Files
openlayers/src/ol/resolutionconstraint.js
2013-07-04 08:58:33 +02:00

77 lines
2.2 KiB
JavaScript

goog.provide('ol.ResolutionConstraint');
goog.provide('ol.ResolutionConstraintType');
goog.require('goog.math');
goog.require('ol.array');
/**
* @typedef {function((number|undefined), number, number): (number|undefined)}
*/
ol.ResolutionConstraintType;
/**
* @param {Array.<number>} resolutions Resolutions.
* @return {ol.ResolutionConstraintType} Zoom function.
*/
ol.ResolutionConstraint.createSnapToResolutions =
function(resolutions) {
return (
/**
* @param {number|undefined} resolution Resolution.
* @param {number} delta Delta.
* @param {number} direction Direction.
* @return {number|undefined} Resolution.
*/
function(resolution, delta, direction) {
if (goog.isDef(resolution)) {
var z =
ol.array.linearFindNearest(resolutions, resolution, direction);
z = goog.math.clamp(z + delta, 0, resolutions.length - 1);
return resolutions[z];
} else {
return undefined;
}
});
};
/**
* @param {number} power Power.
* @param {number} maxResolution Maximum resolution.
* @param {number=} opt_maxLevel Maximum level.
* @return {ol.ResolutionConstraintType} Zoom function.
*/
ol.ResolutionConstraint.createSnapToPower =
function(power, maxResolution, opt_maxLevel) {
return (
/**
* @param {number|undefined} resolution Resolution.
* @param {number} delta Delta.
* @param {number} direction Direction.
* @return {number|undefined} Resolution.
*/
function(resolution, delta, direction) {
if (goog.isDef(resolution)) {
var offset;
if (direction > 0) {
offset = 0;
} else if (direction < 0) {
offset = 1;
} else {
offset = 0.5;
}
var oldLevel = Math.floor(
Math.log(maxResolution / resolution) / Math.log(power) + offset);
var newLevel = Math.max(oldLevel + delta, 0);
if (goog.isDef(opt_maxLevel)) {
newLevel = Math.min(newLevel, opt_maxLevel);
}
return maxResolution / Math.pow(power, newLevel);
} else {
return undefined;
}
});
};