Print Preview: Adding UI for margin settings.

chrome/browser/resources/print_preview/margin_utils.js

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+cr.define('print_preview', function() {
+  'use strict';
+
+  /**
+   * Checks if |text| has a valid margin value format. A valid format is
+   * parsable as a number and is greater than zero.
+   * Example: "1.00", "1", ".5", "1.1" are valid values.
+   * Example: "1.4dsf", "-1" are invalid.
+   * Note: The inch symbol (") at the end of |text| is allowed.
+   *
+   * @param {string} text The text to check.
+   * @return {boolean} true if the |text| represents a valid margin value
+   */
+  function extractMarginValue(text) {
+    // Remove whitespace anywhere in the string.
+    text.replace(/\s*/g, '');
+    // TODO(dpapad): Return -1 instead of null to indicate an invalid value.
+    if (text.length == 0)
+      return null;
+    // Remove the inch(") symbol at end of string if present.
+    if (text.charAt(text.length - 1) == '\"')
+      text = text.slice(0, text.length - 1);
+    var regex = /^\d*(\.\d+)?$/
+    if (regex.test(text))
+      return text;
+    return null;
+  }
+
+  /**
+   * @param {sting} text The text to check (in inches).
+   * @param {number} limit The upper bound of the valid margin range (in
+   *     points).
+   * @return {boolean} True of |text| can be parsed and it is within the allowed
+   *     range.
+   */
+  function isMarginTextValid(text, limit) {
+    var value = extractMarginValue(text);
+    if (value ==  null)
+      return false;
+    value = print_preview.MarginSettings.convertInchesToPoints(value);
+    // TODO(dpapad): convert |value| to number before comparing.

[Evan Stade, 2011/10/05 03:05:23]

I don't understand this comment, if value is not a number then how can you
compare it

[dpapad, 2011/10/05 16:39:49]

It is already of type number. The comment is obsolete, removed it.

+    return value <= limit;
+  }
+
+  /**
+   * Creates a Point object. This object describes a point in a 2D plane.
+   * @constructor
+   */
+  function Point(x, y) {

[Evan Stade, 2011/10/05 03:05:23]

what is the point of point? why not just do var point = { x: x, y: y};

[dpapad, 2011/10/05 16:39:49]

Having a class instead of creating an object on the fly makes it easier when
documenting functions/methods (currently used in 2 places besides this file).
Also thre might be a need to add some behavior to the Point class in the future
(when dragging will be added, for example offset(dx, dy)). Let's leave it as is,
unless you strongly believe that this class is unnecessary.

+    this.x_ = x;
+    this.y_ = y;
+  };
+
+  Point.prototype = {
+    get x() {
+      return this.x_;
+    },
+
+    get y() {
+      return this.y_;
+    },
+
+    set x(x) {
+      this.x_ = x;;
+    },
+
+    set y(y) {
+      return this.y_ = y;
+    }
+  };
+
+  /**
+   * Creates a Rect object. This object describes a rectangle in a 2D plane.
+   * @constructor
+   */
+  function Rect(x, y, width, height) {
+    this.origin_ = new Point(x, y);
+    this.width_ = width;
+    this.height_ = height;
+  };
+
+  Rect.prototype = {
+    get x() {
+      return this.origin_.x;
+    },
+    get y() {
+      return this.origin_.y;
+    },
+    get origin() {
+      return this.origin_;
+    },
+    get width() {
+      return this.width_;
+    },
+    get height() {
+      return this.height_;
+    },
+  };
+
+  return {
+    extractMarginValue: extractMarginValue,
+    isMarginTextValid: isMarginTextValid,
+    Point: Point,
+    Rect: Rect,
+  };
+});