使用DirectInput进行交互（3）

除了指定的是鼠标标识符以及鼠标数据格式外，初始化鼠标就和初始化键盘几乎完全相同。

//--------------------------------------------------------------------------------
// Initialize mouse interface, return a mouse interface pointer.
//--------------------------------------------------------------------------------
IDirectInputDevice8* Init_Mouse(HWND hwnd, IDirectInput8* directinput)
{
    IDirectInputDevice8* directinput_device;

    // create the device object
    if(FAILED(directinput->CreateDevice(GUID_SysMouse, &directinput_device, NULL)))
        return NULL;

    // set the data format
    if(FAILED(directinput_device->SetDataFormat(&c_dfDIMouse)))
    {
        directinput_device->Release();
        return NULL;
    }

    // set the coooperative mode
    if(FAILED(directinput_device->SetCooperativeLevel(hwnd, DISCL_FOREGROUND | DISCL_NONEXCLUSIVE)))
    {
        directinput_device->Release();
        return NULL;
    }

    // acquire the device for use
    if(FAILED(directinput_device->Acquire()))
    {
        directinput_device->Release();
        return NULL;
    }

    // everything well, so return a vaild pointer.
    return directinput_device;
}

要调用DirectInputDevice8::GetDeviceState，使用诸如相对移动和按键状态等鼠标的相关信息来填充 DIMOUSESTATE结构体。

DIMOUSESTATE结构体的定义如下：

Describes the state of a mouse device that has up to four buttons, or another device that is being accessed as if it were a mouse device. This structure is used with the IDirectInputDevice8::GetDeviceState method.

Syntax

typedef struct DIMOUSESTATE {
    LONG lX;
    LONG lY;
    LONG lZ;
    BYTE rgbButtons[4];
} DIMOUSESTATE, *LPDIMOUSESTATE;

Members

lX
X-axis.

lY
Y-axis.

lZ
Z-axis, typically a wheel. If the mouse does not have a z-axis, the value is 0.

rgbButtons
Array of buttons. The high-order bit of the byte is set if the corresponding button is down.

Remarks

You must prepare the device for mouse-style access by calling the IDirectInputDevice8::SetDataFormat method, passing the c_dfDIMouse global data format variable.

The mouse is a relative-axis device, so the absolute axis positions for mouse axes are accumulated relative motion. Therefore, the value of the absolute axis position is not meaningful except in comparison with other absolute axis positions.

If an axis is in relative mode, the appropriate member contains the change in position. If it is in absolute mode, the member contains the absolute axis position.

点击下载源码和工程

完整源码示例：

/***************************************************************************************
PURPOSE:
    Mouse device Demo
 ***************************************************************************************/

#define DIRECTINPUT_VERSION 0x0800

#include <windows.h>
#include <stdio.h>
#include <dinput.h>
#include "resource.h"

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

#pragma warning(disable : 4996)

#define Safe_Release(p) if((p)) (p)->Release();

// window handles, class and caption text.
HWND g_hwnd;
char g_class_name[] = "MouseClass";

IDirectInput8* g_directinput;               // directinput component
IDirectInputDevice8* g_directinput_device;  // mouse device

//--------------------------------------------------------------------------------
// Window procedure.
//--------------------------------------------------------------------------------
long WINAPI Window_Proc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
    case WM_DESTROY:
        PostQuitMessage(0);
        return 0;
    }

    return (long) DefWindowProc(hwnd, msg, wParam, lParam);
}

//--------------------------------------------------------------------------------
// Initialize mouse interface, return a mouse interface pointer.
//--------------------------------------------------------------------------------
IDirectInputDevice8* Init_Mouse(HWND hwnd, IDirectInput8* directinput)
{
    IDirectInputDevice8* directinput_device;

    // create the device object
    if(FAILED(directinput->CreateDevice(GUID_SysMouse, &directinput_device, NULL)))
        return NULL;

