example-image-gdiplus.cpp

This is a simple example of how to connect to a ScripTouch device and output a PNG image using the GDI+ drawing library included in Windows.

#include <stdio.h>
#include <Windows.h>
#include <Gdiplus.h>
extern "C" {
    #include "scriptel-proscript.h"
}
 
scriptel_hid_feature_coordinate_range range;
ULONG_PTR gdiplusToken;
CLSID pngClsid;
Gdiplus::GdiplusStartupInput gdiplusStartupInput;
Gdiplus::Bitmap* image;
Gdiplus::Graphics* graphics;
Gdiplus::Pen* pen;
 
double lastX = -1;
double lastY = -1;
 
//Finds the CLSID of a Gdiplus output format type by mime type.
//Example taken directly from MSDN: http://msdn.microsoft.com/en-us/library/windows/desktop/ms533843(v=vs.85).aspx
int GetEncoderClsid(const WCHAR* format, CLSID* pClsid) {
    UINT  num = 0;
    UINT  size = 0;
 
    Gdiplus::ImageCodecInfo* pImageCodecInfo = NULL;
    Gdiplus::GetImageEncodersSize(&num, &size);
    if(size == 0) {
        return -1;
    }
 
    pImageCodecInfo = (Gdiplus::ImageCodecInfo*)(malloc(size));
    if(pImageCodecInfo == NULL) {
        return -1;
    }
 
    Gdiplus::GetImageEncoders(num, size, pImageCodecInfo);
    for(UINT j = 0; j < num; ++j) {
        if( wcscmp(pImageCodecInfo[j].MimeType, format) == 0 ) {
            *pClsid = pImageCodecInfo[j].Clsid;
            free(pImageCodecInfo);
            return j;
        }    
    }
 
    free(pImageCodecInfo);
    return -1;
}
 
void input_callback(scriptel_device* device, scriptel_input_report* report, unsigned char report_id) {
    if(report_id == SCRIPTEL_INPUT_EXTENDEDCOORDINATE) {
        //We got pen input, lets adjust the coordinates into screen aspect.
        double x = device->display_info.width * ((report->extended_coordinate.x - range.x_min) / (double)(range.x_max - range.x_min));
        double y = device->display_info.height * ((report->extended_coordinate.y - range.y_min) / (double)(range.y_max - range.y_min));
 
        printf("Got a coordinate from the device: %4.2f, %4.2f\n", x, y);
 
        if(report->extended_coordinate.sample_info.pen.tip_switch) {
            if(lastX < 0) {
                //Pen Down
                Gdiplus::PointF pt((float)x,(float)y);
                graphics->DrawLine(pen, pt, pt);
            } else {
                //Pen Move
                Gdiplus::PointF pt1((float)lastX,(float)lastY);
                Gdiplus::PointF pt2((float)x,(float)y);
                graphics->DrawLine(pen, pt1, pt2);
            }
            lastX = x;
            lastY = y;
        } else {
            //Pen Up
            Gdiplus::PointF pt1((float)lastX,(float)lastY);
            Gdiplus::PointF pt2((float)x,(float)y);
            graphics->DrawLine(pen, pt1, pt2);
            lastX = -1;
            lastY = -1;
        }
    } else if(report_id == SCRIPTEL_INPUT_BUTTONPRESS) {
        //A button was pressed, if it's the OK button we'll close the device.
        char* caption = report->button_press.region->button.caption;
        printf("Button pressed: %s\n", caption);
        if(strcmp(caption, "OK") == 0) {
            image->Save(L"signature.png", &pngClsid, NULL);
            //The OK button was hit, close the device.
            scriptel_close_device(device);
        } else {
            //The cancel button was hit, clear the image.
            graphics->Clear(Gdiplus::Color::Transparent);
        }
    }
}
 
int main() {
    scriptel_device* device;
 
    //Initialize the library.
    scriptel_init();
 
    //List the devices.
    if(scriptel_list_devices(&device) == SCRIPTEL_CODE_SUCCESS) {
        //Test to see if we have more than zero devices.
        if(device != NULL) {
            printf("Found %i devices.\n", scriptel_count_device_list(device));
 
            //Lets open the first device and get some information from it.
            if(scriptel_open_device(device) == SCRIPTEL_CODE_SUCCESS) {
                printf("Successfully connected to %s - %s at: %s\n", device->manufacturer, device->model, device->path);
                
                //Register an input callback, this will be called when we get input from the pad.
                scriptel_register_input_callback(device, input_callback);
 
                //Get the coordinate scaling information we'll need later.
                range = scriptel_get_coordinate_range(device);
 
                //Start up GDI+
                GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);
                image = new Gdiplus::Bitmap(device->display_info.width, device->display_info.height, PixelFormat32bppARGB);
                graphics = Gdiplus::Graphics::FromImage(image);
                pen = new Gdiplus::Pen(Gdiplus::Color::Black, 1);
                graphics->Clear(Gdiplus::Color::Transparent);
                graphics->SetSmoothingMode(Gdiplus::SmoothingModeAntiAlias);
                GetEncoderClsid(L"image/png", &pngClsid);
 
                //Wait for input from the pad.
                while(device->open) {
                    scriptel_device_read(device);
                }
 
                //Free GDI+
                delete graphics;
                delete image;
                delete pen;
                Gdiplus::GdiplusShutdown(gdiplusToken);
 
                scriptel_free_device_list(device);
            } else {
                printf("Problem opening device: %s\n", scriptel_get_last_error());
                return 1;
            }
        } else {
            printf("No devices found!\n");
            return 2;
        }
    } else {
        printf("Problem enumerating devices: %s\n", scriptel_get_last_error());
        return 3;
    }
}