Tools/LayoutReloaded/FormattingContext/FloatingContext.js

   1 /*
   2  * Copyright (C) 2018 Apple Inc. All Rights Reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 class FloatingContext {
  27     constructor(formattingContext) {
  28         this.m_leftFloatingBoxStack = new Array();
  29         this.m_rightFloatingBoxStack = new Array();
  30         this.m_lastFloating = null;
  31         this.m_formattingContext = formattingContext;
  32     }
  33
  34     computePosition(layoutBox) {
  35         if (layoutBox.isOutOfFlowPositioned())
  36             return;
  37         let displayBox = this._formattingContext().toDisplayBox(layoutBox);
  38         if (layoutBox.isFloatingPositioned()) {
  39             let position = this._positionForFloating(layoutBox);
  40             this._addFloating(layoutBox);
  41             return displayBox.setTopLeft(position);
  42         }
  43         if (Utils.hasClear(layoutBox))
  44             return displayBox.setTopLeft(this._positionForClear(layoutBox));
  45         // Intruding floats might force this box move.
  46         displayBox.setTopLeft(this._computePositionToAvoidIntrudingFloats(layoutBox));
  47     }
  48
  49     bottom() {
  50         let leftBottom = this._bottom(this.m_leftFloatingBoxStack);
  51         let rightBottom = this._bottom(this.m_rightFloatingBoxStack);
  52         if (Number.isNaN(leftBottom) && Number.isNaN(rightBottom))
  53             return Number.NaN;
  54         if (!Number.isNaN(leftBottom) && !Number.isNaN(rightBottom))
  55             return Math.max(leftBottom, rightBottom);
  56         if (!Number.isNaN(leftBottom))
  57             return leftBottom;
  58         return rightBottom;
  59     }
  60
  61     _positionForFloating(floatingBox) {
  62         if (this._isEmpty())
  63             return this._adjustedFloatingPosition(floatingBox, this._formattingContext().absoluteMarginBox(floatingBox).top());
  64         let verticalPosition = Math.max(this._formattingContext().absoluteMarginBox(floatingBox).top(), this._formattingContext().absoluteMarginBox(this.m_lastFloating).top());
  65         let spaceNeeded = this._formattingContext().absoluteMarginBox(floatingBox).width();
  66         while (true) {
  67             let floatingPair = this._findInnerMostLeftAndRight(verticalPosition);
  68             if (this._availableSpace(floatingBox.containingBlock(), floatingPair) >= spaceNeeded)
  69                 return this._adjustedFloatingPosition(floatingBox, verticalPosition, floatingPair);
  70             verticalPosition = this._moveToNextVerticalPosition(floatingPair);
  71         }
  72         return Math.Nan;
  73     }
  74
  75     _positionForClear(layoutBox) {
  76         ASSERT(Utils.hasClear(layoutBox));
  77         let displayBox = this._formattingContext().toDisplayBox(layoutBox);
  78         if (this._isEmpty())
  79             return displayBox.topLeft();
  80
  81         let leftBottom = Number.NaN;
  82         let rightBottom = Number.NaN;
  83         if (Utils.hasClearLeft(layoutBox) || Utils.hasClearBoth(layoutBox))
  84             leftBottom = this._bottom(this.m_leftFloatingBoxStack);
  85         if (Utils.hasClearRight(layoutBox) || Utils.hasClearBoth(layoutBox))
  86             rightBottom = this._bottom(this.m_rightFloatingBoxStack);
  87
  88         if (!Number.isNaN(leftBottom) && !Number.isNaN(rightBottom))
  89             return new LayoutPoint(Math.max(leftBottom, rightBottom), displayBox.left());
  90         if (!Number.isNaN(leftBottom))
  91             return new LayoutPoint(leftBottom, displayBox.left());
  92         if (!Number.isNaN(rightBottom))
  93             return new LayoutPoint(rightBottom, displayBox.left());
  94         return displayBox.topLeft();
  95     }
  96
  97     _computePositionToAvoidIntrudingFloats(layoutBox) {
  98         if (!layoutBox.establishesBlockFormattingContext() || this._isEmpty())
  99             return this._formattingContext().toDisplayBox(layoutBox).topLeft();
 100         // The border box of a table, a block-level replaced element, or an element in the normal flow that establishes
 101         // a new block formatting context (such as an element with 'overflow' other than 'visible') must not overlap the
 102         // margin box of any floats in the same block formatting context as the element itself.
 103         // For some reason, we position this as if it was floating left.
