third_party/WebKit/Source/core/layout/LayoutSliderContainer.cpp

/*
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 * Copyright (C) 2010 Google Inc. All rights reserved.
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#include "core/layout/LayoutSliderContainer.h"

#include "core/dom/shadow/ShadowRoot.h"
#include "core/html/HTMLInputElement.h"
#include "core/html/parser/HTMLParserIdioms.h"
#include "core/html/shadow/ShadowElementNames.h"
#include "core/html/shadow/SliderThumbElement.h"
#include "core/layout/LayoutSlider.h"
#include "core/layout/LayoutTheme.h"

namespace blink {

LayoutSliderContainer::LayoutSliderContainer(SliderContainerElement* element)
    : LayoutFlexibleBox(element) {}

inline static Decimal sliderPosition(HTMLInputElement* element) {
  const StepRange stepRange(element->createStepRange(RejectAny));
  const Decimal oldValue =
      parseToDecimalForNumberType(element->value(), stepRange.defaultValue());
  return stepRange.proportionFromValue(stepRange.clampValue(oldValue));
}

inline static bool hasVerticalAppearance(HTMLInputElement* input) {
  ASSERT(input->layoutObject());
  const ComputedStyle& sliderStyle = input->layoutObject()->styleRef();

  return sliderStyle.appearance() == SliderVerticalPart;
}

void LayoutSliderContainer::computeLogicalHeight(
    LayoutUnit logicalHeight,
    LayoutUnit logicalTop,
    LogicalExtentComputedValues& computedValues) const {
  HTMLInputElement* input = toHTMLInputElement(node()->ownerShadowHost());
  bool isVertical = hasVerticalAppearance(input);

  if (input->layoutObject()->isSlider() && !isVertical && input->list()) {
    int offsetFromCenter =
        LayoutTheme::theme().sliderTickOffsetFromTrackCenter();
    LayoutUnit trackHeight;
    if (offsetFromCenter < 0) {
      trackHeight = LayoutUnit(-2 * offsetFromCenter);
    } else {
      int tickLength = LayoutTheme::theme().sliderTickSize().height();
      trackHeight = LayoutUnit(2 * (offsetFromCenter + tickLength));
    }
    float zoomFactor = style()->effectiveZoom();
    if (zoomFactor != 1.0)
      trackHeight *= zoomFactor;

    // FIXME: The trackHeight should have been added before updateLogicalHeight
    // was called to avoid this hack.
    setIntrinsicContentLogicalHeight(trackHeight);

    LayoutBox::computeLogicalHeight(trackHeight, logicalTop, computedValues);
    return;
  }
  if (isVertical)
    logicalHeight = LayoutUnit(LayoutSlider::defaultTrackLength);

  // FIXME: The trackHeight should have been added before updateLogicalHeight
  // was called to avoid this hack.
  setIntrinsicContentLogicalHeight(logicalHeight);

  LayoutBox::computeLogicalHeight(logicalHeight, logicalTop, computedValues);
}

void LayoutSliderContainer::layout() {
  HTMLInputElement* input = toHTMLInputElement(node()->ownerShadowHost());
  bool isVertical = hasVerticalAppearance(input);
  mutableStyleRef().setFlexDirection(isVertical ? FlowColumn : FlowRow);
  TextDirection oldTextDirection = style()->direction();
  if (isVertical) {
    // FIXME: Work around rounding issues in RTL vertical sliders. We want them
    // to render identically to LTR vertical sliders. We can remove this work
    // around when subpixel rendering is enabled on all ports.
    mutableStyleRef().setDirection(LTR);
  }

  Element* thumbElement = input->userAgentShadowRoot()->getElementById(
      ShadowElementNames::sliderThumb());
  Element* trackElement = input->userAgentShadowRoot()->getElementById(
      ShadowElementNames::sliderTrack());
  LayoutBox* thumb = thumbElement ? thumbElement->layoutBox() : 0;
  LayoutBox* track = trackElement ? trackElement->layoutBox() : 0;

  SubtreeLayoutScope layoutScope(*this);
  // Force a layout to reset the position of the thumb so the code below doesn't
  // move the thumb to the wrong place.
  // FIXME: Make a custom layout class for the track and move the thumb
  // positioning code there.
  if (track)
    layoutScope.setChildNeedsLayout(track);

  LayoutFlexibleBox::layout();

  mutableStyleRef().setDirection(oldTextDirection);
  // These should always exist, unless someone mutates the shadow DOM (e.g., in
  // the inspector).
  if (!thumb || !track)
    return;

  double percentageOffset = sliderPosition(input).toDouble();
  LayoutUnit availableExtent =
      isVertical ? track->contentHeight() : track->contentWidth();
  availableExtent -=
      isVertical ? thumb->size().height() : thumb->size().width();
  LayoutUnit offset(percentageOffset * availableExtent);
  LayoutPoint thumbLocation = thumb->location();
  if (isVertical)
    thumbLocation.setY(thumbLocation.y() + track->contentHeight() -
                       thumb->size().height() - offset);
  else if (style()->isLeftToRightDirection())
    thumbLocation.setX(thumbLocation.x() + offset);
  else
    thumbLocation.setX(thumbLocation.x() - offset);
  thumb->setLocation(thumbLocation);

  // We need one-off invalidation code here because painting of the timeline
  // element does not go through style.
  // Instead it has a custom implementation in C++ code.
  // Therefore the style system cannot understand when it needs to be paint
  // invalidated.
  setShouldDoFullPaintInvalidation();
}

}  // namespace blink