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FeatureGrid.js
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FeatureGrid.js
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import {
LatLngBounds,
toLatLngBounds as latLngBounds,
Layer,
Browser,
Util,
Point,
Bounds
} from 'leaflet';
export var FeatureGrid = Layer.extend({
// @section
// @aka GridLayer options
options: {
// @option cellSize: Number|Point = 256
// Width and height of cells in the grid. Use a number if width and height are equal, or `L.point(width, height)` otherwise.
cellSize: 512,
// @option updateWhenIdle: Boolean = (depends)
// Load new cells only when panning ends.
// `true` by default on mobile browsers, in order to avoid too many requests and keep smooth navigation.
// `false` otherwise in order to display new cells _during_ panning, since it is easy to pan outside the
// [`keepBuffer`](#gridlayer-keepbuffer) option in desktop browsers.
updateWhenIdle: Browser.mobile,
// @option updateInterval: Number = 150
// Cells will not update more than once every `updateInterval` milliseconds when panning.
updateInterval: 150,
// @option noWrap: Boolean = false
// Whether the layer is wrapped around the antimeridian. If `true`, the
// GridLayer will only be displayed once at low zoom levels. Has no
// effect when the [map CRS](#map-crs) doesn't wrap around. Can be used
// in combination with [`bounds`](#gridlayer-bounds) to prevent requesting
// cells outside the CRS limits.
noWrap: false,
// @option keepBuffer: Number = 1.5
// When panning the map, keep this many rows and columns of cells before unloading them.
keepBuffer: 1.5
},
initialize: function (options) {
Util.setOptions(this, options);
},
onAdd: function (map) {
this._cells = {};
this._activeCells = {};
this._resetView();
this._update();
},
onRemove: function (map) {
this._removeAllCells();
this._cellZoom = undefined;
},
// @method isLoading: Boolean
// Returns `true` if any cell in the grid layer has not finished loading.
isLoading: function () {
return this._loading;
},
// @method redraw: this
// Causes the layer to clear all the cells and request them again.
redraw: function () {
if (this._map) {
this._removeAllCells();
this._update();
}
return this;
},
getEvents: function () {
var events = {
viewprereset: this._invalidateAll,
viewreset: this._resetView,
zoom: this._resetView,
moveend: this._onMoveEnd
};
if (!this.options.updateWhenIdle) {
// update cells on move, but not more often than once per given interval
if (!this._onMove) {
this._onMove = Util.throttle(
this._onMoveEnd,
this.options.updateInterval,
this
);
}
events.move = this._onMove;
}
return events;
},
// @section Extension methods
// Layers extending `GridLayer` shall reimplement the following method.
// @method createCell(coords: Object, done?: Function): HTMLElement
// Called only internally, must be overridden by classes extending `GridLayer`.
// Returns the `HTMLElement` corresponding to the given `coords`. If the `done` callback
// is specified, it must be called when the cell has finished loading and drawing.
createCell: function () {
return document.createElement('div');
},
removeCell: function () {
},
reuseCell: function () {
},
cellLeave: function () {
},
cellEnter: function () {
},
// @section
// @method getCellSize: Point
// Normalizes the [cellSize option](#gridlayer-cellsize) into a point. Used by the `createCell()` method.
getCellSize: function () {
var s = this.options.cellSize;
return s instanceof Point ? s : new Point(s, s);
},
_pruneCells: function () {
if (!this._map) {
return;
}
var key, cell;
for (key in this._cells) {
cell = this._cells[key];
cell.retain = cell.current;
}
for (key in this._cells) {
cell = this._cells[key];
if (cell.current && !cell.active) {
var coords = cell.coords;
if (!this._retainParent(coords.x, coords.y, coords.z, coords.z - 5)) {
this._retainChildren(coords.x, coords.y, coords.z, coords.z + 2);
}
}
}
for (key in this._cells) {
if (!this._cells[key].retain) {
this._removeCell(key);
}
}
},
_removeAllCells: function () {
for (var key in this._cells) {
