javascript - transforming mouse coordinates in CANVAS using fabric.js -


i have designed ruler using fabric.js , when user mouses on specific part of ruler want print screen x-coordinate of ruler (i.e. not screen coordinate). right ruler canvas starts @ position 37 , ends @ 726 relative ruler, ruler goes 1 4600 (it start @ 1 length of ruler can change). how transform mouse coordinates accurately reflect it's position on ruler? here code:

var canvas = new fabric.canvas('canvas');  line_length = input_len;  adjusted_length = (line_length / 666) * 100;  canvas.add(new fabric.line([0, 0, adjusted_length, 0], {     left: 30,     top: 0,     stroke: '#d89300',     strokewidth: 3 }));  $('#canvas_container').css('overflow-x', 'scroll'); $('#canvas_container').css('overflow-y', 'hidden');  drawruler();   function drawruler() {     $("#ruler[data-items]").val(line_length / 200);      $("#ruler[data-items]").each(function () {         var ruler = $(this).empty(),             len = number($("#ruler[data-items]").val()) || 0,             item = $(document.createelement("li")),             i;         ruler.append(item.clone().text(1));         (i = 1; < len; i++) {             ruler.append(item.clone().text(i * 200));         }         ruler.append(item.clone().text(i * 200));     }); }   canvas.add(new fabric.text('x-cord', {     fontstyle: 'italic',     fontfamily: 'hoefler text',     fontsize: 12,     left: 0,     top: 0,     hascontrols: false,     selectable: false }));  canvas.on('mouse:move', function (options) {     getmouse(options);  });   function getmouse(options) {     canvas.getobjects('text')[0].text =         "x-coords: " + options.e.clientx  ; //+ " y: " + options.e.clienty;     canvas.renderall(); }

use getpointer merthod on canvas instance. in case should canvas.getpointer(options.e)which returns object x , y properties represent pointer coordinates relative canvas.


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