 104         return this._positionForFloating(layoutBox);
 105     }
 106
 107     _addFloating(floatingBox) {
 108         this.m_lastFloating = floatingBox;
 109         if (Utils.isFloatingLeft(floatingBox)) {
 110             this.m_leftFloatingBoxStack.push(floatingBox);
 111             return;
 112         }
 113         this.m_rightFloatingBoxStack.push(floatingBox);
 114     }
 115
 116     _findInnerMostLeftAndRight(verticalPosition) {
 117         let leftFloating = this._findFloatingAtVerticalPosition(verticalPosition, this.m_leftFloatingBoxStack);
 118         let rightFloating = this._findFloatingAtVerticalPosition(verticalPosition, this.m_rightFloatingBoxStack);
 119         return { left: leftFloating, right: rightFloating };
 120     }
 121
 122     _moveToNextVerticalPosition(floatingPair) {
 123         if (!floatingPair.left && !floatingPair.right)
 124             return Math.NaN;
 125         let leftBottom = Number.POSITIVE_INFINITY;
 126         let rightBottom = Number.POSITIVE_INFINITY;
 127         if (floatingPair.left)
 128             leftBottom = this._formattingContext().absoluteMarginBox(floatingPair.left).bottom();
 129         if (floatingPair.right)
 130             rightBottom = this._formattingContext().absoluteMarginBox(floatingPair.right).bottom();
 131         return Math.min(leftBottom, rightBottom);
 132     }
 133
 134     _availableSpace(containingBlock, floatingPair) {
 135         if (floatingPair.left && floatingPair.right)
 136             return this._formattingContext().absoluteMarginBox(floatingPair.right).left() - this._formattingContext().absoluteMarginBox(floatingPair.left).right();
 137         if (floatingPair.left)
 138             return containingBlock.contentBox().width() - (this._formattingContext().absoluteMarginBox(floatingPair.left).right() - this._formattingContext().absoluteBorderBox(containingBlock).left());
 139         if (floatingPair.right)
 140             return this._formattingContext().absoluteMarginBox(floatingPair.right).left();
 141         return containingBlock.contentBox().width();
 142     }
 143
 144     _findFloatingAtVerticalPosition(verticalPosition, floatingStack) {
 145         let index = floatingStack.length;
 146         while (--index >= 0 && this._formattingContext().absoluteMarginBox(floatingStack[index]).bottom() <= verticalPosition);
 147         return index >= 0 ? floatingStack[index] : null;
 148     }
 149
 150     _isEmpty() {
 151         return !this.m_leftFloatingBoxStack.length && !this.m_rightFloatingBoxStack.length;
 152     }
 153
 154     _adjustedFloatingPosition(floatingBox, verticalPosition, leftRightFloatings) {
 155         let containingBlock = floatingBox.containingBlock();
 156         // Convert all coordinates relative to formatting context's root.
 157         let left = this._formattingContext().absoluteContentBox(containingBlock).left();
 158         let right = this._formattingContext().absoluteContentBox(containingBlock).right();
 159         if (leftRightFloatings) {
 160             if (leftRightFloatings.left) {
 161                 let floatingBoxRight = this._formattingContext().absoluteMarginBox(leftRightFloatings.left).right();
 162                 if (floatingBoxRight > left)
 163                     left = floatingBoxRight;
 164             }
 165
 166             if (leftRightFloatings.right) {
 167                 let floatingBoxLeft = this._formattingContext().absoluteMarginBox(leftRightFloatings.right).left();
 168                 if (floatingBoxLeft < right)
 169                     right = floatingBoxLeft;
 170             }
 171         }
 172         left += this._formattingContext().marginLeft(floatingBox);
 173         right -= this._formattingContext().marginRight(floatingBox);
 174         verticalPosition += this._formattingContext().marginTop(floatingBox);
 175         // No convert them back relative to the floatingBox's containing block.
 176         let containingBlockLeft = this._formattingContext().absoluteBorderBox(containingBlock).left();
 177         let containingBlockTop = this._formattingContext().absoluteBorderBox(containingBlock).top();
 178         left -= containingBlockLeft;
 179         right -= containingBlockLeft;
 180         verticalPosition -= containingBlockTop;
 181
 182         if (Utils.isFloatingLeft(floatingBox) || !Utils.isFloatingPositioned(floatingBox))
 183             return new LayoutPoint(verticalPosition, left);
 184         return new LayoutPoint(verticalPosition, right - this._formattingContext().toDisplayBox(floatingBox).rect().width());
 185     }
 186
 187     _bottom(floatingStack) {
 188         if (!floatingStack || !floatingStack.length)
 189             return Number.NaN;
 190         let max = Number.NEGATIVE_INFINITY;
 191         for (let i = 0; i < floatingStack.length; ++i)
 192             max = Math.max(this._formattingContext().absoluteMarginBox(floatingStack[i]).bottom(), max);
 193         return max;
 194     }
 195
 196     _formattingContext() {
 197         return this.m_formattingContext;
 198     }
 199 }