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Commit scale-based methods back into trunk. Layers or Maps now support setting

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a list of scales or resolutions in the options to the constructor, from which
resolutions are calculated. Map now has a 'setScale' function which will allow
you to zoom to as close to a given scale as possible.


git-svn-id: http://svn.openlayers.org/trunk/openlayers@1171 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf
This commit is contained in:
crschmidt
2006-08-09 19:14:16 +00:00
parent e3df606001
commit 6efaf328e5
5 changed files with 120 additions and 30 deletions
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54
lib/OpenLayers/Util.js
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@@ -1113,32 +1113,58 @@ OpenLayers.Util.createUniqueID = function(prefix) {
return prefix + Math.round(Math.random() * 10000);
};
/** constant inches per unit */
OpenLayers.INCHES_PER_UNIT = { // borrowed from MapServer mapscale.c
/** Constant inches per unit
* -- borrowed from MapServer mapscale.c
*
* @type Object */
OpenLayers.INCHES_PER_UNIT = {
'inches': 1.0,
'in': 1.0,
'ft': 12.0,
'mi': 63360.0,
'm': 39.3701,
'km': 39370.1,
'dd': 4374754,
'degrees': 4374754
};
OpenLayers.INCHES_PER_UNIT["in"]= OpenLayers.INCHES_PER_UNIT.inches;
OpenLayers.INCHES_PER_UNIT["degrees"] = OpenLayers.INCHES_PER_UNIT.dd;
/** sensible default */
/** A sensible default
* @type int */
OpenLayers.DOTS_PER_INCH = 72;
/**
* @param {float} scale
*
* @returns A normalized scale value, in 1 / X format.
* This means that if a value less than one ( already 1/x) is passed
* in, it just returns scale directly. Otherwise, it returns
* 1 / scale
* @type float
*/
OpenLayers.Util.normalizeScale = function (scale) {
if (scale > 1.0)
return 1.0 / scale;
else
return scale;
var normScale = (scale > 1.0) ? (1.0 / scale)
: scale;
return normScale;
};
/**
* @param {float} scale
* @param {String} units Index into OpenLayers.INCHES_PER_UNIT hashtable.
* Default is degrees
*
* @returns The corresponding resolution given passed-in scale and unit
* parameters.
* @type float
*/
OpenLayers.Util.getResolutionFromScale = function (scale, units) {
if (!units) units = "degrees";
scale = OpenLayers.Util.normalizeScale(scale);
return 1 / (scale * OpenLayers.INCHES_PER_UNIT[units]
* OpenLayers.DOTS_PER_INCH);
};
if (units == null) {
units = "degrees";
}
normScale = OpenLayers.Util.normalizeScale(scale);
var resolution = 1 / (normScale * OpenLayers.INCHES_PER_UNIT[units]
* OpenLayers.DOTS_PER_INCH);
return resolution;
};