third_party/WebKit/Source/core/layout/LayoutScrollbarPart.h

   1 /*
   2  * Copyright (C) 2008 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 #ifndef LayoutScrollbarPart_h
  27 #define LayoutScrollbarPart_h
  28
  29 #include "core/layout/LayoutBlock.h"
  30 #include "platform/scroll/ScrollTypes.h"
  31
  32 namespace blink {
  33
  34 class LayoutScrollbar;
  35
  36 class LayoutScrollbarPart final : public LayoutBlock {
  37 public:
  38     static LayoutScrollbarPart* createAnonymous(Document*, LayoutScrollbar* = nullptr, ScrollbarPart = NoPart);
  39     ~LayoutScrollbarPart() override;
  40
  41     const char* name() const override { return "LayoutScrollbarPart"; }
  42
  43     DeprecatedPaintLayerType layerTypeRequired() const override { return NoDeprecatedPaintLayer; }
  44
  45     void layout() override;
  46
  47     // Scrollbar parts needs to be rendered at device pixel boundaries.
  48     LayoutRectOutsets marginBoxOutsets() const override
  49     {
  50         ASSERT(isIntegerValue(LayoutBlock::marginBoxOutsets().top()));
  51         return LayoutBlock::marginBoxOutsets();
  52     }
  53     LayoutUnit marginTop() const override
  54     {
  55         ASSERT(isIntegerValue(LayoutBlock::marginTop()));
  56         return LayoutBlock::marginTop();
  57     }
  58     LayoutUnit marginBottom() const override
  59     {
  60         ASSERT(isIntegerValue(LayoutBlock::marginBottom()));
  61         return LayoutBlock::marginBottom();
  62     }
  63     LayoutUnit marginLeft() const override
  64     {
  65         ASSERT(isIntegerValue(LayoutBlock::marginLeft()));
  66         return LayoutBlock::marginLeft();
  67     }
  68     LayoutUnit marginRight() const override
  69     {
  70         ASSERT(isIntegerValue(LayoutBlock::marginRight()));
  71         return LayoutBlock::marginRight();
  72     }
  73
  74     bool isOfType(LayoutObjectType type) const override { return type == LayoutObjectLayoutScrollbarPart || LayoutBlock::isOfType(type); }
  75     LayoutObject* layoutObjectOwningScrollbar() const;
  76
  77 protected:
  78     void styleWillChange(StyleDifference, const ComputedStyle& newStyle) override;
  79     void styleDidChange(StyleDifference, const ComputedStyle* oldStyle) override;
  80     void imageChanged(WrappedImagePtr, const IntRect* = nullptr) override;
  81
  82 private:
  83     LayoutScrollbarPart(LayoutScrollbar*, ScrollbarPart);
  84
  85     void computePreferredLogicalWidths() override;
  86
  87     // Have all padding getters return 0. The important point here is to avoid resolving percents
  88     // against the containing block, since scroll bar corners don't always have one (so it would
  89     // crash). Scroll bar corners are not actually laid out, and they don't have child content, so
  90     // what we return here doesn't really matter.
  91     LayoutUnit paddingTop() const override { return LayoutUnit(); }
  92     LayoutUnit paddingBottom() const override { return LayoutUnit(); }
  93     LayoutUnit paddingLeft() const override { return LayoutUnit(); }
  94     LayoutUnit paddingRight() const override { return LayoutUnit(); }
  95     LayoutUnit paddingBefore() const override { return LayoutUnit(); }
  96     LayoutUnit paddingAfter() const override { return LayoutUnit(); }
  97     LayoutUnit paddingStart() const override { return LayoutUnit(); }
  98     LayoutUnit paddingEnd() const override { return LayoutUnit(); }
  99
 100     void layoutHorizontalPart();
 101     void layoutVerticalPart();
 102
 103     void computeScrollbarWidth();
 104     void computeScrollbarHeight();
 105
 106     GC_PLUGIN_IGNORE("http://crbug.com/509911")
 107     LayoutScrollbar* m_scrollbar;
 108     ScrollbarPart m_part;
 109 };
 110
 111 DEFINE_LAYOUT_OBJECT_TYPE_CASTS(LayoutScrollbarPart, isLayoutScrollbarPart());
 112
 113 } // namespace blink
 114
 115 #endif // LayoutScrollbarPart_h