Windows raw input api

hi,

im working with a scanner to get barcodes. it is a plug and play device but i want to data process the data myself.

to catch al the data i am using windows raw input api.
when i can a couple of barcodes my calback function is never called. but i dont understand why.

using windows 7 and qt 5.

My code:

#include "mainwindow.h"
#include <QApplication>

#include <windows.h>
#include <QDebug>

// register Scanner
void InitRawInput(HWND hWnd){

    RAWINPUTDEVICE Rid[1];
    Rid[0].usUsagePage = 0x01;
    Rid[0].usUsage = 0x06;
    Rid[0].dwFlags = RIDEV_INPUTSINK;
    Rid[0].hwndTarget = hWnd;
    if (RegisterRawInputDevices(Rid,1,sizeof(Rid[0])) == false)
        {
        qDebug() << "Registration failed";
        return;
        }
    qDebug() << "Registration updated";
}

/*
 * Function that receives messages from OS
 *
 * LRESULT --> returns a 32-bit number (64 for 64 OS)
 * CALLBACK --> specifies how in assembly parameters will get passed
 * 				and returned from the function
 * HWND --> Handle to the window that is receiving messages from the OS
 * UINT --> Says what type of message is being sent
 * WPARAM/LPARAM --> es. X and Y mouse position
*/
LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) {

    qDebug() << "calback";
    LPBYTE lpb;
    UINT dwSize;
    RAWINPUT *raw;
        switch(msg)
        {
        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
            break;

        case WM_INPUT:
            {

            GetRawInputData((HRAWINPUT)lParam, RID_INPUT, NULL, &dwSize, sizeof(RAWINPUTHEADER));

            lpb = new BYTE[dwSize];

            if (lpb == NULL)
                return 0;

            if (GetRawInputData((HRAWINPUT)lParam,
                RID_INPUT,
                lpb,
                &dwSize,
                sizeof(RAWINPUTHEADER)) != dwSize)
                {
                qDebug() << "GetRawInputData doesn't return correct siz";
                //OutputDebugStr(TEXT("GetRawInputData doesn't return correct size\n"));
                }

            raw = (RAWINPUT*) lpb;

            qDebug() << "whaa";
            if (raw->header.dwType == RIM_TYPEKEYBOARD)
                {
                if (raw->data.keyboard.Message == WM_KEYDOWN ||
                    raw->data.keyboard.Message == WM_SYSKEYDOWN)
                    {
                        USHORT usKey;
                        usKey = raw->data.keyboard.VKey;
                        CHAR szTest[4];
                        _itoa_s((int)usKey,szTest,4,10);

                        WCHAR str[4];
                        MultiByteToWideChar( 0,0, szTest, 4, str, 4);

//                        SetWindowText(hWnd,szTest);
                       SetWindowText(hWnd,str);
                    }
                }

            delete[] lpb;
            return 0;
            }
        }

    return DefWindowProc(hWnd, msg, wParam, lParam);
}

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

       // TODO: code your application's behavior here.

       UINT nDevices;
       PRAWINPUTDEVICELIST pRawInputDeviceList;

       if (GetRawInputDeviceList(NULL, &nDevices, sizeof(RAWINPUTDEVICELIST)) != 0)
       {
          qDebug() << "Errors...";
          return 1;
       }

       if ((pRawInputDeviceList = (PRAWINPUTDEVICELIST)malloc(sizeof(RAWINPUTDEVICELIST) * nDevices)) == NULL)
       {
          qDebug() << "Initialization failed...";
          return 1;
       }

       int nNoOfDevices = 0;
       if ((nNoOfDevices = GetRawInputDeviceList(pRawInputDeviceList, &nDevices, sizeof(RAWINPUTDEVICELIST))) == ((UINT) - 1))
       {
          // Error
          return 1;
       }

