michael@0: /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef DISPLAYLISTCLIPSTATE_H_
michael@0: #define DISPLAYLISTCLIPSTATE_H_
michael@0: 
michael@0: #include "DisplayItemClip.h"
michael@0: 
michael@0: #include "mozilla/DebugOnly.h"
michael@0: 
michael@0: class nsIFrame;
michael@0: class nsDisplayListBuilder;
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: /**
michael@0:  * All clip coordinates are in appunits relative to the reference frame
michael@0:  * for the display item we're building.
michael@0:  */
michael@0: class DisplayListClipState {
michael@0: public:
michael@0:   DisplayListClipState()
michael@0:     : mClipContentDescendants(nullptr)
michael@0:     , mClipContainingBlockDescendants(nullptr)
michael@0:     , mCurrentCombinedClip(nullptr)
michael@0:   {}
michael@0: 
michael@0:   /**
michael@0:    * Returns intersection of mClipContainingBlockDescendants and
michael@0:    * mClipContentDescendants, allocated on aBuilder's arena.
michael@0:    */
michael@0:   const DisplayItemClip* GetCurrentCombinedClip(nsDisplayListBuilder* aBuilder);
michael@0: 
michael@0:   const DisplayItemClip* GetClipForContainingBlockDescendants() const
michael@0:   {
michael@0:     return mClipContainingBlockDescendants;
michael@0:   }
michael@0:   const DisplayItemClip* GetClipForContentDescendants() const
michael@0:   {
michael@0:     return mClipContentDescendants;
michael@0:   }
michael@0: 
michael@0:   class AutoSaveRestore;
michael@0:   friend class AutoSaveRestore;
michael@0: 
michael@0:   class AutoClipContainingBlockDescendantsToContentBox;
michael@0:   friend class AutoClipContainingBlockDescendantsToContentBox;
michael@0: 
michael@0:   class AutoClipMultiple;
michael@0:   friend class AutoClipMultiple;
michael@0: 
michael@0:   enum {
michael@0:     ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT = 0x01
michael@0:   };
michael@0: 
michael@0: private:
michael@0:   void SetClipForContainingBlockDescendants(const DisplayItemClip* aClip)
michael@0:   {
michael@0:     mClipContainingBlockDescendants = aClip;
michael@0:     mCurrentCombinedClip = nullptr;
michael@0:   }
michael@0: 
michael@0:   void Clear()
michael@0:   {
michael@0:     mClipContentDescendants = nullptr;
michael@0:     mClipContainingBlockDescendants = nullptr;
michael@0:     mCurrentCombinedClip = nullptr;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Intersects the given clip rect (with optional aRadii) with the current
michael@0:    * mClipContainingBlockDescendants and sets mClipContainingBlockDescendants to
michael@0:    * the result, stored in aClipOnStack.
michael@0:    */
michael@0:   void ClipContainingBlockDescendants(const nsRect& aRect,
michael@0:                                       const nscoord* aRadii,
michael@0:                                       DisplayItemClip& aClipOnStack);
michael@0: 
michael@0:   void ClipContentDescendants(const nsRect& aRect,
michael@0:                               const nscoord* aRadii,
michael@0:                               DisplayItemClip& aClipOnStack);
michael@0: 
michael@0:   /**
michael@0:    * Clips containing-block descendants to the frame's content-box,
michael@0:    * taking border-radius into account.
michael@0:    * If aFlags contains ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT then
michael@0:    * we assume display items will not draw outside the content rect, so
michael@0:    * clipping is only required if there is a border-radius. This is an
michael@0:    * optimization to reduce the amount of clipping required.
michael@0:    */
michael@0:   void ClipContainingBlockDescendantsToContentBox(nsDisplayListBuilder* aBuilder,
michael@0:                                                   nsIFrame* aFrame,
michael@0:                                                   DisplayItemClip& aClipOnStack,
michael@0:                                                   uint32_t aFlags);
michael@0: 
michael@0:   /**
michael@0:    * All content descendants (i.e. following placeholder frames to their
michael@0:    * out-of-flows if necessary) should be clipped by mClipContentDescendants.
michael@0:    * Null if no clipping applies.
michael@0:    */
michael@0:   const DisplayItemClip* mClipContentDescendants;
michael@0:   /**
michael@0:    * All containing-block descendants (i.e. frame descendants), including
michael@0:    * display items for the current frame, should be clipped by
michael@0:    * mClipContainingBlockDescendants.
michael@0:    * Null if no clipping applies.
michael@0:    */
michael@0:   const DisplayItemClip* mClipContainingBlockDescendants;
michael@0:   /**
michael@0:    * The intersection of mClipContentDescendants and
michael@0:    * mClipContainingBlockDescendants.
michael@0:    * Allocated in the nsDisplayListBuilder arena. Null if none has been
michael@0:    * allocated or both mClipContentDescendants and mClipContainingBlockDescendants
michael@0:    * are null.
michael@0:    */
michael@0:   const DisplayItemClip* mCurrentCombinedClip;
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * A class to automatically save and restore the current clip state. Also
michael@0:  * offers methods for modifying the clip state. Only one modification is allowed
michael@0:  * to be in scope at a time using one of these objects; multiple modifications
michael@0:  * require nested objects. The interface is written this way to prevent
michael@0:  * dangling pointers to DisplayItemClips.
