Reapply Box Model convenience classes

tools/dom/src/CssRectangle.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of html;
+
+/**
+ * A rectangle representing all the content of the element in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _ContentCssRect extends CssRect {
+
+  _ContentCssRect(element) : super(element);
+
+  num get height => _element.offsetHeight +
+      _addOrSubtractToBoxModel(_HEIGHT, _CONTENT);
+
+  num get width => _element.offsetWidth +
+      _addOrSubtractToBoxModel(_WIDTH, _CONTENT);
+
+  /**
+   * Set the height to `newHeight`.
+   *
+   * newHeight can be either a [num] representing the height in pixels or a
+   * [Dimension] object. Values of newHeight that are less than zero are
+   * converted to effectively setting the height to 0. This is equivalent to the
+   * `height` function in jQuery and the calculated `height` CSS value,
+   * converted to a num in pixels.
+   */
+  void set height(newHeight) {
+    if (newHeight is Dimension) {
+      if (newHeight.value < 0) newHeight = new Dimension.px(0);
+      _element.style.height = newHeight.toString();
+    } else {
+      if (newHeight < 0) newHeight = 0;
+      _element.style.height = '${newHeight}px';
+    }
+  }
+
+  /**
+   * Set the current computed width in pixels of this element.
+   *
+   * newWidth can be either a [num] representing the width in pixels or a
+   * [Dimension] object. This is equivalent to the `width` function in jQuery
+   * and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels.
+   */
+  void set width(newWidth) {
+    if (newWidth is Dimension) {
+      if (newWidth.value < 0) newWidth = new Dimension.px(0);
+      _element.style.width = newWidth.toString();
+    } else {
+      if (newWidth < 0) newWidth = 0;
+      _element.style.width = '${newWidth}px';
+    }
+  }
+
+  num get left => _element.getBoundingClientRect().left -
+      _addOrSubtractToBoxModel(['left'], _CONTENT);
+  num get top => _element.getBoundingClientRect().top -
+      _addOrSubtractToBoxModel(['top'], _CONTENT);
+}
+
+/**
+ * A list of element content rectangles in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _ContentCssListRect extends _ContentCssRect {
+  List<Element> _elementList;
+
+  _ContentCssListRect(elementList) : super(elementList.first) {
+    _elementList = elementList;
+  }
+
+  /**
+   * Set the height to `newHeight`.
+   *
+   * Values of newHeight that are less than zero are converted to effectively
+   * setting the height to 0. This is equivalent to the `height`
+   * function in jQuery and the calculated `height` CSS value, converted to a
+   * num in pixels.
+   */
+  void set height(newHeight) {
+    _elementList.forEach((e) => e.contentEdge.height = newHeight);
+  }
+
+  /**
+   * Set the current computed width in pixels of this element.
+   *
+   * This is equivalent to the `width` function in jQuery and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels.
+   */
+  void set width(newWidth) {
+    _elementList.forEach((e) => e.contentEdge.width = newWidth);
+  }
+}
+
+/**
+ * A rectangle representing the dimensions of the space occupied by the
+ * element's content + padding in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _PaddingCssRect extends CssRect {
+  _PaddingCssRect(element) : super(element);
+  num get height => _element.offsetHeight +
+      _addOrSubtractToBoxModel(_HEIGHT, _PADDING);
+  num get width => _element.offsetWidth +
+      _addOrSubtractToBoxModel(_WIDTH, _PADDING);
+
+  num get left => _element.getBoundingClientRect().left -
+      _addOrSubtractToBoxModel(['left'], _PADDING);
+  num get top => _element.getBoundingClientRect().top -
+      _addOrSubtractToBoxModel(['top'], _PADDING);
+}
+
+/**
+ * A rectangle representing the dimensions of the space occupied by the
+ * element's content + padding + border in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _BorderCssRect extends CssRect {
+  _BorderCssRect(element) : super(element);
+  num get height => _element.offsetHeight;
+  num get width => _element.offsetWidth;
+
+  num get left => _element.getBoundingClientRect().left;
+  num get top => _element.getBoundingClientRect().top;
+}
+
+/**
+ * A rectangle representing the dimensions of the space occupied by the
+ * element's content + padding + border + margin in the
+ * [box model](http://www.w3.org/TR/CSS2/box.html).
