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// Copyright 2007 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Graphics utility functions for advanced coordinates.
*
* This file assists the use of advanced coordinates in goog.graphics. Coords
* can be specified as simple numbers which will correspond to units in the
* graphics element's coordinate space. Alternately, coords can be expressed
* in pixels, meaning no matter what tranformations or coordinate system changes
* are present, the number of pixel changes will remain constant. Coords can
* also be expressed as percentages of their parent's size.
*
* This file also allows for elements to have margins, expressable in any of
* the ways described above.
*
* Additional pieces of advanced coordinate functionality can (soon) be found in
* element.js and groupelement.js.
*
* @author robbyw@google.com (Robby Walker)
*/
goog.provide('goog.graphics.ext.coordinates');
goog.require('goog.string');
/**
* Cache of boolean values. For a given string (key), is it special? (value)
* @type {Object}
* @private
*/
goog.graphics.ext.coordinates.specialCoordinateCache_ = {};
/**
* Determines if the given coordinate is a percent based coordinate or an
* expression with a percent based component.
* @param {string} coord The coordinate to test.
* @return {boolean} Whether the coordinate contains the string '%'.
* @private
*/
goog.graphics.ext.coordinates.isPercent_ = function(coord) {
return goog.string.contains(coord, '%');
};
/**
* Determines if the given coordinate is a pixel based coordinate or an
* expression with a pixel based component.
* @param {string} coord The coordinate to test.
* @return {boolean} Whether the coordinate contains the string 'px'.
* @private
*/
goog.graphics.ext.coordinates.isPixels_ = function(coord) {
return goog.string.contains(coord, 'px');
};
/**
* Determines if the given coordinate is special - i.e. not just a number.
* @param {string|number|null} coord The coordinate to test.
* @return {boolean} Whether the coordinate is special.
*/
goog.graphics.ext.coordinates.isSpecial = function(coord) {
var cache = goog.graphics.ext.coordinates.specialCoordinateCache_;
if (!(coord in cache)) {
cache[coord] = goog.isString(coord) && (
goog.graphics.ext.coordinates.isPercent_(coord) ||
goog.graphics.ext.coordinates.isPixels_(coord));
}
return cache[coord];
};
/**
* Returns the value of the given expression in the given context.
*
* Should be treated as package scope.
*
* @param {string|number} coord The coordinate to convert.
* @param {number} size The size of the parent element.
* @param {number} scale The ratio of pixels to units.
* @return {number} The number of coordinate space units that corresponds to
* this coordinate.
*/
goog.graphics.ext.coordinates.computeValue = function(coord, size, scale) {
var number = parseFloat(String(coord));
if (goog.isString(coord)) {
if (goog.graphics.ext.coordinates.isPercent_(coord)) {
return number * size / 100;
} else if (goog.graphics.ext.coordinates.isPixels_(coord)) {
return number / scale;
}
}
return number;
};
/**
* Converts the given coordinate to a number value in units.
*
* Should be treated as package scope.
*
* @param {string|number} coord The coordinate to retrieve the value for.
* @param {boolean|undefined} forMaximum Whether we are computing the largest
* value this coordinate would be in a parent of no size. The container
* size in this case should be set to the size of the current element.
* @param {number} containerSize The unit value of the size of the container of
* this element. Should be set to the minimum width of this element if
* forMaximum is true.
* @param {number} scale The ratio of pixels to units.
* @param {Object=} opt_cache Optional (but highly recommend) object to store
* cached computations in. The calling class should manage clearing out
* the cache when the scale or containerSize changes.
* @return {number} The correct number of coordinate space units.
*/
goog.graphics.ext.coordinates.getValue = function(coord, forMaximum,
containerSize, scale, opt_cache) {
if (!goog.isNumber(coord)) {
var cacheString = opt_cache && ((forMaximum ? 'X' : '') + coord);
if (opt_cache && cacheString in opt_cache) {
coord = opt_cache[cacheString];
} else {
if (goog.graphics.ext.coordinates.isSpecial(
/** @type {string} */ (coord))) {
coord = goog.graphics.ext.coordinates.computeValue(coord,
containerSize, scale);
} else {
// Simple coordinates just need to be converted from a string to a
// number.
coord = parseFloat(/** @type {string} */ (coord));
}
// Cache the result.
if (opt_cache) {
opt_cache[cacheString] = coord;
}
}
}
return coord;
};
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