gecko/toolkit/content/Geometry.jsm

// -*- Mode: js2; tab-width: 2; indent-tabs-mode: nil; js2-basic-offset: 2; js2-skip-preprocessor-directives: t; -*-
/*
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Mobile Browser.
 *
 * The Initial Developer of the Original Code is
 * Mozilla Corporation.
 * Portions created by the Initial Developer are Copyright (C) 2009
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Roy Frostig <rfrostig@mozilla.com>
 *   Ben Combee <bcombee@mozilla.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

let Ci = Components.interfaces;

// -----------------------------------------------------------
// General util/convenience tools
//

let Util = {

  bind: function bind(f, thisObj) {
    return function() {
      return f.apply(thisObj, arguments);
    };
  },

  bindAll: function bindAll(instance) {
    let bind = Util.bind;
    for (let key in instance)
      if (instance[key] instanceof Function)
        instance[key] = bind(instance[key], instance);
  },

  /** printf-like dump function */
  dumpf: function dumpf(str) {
    var args = arguments;
    var i = 1;
    dump(str.replace(/%s/g, function() {
      if (i >= args.length) {
        throw "dumps received too many placeholders and not enough arguments";
      }
      return args[i++].toString();
    }));
  },

  /** Like dump, but each arg is handled and there's an automatic newline */
  dumpLn: function dumpLn() {
    for (var i = 0; i < arguments.length; i++) { dump(arguments[i] + " "); }
    dump("\n");
  },

  /** Executes aFunc after other events have been processed. */
  executeSoon: function executeSoon(aFunc) {
    let tm = Cc["@mozilla.org/thread-manager;1"].getService(Ci.nsIThreadManager);
    tm.mainThread.dispatch({
      run: function() {
        aFunc();
      }
    }, Ci.nsIThread.DISPATCH_NORMAL);
  }

};


/**
 * Simple Point class.
 *
 * Any method that takes an x and y may also take a point.
 */
function Point(x, y) {
  this.set(x, y);
}

Point.prototype = {
  clone: function clone() {
    return new Point(this.x, this.y);
  },

  set: function set(x, y) {
    this.x = x;
    this.y = y;
    return this;
  },
  
  equals: function equals(x, y) {
    return this.x == x && this.y == y;
  },

  toString: function toString() {
    return "(" + this.x + "," + this.y + ")";
  },

  map: function map(f) {
    this.x = f.call(this, this.x);
    this.y = f.call(this, this.y);
    return this;
  },

  add: function add(x, y) {
    this.x += x;
    this.y += y;
    return this;
  },

  subtract: function subtract(x, y) {
    this.x -= x;
    this.y -= y;
    return this;
  },

  scale: function scale(s) {
    this.x *= s;
    this.y *= s;
    return this;
  },

  isZero: function() {
    return this.x == 0 && this.y == 0;
  }
};

(function() {
  function takePointOrArgs(f) {
    return function(arg1, arg2) {
      if (arg2 === undefined)
        return f.call(this, arg1.x, arg1.y);
      else
        return f.call(this, arg1, arg2);
    };
  }

  for each (let f in ['add', 'subtract', 'equals', 'set'])
    Point.prototype[f] = takePointOrArgs(Point.prototype[f]);
})();


/**
 * Rect is a simple data structure for representation of a rectangle supporting
 * many basic geometric operations.
 *
 * NOTE: Since its operations are closed, rectangles may be empty and will report
 * non-positive widths and heights in that case.
 */

function Rect(x, y, w, h) {
  this.left = x;
  this.top = y;
  this.right = x+w;
  this.bottom = y+h;
};

Rect.fromRect = function fromRect(r) {
  return new Rect(r.left, r.top, r.right - r.left, r.bottom - r.top);
}