    // set the data format
    if(FAILED(directinput_device->SetDataFormat(&c_dfDIMouse)))
    {
        directinput_device->Release();
        return NULL;
    }

    // set the coooperative mode
    if(FAILED(directinput_device->SetCooperativeLevel(hwnd, DISCL_FOREGROUND | DISCL_NONEXCLUSIVE)))
    {
        directinput_device->Release();
        return NULL;
    }

    // acquire the device for use
    if(FAILED(directinput_device->Acquire()))
    {
        directinput_device->Release();
        return NULL;
    }

    // everything well, so return a vaild pointer.
    return directinput_device;
}

//--------------------------------------------------------------------------------
// Read mouse buffer.
//--------------------------------------------------------------------------------
BOOL Read_Device(IDirectInputDevice8* directinput_device, void* buffer, long buffer_size)
{
    HRESULT rv;

    while(1)
    {
        // poll device
        g_directinput_device->Poll();

        // read in state
        if(SUCCEEDED(rv = g_directinput_device->GetDeviceState(buffer_size, buffer)))
            break;

        // return when an unknown error
        if(rv != DIERR_INPUTLOST || rv != DIERR_NOTACQUIRED)
            return FALSE;

        // re-acquire and try again
        if(FAILED(g_directinput_device->Acquire()))
            return FALSE;
    }

    return TRUE;
}

//--------------------------------------------------------------------------------
// Main function, routine entry.
//--------------------------------------------------------------------------------
int WINAPI WinMain(HINSTANCE inst, HINSTANCE, LPSTR cmd_line, int cmd_show)
{
    WNDCLASS        win_class;
    MSG             msg;
    DIMOUSESTATE    mouse_state = {0};
    char            text[256];
    long            x_pos = 0, y_pos = 0;

    // create window class and register it
    win_class.style         = CS_HREDRAW | CS_VREDRAW;
    win_class.lpfnWndProc   = Window_Proc;
    win_class.cbClsExtra    = 0;
    win_class.cbWndExtra    = DLGWINDOWEXTRA;
    win_class.hInstance     = inst;
    win_class.hIcon         = LoadIcon(inst, IDI_APPLICATION);
    win_class.hCursor       = LoadCursor(NULL, IDC_ARROW);
    win_class.hbrBackground = (HBRUSH) (COLOR_BTNFACE + 1);
    win_class.lpszMenuName  = NULL;
    win_class.lpszClassName = g_class_name;    

    if(! RegisterClass(&win_class))
        return FALSE;

    // create the main window
    g_hwnd = CreateDialog(inst, MAKEINTRESOURCE(IDD_MOUSE), 0, NULL);

    ShowWindow(g_hwnd, cmd_show);
    UpdateWindow(g_hwnd);

    // initialize directinput and get keyboard device
    DirectInput8Create(inst, DIRECTINPUT_VERSION, IID_IDirectInput8, (void **) &g_directinput, NULL);

    // initialize mouse
    g_directinput_device = Init_Mouse(g_hwnd, g_directinput);

    // start message pump, waiting for signal to quit.
    ZeroMemory(&msg, sizeof(MSG));

    while(msg.message != WM_QUIT)
    {
        if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        
        // read in mouse and display coordinates
        Read_Device(g_directinput_device, &mouse_state, sizeof(DIMOUSESTATE));

        x_pos += mouse_state.lX;
        y_pos += mouse_state.lY;

        if(mouse_state.lX != 0 || mouse_state.lY != 0)
        {
            sprintf(text, "%ld, %ld", x_pos, y_pos);
            SetWindowText(GetDlgItem(g_hwnd, IDC_COORDINATES), text);
        }
    }

    // release directinput objects
    g_directinput_device->Unacquire();
    g_directinput_device->Release();
    g_directinput->Release();

    UnregisterClass(g_class_name, inst);
    
    return (int) msg.wParam;
}

运行截图: