layout/generic/ReflowOutput.cpp

   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 /* struct containing the output from nsIFrame::Reflow */
   8
   9 #include "mozilla/ReflowOutput.h"
  10 #include "mozilla/ReflowInput.h"
  11
  12 namespace mozilla {
  13
  14 static bool IsValidOverflowRect(const nsRect& aRect) {
  15   // `IsEmpty` in the context of `nsRect` means "width OR height is zero."
  16   // However, in the context of overflow, the rect having one axis as zero is
  17   // NOT considered empty.
  18   if (MOZ_LIKELY(!aRect.IsEmpty())) {
  19     return true;
  20   }
  21
  22   // Be defensive and consider rects with any negative size as invalid.
  23   return !aRect.IsEqualEdges(nsRect()) && aRect.Width() >= 0 &&
  24          aRect.Height() >= 0;
  25 }
  26
  27 /* static */
  28 nsRect OverflowAreas::GetOverflowClipRect(const nsRect& aRectToClip,
  29                                           const nsRect& aBounds,
  30                                           PhysicalAxes aClipAxes,
  31                                           const nsSize& aOverflowMargin) {
  32   auto inflatedBounds = aBounds;
  33   inflatedBounds.Inflate(aOverflowMargin);
  34   auto clip = aRectToClip;
  35   if (aClipAxes & PhysicalAxes::Vertical) {
  36     clip.y = inflatedBounds.y;
  37     clip.height = inflatedBounds.height;
  38   }
  39   if (aClipAxes & PhysicalAxes::Horizontal) {
  40     clip.x = inflatedBounds.x;
  41     clip.width = inflatedBounds.width;
  42   }
  43   return clip;
  44 }
  45
  46 /* static */
  47 void OverflowAreas::ApplyOverflowClippingOnRect(nsRect& aOverflowRect,
  48                                                 const nsRect& aBounds,
  49                                                 PhysicalAxes aClipAxes,
  50                                                 const nsSize& aOverflowMargin) {
  51   aOverflowRect = aOverflowRect.Intersect(
  52       GetOverflowClipRect(aOverflowRect, aBounds, aClipAxes, aOverflowMargin));
  53 }
  54
  55 void OverflowAreas::UnionWith(const OverflowAreas& aOther) {
  56   if (IsValidOverflowRect(aOther.InkOverflow())) {
  57     InkOverflow().UnionRect(InkOverflow(), aOther.InkOverflow());
  58   }
  59   if (IsValidOverflowRect(aOther.ScrollableOverflow())) {
  60     ScrollableOverflow().UnionRect(ScrollableOverflow(),
  61                                    aOther.ScrollableOverflow());
  62   }
  63 }
  64
  65 void OverflowAreas::UnionAllWith(const nsRect& aRect) {
  66   if (!IsValidOverflowRect(aRect)) {
  67     // Same as `UnionWith()` - avoid losing information.
  68     return;
  69   }
  70   InkOverflow().UnionRect(InkOverflow(), aRect);
  71   ScrollableOverflow().UnionRect(ScrollableOverflow(), aRect);
  72 }
  73
  74 void OverflowAreas::SetAllTo(const nsRect& aRect) {
  75   InkOverflow() = aRect;
  76   ScrollableOverflow() = aRect;
  77 }
  78
  79 ReflowOutput::ReflowOutput(const ReflowInput& aReflowInput)
  80     : ReflowOutput(aReflowInput.GetWritingMode()) {}
  81
  82 void ReflowOutput::SetOverflowAreasToDesiredBounds() {
  83   mOverflowAreas.SetAllTo(nsRect(0, 0, Width(), Height()));
  84 }
  85
  86 void ReflowOutput::UnionOverflowAreasWithDesiredBounds() {
  87   mOverflowAreas.UnionAllWith(nsRect(0, 0, Width(), Height()));
  88 }
  89
  90 }  // namespace mozilla