What I want to do is
1) I want to draw a length on image and want to add handle to edit it.
2) When I want to zoom the image the drawn length should match the zoom level.
ctx.beginPath();
ctx.moveTo(linearr[i].x1, linearr[i].y1);
ctx.lineTo(linearr[i].x2, linearr[i].y2);
ctx.closePath();
ctx.stroke();
ctx.beginPath();
ctx.arc(linearr[i].x1, linearr[i].y1, 2, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fillStyle = 'green';
ctx.fill();
ctx.stroke();
ctx.beginPath();
ctx.arc(linearr[i].x2, linearr[i].y2, 2, 0, Math.PI * 2, true);
ctx.closePath();
ctx.fillStyle = 'green';
ctx.fill();
ctx.stroke();
where linearr
is an array