// Copyright 2006 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 A utility class for representing two-dimensional positions.
*/
goog.provide('goog.math.Coordinate');
goog.require('goog.math');
/**
* Class for representing coordinates and positions.
* @param {number=} opt_x Left, defaults to 0.
* @param {number=} opt_y Top, defaults to 0.
* @struct
* @constructor
*/
goog.math.Coordinate = function(opt_x, opt_y) {
/**
* X-value
* @type {number}
*/
this.x = goog.isDef(opt_x) ? opt_x : 0;
/**
* Y-value
* @type {number}
*/
this.y = goog.isDef(opt_y) ? opt_y : 0;
};
/**
* Returns a new copy of the coordinate.
* @return {!goog.math.Coordinate} A clone of this coordinate.
*/
goog.math.Coordinate.prototype.clone = function() {
return new goog.math.Coordinate(this.x, this.y);
};
if (goog.DEBUG) {
/**
* Returns a nice string representing the coordinate.
* @return {string} In the form (50, 73).
* @override
*/
goog.math.Coordinate.prototype.toString = function() {
return '(' + this.x + ', ' + this.y + ')';
};
}
/**
* Compares coordinates for equality.
* @param {goog.math.Coordinate} a A Coordinate.
* @param {goog.math.Coordinate} b A Coordinate.
* @return {boolean} True iff the coordinates are equal, or if both are null.
*/
goog.math.Coordinate.equals = function(a, b) {
if (a == b) {
return true;
}
if (!a || !b) {
return false;
}
return a.x == b.x && a.y == b.y;
};
/**
* Returns the distance between two coordinates.
* @param {!goog.math.Coordinate} a A Coordinate.
* @param {!goog.math.Coordinate} b A Coordinate.
* @return {number} The distance between {@code a} and {@code b}.
*/
goog.math.Coordinate.distance = function(a, b) {
var dx = a.x - b.x;
var dy = a.y - b.y;
return Math.sqrt(dx * dx + dy * dy);
};
/**
* Returns the magnitude of a coordinate.
* @param {!goog.math.Coordinate} a A Coordinate.
* @return {number} The distance between the origin and {@code a}.
*/
goog.math.Coordinate.magnitude = function(a) {
return Math.sqrt(a.x * a.x + a.y * a.y);
};
/**
* Returns the angle from the origin to a coordinate.
* @param {!goog.math.Coordinate} a A Coordinate.
* @return {number} The angle, in degrees, clockwise from the positive X
* axis to {@code a}.
*/
goog.math.Coordinate.azimuth = function(a) {
return goog.math.angle(0, 0, a.x, a.y);
};
/**
* Returns the squared distance between two coordinates. Squared distances can
* be used for comparisons when the actual value is not required.
*
* Performance note: eliminating the square root is an optimization often used
* in lower-level languages, but the speed difference is not nearly as
* pronounced in JavaScript (only a few percent.)
*
* @param {!goog.math.Coordinate} a A Coordinate.
* @param {!goog.math.Coordinate} b A Coordinate.
* @return {number} The squared distance between {@code a} and {@code b}.
*/
goog.math.Coordinate.squaredDistance = function(a, b) {
var dx = a.x - b.x;
var dy = a.y - b.y;
return dx * dx + dy * dy;
};
/**
* Returns the difference between two coordinates as a new
* goog.math.Coordinate.
* @param {!goog.math.Coordinate} a A Coordinate.
* @param {!goog.math.Coordinate} b A Coordinate.
* @return {!goog.math.Coordinate} A Coordinate representing the difference
* between {@code a} and {@code b}.
*/
goog.math.Coordinate.difference = function(a, b) {
return new goog.math.Coordinate(a.x - b.x, a.y - b.y);
};
/**
* Returns the sum of two coordinates as a new goog.math.Coordinate.
* @param {!goog.math.Coordinate} a A Coordinate.
* @param {!goog.math.Coordinate} b A Coordinate.
* @return {!goog.math.Coordinate} A Coordinate representing the sum of the two
* coordinates.
*/
goog.math.Coordinate.sum = function(a, b) {
return new goog.math.Coordinate(a.x + b.x, a.y + b.y);
};
/**
* Rounds the x and y fields to the next larger integer values.
* @return {!goog.math.Coordinate} This coordinate with ceil'd fields.
*/
goog.math.Coordinate.prototype.ceil = function() {
this.x = Math.ceil(this.x);
this.y = Math.ceil(this.y);
return this;
};
/**
* Rounds the x and y fields to the next smaller integer values.
* @return {!goog.math.Coordinate} This coordinate with floored fields.
*/
goog.math.Coordinate.prototype.floor = function() {
this.x = Math.floor(this.x);
this.y = Math.floor(this.y);
return this;
};
/**
* Rounds the x and y fields to the nearest integer values.
* @return {!goog.math.Coordinate} This coordinate with rounded fields.
*/
goog.math.Coordinate.prototype.round = function() {
this.x = Math.round(this.x);
this.y = Math.round(this.y);
return this;
};
/**
* Translates this box by the given offsets. If a {@code goog.math.Coordinate}
* is given, then the x and y values are translated by the coordinate's x and y.
* Otherwise, x and y are translated by {@code tx} and {@code opt_ty}
* respectively.
* @param {number|goog.math.Coordinate} tx The value to translate x by or the
* the coordinate to translate this coordinate by.
* @param {number=} opt_ty The value to translate y by.
* @return {!goog.math.Coordinate} This coordinate after translating.
*/
goog.math.Coordinate.prototype.translate = function(tx, opt_ty) {
if (tx instanceof goog.math.Coordinate) {
this.x += tx.x;
this.y += tx.y;
} else {
this.x += tx;
if (goog.isNumber(opt_ty)) {
this.y += opt_ty;
}
}
return this;
};
/**
* Scales this coordinate by the given scale factors. The x and y values are
* scaled by {@code sx} and {@code opt_sy} respectively. If {@code opt_sy}
* is not given, then {@code sx} is used for both x and y.
* @param {number} sx The scale factor to use for the x dimension.
* @param {number=} opt_sy The scale factor to use for the y dimension.
* @return {!goog.math.Coordinate} This coordinate after scaling.
*/
goog.math.Coordinate.prototype.scale = function(sx, opt_sy) {
var sy = goog.isNumber(opt_sy) ? opt_sy : sx;
this.x *= sx;
this.y *= sy;
return this;
};
/**
* Rotates this coordinate clockwise about the origin (or, optionally, the given
* center) by the given angle, in radians.
* @param {number} radians The angle by which to rotate this coordinate
* clockwise about the given center, in radians.
* @param {!goog.math.Coordinate=} opt_center The center of rotation. Defaults
* to (0, 0) if not given.
*/
goog.math.Coordinate.prototype.rotateRadians = function(radians, opt_center) {
var center = opt_center || new goog.math.Coordinate(0, 0);
var x = this.x;
var y = this.y;
var cos = Math.cos(radians);
var sin = Math.sin(radians);
this.x = (x - center.x) * cos - (y - center.y) * sin + center.x;
this.y = (x - center.x) * sin + (y - center.y) * cos + center.y;
};
/**
* Rotates this coordinate clockwise about the origin (or, optionally, the given
* center) by the given angle, in degrees.
* @param {number} degrees The angle by which to rotate this coordinate
* clockwise about the given center, in degrees.
* @param {!goog.math.Coordinate=} opt_center The center of rotation. Defaults
* to (0, 0) if not given.
*/
goog.math.Coordinate.prototype.rotateDegrees = function(degrees, opt_center) {
this.rotateRadians(goog.math.toRadians(degrees), opt_center);
};
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