[DirectX][DirectInput][JoyStick]DirectInput的JoyStick创建步骤整理

简介：DirectInput和其他DirectX组成部分一样，是通过硬件抽象层（HAL）和硬件仿真层（HEL）来实现，处理的输入设备一般包括鼠标、键盘、游戏控制杆、操作杆等。而且现在的DirectInput还能够支持力反馈设备。

Step 1: Creating the DirectInput Object

create a single DirectInput object as overall manager.

DirectInput8Create

 

// HINSTANCE  g_hinst; // initialized earlier
HRESULT         hr;
LPDIRECTINPUT8  g_lpDI;

hr = DirectInput8Create(g_hinst, DIRECTINPUT_VERSION,
        IID_IDirectInput8, (void**)&g_lpDI, NULL);
if FAILED(hr)
{
    // DirectInput not available; take appropriate action
}

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Step 2: Enumerating the Joysticks

 IDirectInput8::EnumDevices

 

//g_pDI is an initialized pointer to IDirectInput8
g_pDI->EnumDevices(DI8DEVCLASS_GAMECTRL, EnumJoysticksCallback,
                       NULL, DIEDFL_ATTACHEDONLY)

 

 

 

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Step 4: Setting the Joystick Data Format

 

call the  IDirectInputDevice8::SetDataFormat  to manipulate that device

 

if (FAILED(hr = g_pJoystick->SetDataFormat(&c_dfDIJoystick2)))
    return hr;

 

typedef struct {
    LONG lX;
    LONG lY;
    LONG lZ;
    LONG lRx;
    LONG lRy;
    LONG lRz;
    LONG rglSlider[2];
    DWORD rgdwPOV[4];
    BYTE rgbButtons[128];
    LONG lVX;
    LONG lVY;
    LONG lVZ;
    LONG lVRx;
    LONG lVRy;
    LONG lVRz;
    LONG rglVSlider[2];
    LONG lAX;
    LONG lAY;
    LONG lAZ;
    LONG lARx;
    LONG lARy;
    LONG lARz;
    LONG rglASlider[2];
    LONG lFX;
    LONG lFY;
    LONG lFZ;
    LONG lFRx;
    LONG lFRy;
    LONG lFRz;
    LONG rglFSlider[2];
} DIJOYSTATE2, *LPDIJOYSTATE2;

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Step 5: Setting the Joystick Behavior

The joystick device has been created, and its data format has been set. The next step is to set its cooperative level.

 

if (FAILED(hr = g_pJoystick->SetCooperativeLevel(hDlg,
                    DISCL_EXCLUSIVE | DISCL_FOREGROUND)))
    return hr;

 

The next step is to gather information about the capabilities of the joystick.

 

g_diDevCaps.dwSize = sizeof(DIDEVCAPS);//must be first initailized
if (FAILED(hr = g_pJoystick->GetCapabilities(&g_diDevCaps)))
    return hr;

 

if (FAILED(hr = g_pJoystick->EnumObjects(EnumAxesCallback,
                                       (VOID*)hDlg, DIDFT_AXIS)))
    return hr;

 

 

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 Step6: Gaining Access to the Joystick

 

 IDirectInputDevice8::Acquire

 

hr = g_pJoystick->Poll();
if (FAILED(hr))
{
    hr = g_pJoystick->Acquire();
    while(hr == DIERR_INPUTLOST)
        hr = g_pJoystick->Acquire();
    return S_OK;
}

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• The DI8DEVCLASS_GAMECTRL constant specifies the class of device to be enumerated.
• EnumJoysticksCallback is the address of a callback function to be called each time a joystick is found.
• The third parameter can be any 32-bit value that you want to make available to the callback function.
• The last parameter, DIEDFL_ATTACHEDONLY, is a flag that restricts enumeration to devices that are attached to the computer.

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 Step 7: Retrieving Data from the Joystick

HRESULT UpdateInputState(HWND hDlg)
{
    HRESULT     hr;
    CHAR        strText[128]; // Device state text
    DIJOYSTATE2 js;            // Direct Input joystick state
    CHAR*       str;

    if (NULL == g_pJoystick)
        return S_OK;

    // Poll the device to read the current state
    hr = g_pJoystick->Poll();
    if (FAILED(hr)) 
    {
        // Attempt to reacquire joystick
    }
    hr = g_pJoystick->GetDeviceState(sizeof(DIJOYSTATE2), &js);
    if (FAILED(hr))
        return hr;

 

• DIJOYSTATE2. This structure holds data for up to six axes, 128 buttons, and four point-of-view hats.
• Joystick buttons work just like keys or mouse buttons. If the high bit of the returned byte is 1, the button is pressed.
• 返回字节最高位为1，则按键处于按下状态

Step 3: Creating the DirectInput Joystick Device

 

IDirectInput8::EnumDevices枚举到设备后调用EnumJoysticksCallback回调函数，在回调函数中调用IDirectInput8::CreateDevice建立设备。

 

IDirectInput8::CreateDevice有三个参数：

1.枚举设备GUID（由DIDEVICEINSTANCE结构体提供，枚举到设备后DIDEVICEINSTANCE结构体通过指针传递给回调函数）

2.

 

The EnumJoysticksCallback callback function parameters are as follows:

• A pointer to the device instance, supplied by the DirectInput system when the device is enumerated.
• A pointer to a 32-bit value that you supplied as a parameter to IDirectInput8::EnumDevices

         (NULL = VOID* pContext)

 

    

BOOL CALLBACK EnumJoysticksCallback(const DIDEVICEINSTANCE*    
                                       pdidInstance, VOID* pContext)
{
    HRESULT hr;

    // Obtain an interface to the enumerated joystick.
    hr = g_pDI->CreateDevice(pdidInstance->guidInstance, 
                                &g_pJoystick, NULL);
    if(FAILED(hr))
        return DIENUM_CONTINUE;

    return DIENUM_STOP;

 

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