iwmlib/lib/pixi/maps/mapprojection.js

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/**
* MapProjection contains the informations about how
* a Map has to be interpreted. What are the bounds of the
* map and how to translate coordinates into
* image positions.
*
* @class
* @see {@link mapprojection.html}
*/
export class MapProjection {
/**
* Creates instance of MapProjection
*
* @constructor
* @param {Projection}[projection] - Specifies the projection of the map (e.g. Mercator Projection).
* @param {object}[opts] - Addiditonal options.
* @param {array}[opts.bounds] - Describes the minimum and maximum coordinates on the map in the form of {[[minLat, minLng],[maxLat, maxLng]]}.
* @param {Point}[opts.translate] - Defines a translation, when clipping is not an option (e.g. when the whole world is shown, but translated.)
*/
constructor(projection, opts = {}) {
this.opts = Object.assign(
{
translate: { x: 0, y: 0 }
},
opts
)
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this._projection = projection
if (this.opts.clip) {
let _cmin = this.projection.forward(this.opts.clip.min)
let _cmax = this.projection.forward(this.opts.clip.max)
// Swaps the y values, Mercator has it's origin bottom right,
// browser coordinates start top right.
let cmin = { x: _cmin.x, y: _cmax.y }
let cmax = { x: _cmax.x, y: _cmin.y }
this.clipExt = {
coords: {
min: this.opts.clip.min,
max: this.opts.clip.max
},
point: {
min: cmin,
max: cmax
}
}
}
}
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/**
* The projection used by the map projection.
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*
* @member {Projection}
* @readonly
* @memberof MapProjection
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*/
get projection() {
return this._projection
}
/**
* Transforms a pixel point on the map to a geographical coordinate.
*
* @public
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* @param {Point} point - A pixel position on the map.
* @returns {CoordinatePoint} A geographical coordinate.
* @memberof MapProjection
*/
toCoordinates(point) {
if (this.opts.clip) {
let min = this.clipExt.point.min
let max = this.clipExt.point.max
let width = max.x - min.x
let height = max.y - min.y
point.x *= width
point.y *= height
point.x += min.x
point.y += min.y
}
let coordinates = this.projection.backward(point)
if (this.opts.translate) {
coordinates.x -= this.opts.translate.x
coordinates.y -= this.opts.translate.y
}
return coordinates
}
/**
* Transform a geographical coordinate to a pixel point on the map.
*
* @public
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* @param {CoordinatePoint} coordinates - A point in the form of {x:lat,y:lng}.
* @returns {Point} A pixel position on the map.
* @memberof MapProjection
*/
toPixel(coordinates) {
let coords = { x: coordinates.x, y: coordinates.y }
if (this.opts.translate) {
coords.x += this.opts.translate.x
coords.y += this.opts.translate.y
}
let point = this.projection.forward(coords)
if (this.opts.clip) {
let min = this.clipExt.point.min
let max = this.clipExt.point.max
let clippedPoint = {
x: point.x - min.x,
y: point.y - min.y
}
let width = max.x - min.x
let height = max.y - min.y
point.x = clippedPoint.x / width
point.y = clippedPoint.y / height
}
return point
}
/**
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* Clipping describes the
* piece of the map that is shown. The returned object contains a min and max value of the clipping in form of: {min: {x,y}, max:{x,y}}. Where x and y are in between 0 and 1.
*
* E.g. if we just show a map of
* europe, then we have to set the clipping properly, otherwise
* the preojection would produce the wrong results when transforming
* from a point to coordinates or the other way around.
*
* @readonly
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* @member {object}
* @memberof MapProjection
*/
get clip() {
let unclipped = {
min: { x: 0, y: 0 },
max: { x: 1, y: 1 }
}
return this.opts.clip ? this.opts.clip : unclipped
}
/**
* Returns the biggest viewport the map projection allows.
* This is determined by the projecton or the clipping on the mapapp.
*
* @readonly
* @memberof MapProjection
*/
get maxViewport() {
return this.opts.clip ? this.opts.clip : this.projection.maxViewport
}
}
/**
* Special map projection for DeepZoomMap objects.
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*
* Note: It just transform the clipping parameter of the tiles config
* to the clipping of the mapapp.
*
* @export
* @class DeepZoomMapProjection
* @extends {MapProjection}
*/
export class DeepZoomMapProjection extends MapProjection {
constructor(projection, tilesConfig, opts = {}) {
if (tilesConfig.clip) {
opts.clip = {
min: {
x: tilesConfig.clip.bounds.min[0],
y: tilesConfig.clip.bounds.min[1]
},
max: {
x: tilesConfig.clip.bounds.max[0],
y: tilesConfig.clip.bounds.max[1]
}
}
}
super(projection, opts)
this.app = opts.app
}
}