| /* |
| * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights |
| * reserved. |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Library General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Library General Public License for more details. |
| * |
| * You should have received a copy of the GNU Library General Public License |
| * along with this library; see the file COPYING.LIB. If not, write to |
| * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| * |
| */ |
| |
| #ifndef OverflowModel_h |
| #define OverflowModel_h |
| |
| #include "platform/geometry/LayoutRect.h" |
| |
| namespace blink { |
| |
| inline void uniteLayoutOverflowRect(LayoutRect& layoutOverflow, |
| const LayoutRect& rect) { |
| LayoutUnit maxX = std::max(rect.maxX(), layoutOverflow.maxX()); |
| LayoutUnit maxY = std::max(rect.maxY(), layoutOverflow.maxY()); |
| LayoutUnit minX = std::min(rect.x(), layoutOverflow.x()); |
| LayoutUnit minY = std::min(rect.y(), layoutOverflow.y()); |
| // In case the width/height is larger than LayoutUnit can represent, fix the |
| // right/bottom edge and shift the top/left ones. |
| layoutOverflow.setWidth(maxX - minX); |
| layoutOverflow.setHeight(maxY - minY); |
| layoutOverflow.setX(maxX - layoutOverflow.width()); |
| layoutOverflow.setY(maxY - layoutOverflow.height()); |
| } |
| |
| // OverflowModel classes track content that spills out of an object. |
| // SimpleOverflowModel is used by InlineFlowBox, and BoxOverflowModel is |
| // used by LayoutBox. |
| // |
| // SimpleOverflowModel tracks 2 types of overflows: layout and visual |
| // overflows. BoxOverflowModel separates visual overflow into self visual |
| // overflow and contents visual overflow. |
| // |
| // All overflows are in the coordinate space of the object (i.e. physical |
| // coordinates with flipped block-flow direction). See documentation of |
| // LayoutBoxModelObject and LayoutBox::noOverflowRect() for more details. |
| // |
| // The classes model the overflows as rectangles that unite all the sources of |
| // overflow. This is the natural choice for layout overflow (scrollbars are |
| // linear in nature, thus are modeled by rectangles in 2D). For visual overflow |
| // and content visual overflow, this is a first order simplification though as |
| // they can be thought of as a collection of (potentially overlapping) |
| // rectangles. |
| // |
| // Layout overflow is the overflow that is reachable via scrollbars. It is used |
| // to size the scrollbar thumb and determine its position, which is determined |
| // by the maximum layout overflow size. |
| // Layout overflow cannot occur without an overflow clip as this is the only way |
| // to get scrollbars. As its name implies, it is a direct consequence of layout. |
| // Example of layout overflow: |
| // * in the inline case, a tall image could spill out of a line box. |
| // * 'height' / 'width' set to a value smaller than the one needed by the |
| // descendants. |
| // Due to how scrollbars work, no overflow in the logical top and logical left |
| // direction is allowed(see LayoutBox::addLayoutOverflow). |
| // |
| // Visual overflow covers all the effects that visually bleed out of the box. |
| // Its primary use is to determine the area to invalidate. |
| // Visual overflow includes ('text-shadow' / 'box-shadow'), text stroke, |
| // 'outline', 'border-image', etc. |
| // |
| // An overflow model object is allocated only when some of these fields have |
| // non-default values in the owning object. Care should be taken to use adder |
| // functions (addLayoutOverflow, addVisualOverflow, etc.) to keep this |
| // invariant. |
| |
| class SimpleOverflowModel { |
| WTF_MAKE_NONCOPYABLE(SimpleOverflowModel); |
| USING_FAST_MALLOC(SimpleOverflowModel); |
| |
| public: |
| SimpleOverflowModel(const LayoutRect& layoutRect, |
| const LayoutRect& visualRect) |
| : m_layoutOverflow(layoutRect), m_visualOverflow(visualRect) {} |
