        if ((hr == DIERR_INVALIDPARAM) || (hr == DIERR_NOTINITIALIZED)) {
            return E_FAIL;
        }

        // If another application has control of this device, return successfully.
        // We'll just have to wait our turn to use the joystick.
        if (hr == DIERR_OTHERAPPHASPRIO) {
            return S_OK;
        }
    }

    // Get the input's device state
    if (FAILED(hr = joystick->GetDeviceState(sizeof(DIJOYSTATE2), &js))) {
        return hr; // The device should have been acquired during the Poll()
    }

    return S_OK;
}


class CTimer
{
public:
    CTimer() {
        QueryPerformanceFrequency(&mqFreq);
    }
    ~CTimer() {}

    void Start() {
        QueryPerformanceCounter(&mqStart);
    }
    void End() {
        QueryPerformanceCounter(&mqEnd);
    }
    double GetTimeInSeconds() {
        return (mqEnd.QuadPart - mqStart.QuadPart)/(double)mqFreq.QuadPart;
    }
    double GetTimeInMilliseconds() {
        return (1.0e3*(mqEnd.QuadPart - mqStart.QuadPart))/mqFreq.QuadPart;
    }
    double GetTimeInMicroseconds() {
        return (1.0e6*(mqEnd.QuadPart - mqStart.QuadPart))/mqFreq.QuadPart;
    }
    double GetTimeInNanoseconds() {
        return (1.0e9*(mqEnd.QuadPart - mqStart.QuadPart))/mqFreq.QuadPart;
    }

private:
    LARGE_INTEGER mqStart;
    LARGE_INTEGER mqEnd;
    LARGE_INTEGER mqFreq;
};


HRESULT initializedirectinput8() {
    HRESULT hr;
    // Create a DirectInput device
if (FAILED(hr = DirectInput8Create(GetModuleHandle(NULL), DIRECTINPUT_VERSION, 
                                   IID_IDirectInput8, (VOID**)&di, NULL))) {
    return hr;
}
}

void createdikeyboard() {
    di->CreateDevice(GUID_SysKeyboard, &keyboard, NULL);
    keyboard->SetDataFormat(&c_dfDIKeyboard);
    keyboard->SetCooperativeLevel(NULL,DISCL_FOREGROUND | DISCL_EXCLUSIVE);
    keyboard->Acquire();
}

void destroydikeyboard() {
    keyboard->Unacquire();
    keyboard->Release();
}

void closejoystick() {
    if (joystick) { 
    joystick->Unacquire();
    }
    if (joystick) {
        joystick->Release();
    }
}

#define keydown(name,key) (name[key] & 0x80)

void main() {
    HRESULT hr;
    CTimer pollintclass;
    hr=initializedirectinput8();
    createdikeyboard();
    hr=selectjoystick();
    hr=setjoystickproperties();
    hr=enumaxes();
    bool endloop=false;
    double gettime;
    BYTE dikeys[256];
    pollintclass.Start();
    while (endloop==false) {
        pollintclass.End();
        gettime=pollintclass.GetTimeInMilliseconds();
        if (gettime >=5) {
            hr=keyboard->GetDeviceState(256,dikeys);
            if (FAILED(hr)) 
                keyboard->Acquire();
            if (keydown(dikeys,DIK_ESCAPE)) 
                endloop=true;
            polljoy();
            cout << "joy x-axis=" << js.lX << " " << "joy y-axis=" << js.lY << endl;
            pollintclass.Start();
        }
    }
destroydikeyboard();
    closejoystick();

}

Answer 2

你有没有试过用DISCL_FOREGROUND代替DISCL_BACKGROUND？

Answer 3

实际上，当我将它从与控制台窗口(明显存在)的关联更改为我在SetCooperativeLevel()调用中创建的窗口时，错误会神奇地消失。我不知道为什么控制台窗口不能使用，所以我会暂时不接受这个问题，而不是让回答者接受，但这确实解决了问题。