michael@0:  */
michael@0: class DisplayListClipState::AutoSaveRestore {
michael@0: public:
michael@0:   AutoSaveRestore(nsDisplayListBuilder* aBuilder);
michael@0:   void Restore()
michael@0:   {
michael@0:     mState = mSavedState;
michael@0:     mRestored = true;
michael@0:   }
michael@0:   ~AutoSaveRestore()
michael@0:   {
michael@0:     mState = mSavedState;
michael@0:   }
michael@0: 
michael@0:   void Clear()
michael@0:   {
michael@0:     NS_ASSERTION(!mRestored, "Already restored!");
michael@0:     mState.Clear();
michael@0:     mClipUsed = false;
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Intersects the given clip rect (with optional aRadii) with the current
michael@0:    * mClipContainingBlockDescendants and sets mClipContainingBlockDescendants to
michael@0:    * the result, stored in aClipOnStack.
michael@0:    */
michael@0:   void ClipContainingBlockDescendants(const nsRect& aRect,
michael@0:                                       const nscoord* aRadii = nullptr)
michael@0:   {
michael@0:     NS_ASSERTION(!mRestored, "Already restored!");
michael@0:     NS_ASSERTION(!mClipUsed, "mClip already used");
michael@0:     mClipUsed = true;
michael@0:     mState.ClipContainingBlockDescendants(aRect, aRadii, mClip);
michael@0:   }
michael@0: 
michael@0:   void ClipContentDescendants(const nsRect& aRect,
michael@0:                               const nscoord* aRadii = nullptr)
michael@0:   {
michael@0:     NS_ASSERTION(!mRestored, "Already restored!");
michael@0:     NS_ASSERTION(!mClipUsed, "mClip already used");
michael@0:     mClipUsed = true;
michael@0:     mState.ClipContentDescendants(aRect, aRadii, mClip);
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Clips containing-block descendants to the frame's content-box,
michael@0:    * taking border-radius into account.
michael@0:    * If aFlags contains ASSUME_DRAWING_RESTRICTED_TO_CONTENT_RECT then
michael@0:    * we assume display items will not draw outside the content rect, so
michael@0:    * clipping is only required if there is a border-radius. This is an
michael@0:    * optimization to reduce the amount of clipping required.
michael@0:    */
michael@0:   void ClipContainingBlockDescendantsToContentBox(nsDisplayListBuilder* aBuilder,
michael@0:                                                   nsIFrame* aFrame,
michael@0:                                                   uint32_t aFlags = 0)
michael@0:   {
michael@0:     NS_ASSERTION(!mRestored, "Already restored!");
michael@0:     NS_ASSERTION(!mClipUsed, "mClip already used");
michael@0:     mClipUsed = true;
michael@0:     mState.ClipContainingBlockDescendantsToContentBox(aBuilder, aFrame, mClip, aFlags);
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   DisplayListClipState& mState;
michael@0:   DisplayListClipState mSavedState;
michael@0:   DisplayItemClip mClip;
michael@0:   DebugOnly<bool> mClipUsed;
michael@0:   DebugOnly<bool> mRestored;
michael@0: };
michael@0: 
michael@0: class DisplayListClipState::AutoClipContainingBlockDescendantsToContentBox : public AutoSaveRestore {
michael@0: public:
michael@0:   AutoClipContainingBlockDescendantsToContentBox(nsDisplayListBuilder* aBuilder,
michael@0:                                                  nsIFrame* aFrame,
michael@0:                                                  uint32_t aFlags = 0)
michael@0:     : AutoSaveRestore(aBuilder)
michael@0:   {
michael@0:     mClipUsed = true;
michael@0:     mState.ClipContainingBlockDescendantsToContentBox(aBuilder, aFrame, mClip, aFlags);
michael@0:   }
michael@0: };
michael@0: 
michael@0: /**
michael@0:  * Do not use this outside of nsFrame::BuildDisplayListForChild, use
michael@0:  * multiple AutoSaveRestores instead. We provide this class just to ensure
michael@0:  * BuildDisplayListForChild is as efficient as possible.
michael@0:  */
michael@0: class DisplayListClipState::AutoClipMultiple : public AutoSaveRestore {
michael@0: public:
michael@0:   AutoClipMultiple(nsDisplayListBuilder* aBuilder)
michael@0:     : AutoSaveRestore(aBuilder)
michael@0:     , mExtraClipUsed(false)
michael@0:   {}
michael@0: 
michael@0:   /**
michael@0:    * *aClip must survive longer than this object. Be careful!!!
michael@0:    */
michael@0:   void SetClipForContainingBlockDescendants(const DisplayItemClip* aClip)
michael@0:   {
michael@0:     mState.SetClipForContainingBlockDescendants(aClip);
michael@0:   }
michael@0: 
michael@0:   /**
michael@0:    * Intersects the given clip rect (with optional aRadii) with the current
michael@0:    * mClipContainingBlockDescendants and sets mClipContainingBlockDescendants to
michael@0:    * the result, stored in aClipOnStack.
michael@0:    */
michael@0:   void ClipContainingBlockDescendantsExtra(const nsRect& aRect,
michael@0:                                            const nscoord* aRadii)
michael@0:   {
michael@0:     NS_ASSERTION(!mRestored, "Already restored!");
michael@0:     NS_ASSERTION(!mExtraClipUsed, "mExtraClip already used");
michael@0:     mExtraClipUsed = true;
michael@0:     mState.ClipContainingBlockDescendants(aRect, aRadii, mExtraClip);
michael@0:   }
michael@0: 
michael@0: protected:
michael@0:   DisplayItemClip mExtraClip;
michael@0:   DebugOnly<bool> mExtraClipUsed;
michael@0: };
michael@0: 
michael@0: }
michael@0: 
michael@0: #endif /* DISPLAYLISTCLIPSTATE_H_ */