layout/generic/nsFontInflationData.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* Per-block-formatting-context manager of font size inflation for pan and zoom
   8  * UI. */
   9
  10 #ifndef nsFontInflationData_h_
  11 #define nsFontInflationData_h_
  12
  13 #include "nsContainerFrame.h"
  14
  15 class nsFontInflationData {
  16   using ReflowInput = mozilla::ReflowInput;
  17
  18  public:
  19   static nsFontInflationData* FindFontInflationDataFor(const nsIFrame* aFrame);
  20
  21   // Returns whether the usable width changed (which requires the
  22   // caller to mark its descendants dirty)
  23   static bool UpdateFontInflationDataISizeFor(const ReflowInput& aReflowInput);
  24
  25   static void MarkFontInflationDataTextDirty(nsIFrame* aFrame);
  26
  27   bool InflationEnabled() {
  28     if (mTextDirty) {
  29       ScanText();
  30     }
  31     return mInflationEnabled;
  32   }
  33
  34   nscoord UsableISize() const { return mUsableISize; }
  35
  36  private:
  37   explicit nsFontInflationData(nsIFrame* aBFCFrame);
  38
  39   nsFontInflationData(const nsFontInflationData&) = delete;
  40   void operator=(const nsFontInflationData&) = delete;
  41
  42   void UpdateISize(const ReflowInput& aReflowInput);
  43   enum SearchDirection { eFromStart, eFromEnd };
  44   static nsIFrame* FindEdgeInflatableFrameIn(nsIFrame* aFrame,
  45                                              SearchDirection aDirection);
  46
  47   void MarkTextDirty() { mTextDirty = true; }
  48   void ScanText();
  49   // Scan text in the subtree rooted at aFrame.  Increment mTextAmount
  50   // by multiplying the number of characters found by the font size
  51   // (yielding the inline-size that would be occupied by the characters if
  52   // they were all em squares).  But stop scanning if mTextAmount
  53   // crosses mTextThreshold.
  54   void ScanTextIn(nsIFrame* aFrame);
  55
  56   static const nsIFrame* FlowRootFor(const nsIFrame* aFrame) {
  57     while (!aFrame->HasAnyStateBits(NS_FRAME_FONT_INFLATION_FLOW_ROOT)) {
  58       aFrame = aFrame->GetParent();
  59     }
  60     return aFrame;
  61   }
  62
  63   nsIFrame* mBFCFrame;
  64   nscoord mUsableISize;
  65   nscoord mTextAmount, mTextThreshold;
  66   bool mInflationEnabled;  // for this BFC
  67   bool mTextDirty;
  68 };
  69
  70 #endif /* !defined(nsFontInflationData_h_) */