this._removeCell(key);
}
},
_invalidateAll: function () {
this._removeAllCells();
this._cellZoom = undefined;
},
_retainParent: function (x, y, z, minZoom) {
var x2 = Math.floor(x / 2);
var y2 = Math.floor(y / 2);
var z2 = z - 1;
var coords2 = new Point(+x2, +y2);
coords2.z = +z2;
var key = this._cellCoordsToKey(coords2);
var cell = this._cells[key];
if (cell && cell.active) {
cell.retain = true;
return true;
} else if (cell && cell.loaded) {
cell.retain = true;
}
if (z2 > minZoom) {
return this._retainParent(x2, y2, z2, minZoom);
}
return false;
},
_retainChildren: function (x, y, z, maxZoom) {
for (var i = 2 * x; i < 2 * x + 2; i++) {
for (var j = 2 * y; j < 2 * y + 2; j++) {
var coords = new Point(i, j);
coords.z = z + 1;
var key = this._cellCoordsToKey(coords);
var cell = this._cells[key];
if (cell && cell.active) {
cell.retain = true;
continue;
} else if (cell && cell.loaded) {
cell.retain = true;
}
if (z + 1 < maxZoom) {
this._retainChildren(i, j, z + 1, maxZoom);
}
}
}
},
_resetView: function (e) {
var animating = e && (e.pinch || e.flyTo);
if (animating) {
return;
}
this._setView(
this._map.getCenter(),
this._map.getZoom(),
animating,
animating
);
},
_setView: function (center, zoom, noPrune, noUpdate) {
var cellZoom = Math.round(zoom);
if (!noUpdate) {
this._cellZoom = cellZoom;
if (this._abortLoading) {
this._abortLoading();
}
this._resetGrid();
if (cellZoom !== undefined) {
this._update(center);
}
if (!noPrune) {
this._pruneCells();
}
// Flag to prevent _updateOpacity from pruning cells during
// a zoom anim or a pinch gesture
this._noPrune = !!noPrune;
}
},
_resetGrid: function () {
var map = this._map;
var crs = map.options.crs;
var cellSize = (this._cellSize = this.getCellSize());
var cellZoom = this._cellZoom;
var bounds = this._map.getPixelWorldBounds(this._cellZoom);
if (bounds) {
this._globalCellRange = this._pxBoundsToCellRange(bounds);
}
this._wrapX = crs.wrapLng &&
!this.options.noWrap && [
Math.floor(map.project([0, crs.wrapLng[0]], cellZoom).x / cellSize.x),
Math.ceil(map.project([0, crs.wrapLng[1]], cellZoom).x / cellSize.y)
];
this._wrapY = crs.wrapLat &&
!this.options.noWrap && [
Math.floor(map.project([crs.wrapLat[0], 0], cellZoom).y / cellSize.x),
Math.ceil(map.project([crs.wrapLat[1], 0], cellZoom).y / cellSize.y)
];
},
_onMoveEnd: function (e) {
var animating = e && (e.pinch || e.flyTo);
if (animating || !this._map || this._map._animatingZoom) {
return;
}
this._update();
},
_getCelldPixelBounds: function (center) {
var map = this._map;
var mapZoom = map._animatingZoom
? Math.max(map._animateToZoom, map.getZoom())
: map.getZoom();
var scale = map.getZoomScale(mapZoom, this._cellZoom);
var pixelCenter = map.project(center, this._cellZoom).floor();
var halfSize = map.getSize().divideBy(scale * 2);
return new Bounds(
pixelCenter.subtract(halfSize),
pixelCenter.add(halfSize)
);
},
// Private method to load cells in the grid's active zoom level according to map bounds
_update: function (center) {
var map = this._map;
if (!map) {
return;
}
var zoom = Math.round(map.getZoom());
if (center === undefined) {
center = map.getCenter();
}
var pixelBounds = this._getCelldPixelBounds(center);
var cellRange = this._pxBoundsToCellRange(pixelBounds);
var cellCenter = cellRange.getCenter();
var queue = [];
var margin = this.options.keepBuffer;
var noPruneRange = new Bounds(
cellRange.getBottomLeft().subtract([margin, -margin]),
cellRange.getTopRight().add([margin, -margin])
);
// Sanity check: panic if the cell range contains Infinity somewhere.
if (
!(
isFinite(cellRange.min.x) &&
isFinite(cellRange.min.y) &&
isFinite(cellRange.max.x) &&
isFinite(cellRange.max.y)
)
) {
throw new Error('Attempted to load an infinite number of cells');
}
for (var key in this._cells) {
var c = this._cells[key].coords;
if (
c.z !== this._cellZoom ||
!noPruneRange.contains(new Point(c.x, c.y))
) {
this._cells[key].current = false;
}
}
// _update just loads more cells. If the cell zoom level differs too much
// from the map's, let _setView reset levels and prune old cells.
