Meter widget moves the end of "needle" labeled path along "range" labeled
path, according to value of the single accepted variable.
Needle is reduced to a single segment. If "min" a "max" labeled texts
are provided, or if first and second argument are given, then they are used
as respective minimum and maximum value. Otherwise, value is expected to be
If "value" labeled text is found, then its content is replaced by value.
shortdesc > Moves "needle" along "range"
arg name="min" count="optional" accepts="int,real" > minimum value
arg name="max" count="optional" accepts="int,real" > maximum value
// TODO: add printf-like format
path name="value" accepts="HMI_INT,HMI_REAL" > Value to display
this.display_val = value;
this.value_elt.textContent = String(this.display_val);
let [min,max,totallength] = this.range;
let length = Math.max(0,Math.min(totallength,(Number(this.display_val)-min)*totallength/(max-min)));
let tip = this.range_elt.getPointAtLength(length);
this.needle_elt.setAttribute('d', "M "+this.origin.x+","+this.origin.y+" "+tip.x+","+tip.y);
let [min,max] = [[this.min_elt,0],[this.max_elt,100]].map(([elt,def],i)=>elt?
Number(elt.textContent) :
this.args.length >= i+1 ? this.args[i] : def);
this.range = [min, max, this.range_elt.getTotalLength()]
this.origin = this.needle_elt.getPointAtLength(0);
optional_labels("value min max");