Enable pointRotation for pointStyle: image

[nyammy]

Feature Proposal

Adding ability to rotate points with image like other types of point.

Feature Use Case

It will be possible to ...

• make multiple styles with single image file.
• use different rotation for each point. It's good for the vector data (which has both of amplitude and direction).

Possible Implementation

In drawPoint, change

if (style && typeof style === 'object') {
	type = style.toString();
	if (type === '[object HTMLImageElement]' || type === '[object HTMLCanvasElement]') {
		ctx.drawImage(style, x - style.width / 2, y - style.height / 2, style.width, style.height);
		return;
	}
}

to

if (style && typeof style === 'object') {
	type = style.toString();
	if (type === '[object HTMLImageElement]' || type === '[object HTMLCanvasElement]') {
		ctx.save();
		ctx.translate(x, y);
		ctx.rotate(rotation * Math.PI / 180);
		ctx.drawImage(style, -1 * style.width / 2, -1 * style.height / 2, style.width, style.height);
		ctx.restore();
		return;
	}
}

[nagix]

I think this is a good enhancement. Do you want to create a PR for this (including unit tests)?

[nyammy]

Like this?
https://jsfiddle.net/nyammy/vx8cd9w4/3/