Gallery: Random fixes for the Viewport class.

ui/file_manager/gallery/js/image_editor/image_util.js

 // Copyright 2014 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.
 
 'use strict';
 
 
 // Namespace object for the utilities.
 function ImageUtil() {}
 
@@ skipping 121 matching lines @@
       this.left = 0;
       this.top = 0;
       this.width = 0;
       this.height = 0;
       return;
   }
   console.error('Invalid Rect constructor arguments:',
        Array.apply(null, arguments));
 }
 
+Rect.prototype = {
+  /**
+   * Obtains the x coordinate number of right edge.

[mtomasz, 2014/07/17 06:08:56]

nit: Please add a comment, that the edge is one pixel after the last pixel, or
sth like that.

[hirono, 2014/07/17 06:26:54]

Done.

+   * @return {number}
+   */
+  get right() {
+    return this.left + this.width;

[mtomasz, 2014/07/17 05:43:20]

I think it should be:
this.left + this.width - 1.

Eg. For rect: left = 0, top = 0, width = 1, height = 1.
The right most pixel is at 0 position, not 1.

[hirono, 2014/07/17 05:56:47]

Exactly. but the right edge of the pixel is a line (x = 1).
The number is not a position of pixel, it is the coordinate value of the right
edge. The definition is sometimes convenient to calculate geometry. e.g. var
center = (rect.left + rect.right) / 2; WDYT?

[mtomasz, 2014/07/17 06:08:56]

This is quite confusing. The left edge is within the image, but the right
outside. However, seems that SkRect in Chromium uses the same logic, so I'm fine
with it.

https://code.google.com/p/chromium/codesearch#chromium/src/third_party/skia/i...

[hirono, 2014/07/17 06:26:54]

Maybe this is common when implementing rectangle class. I also saw the logic in
.NET.
http://msdn.microsoft.com/en-us//library/system.windows.rect.right(v=vs.110)....

+  },
+
+  /**
+   * Obtains the y coordinate number of bottom edge.

[mtomasz, 2014/07/17 06:08:56]

nit: coordinate number -> coordinate

[hirono, 2014/07/17 06:26:54]

Done.

+   * @return {number}
+   */
+  get bottom() {
+    return this.top + this.height;
+  }
+};
+
 /**
  * @param {number} factor Factor to scale.
  * @return {Rect} A rectangle with every dimension scaled.
  */
 Rect.prototype.scale = function(factor) {
   return new Rect(
       this.left * factor,
       this.top * factor,
       this.width * factor,
       this.height * factor);
@@ skipping 511 matching lines @@
  * @return {string} Full name.
  */
 ImageUtil.getMetricName = function(name) {
   return 'PhotoEditor.' + name;
 };
 
 /**
  * Used for metrics reporting, keep in sync with the histogram description.
  */
 ImageUtil.FILE_TYPES = ['jpg', 'png', 'gif', 'bmp', 'webp'];