Rect.prototype = {
  get x() { return this.left; },
  get y() { return this.top; },
  get width() { return this.right - this.left; },
  get height() { return this.bottom - this.top; },
  set x(v) {
    let diff = this.left - v;
    this.left = v;
    this.right -= diff;
  },
  set y(v) {
    let diff = this.top - v;
    this.top = v;
    this.bottom -= diff;
  },
  set width(v) { this.right = this.left + v; },
  set height(v) { this.bottom = this.top + v; },

  isEmpty: function isEmpty() {
    return this.left >= this.right || this.top >= this.bottom;
  },

  setRect: function(x, y, w, h) {
    this.left = x;
    this.top = y;
    this.right = x+w;
    this.bottom = y+h;

    return this;
  },

  setBounds: function(t, l, b, r) {
    this.top = t;
    this.left = l;
    this.bottom = b;
    this.right = r;

    return this;
  },

  equals: function equals(other) {
    return (other != null &&
            this.top == other.top &&
            this.left == other.left &&
            this.bottom == other.bottom &&
            this.right == other.right);
  },

  clone: function clone() {
    return new Rect(this.left, this.top, this.right - this.left, this.bottom - this.top);
  },

  center: function center() {
    if (this.isEmpty())
      throw "Empty rectangles do not have centers";
    return new Point(this.left + (this.right - this.left) / 2,
                          this.top + (this.bottom - this.top) / 2);
  },

  copyFrom: function(other) {
    this.top = other.top;
    this.left = other.left;
    this.bottom = other.bottom;
    this.right = other.right;

    return this;
  },

  translate: function(x, y) {
    this.left += x;
    this.right += x;
    this.top += y;
    this.bottom += y;

    return this;
  },

  toString: function() {
    return "[" + this.x + "," + this.y + "," + this.width + "," + this.height + "]";
  },

  /** return a new rect that is the union of that one and this one */
  union: function(other) {
    return this.clone().expandToContain(other);
  },

  contains: function(other) {
    if (other.isEmpty()) return true;
    if (this.isEmpty()) return false;

    return (other.left >= this.left &&
            other.right <= this.right &&
            other.top >= this.top &&
            other.bottom <= this.bottom);
  },

  intersect: function(other) {
    return this.clone().restrictTo(other);
  },

  intersects: function(other) {
    if (this.isEmpty() || other.isEmpty())
      return false;

    let x1 = Math.max(this.left, other.left);
    let x2 = Math.min(this.right, other.right);
    let y1 = Math.max(this.top, other.top);
    let y2 = Math.min(this.bottom, other.bottom);
    return x1 < x2 && y1 < y2;
  },

  /** Restrict area of this rectangle to the intersection of both rectangles. */
  restrictTo: function restrictTo(other) {
    if (this.isEmpty() || other.isEmpty())
      return this.setRect(0, 0, 0, 0);

    let x1 = Math.max(this.left, other.left);
    let x2 = Math.min(this.right, other.right);
    let y1 = Math.max(this.top, other.top);
    let y2 = Math.min(this.bottom, other.bottom);
    // If width or height is 0, the intersection was empty.
    return this.setRect(x1, y1, Math.max(0, x2 - x1), Math.max(0, y2 - y1));
  },

  /** Expand this rectangle to the union of both rectangles. */
  expandToContain: function expandToContain(other) {
    if (this.isEmpty()) return this.copyFrom(other);
    if (other.isEmpty()) return this;

    let l = Math.min(this.left, other.left);
    let r = Math.max(this.right, other.right);
    let t = Math.min(this.top, other.top);
    let b = Math.max(this.bottom, other.bottom);
    return this.setRect(l, t, r-l, b-t);
  },

  /**
   * Expands to the smallest rectangle that contains original rectangle and is bounded
   * by lines with integer coefficients.
   */
  expandToIntegers: function round() {
    this.left = Math.floor(this.left);
    this.top = Math.floor(this.top);
    this.right = Math.ceil(this.right);
    this.bottom = Math.ceil(this.bottom);
    return this;
  },

  scale: function scale(xscl, yscl) {
    this.left *= xscl;
    this.right *= xscl;
    this.top *= yscl;
    this.bottom *= yscl;
    return this;
  },

  map: function map(f) {
    this.left = f.call(this, this.left);
    this.top = f.call(this, this.top);
    this.right = f.call(this, this.right);
    this.bottom = f.call(this, this.bottom);
    return this;
  }
};