gecko-dev/layout/generic/nsFontInflationData.h

/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the font size inflation manager.
 *
 * The Initial Developer of the Original Code is the Mozilla Foundation.
 * Portions created by the Initial Developer are Copyright (C) 2012
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/* 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);

  static void
    UpdateFontInflationDataWidthFor(const nsHTMLReflowState& aReflowState);

  static void MarkFontInflationDataTextDirty(nsIFrame *aFrame);

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

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 mTextAmount, mTextThreshold;
  bool mInflationEnabled; // for this BFC
  bool mTextDirty;
};

#endif /* !defined(nsFontInflationData_h_) */