+ */
+class _MarginCssRect extends CssRect {
+  _MarginCssRect(element) : super(element);
+  num get height => _element.offsetHeight +
+      _addOrSubtractToBoxModel(_HEIGHT, _MARGIN);
+  num get width =>
+      _element.offsetWidth + _addOrSubtractToBoxModel(_WIDTH, _MARGIN);
+
+  num get left => _element.getBoundingClientRect().left -
+      _addOrSubtractToBoxModel(['left'], _MARGIN);
+  num get top => _element.getBoundingClientRect().top -
+      _addOrSubtractToBoxModel(['top'], _MARGIN);
+}
+
+/**
+ * A class for representing CSS dimensions.
+ *
+ * In contrast to the more general purpose [Rect] class, this class's values are
+ * mutable, so one can change the height of an element programmatically.
+ *
+ * _Important_ _note_: use of these methods will perform CSS calculations that
+ * can trigger a browser reflow. Therefore, use of these properties _during_ an
+ * animation frame is discouraged. See also:
+ * [Browser Reflow](https://developers.google.com/speed/articles/reflow)
+ */
+abstract class CssRect extends RectBase implements Rect {
+  Element _element;
+
+  CssRect(this._element);
+
+  num get left;
+
+  num get top;
+
+  /**
+   * The height of this rectangle.
+   *
+   * This is equivalent to the `height` function in jQuery and the calculated
+   * `height` CSS value, converted to a dimensionless num in pixels. Unlike
+   * [getBoundingClientRect], `height` will return the same numerical width if
+   * the element is hidden or not.
+   */
+  num get height;
+
+  /**
+   * The width of this rectangle.
+   *
+   * This is equivalent to the `width` function in jQuery and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels. Unlike
+   * [getBoundingClientRect], `width` will return the same numerical width if
+   * the element is hidden or not.
+   */
+  num get width;
+
+  /**
+   * Set the height to `newHeight`.
+   *
+   * newHeight can be either a [num] representing the height in pixels or a
+   * [Dimension] object. Values of newHeight that are less than zero are
+   * converted to effectively setting the height to 0. This is equivalent to the
+   * `height` function in jQuery and the calculated `height` CSS value,
+   * converted to a num in pixels.
+   *
+   * Note that only the content height can actually be set via this method.
+   */
+  void set height(newHeight) {
+    throw new UnsupportedError("Can only set height for content rect.");
+  }
+
+  /**
+   * Set the current computed width in pixels of this element.
+   *
+   * newWidth can be either a [num] representing the width in pixels or a
+   * [Dimension] object. This is equivalent to the `width` function in jQuery
+   * and the calculated
+   * `width` CSS value, converted to a dimensionless num in pixels.
+   *
+   * Note that only the content width can be set via this method.
+   */
+  void set width(newWidth) {
+    throw new UnsupportedError("Can only set width for content rect.");
+  }
+
+  /**
+   * Return a value that is used to modify the initial height or width
+   * measurement of an element. Depending on the value (ideally an enum) passed
+   * to augmentingMeasurement, we may need to add or subtract margin, padding,
+   * or border values, depending on the measurement we're trying to obtain.
+   */
+  num _addOrSubtractToBoxModel(List<String> dimensions,
+      String augmentingMeasurement) {
+    // getComputedStyle always returns pixel values (hence, computed), so we're
+    // always dealing with pixels in this method.
+    var styles = _element.getComputedStyle();
+
+    var val = 0;
+
+    for (String measurement in dimensions) {
+      // The border-box and default box model both exclude margin in the regular
+      // height/width calculation, so add it if we want it for this measurement.
+      if (augmentingMeasurement == _MARGIN) {
+        val += new Dimension.css(styles.getPropertyValue(
+            '$augmentingMeasurement-$measurement')).value;
+      }
+
+      // The border-box includes padding and border, so remove it if we want
+      // just the content itself.
+      if (augmentingMeasurement == _CONTENT) {
+        val -= new Dimension.css(
+            styles.getPropertyValue('${_PADDING}-$measurement')).value;
+      }
+
+      // At this point, we don't wan't to augment with border or margin,
+      // so remove border.
+      if (augmentingMeasurement != _MARGIN) {
+              val -= new Dimension.css(styles.getPropertyValue(
+            'border-${measurement}-width')).value;
+      }
+    }
+    return val;
+  }
+}
+
+final _HEIGHT = ['top', 'bottom'];
+final _WIDTH = ['right', 'left'];
+final _CONTENT = 'content';
+final _PADDING = 'padding';
+final _MARGIN = 'margin';