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// svghmi.js

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var cache = hmitree_types.map(_ignored => undefined);

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function dispatch_value_to_widget(widget, index, value, oldval) {

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    let idxidx = widget.indexes.indexOf(index);

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    if(idxidx == -1){

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        throw new Error("Dispatching to widget not interested, should not happen.");

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    }

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    let d = widget.dispatch;

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    if(typeof(d) == "function" && idxidx == 0){

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        return d.call(widget, value, oldval);

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    }else if(typeof(d) == "object" && d.length >= idxidx){

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        return d[idxidx].call(widget, value, oldval);

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    }/* else dispatch_0, ..., dispatch_n ? */

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    /*else {

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        throw new Error("Dunno how to dispatch to widget at index = " + index);

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    }*/

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}

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function dispatch_value(index, value) {

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    let widgets = subscribers[index];

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    let oldval = cache[index];

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    cache[index] = value;

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    if(widgets.size > 0) {

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        for(let widget of widgets){

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            dispatch_value_to_widget(widget, index, value, oldval);

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        }

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    }

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};

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function init_widgets() {

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    Object.keys(hmi_widgets).forEach(function(id) {

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        let widget = hmi_widgets[id];

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        let init = widget.init;

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        if(typeof(init) == "function"){

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            return init.call(widget);

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        }

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    });

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};

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// Open WebSocket to relative "/ws" address

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var ws = new WebSocket(window.location.href.replace(/^http(s?:\/\/[^\/]*)\/.*$/, 'ws$1/ws'));

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ws.binaryType = 'arraybuffer';

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const dvgetters = {

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    INT: (dv,offset) => [dv.getInt16(offset, true), 2],

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    BOOL: (dv,offset) => [dv.getInt8(offset, true), 1],

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    STRING: (dv, offset) => {

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        size = dv.getInt8(offset);

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        return [

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            String.fromCharCode.apply(null, new Uint8Array(

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                dv.buffer, /* original buffer */

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                offset + 1, /* string starts after size*/

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                size /* size of string */

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            )), size + 1]; /* total increment */

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    }

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};

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// Register message reception handler 

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ws.onmessage = function (evt) {

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    let data = evt.data;

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    let dv = new DataView(data);

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    let i = 0;

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    try {

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        for(let hash_int of hmi_hash) {

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            if(hash_int != dv.getUint8(i)){

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                throw new Error("Hash doesn't match");

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            };

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            i++;

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        };

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        while(i < data.byteLength){

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            let index = dv.getUint32(i, true);

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            i += 4;

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            let iectype = hmitree_types[index];

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            if(iectype != undefined){

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                let dvgetter = dvgetters[iectype];

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                let [value, bytesize] = dvgetter(dv,i);

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                dispatch_value(index, value);

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                i += bytesize;

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            } else {

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                throw new Error("Unknown index "+index)

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            }

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        };

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    } catch(err) {

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        // 1003 is for "Unsupported Data"

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        // ws.close(1003, err.message);

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        // TODO : remove debug alert ?

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        alert("Error : "+err.message+"\\\\nHMI will be reloaded.");

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        // force reload ignoring cache

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        location.reload(true);

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    }

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};

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function send_blob(data) {

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    if(data.length > 0) {

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        ws.send(new Blob([new Uint8Array(hmi_hash)].concat(data)));

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    };

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};

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const typedarray_types = {

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    INT: Int16Array,

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    BOOL: Uint8Array

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    /* TODO */

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};

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function send_reset() {

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    send_blob(new Uint8Array([1])); /* reset = 1 */

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};

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// subscription state, as it should be in hmi server

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// hmitree indexed array of integers

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var subscriptions =  hmitree_types.map(_ignored => 0);

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// subscription state as needed by widget now

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// hmitree indexed array of Sets of widgets objects

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var subscribers = hmitree_types.map(_ignored => new Set());

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// artificially subscribe the watchdog widget to "/heartbeat" hmi variable

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// Since dispatch directly calls change_hmi_value, 

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// PLC will periodically send variable at given frequency

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subscribers[heartbeat_index].add({

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    /* type: "Watchdog", */

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    frequency: 1,

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    indexes: [heartbeat_index],

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    dispatch: function(value) {

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        change_hmi_value(this.indexes[0], "+1");

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    }

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});

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function update_subscriptions() {

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    let delta = [];

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    for(let index = 0; index < subscribers.length; index++){

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        let widgets = subscribers[index];

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        // periods are in ms

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        let previous_period = subscriptions[index];

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        // subscribing with a zero period is unsubscribing

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        let new_period = 0;

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        if(widgets.size > 0) {

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            let maxfreq = 0;

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            for(let widget of widgets)

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                if(maxfreq < widget.frequency)

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                    maxfreq = widget.frequency;

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            if(maxfreq != 0)

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                new_period = 1000/maxfreq;

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        }

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        if(previous_period != new_period) {

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            subscriptions[index] = new_period;

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            delta.push(

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                new Uint8Array([2]), /* subscribe = 2 */

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                new Uint32Array([index]),

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                new Uint16Array([new_period]));

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        }

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    }

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    send_blob(delta);

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};

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function send_hmi_value(index, value) {

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    let iectype = hmitree_types[index];

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    let jstype = typedarray_types[iectype];

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    send_blob([

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        new Uint8Array([0]),  /* setval = 0 */

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        new Uint32Array([index]), 

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        new jstype([value])]);

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    cache[index] = value;

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};

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function change_hmi_value(index, opstr) {

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    let op = opstr[0];

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    let given_val = opstr.slice(1);

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    let old_val = cache[index]

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    let new_val;

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    switch(op){

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      case "=":

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        eval("new_val"+opstr);

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        break;

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      case "+":

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      case "-":

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      case "*":

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      case "/":

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        if(old_val != undefined)

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            new_val = eval("old_val"+opstr);

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        break;

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    }

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    if(new_val != undefined && old_val != new_val)

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        send_hmi_value(index, new_val);

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    return new_val;

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}

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var current_page;

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function switch_page(page_name) {

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    let old_desc = page_desc[current_page];

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    let new_desc = page_desc[page_name];

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    /* TODO hide / show widgets */

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    /* remove subsribers of previous page if any */

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    if(old_desc) for(let widget of old_desc.widgets){

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        for(let index of widget.indexes){

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            subscribers[index].delete(widget);

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        }

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    }

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    if(new_desc) {

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        /* add new subsribers if any */

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        for(let widget of new_desc.widgets){

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            for(let index of widget.indexes){

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                subscribers[index].add(widget);

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                let cached_val = cache[index];

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                if(cached_val != undefined)

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                    dispatch_value_to_widget(widget, index, cached_val, cached_val);

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            }

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        }

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        svg_root.setAttribute('viewBox',new_desc.bbox.join(" "));

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        // TODO dispatch current cache in newly opened page

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    }

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    current_page = page_name;

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    update_subscriptions();

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};

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// Once connection established

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ws.onopen = function (evt) {

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    init_widgets();

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    send_reset();

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    // show main page

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    switch_page(default_page);

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};

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ws.onclose = function (evt) {

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    // TODO : add visible notification while waiting for reload

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    console.log("Connection closed. code:"+evt.code+" reason:"+evt.reason+" wasClean:"+evt.wasClean+" Reload in 10s.");

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    // TODO : re-enable auto reload when not in debug

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    //window.setTimeout(() => location.reload(true), 10000);

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    alert("Connection closed. code:"+evt.code+" reason:"+evt.reason+" wasClean:"+evt.wasClean+".");

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};