layout/painting/DisplayItemClip.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 #ifndef DISPLAYITEMCLIP_H_
   8 #define DISPLAYITEMCLIP_H_
   9
  10 #include "mozilla/RefPtr.h"
  11 #include "nsRect.h"
  12 #include "nsTArray.h"
  13
  14 class gfxContext;
  15 class nsPresContext;
  16 class nsRegion;
  17
  18 namespace mozilla {
  19 namespace gfx {
  20 class DrawTarget;
  21 class Path;
  22 }  // namespace gfx
  23 namespace layers {
  24 class StackingContextHelper;
  25 }  // namespace layers
  26 namespace wr {
  27 struct ComplexClipRegion;
  28 }  // namespace wr
  29 }  // namespace mozilla
  30
  31 namespace mozilla {
  32
  33 /**
  34  * An DisplayItemClip represents the intersection of an optional rectangle
  35  * with a list of rounded rectangles (which is often empty), all in appunits.
  36  * It can represent everything CSS clipping can do to an element (except for
  37  * SVG clip-path), including no clipping at all.
  38  */
  39 class DisplayItemClip {
  40   typedef mozilla::gfx::DeviceColor DeviceColor;
  41   typedef mozilla::gfx::DrawTarget DrawTarget;
  42   typedef mozilla::gfx::Path Path;
  43
  44  public:
  45   struct RoundedRect {
  46     nsRect mRect;
  47     // Indices into mRadii are the HalfCorner values in gfx/2d/Types.h
  48     nscoord mRadii[8];
  49
  50     RoundedRect operator+(const nsPoint& aOffset) const {
  51       RoundedRect r = *this;
  52       r.mRect += aOffset;
  53       return r;
  54     }
  55     bool operator==(const RoundedRect& aOther) const {
  56       if (!mRect.IsEqualInterior(aOther.mRect)) {
  57         return false;
  58       }
  59
  60       for (const auto corner : mozilla::AllPhysicalHalfCorners()) {
  61         if (mRadii[corner] != aOther.mRadii[corner]) {
  62           return false;
  63         }
  64       }
  65       return true;
  66     }
  67     bool operator!=(const RoundedRect& aOther) const {
  68       return !(*this == aOther);
  69     }
  70   };
  71
  72   // Constructs a DisplayItemClip that does no clipping at all.
  73   DisplayItemClip() : mHaveClipRect(false) {}
  74
  75   void SetTo(const nsRect& aRect);
  76   void SetTo(const nsRect& aRect, const nscoord* aRadii);
  77   void SetTo(const nsRect& aRect, const nsRect& aRoundedRect,
  78              const nscoord* aRadii);
  79   void IntersectWith(const DisplayItemClip& aOther);
  80
  81   // Apply this |DisplayItemClip| to the given gfxContext.  Any saving of state
  82   // or clearing of other clips must be done by the caller.
  83   // See aBegin/aEnd note on ApplyRoundedRectsTo.
  84   void ApplyTo(gfxContext* aContext, int32_t A2D) const;
  85
  86   void ApplyRectTo(gfxContext* aContext, int32_t A2D) const;
  87   // Applies the rounded rects in this Clip to aContext
  88   // Will only apply rounded rects from aBegin (inclusive) to aEnd
  89   // (exclusive) or the number of rounded rects, whichever is smaller.
  90   void ApplyRoundedRectClipsTo(gfxContext* aContext, int32_t A2DPRInt32,
  91                                uint32_t aBegin, uint32_t aEnd) const;
  92
  93   // Draw (fill) the rounded rects in this clip to aContext
  94   void FillIntersectionOfRoundedRectClips(gfxContext* aContext,
  95                                           const DeviceColor& aColor,
  96                                           int32_t aAppUnitsPerDevPixel) const;
  97   // 'Draw' (create as a path, does not stroke or fill) aRoundRect to aContext
  98   already_AddRefed<Path> MakeRoundedRectPath(
  99       DrawTarget& aDrawTarget, int32_t A2D,
 100       const RoundedRect& aRoundRect) const;
 101
 102   // Returns true if the intersection of aRect and this clip region is
 103   // non-empty. This is precise for DisplayItemClips with at most one
 104   // rounded rectangle. When multiple rounded rectangles are present, we just
 105   // check that the rectangle intersects all of them (but possibly in different
 106   // places). So it may return true when the correct answer is false.
