/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* 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 GFX_STACKINGCONTEXTHELPER_H

#define GFX_STACKINGCONTEXTHELPER_H

#include "mozilla/Attributes.h"

#include "mozilla/gfx/MatrixFwd.h"

#include "mozilla/webrender/WebRenderAPI.h"

#include "mozilla/webrender/WebRenderTypes.h"

#include "Units.h"

class nsDisplayTransform;

namespace mozilla {

namespace layers {

/**

 * This is a helper class that pushes/pops a stacking context, and manages

 * some of the coordinate space transformations needed.

 */

class MOZ_RAII StackingContextHelper

{

public:

  StackingContextHelper(const StackingContextHelper& aParentSC,

                        wr::DisplayListBuilder& aBuilder,

                        const nsTArray<wr::WrFilterOp>& aFilters = nsTArray<wr::WrFilterOp>(),

                        const LayoutDeviceRect& aBounds = LayoutDeviceRect(),

                        const gfx::Matrix4x4* aBoundTransform = nullptr,

                        const wr::WrAnimationProperty* aAnimation = nullptr,

                        const float* aOpacityPtr = nullptr,

                        const gfx::Matrix4x4* aTransformPtr = nullptr,

                        const gfx::Matrix4x4* aPerspectivePtr = nullptr,

                        const gfx::CompositionOp& aMixBlendMode = gfx::CompositionOp::OP_OVER,

                        bool aBackfaceVisible = true,

                        bool aIsPreserve3D = false,

                        const Maybe<nsDisplayTransform*>& aDeferredTransformItem = Nothing(),

                        const wr::WrClipId* aClipNodeId = nullptr,

                        bool aAnimated = false);

  // This version of the constructor should only be used at the root level

  // of the tree, so that we have a StackingContextHelper to pass down into

  // the RenderLayer traversal, but don't actually want it to push a stacking

  // context on the display list builder.

  StackingContextHelper();

  // Pops the stacking context, if one was pushed during the constructor.

  ~StackingContextHelper();

  // Export the inherited scale

  gfx::Size GetInheritedScale() const { return mScale; }

  const gfx::Matrix& GetInheritedTransform() const

  {

    return mInheritedTransform;

  }

  const gfx::Matrix& GetSnappingSurfaceTransform() const

  {

    return mSnappingSurfaceTransform;

  }

  const Maybe<nsDisplayTransform*>& GetDeferredTransformItem() const;

  bool AffectsClipPositioning() const { return mAffectsClipPositioning; }

  Maybe<wr::WrClipId> ReferenceFrameId() const { return mReferenceFrameId; }

private:

  wr::DisplayListBuilder* mBuilder;

  gfx::Size mScale;

  gfx::Matrix mInheritedTransform;

  // The "snapping surface" defines the space that we want to snap in.

  // You can think of it as the nearest physical surface.

  // Animated transforms create a new snapping surface, so that changes to their transform don't affect the snapping of their contents.

  // Non-animated transforms do *not* create a new snapping surface,

  // so that for example the existence of a non-animated identity transform does not affect snapping.

  gfx::Matrix mSnappingSurfaceTransform;

  bool mAffectsClipPositioning;

  Maybe<wr::WrClipId> mReferenceFrameId;

  Maybe<nsDisplayTransform*> mDeferredTransformItem;

  bool mIsPreserve3D;

  bool mRasterizeLocally;

};

} // namespace layers

} // namespace mozilla

#endif /* GFX_STACKINGCONTEXTHELPER_H */