       RID_DEVICE_INFO rdi;
       rdi.cbSize = sizeof(RID_DEVICE_INFO);

       for(int i = 0; i < nNoOfDevices; i++)
       {
          UINT size = 256;
          TCHAR tBuffer[256] = {0};
          tBuffer[0] = '\0';
          if(GetRawInputDeviceInfo(pRawInputDeviceList[i].hDevice, RIDI_DEVICENAME, tBuffer, &size) < 0)
          {
             // Error in reading device name
              qDebug() << "error reading device name";
          }

           qDebug() << "Device Name: " << tBuffer;
          //_tprintf(L"Device Name: %s\n", tBuffer);

          UINT cbSize = rdi.cbSize;
          if(GetRawInputDeviceInfo(pRawInputDeviceList[i].hDevice, RIDI_DEVICEINFO, &rdi, &cbSize) < 0)
          {
             // Error in reading information
          }

          if(rdi.dwType == RIM_TYPEMOUSE)
          {
             qDebug() << "ID for Mouse:" << rdi.mouse.dwId;
             qDebug() << "Number of Buttons:" << rdi.mouse.dwNumberOfButtons;
             qDebug() << "Sample rate(Number of data points):" << rdi.mouse.dwSampleRate;
             qDebug() << "**************************";
          }

          if(rdi.dwType == RIM_TYPEKEYBOARD)
          {
             qDebug() << "Keyboard Mode:" << rdi.keyboard.dwKeyboardMode;
             qDebug() << "Number of function keys:" << rdi.keyboard.dwNumberOfFunctionKeys;
             qDebug() << "Number of indicators:" << rdi.keyboard.dwNumberOfIndicators;
             qDebug() << "Number of keys total: " << rdi.keyboard.dwNumberOfKeysTotal;
             qDebug() << "Type of the keyboard: " << rdi.keyboard.dwType;
             qDebug() << "Subtype of the keyboard: " << rdi.keyboard.dwSubType;
             qDebug() << "***********************";
          }

          if(rdi.dwType == RIM_TYPEHID)
          {
             qDebug() << "Vendor Id:" << rdi.hid.dwVendorId;
             qDebug() << "Product Id:" << rdi.hid.dwProductId;
             qDebug() << "Version No:" << rdi.hid.dwVersionNumber;
             qDebug() << "Usage for the device: " << rdi.hid.usUsage;
             qDebug() << "Usage Page for the device: " << rdi.hid.usUsagePage;
             qDebug() << "***********************";
          }
       }

       free(pRawInputDeviceList);

       HWND temper = (HWND)w.effectiveWinId();
       InitRawInput(temper);

//        //Struct to hold windows event messages
//        MSG msg;

//        while (GetMessage(&msg, NULL,0,0))
//        {
//            qDebug() << "testersa";
//            TranslateMessage(&msg);
//            DispatchMessage(&msg);
//        }

//    return msg.wParam;
    return a.exec();
}

Device Name:  0x28fa10 
Keyboard Mode: 1 
Number of function keys: 12 
Number of indicators: 3 
Number of keys total:  101 
Type of the keyboard:  81 
Subtype of the keyboard:  0 
*********************** 
Device Name:  0x28fa10 
Keyboard Mode: 1 
Number of function keys: 12 
Number of indicators: 3 
Number of keys total:  264 
Type of the keyboard:  81 
Subtype of the keyboard:  0 
*********************** 
Device Name:  0x28fa10 
ID for Mouse: 2 
Number of Buttons: 2 
Sample rate(Number of data points): 60 
************************** 
Device Name:  0x28fa10 
ID for Mouse: 256 
Number of Buttons: 8 
Sample rate(Number of data points): 0 
************************** 

// + Scanner
Device Name:  0x28fa10 
Keyboard Mode: 1 
Number of function keys: 12 
Number of indicators: 3 
Number of keys total:  154 
Type of the keyboard:  81 
Subtype of the keyboard:  0 
*********************** 
Device Name:  0x28fa10 
Vendor Id: 1035 
Product Id: 25923 
Version No: 256 
Usage for the device:  1 
Usage Page for the device:  65280 
***********************
Registration updated

methodos (60)

Have you tried uncommenting the messageloop? The DispatchMessage function is probably the one that calls your CALLBACK function WndProc.

