JS Canvas Pinch Effect

Pinch/pucker an image in canvas (StackOverflow)

An attempt at imitating the pinch effect on canvas. The desired effect is the one in Gimp or glfx.js Photoshop one is okay.

Source code for both Gimp and glfx.js is available, but I have no knowledge about WebGL (glfx.js) or C (Gimp). I'm stuck at the moment.

function pinch(canvas, x, y, radius, strength) {
	// code
	return pinchedCanvas;
}