if (Math.abs(zoom - this._cellZoom) > 1) {
this._setView(center, zoom);
return;
}
// create a queue of coordinates to load cells from
for (var j = cellRange.min.y; j <= cellRange.max.y; j++) {
for (var i = cellRange.min.x; i <= cellRange.max.x; i++) {
var coords = new Point(i, j);
coords.z = this._cellZoom;
if (!this._isValidCell(coords)) {
continue;
}
var cell = this._cells[this._cellCoordsToKey(coords)];
if (cell) {
cell.current = true;
} else {
queue.push(coords);
}
}
}
// sort cell queue to load cells in order of their distance to center
queue.sort(function (a, b) {
return a.distanceTo(cellCenter) - b.distanceTo(cellCenter);
});
if (queue.length !== 0) {
// if it's the first batch of cells to load
if (!this._loading) {
this._loading = true;
}
for (i = 0; i < queue.length; i++) {
var _key = this._cellCoordsToKey(queue[i]);
var _coords = this._keyToCellCoords(_key);
if (this._activeCells[_coords]) {
this._reuseCell(queue[i]);
} else {
this._createCell(queue[i]);
}
}
}
},
_isValidCell: function (coords) {
var crs = this._map.options.crs;
if (!crs.infinite) {
// don't load cell if it's out of bounds and not wrapped
var bounds = this._globalCellRange;
if (
(!crs.wrapLng &&
(coords.x < bounds.min.x || coords.x > bounds.max.x)) ||
(!crs.wrapLat && (coords.y < bounds.min.y || coords.y > bounds.max.y))
) {
return false;
}
}
if (!this.options.bounds) {
return true;
}
// don't load cell if it doesn't intersect the bounds in options
var cellBounds = this._cellCoordsToBounds(coords);
return latLngBounds(this.options.bounds).overlaps(cellBounds);
},
_keyToBounds: function (key) {
return this._cellCoordsToBounds(this._keyToCellCoords(key));
},
_cellCoordsToNwSe: function (coords) {
var map = this._map;
var cellSize = this.getCellSize();
var nwPoint = coords.scaleBy(cellSize);
var sePoint = nwPoint.add(cellSize);
var nw = map.unproject(nwPoint, coords.z);
var se = map.unproject(sePoint, coords.z);
return [nw, se];
},
// converts cell coordinates to its geographical bounds
_cellCoordsToBounds: function (coords) {
var bp = this._cellCoordsToNwSe(coords);
var bounds = new LatLngBounds(bp[0], bp[1]);
if (!this.options.noWrap) {
bounds = this._map.wrapLatLngBounds(bounds);
}
return bounds;
},
// converts cell coordinates to key for the cell cache
_cellCoordsToKey: function (coords) {
return coords.x + ':' + coords.y + ':' + coords.z;
},
// converts cell cache key to coordinates
_keyToCellCoords: function (key) {
var k = key.split(':');
var coords = new Point(+k[0], +k[1]);
coords.z = +k[2];
return coords;
},
_removeCell: function (key) {
var cell = this._cells[key];
if (!cell) {
return;
}
var coords = this._keyToCellCoords(key);
var wrappedCoords = this._wrapCoords(coords);
var cellBounds = this._cellCoordsToBounds(this._wrapCoords(coords));
cell.current = false;
delete this._cells[key];
this._activeCells[key] = cell;
this.cellLeave(cellBounds, wrappedCoords, key);
this.fire('cellleave', {
key: key,
coords: wrappedCoords,
bounds: cellBounds
});
},
_reuseCell: function (coords) {
var key = this._cellCoordsToKey(coords);
// save cell in cache
this._cells[key] = this._activeCells[key];
this._cells[key].current = true;
var wrappedCoords = this._wrapCoords(coords);
var cellBounds = this._cellCoordsToBounds(this._wrapCoords(coords));
this.cellEnter(cellBounds, wrappedCoords, key);
this.fire('cellenter', {
key: key,
coords: wrappedCoords,
bounds: cellBounds
});
},
_createCell: function (coords) {
var key = this._cellCoordsToKey(coords);
var wrappedCoords = this._wrapCoords(coords);
var cellBounds = this._cellCoordsToBounds(this._wrapCoords(coords));
this.createCell(cellBounds, wrappedCoords, key);
this.fire('cellcreate', {
key: key,
coords: wrappedCoords,
bounds: cellBounds
});
// save cell in cache
this._cells[key] = {
coords: coords,
current: true
};
Util.requestAnimFrame(this._pruneCells, this);
},
_cellReady: function (coords, err, cell) {
var key = this._cellCoordsToKey(coords);
cell = this._cells[key];
if (!cell) {
return;
}
cell.loaded = +new Date();
cell.active = true;
},
_getCellPos: function (coords) {
return coords.scaleBy(this.getCellSize());
},
_wrapCoords: function (coords) {
var newCoords = new Point(
this._wrapX ? Util.wrapNum(coords.x, this._wrapX) : coords.x,
this._wrapY ? Util.wrapNum(coords.y, this._wrapY) : coords.y
);
newCoords.z = coords.z;
return newCoords;
},
_pxBoundsToCellRange: function (bounds) {
var cellSize = this.getCellSize();
return new Bounds(
bounds.min.unscaleBy(cellSize).floor(),
bounds.max.unscaleBy(cellSize).ceil().subtract([1, 1])
);
}
});