2

I have a graphics tablet (ug-1200b) which I'm using with Ubuntu. I have written a (somewhat ugly) script which uses libusb to take the raw input and xdotool to emulate mouse movements and clicks. This works quite well, but I was wondering if there was a way of accessing the finer resolution of the tablet.

The tablet has a stylus resolution of roughly 144336x8192 and a screen resolution of 1024x782, so there are >10 steps in the stylus position per pixel. I would like to report these as mouse movements.

My problem is that xdotool has a pixel based mouse-movement system. I'm using xdo_move_mouse(xdo, X, Y, 0); but this is limited to integer values, so I am having to round, and remove the extra resolution.

Is there any way of getting around this problem?

//compile with g++ myLibusbFile1.cpp -lusb-1.0 -lxdo
//this is a custom "driver" for the ug-1200b tablet.

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <usb.h>
#include <libusb-1.0/libusb.h>
extern "C" {
    #include <xdo.h>
}
#define CURRENTWINDOW (0)

uint16_t VENDOR = 21827; /* =0x5543 */
uint16_t PRODUCT = 74; /* =0x004a */
int ENDPOINT_IN = 129; /* = 0x81 */ 


void printData(unsigned char dataIn[]){
    for(int i = 0; i < 8; i++){
        printf("%d ",dataIn[i]);
    }
    printf("\n");
}

int main() {
    xdo_t *xdo = xdo_new(NULL);
    libusb_context *context = NULL;
    libusb_device **list = NULL;
    ssize_t count = 0;
    libusb_device **devs;
    libusb_device_handle *device_handle;
    int r;
    struct libusb_config_descriptor *conf;

    printf("intialising\n");
    if(libusb_init(&context)<0){
        printf("intialisation failed\n");
        return 0;
    }

    printf("getting list of USB's\n");
    count = libusb_get_device_list(context, &list);
    if(count <= 0) {
        printf("could not find USB device");
        return 0;
    }

    bool found_device =false;

    for (size_t idx = 0; idx < count && ! found_device; ++idx) {
        libusb_device *device = list[idx];
        libusb_device_descriptor desc = {0};

        libusb_get_device_descriptor(device, &desc);
        printf("Vendor:Device = %04x:%04x\n", desc.idVendor, desc.idProduct);
        if(desc.idVendor == VENDOR && desc.idProduct == PRODUCT){
            if(libusb_open(device, &device_handle) < 0){
                printf("failed to open device\n");
                return 0;
            }
            found_device = true;
            printf("opened device\n");
        }
    }

    if(! found_device){
        printf("Tablet not found");
        return 0;
    }

    //automatically get and re-set kernel interface
    if(libusb_set_auto_detach_kernel_driver(device_handle, 1) < 0)
        {
            printf("failed set auto detach\n");
            return 0; 
        }

    //claim interface
    if(libusb_claim_interface(device_handle, 0) < 0){
        printf("failed to claim interface\n");
        libusb_close(device_handle);
        return 0;
    }
    printf("interface claimed\n");

    bool mouseIsDown=false;
    bool complete = false;
    while(!complete){
        unsigned char dataIn[8];
        int transferred;
        if( libusb_interrupt_transfer(device_handle, ENDPOINT_IN, dataIn, 8, &transferred, 0) < 0){
            printf("interrupt transfer failed!\n");
            complete = true;
        } else {

        int X = (int) (dataIn[2] | (dataIn[3]) << 8);
        int Y = (int) (dataIn[4] | (dataIn[5]) << 8);
        int Z = (int) (dataIn[6] | (dataIn[7]) << 8);

        X = X / 14;
        Y = (Y * 3) / 32;

        if((int) dataIn[0] != 9 || !((int) dataIn[1] != 0 ^ Z == 0)){
            printData(dataIn);
            printf("unfamiliar string!\n");
            return 0;
        }
        xdo_move_mouse(xdo, X, Y, 0);
        if(mouseIsDown && Z == 0){
            mouseIsDown = false;
            xdo_mouse_up(xdo, CURRENTWINDOW, 1);
        }
        if(!mouseIsDown && Z != 0){
            mouseIsDown = true;
            xdo_mouse_down(xdo, CURRENTWINDOW, 1);
        }


        }
    }

    //close interface and usb, and deinitialise
    printf("releasing interface\n");
    libusb_release_interface(device_handle,0);
    printf("closing device\n");
    libusb_close(device_handle);
    printf("exiting\n");
    libusb_exit(context);
    printf("done!\n");

    return 0;

}

0

You must log in to answer this question.

Browse other questions tagged .