| |
| const LayoutRect& layoutOverflowRect() const { return m_layoutOverflow; } |
| void setLayoutOverflow(const LayoutRect& rect) { m_layoutOverflow = rect; } |
| void addLayoutOverflow(const LayoutRect& rect) { |
| uniteLayoutOverflowRect(m_layoutOverflow, rect); |
| } |
| |
| const LayoutRect& visualOverflowRect() const { return m_visualOverflow; } |
| void setVisualOverflow(const LayoutRect& rect) { m_visualOverflow = rect; } |
| void addVisualOverflow(const LayoutRect& rect) { |
| m_visualOverflow.unite(rect); |
| } |
| |
| void move(LayoutUnit dx, LayoutUnit dy) { |
| m_layoutOverflow.move(dx, dy); |
| m_visualOverflow.move(dx, dy); |
| } |
| |
| private: |
| LayoutRect m_layoutOverflow; |
| LayoutRect m_visualOverflow; |
| }; |
| |
| // BoxModelOverflow tracks overflows of a LayoutBox. It separates visual |
| // overflow into self visual overflow and contents visual overflow. |
| // |
| // Self visual overflow covers all the effects of the object itself that |
| // visually bleed out of the box. |
| // |
| // Content visual overflow includes anything that would bleed out of the box and |
| // would be clipped by the overflow clip ('overflow' != visible). This |
| // corresponds to children that overflows their parent. |
| // It's important to note that this overflow ignores descendants with |
| // self-painting layers (see the SELF-PAINTING LAYER section in PaintLayer). |
| // This is required by the simplification made by this model (single united |
| // rectangle) to avoid gigantic invalidation. A good example for this is |
| // positioned objects that can be anywhere on the page and could artificially |
| // inflate the visual overflow. |
| // The main use of content visual overflow is to prevent unneeded clipping in |
| // BoxPainter (see https://crbug.com/238732). Note that the code path for |
| // self-painting layer is handled by PaintLayerPainter, which relies on |
| // PaintLayerClipper and thus ignores this optimization. |
| // |
| // Visual overflow covers self visual overflow, and if the box doesn't clip |
| // overflow, also content visual overflow. OverflowModel doesn't keep visual |
| // overflow, but keeps self visual overflow and contents visual overflow |
| // separately. The box should use self visual overflow as visual overflow if |
| // it clips overflow, otherwise union of self visual overflow and contents |
| // visual overflow. |
| |
| class BoxOverflowModel { |
| public: |
| BoxOverflowModel(const LayoutRect& layoutRect, |
| const LayoutRect& selfVisualOverflowRect) |
| : m_layoutOverflow(layoutRect), |
| m_selfVisualOverflow(selfVisualOverflowRect) {} |
| |
| const LayoutRect& layoutOverflowRect() const { return m_layoutOverflow; } |
| void setLayoutOverflow(const LayoutRect& rect) { m_layoutOverflow = rect; } |
| void addLayoutOverflow(const LayoutRect& rect) { |
| uniteLayoutOverflowRect(m_layoutOverflow, rect); |
| } |
| |
| const LayoutRect& selfVisualOverflowRect() const { |
| return m_selfVisualOverflow; |
| } |
| void addSelfVisualOverflow(const LayoutRect& rect) { |
| m_selfVisualOverflow.unite(rect); |
| } |
| |
| const LayoutRect& contentsVisualOverflowRect() const { |
| return m_contentsVisualOverflow; |
| } |
| void addContentsVisualOverflow(const LayoutRect& rect) { |
| m_contentsVisualOverflow.unite(rect); |
| } |
| |
| void move(LayoutUnit dx, LayoutUnit dy) { |
| m_layoutOverflow.move(dx, dy); |
| m_selfVisualOverflow.move(dx, dy); |
| m_contentsVisualOverflow.move(dx, dy); |
| } |
| |
| LayoutUnit layoutClientAfterEdge() const { return m_layoutClientAfterEdge; } |
| void setLayoutClientAfterEdge(LayoutUnit clientAfterEdge) { |
| m_layoutClientAfterEdge = clientAfterEdge; |
| } |
| |
| private: |
| LayoutRect m_layoutOverflow; |
| LayoutRect m_selfVisualOverflow; |
| LayoutRect m_contentsVisualOverflow; |
| LayoutUnit m_layoutClientAfterEdge; |
| }; |
| |
| } // namespace blink |
| |
| #endif // OverflowModel_h |