 107   bool MayIntersect(const nsRect& aRect) const;
 108
 109   // Return a rectangle contained in the intersection of aRect with this
 110   // clip region. Tries to return the largest possible rectangle, but may
 111   // not succeed.
 112   nsRect ApproximateIntersectInward(const nsRect& aRect) const;
 113
 114   /*
 115    * Computes a region which contains the clipped area of this DisplayItemClip,
 116    * or if aOldClip is non-null, the union of the clipped area of this
 117    * DisplayItemClip with the clipped area of aOldClip translated by aShift.
 118    * The result is stored in aCombined. If the result would be infinite
 119    * (because one or both of the clips does no clipping), returns false.
 120    */
 121   bool ComputeRegionInClips(const DisplayItemClip* aOldClip,
 122                             const nsPoint& aShift, nsRegion* aCombined) const;
 123
 124   // Returns false if aRect is definitely not clipped by a rounded corner in
 125   // this clip. Returns true if aRect is clipped by a rounded corner in this
 126   // clip or it can not be quickly determined that it is not clipped by a
 127   // rounded corner in this clip.
 128   bool IsRectClippedByRoundedCorner(const nsRect& aRect) const;
 129
 130   // Returns false if aRect is definitely not clipped by anything in this clip.
 131   // Fast but not necessarily accurate.
 132   bool IsRectAffectedByClip(const nsRect& aRect) const;
 133   bool IsRectAffectedByClip(const nsIntRect& aRect, float aXScale,
 134                             float aYScale, int32_t A2D) const;
 135
 136   // Intersection of all rects in this clip ignoring any rounded corners.
 137   nsRect NonRoundedIntersection() const;
 138
 139   // Intersect the given rects with all rects in this clip, ignoring any
 140   // rounded corners.
 141   nsRect ApplyNonRoundedIntersection(const nsRect& aRect) const;
 142
 143   // Gets rid of any rounded corners in this clip.
 144   void RemoveRoundedCorners();
 145
 146   // Adds the difference between Intersect(*this + aPoint, aBounds) and
 147   // Intersect(aOther, aOtherBounds) to aDifference (or a bounding-box thereof).
 148   void AddOffsetAndComputeDifference(const nsPoint& aPoint,
 149                                      const nsRect& aBounds,
 150                                      const DisplayItemClip& aOther,
 151                                      const nsRect& aOtherBounds,
 152                                      nsRegion* aDifference);
 153
 154   bool operator==(const DisplayItemClip& aOther) const {
 155     return mHaveClipRect == aOther.mHaveClipRect &&
 156            (!mHaveClipRect || mClipRect.IsEqualInterior(aOther.mClipRect)) &&
 157            mRoundedClipRects == aOther.mRoundedClipRects;
 158   }
 159   bool operator!=(const DisplayItemClip& aOther) const {
 160     return !(*this == aOther);
 161   }
 162
 163   bool HasClip() const { return mHaveClipRect; }
 164   const nsRect& GetClipRect() const {
 165     NS_ASSERTION(HasClip(), "No clip rect!");
 166     return mClipRect;
 167   }
 168
 169   void MoveBy(const nsPoint& aPoint);
 170
 171   nsCString ToString() const;
 172
 173   uint32_t GetRoundedRectCount() const { return mRoundedClipRects.Length(); }
 174   void AppendRoundedRects(nsTArray<RoundedRect>* aArray) const;
 175
 176   void ToComplexClipRegions(int32_t aAppUnitsPerDevPixel,
 177                             nsTArray<wr::ComplexClipRegion>& aOutArray) const;
 178
 179   static const DisplayItemClip& NoClip();
 180
 181   static void Shutdown();
 182
 183  private:
 184   nsRect mClipRect;
 185   CopyableTArray<RoundedRect> mRoundedClipRects;
 186   // If mHaveClipRect is false then this object represents no clipping at all
 187   // and mRoundedClipRects must be empty.
 188   bool mHaveClipRect;
 189 };
 190
 191 }  // namespace mozilla
 192
 193 #endif /* DISPLAYITEMCLIP_H_ */