Project: svg
Task (challenging): When click label curve, use mouse in canvas to draw a svg path quadratic curve (no fill, line width is '.line-width' value, line color is '.color' value). There is a rect whose left-top is the point when mouse pressing down and right-bottom is the point when mouse pressing up. The curve's start point is rect left-bottom, end point is rect right-bottom, and control point is the center of rect top edge.