layout/generic/nsFontInflationData.h

   1 /* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 /* Per-block-formatting-context manager of font size inflation for pan and zoom UI. */
   7
   8 #ifndef nsFontInflationData_h_
   9 #define nsFontInflationData_h_
  10
  11 #include "nsContainerFrame.h"
  12
  13 struct nsHTMLReflowState;
  14
  15 class nsFontInflationData
  16 {
  17 public:
  18
  19   static nsFontInflationData* FindFontInflationDataFor(const nsIFrame *aFrame);
  20
  21   // Returns whether the effective width changed (which requires the
  22   // caller to mark its descendants dirty
  23   static bool
  24     UpdateFontInflationDataWidthFor(const nsHTMLReflowState& aReflowState);
  25
  26   static void MarkFontInflationDataTextDirty(nsIFrame *aFrame);
  27
  28   bool InflationEnabled() {
  29     if (mTextDirty) {
  30       ScanText();
  31     }
  32     return mInflationEnabled;
  33   }
  34
  35   nscoord EffectiveWidth() const {
  36     return mNCAWidth;
  37   }
  38
  39 private:
  40
  41   explicit nsFontInflationData(nsIFrame* aBFCFrame);
  42
  43   nsFontInflationData(const nsFontInflationData&) MOZ_DELETE;
  44   void operator=(const nsFontInflationData&) MOZ_DELETE;
  45
  46   void UpdateWidth(const nsHTMLReflowState &aReflowState);
  47   enum SearchDirection { eFromStart, eFromEnd };
  48   static nsIFrame* FindEdgeInflatableFrameIn(nsIFrame *aFrame,
  49                                              SearchDirection aDirection);
  50
  51   void MarkTextDirty() { mTextDirty = true; }
  52   void ScanText();
  53   // Scan text in the subtree rooted at aFrame.  Increment mTextAmount
  54   // by multiplying the number of characters found by the font size
  55   // (yielding the width that would be occupied by the characters if
  56   // they were all em squares).  But stop scanning if mTextAmount
  57   // crosses mTextThreshold.
  58   void ScanTextIn(nsIFrame *aFrame);
  59
  60   static const nsIFrame* FlowRootFor(const nsIFrame *aFrame)
  61   {
  62     while (!(aFrame->GetStateBits() & NS_FRAME_FONT_INFLATION_FLOW_ROOT)) {
  63       aFrame = aFrame->GetParent();
  64     }
  65     return aFrame;
  66   }
  67
  68   nsIFrame *mBFCFrame;
  69   nscoord mNCAWidth;
  70   nscoord mTextAmount, mTextThreshold;
  71   bool mInflationEnabled; // for this BFC
  72   bool mTextDirty;
  73 };
  74
  75 #endif /* !defined(nsFontInflationData_h_) */