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Function for creating tile grids from extents

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This commit is contained in:
Tim Schaub
2013-10-11 17:21:10 -06:00
parent dd5e7693da
commit 63ad916ca7
2 changed files with 107 additions and 15 deletions
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62
src/ol/tilegrid/tilegrid.js
View File

@@ -8,6 +8,7 @@ goog.require('ol.TileCoord');
goog.require('ol.TileRange');
goog.require('ol.array');
goog.require('ol.extent');
goog.require('ol.extent.Corner');
goog.require('ol.proj.METERS_PER_UNIT');
goog.require('ol.proj.Projection');
goog.require('ol.proj.Units');
@@ -404,31 +405,62 @@ ol.tilegrid.getForProjection = function(projection) {
/**
* @param {ol.proj.Projection} projection Projection.
* @param {number=} opt_maxZoom Maximum zoom level.
* @param {number=} opt_tileSize Tile size.
* @param {ol.Extent} extent Extent.
* @param {number=} opt_maxZoom Maximum zoom level (default is
* ol.DEFAULT_MAX_ZOOM).
* @param {number=} opt_tileSize Tile size (default uses ol.DEFAULT_TILE_SIZE).
* @param {ol.extent.Corner=} opt_corner Extent corner (default is
* ol.extent.Corner.BOTTOM_LEFT).
* @return {ol.tilegrid.TileGrid} TileGrid instance.
*/
ol.tilegrid.createForProjection =
function(projection, opt_maxZoom, opt_tileSize) {
var projectionExtent = projection.getExtent();
var size = goog.isNull(projectionExtent) ?
360 * ol.proj.METERS_PER_UNIT[ol.proj.Units.DEGREES] /
projection.getMetersPerUnit() :
Math.max(projectionExtent[2] - projectionExtent[0],
projectionExtent[3] - projectionExtent[1]);
ol.tilegrid.createForExtent =
function(extent, opt_maxZoom, opt_tileSize, opt_corner) {
var maxZoom = goog.isDef(opt_maxZoom) ?
opt_maxZoom : ol.DEFAULT_MAX_ZOOM;
var tileSize = goog.isDef(opt_tileSize) ? opt_tileSize : ol.DEFAULT_TILE_SIZE;
var tileSize = goog.isDef(opt_tileSize) ?
opt_tileSize : ol.DEFAULT_TILE_SIZE;
var corner = goog.isDef(opt_corner) ?
opt_corner : ol.extent.Corner.BOTTOM_LEFT;
var extentHeight = ol.extent.getHeight(extent);
var extentWidth = ol.extent.getWidth(extent);
var maxResolution = Math.max(
extentWidth / tileSize, extentHeight / tileSize);
var resolutions = new Array(maxZoom + 1);
var maxResolution = size / tileSize;
for (var z = 0, zz = resolutions.length; z < zz; ++z) {
resolutions[z] = maxResolution / Math.pow(2, z);
}
return new ol.tilegrid.TileGrid({
origin: goog.isNull(projectionExtent) ? [0, 0] :
ol.extent.getBottomLeft(projectionExtent),
origin: ol.extent.getCorner(extent, corner),
resolutions: resolutions,
tileSize: tileSize
});
};
/**
* @param {ol.proj.Projection} projection Projection.
* @param {number=} opt_maxZoom Maximum zoom level (default is
* ol.DEFAULT_MAX_ZOOM).
* @param {number=} opt_tileSize Tile size (default uses ol.DEFAULT_TILE_SIZE).
* @param {ol.extent.Corner=} opt_corner Extent corner (default is
* ol.extent.Corner.BOTTOM_LEFT).
* @return {ol.tilegrid.TileGrid} TileGrid instance.
*/
ol.tilegrid.createForProjection =
function(projection, opt_maxZoom, opt_tileSize, opt_corner) {
var extent = projection.getExtent();
if (goog.isNull(extent)) {
var half = 180 * ol.proj.METERS_PER_UNIT[ol.proj.Units.DEGREES] /
projection.getMetersPerUnit();
extent = ol.extent.createOrUpdate(-half, -half, half, half);
}
return ol.tilegrid.createForExtent(
extent, opt_maxZoom, opt_tileSize, opt_corner);
};

60
test/spec/ol/tilegrid/tilegrid.test.js
View File

@@ -161,6 +161,18 @@ describe('ol.tilegrid.TileGrid', function() {
});
});
describe('createForExtent', function() {
it('allows creation of tile grid from extent', function() {
var extent = ol.extent.createOrUpdate(-100, -100, 100, 100);
var grid = ol.tilegrid.createForExtent(extent);
expect(grid).to.be.a(ol.tilegrid.TileGrid);
var resolutions = grid.getResolutions();
expect(resolutions.length).to.be(ol.DEFAULT_MAX_ZOOM + 1);
expect(grid.getOrigin()).to.eql([-100, -100]);
});
});
describe('createForProjection', function() {
it('allows easier creation of a tile grid', function() {
@@ -200,6 +212,50 @@ describe('ol.tilegrid.TileGrid', function() {
ol.DEFAULT_TILE_SIZE / Math.pow(2, 5));
});
it('assumes origin is bottom-left', function() {
var projection = ol.proj.get('EPSG:3857');
var grid = ol.tilegrid.createForProjection(projection);
var origin = grid.getOrigin();
var half = ol.proj.EPSG3857.HALF_SIZE;
expect(origin).to.eql([-half, -half]);
});
it('accepts bottom-left as corner', function() {
var projection = ol.proj.get('EPSG:3857');
var grid = ol.tilegrid.createForProjection(
projection, undefined, undefined, ol.extent.Corner.BOTTOM_LEFT);
var origin = grid.getOrigin();
var half = ol.proj.EPSG3857.HALF_SIZE;
expect(origin).to.eql([-half, -half]);
});
it('accepts bottom-right as corner', function() {
var projection = ol.proj.get('EPSG:3857');
var grid = ol.tilegrid.createForProjection(
projection, undefined, undefined, ol.extent.Corner.BOTTOM_RIGHT);
var origin = grid.getOrigin();
var half = ol.proj.EPSG3857.HALF_SIZE;
expect(origin).to.eql([half, -half]);
});
it('accepts top-left as corner', function() {
var projection = ol.proj.get('EPSG:3857');
var grid = ol.tilegrid.createForProjection(
projection, undefined, undefined, ol.extent.Corner.TOP_LEFT);
var origin = grid.getOrigin();
var half = ol.proj.EPSG3857.HALF_SIZE;
expect(origin).to.eql([-half, half]);
});
it('accepts top-right as corner', function() {
var projection = ol.proj.get('EPSG:3857');
var grid = ol.tilegrid.createForProjection(
projection, undefined, undefined, ol.extent.Corner.TOP_RIGHT);
var origin = grid.getOrigin();
var half = ol.proj.EPSG3857.HALF_SIZE;
expect(origin).to.eql([half, half]);
});
});
describe('getForProjection', function() {
@@ -643,8 +699,12 @@ describe('ol.tilegrid.TileGrid', function() {
});
goog.require('ol.Coordinate');
goog.require('ol.extent');
goog.require('ol.extent.Corner');
goog.require('ol.proj');
goog.require('ol.proj.METERS_PER_UNIT');
goog.require('ol.proj');
goog.require('ol.proj.EPSG3857');
goog.require('ol.proj.Projection');
goog.require('ol.proj.Units');
goog.require('ol.tilegrid.TileGrid');