Leaflet.ImageOverlay.Rotated.js

/*
 * 🍂class ImageOverlay.Rotated
 * 🍂inherits ImageOverlay
 *
 * Like `ImageOverlay`, but rotates and skews the image. This is done by using
 * *three* control points instead of *two*.
 *
 * @example
 *
 * ```
 * var topleft    = L.latLng(40.52256691873593, -3.7743186950683594),
 * 	topright   = L.latLng(40.5210255066156, -3.7734764814376835),
 * 	bottomleft = L.latLng(40.52180437272552, -3.7768453359603886);
 *
 * var overlay = L.imageOverlay.rotated("./palacio.jpg", topleft, topright, bottomleft, {
 * 	opacity: 0.4,
 * 	interactive: true,
 * 	attribution: "&copy; <a href='http://www.ign.es'>Instituto Geográfico Nacional de España</a>"
 * });
 * ```
 *
 */

L.ImageOverlay.Rotated = L.ImageOverlay.extend({

	initialize: function (image, topleft, topright, bottomleft, options) {

		if (typeof(image) === 'string') {
			this._url = image;
		} else {
			// Assume that the first parameter is an instance of HTMLImage or HTMLCanvas
			this._rawImage = image;
		}

		this._topLeft    = L.latLng(topleft);
		this._topRight   = L.latLng(topright);
		this._bottomLeft = L.latLng(bottomleft);

		L.setOptions(this, options);
	},


	onAdd: function (map) {
		if (!this._image) {
			this._initImage();

			if (this.options.opacity < 1) {
				this._updateOpacity();
			}
		}

		if (this.options.interactive) {
			L.DomUtil.addClass(this._rawImage, 'leaflet-interactive');
			this.addInteractiveTarget(this._rawImage);
		}

		map.on('zoomend resetview', this._reset, this);

		this.getPane().appendChild(this._image);
		this._reset();
	},


    onRemove: function(map) {
        map.off('zoomend resetview', this._reset, this);
        L.ImageOverlay.prototype.onRemove.call(this, map);
    },


	_initImage: function () {
		var img = this._rawImage;
		if (this._url) {
			img = L.DomUtil.create('img');
			img.style.display = 'none';	// Hide while the first transform (zero or one frames) is being done

			if (this.options.crossOrigin) {
				img.crossOrigin = '';
			}

			img.src = this._url;
			this._rawImage = img;
		}
		L.DomUtil.addClass(img, 'leaflet-image-layer');

		// this._image is reused by some of the methods of the parent class and
		// must keep the name, even if it is counter-intuitive.
		var div = this._image = L.DomUtil.create('div',
				'leaflet-image-layer ' + (this._zoomAnimated ? 'leaflet-zoom-animated' : ''));

		this._updateZIndex(); // apply z-index style setting to the div (if defined)
		
		div.appendChild(img);

		div.onselectstart = L.Util.falseFn;
		div.onmousemove = L.Util.falseFn;

		img.onload = function(){
			this._reset();
			img.style.display = 'block';
			this.fire('load');
		}.bind(this);

		img.alt = this.options.alt;
	},


	_reset: function () {
		var div = this._image;

		// Project control points to container-pixel coordinates
		var pxTopLeft    = this._map.latLngToLayerPoint(this._topLeft);
		var pxTopRight   = this._map.latLngToLayerPoint(this._topRight);
		var pxBottomLeft = this._map.latLngToLayerPoint(this._bottomLeft);

		// Infer coordinate of bottom right
		var pxBottomRight = pxTopRight.subtract(pxTopLeft).add(pxBottomLeft);

		// pxBounds is mostly for positioning the <div> container
		var pxBounds = L.bounds([pxTopLeft, pxTopRight, pxBottomLeft, pxBottomRight]);
		var size = pxBounds.getSize();
		var pxTopLeftInDiv = pxTopLeft.subtract(pxBounds.min);

		// Calculate the skew angles, both in X and Y
		var vectorX = pxTopRight.subtract(pxTopLeft);
		var vectorY = pxBottomLeft.subtract(pxTopLeft);
		var skewX = Math.atan2( vectorX.y, vectorX.x );
		var skewY = Math.atan2( vectorY.x, vectorY.y );

		// LatLngBounds used for animations
		this._bounds = L.latLngBounds( this._map.layerPointToLatLng(pxBounds.min),
		                               this._map.layerPointToLatLng(pxBounds.max) );

		L.DomUtil.setPosition(div, pxBounds.min);

		div.style.width  = size.x + 'px';
		div.style.height = size.y + 'px';

		var imgW = this._rawImage.width;
		var imgH = this._rawImage.height;
		if (!imgW || !imgH) {
			return;	// Probably because the image hasn't loaded yet.
		}

		var scaleX = pxTopLeft.distanceTo(pxTopRight)   / imgW * Math.cos(skewX);
		var scaleY = pxTopLeft.distanceTo(pxBottomLeft) / imgH * Math.cos(skewY);

		this._rawImage.style.transformOrigin = '0 0';

		this._rawImage.style.transform =
			'translate(' + pxTopLeftInDiv.x + 'px, ' + pxTopLeftInDiv.y + 'px)' +
			'skew(' + skewY + 'rad, ' + skewX + 'rad) ' +
			'scale(' + scaleX + ', ' + scaleY + ') ';
	},


	reposition: function(topleft, topright, bottomleft) {
		this._topLeft    = L.latLng(topleft);
		this._topRight   = L.latLng(topright);
		this._bottomLeft = L.latLng(bottomleft);
		this._reset();
	},


	setUrl: function (url) {
		this._url = url;

		if (this._rawImage) {
			this._rawImage.src = url;
		}
		return this;
	}
});

/* 🍂factory imageOverlay.rotated(imageUrl: String|HTMLImageElement|HTMLCanvasElement, topleft: LatLng, topright: LatLng, bottomleft: LatLng, options?: ImageOverlay options)
 * Instantiates a rotated/skewed image overlay, given the image URL and
 * the `LatLng`s of three of its corners.
 *
 * Alternatively to specifying the URL of the image, an existing instance of `HTMLImageElement`
 * or `HTMLCanvasElement` can be used.
 */
L.imageOverlay.rotated = function(imgSrc, topleft, topright, bottomleft, options) {
	return new L.ImageOverlay.Rotated(imgSrc, topleft, topright, bottomleft, options);
};