//        //Struct to hold windows event messages
//        MSG msg;

//        while (GetMessage(&msg, NULL,0,0))
//        {
//            qDebug() << "testersa";
//            TranslateMessage(&msg);
//            DispatchMessage(&msg);
//        }

//    return msg.wParam;

Last edited on

thejman250 (138)

- and i suppose that you use a main() function in Qt instead of a WinMain() function as you would in regular WinAPI?

Last edited on

aMuis (3)

the message loop is not calling WndProc. it is commented for that reason.

I think that the WndProc function is not going to work under QT.

guestgulkan (2942)

thejman250 wrote:
- and i suppose that you use a main() function in Qt instead of a WinMain() function as you would in regular WinAPI?

Yes, If you make a QT project - the winmain is provided by QT - and that winmain calls your main function.

----But just taking a normal windows or console project and adding some QT headers to it does not make it a QT project if you see what I mean----.

In the original post - the windows procedure is never going to get called by Windows - I think the original poster is very confused

modoran (2077)

You should override QCoreApplication::winEventFilter in your Qt application to be able to receive normal windows messages:
http://qt-project.org/doc/qt-4.8/qcoreapplication.html#winEventFilter

aMuis (3)

@guestgulkan Yes i was really confused.

i have something working now. i am using the function NativeEvent from qt 5 now.

But there is a new problem, i want to catch the data from 1 device and not from both. both are keyboards. but in the message i cant find the device where it originated from.

thejman250 (138)

guestgulkan wrote:
Yes, If you make a QT project - the winmain is provided by QT - and that winmain calls your main function. ----But just taking a normal windows or console project and adding some QT headers to it does not make it a QT project if you see what I mean----. In the original post - the windows procedure is never going to get called by Windows - I think the original poster is very confused

- Thanks for explaining that, and yes i understand.

- If this were WinAPI, the DispatchMessage() function would result in windows calling the windows procedure as far as i know, but i have no clue about Qt.

Last edited on

xgrlab (1)

You can create Application:QApplication. And then reimplement this function if you want to process window messages msg that are not processed by Qt.

Like This:

bool Application::winEventFilter(MSG *msg, long *result)
{
    LPARAM lParam = msg->lParam;
    LPBYTE lpb;
    UINT dwSize;
    RAWINPUT *raw;
    if (msg->message == WM_INPUT) {

        GetRawInputData((HRAWINPUT)lParam, RID_INPUT, NULL, &dwSize, sizeof(RAWINPUTHEADER));

        lpb = new BYTE[dwSize];

        if (lpb == NULL)
            return 0;
        if (GetRawInputData((HRAWINPUT)lParam,
                            RID_INPUT,
                            lpb,
                            &dwSize,
                            sizeof(RAWINPUTHEADER)) != dwSize)
        {
            qDebug() << "GetRawInputData doesn't return correct siz";
            //OutputDebugStr(TEXT("GetRawInputData doesn't return correct size\n"));
        }

        raw = (RAWINPUT*) lpb;
        if (Application::m_deviceId == raw->header.hDevice) {
            if (raw->header.dwType == RIM_TYPEKEYBOARD) {
                if (raw->data.keyboard.Message == WM_KEYDOWN ||
                        raw->data.keyboard.Message == WM_SYSKEYDOWN)
                {
                    USHORT usKey;
                    usKey = raw->data.keyboard.VKey;
                    qDebug() << usKey;
//                    qDebug() << "hDevice" << raw->header.hDevice;
                }

            }
            result = 0;
            msg = 0;
            return true;
        }
        qDebug() << "id" << raw->header.dwType << raw->data.keyboard.VKey;
        delete[] lpb;

    }
    return QApplication::winEventFilter(msg,result);
}

Application::m_deviceId is scanner device id.

But I have a problem .When I return true, the message still pass to the text edit widget. And I don't know why?
If you done,please let me know. (xgrlab@126.com)

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Windows raw input api

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