The Tor Browser: layout/base/DisplayListClipState.h@b8a032363ba2 (annotated)

layout/base/DisplayListClipState.h@b8a032363ba2 (annotated)

layout/base/DisplayListClipState.h

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

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

The Tor Browser / annotate

layout/base/DisplayListClipState.h@b8a032363ba2 (annotated)

layout/base/DisplayListClipState.h