gecko/layout/generic/nsFontInflationData.h

/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* Per-block-formatting-context manager of font size inflation for pan and zoom UI. */

#ifndef nsFontInflationData_h_
#define nsFontInflationData_h_

#include "nsIFrame.h"
#include "nsLayoutUtils.h"
#include "nsBlockFrame.h"

struct nsHTMLReflowState;

class nsFontInflationData
{
public:

  static nsFontInflationData* FindFontInflationDataFor(const nsIFrame *aFrame);

  // Returns whether the effective width changed (which requires the
  // caller to mark its descendants dirty
  static bool
    UpdateFontInflationDataWidthFor(const nsHTMLReflowState& aReflowState);

  static void MarkFontInflationDataTextDirty(nsIFrame *aFrame);

  bool InflationEnabled() {
    if (mTextDirty) {
      ScanText();
    }
    return mInflationEnabled;
  }

  nscoord EffectiveWidth() const {
    return mNCAWidth;
  }

private:

  nsFontInflationData(nsIFrame* aBFCFrame);

  nsFontInflationData(const nsFontInflationData&) MOZ_DELETE;
  void operator=(const nsFontInflationData&) MOZ_DELETE;

  void UpdateWidth(const nsHTMLReflowState &aReflowState);
  enum SearchDirection { eFromStart, eFromEnd };
  static nsIFrame* FindEdgeInflatableFrameIn(nsIFrame *aFrame,
                                             SearchDirection aDirection);

  void MarkTextDirty() { mTextDirty = true; }
  void ScanText();
  // Scan text in the subtree rooted at aFrame.  Increment mTextAmount
  // by multiplying the number of characters found by the font size
  // (yielding the width that would be occupied by the characters if
  // they were all em squares).  But stop scanning if mTextAmount
  // crosses mTextThreshold.
  void ScanTextIn(nsIFrame *aFrame);

  static const nsIFrame* FlowRootFor(const nsIFrame *aFrame)
  {
    while (!(aFrame->GetStateBits() & NS_FRAME_FONT_INFLATION_FLOW_ROOT)) {
      aFrame = aFrame->GetParent();
    }
    return aFrame;
  }

  nsIFrame *mBFCFrame;
  nscoord mNCAWidth;
  nscoord mTextAmount, mTextThreshold;
  bool mInflationEnabled; // for this BFC
  bool mTextDirty;
};

#endif /* !defined(nsFontInflationData_h_) */