/* -*- 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 MOZILLA_SVGCONTEXT_H_

#define MOZILLA_SVGCONTEXT_H_

#include "mozilla/Maybe.h"

#include "mozilla/SVGContextPaint.h"

#include "SVGPreserveAspectRatio.h"

#include "Units.h"

class nsIFrame;

namespace mozilla {

class ComputedStyle;

// SVG image-specific rendering context. For imgIContainer::Draw.

// Used to pass information such as

//  - viewport information from CSS, and

//  - overridden attributes from an SVG <image> element

// to the image's internal SVG document when it's drawn.

class SVGImageContext

{

public:

  SVGImageContext() {}

  /**

   * Currently it seems that the aViewportSize parameter ends up being used

   * for different things by different pieces of code, and probably in some

   * cases being used incorrectly (specifically in the case of pixel snapping

   * under the nsLayoutUtils::Draw*Image() methods).  An unfortunate result of

   * the messy code is that aViewportSize is currently a Maybe<T> since it

   * is difficult to create a utility function that consumers can use up

   * front to get the "correct" viewport size (i.e. which for compatibility

   * with the current code (bugs and all) would mean the size including all

   * the snapping and resizing magic that happens in various places under the

   * nsLayoutUtils::Draw*Image() methods on the way to DrawImageInternal

   * creating |fallbackContext|).  Using Maybe<T> allows code to pass Nothing()

   * in order to get the size that's created for |fallbackContext|.  At some

   * point we need to clean this code up, make our abstractions clear, create

   * that utility and stop using Maybe for this parameter.

   */

  explicit SVGImageContext(const Maybe<CSSIntSize>& aViewportSize,

                           const Maybe<SVGPreserveAspectRatio>& aPreserveAspectRatio  = Nothing())

    : mViewportSize(aViewportSize)

    , mPreserveAspectRatio(aPreserveAspectRatio)

  { }

  static void MaybeStoreContextPaint(Maybe<SVGImageContext>& aContext,

                                     nsIFrame* aFromFrame,

                                     imgIContainer* aImgContainer);

  static void MaybeStoreContextPaint(Maybe<SVGImageContext>& aContext,

                                     ComputedStyle* aFromComputedStyle,

                                     imgIContainer* aImgContainer);

  const Maybe<CSSIntSize>& GetViewportSize() const {

    return mViewportSize;

  }

  void SetViewportSize(const Maybe<CSSIntSize>& aSize) {

    mViewportSize = aSize;

  }

  const Maybe<SVGPreserveAspectRatio>& GetPreserveAspectRatio() const {

    return mPreserveAspectRatio;

  }

  void SetPreserveAspectRatio(const Maybe<SVGPreserveAspectRatio>& aPAR) {

    mPreserveAspectRatio = aPAR;

  }

  const SVGEmbeddingContextPaint* GetContextPaint() const {

    return mContextPaint.get();

  }

  void ClearContextPaint() {

    mContextPaint = nullptr;

  }

  bool operator==(const SVGImageContext& aOther) const {

    bool contextPaintIsEqual =

      // neither have context paint, or they have the same object:

      (mContextPaint == aOther.mContextPaint) ||

      // or both have context paint that are different but equivalent objects:

      (mContextPaint && aOther.mContextPaint &&

       *mContextPaint == *aOther.mContextPaint);

    return contextPaintIsEqual &&

           mViewportSize == aOther.mViewportSize &&

           mPreserveAspectRatio == aOther.mPreserveAspectRatio;

  }

  bool operator!=(const SVGImageContext& aOther) const {

    return !(*this == aOther);

  }

  PLDHashNumber Hash() const {

    PLDHashNumber hash = 0;

    if (mContextPaint) {

      hash = HashGeneric(hash, mContextPaint->Hash());

    }

    return HashGeneric(hash,

                       mViewportSize.map(HashSize).valueOr(0),

                       mPreserveAspectRatio.map(HashPAR).valueOr(0));

  }

private:

  static PLDHashNumber HashSize(const CSSIntSize& aSize) {

    return HashGeneric(aSize.width, aSize.height);

  }

  static PLDHashNumber HashPAR(const SVGPreserveAspectRatio& aPAR) {

    return aPAR.Hash();

  }

  // NOTE: When adding new member-vars, remember to update Hash() & operator==.

  RefPtr<SVGEmbeddingContextPaint> mContextPaint;

  Maybe<CSSIntSize>             mViewportSize;

  Maybe<SVGPreserveAspectRatio> mPreserveAspectRatio;

};

} // namespace mozilla

#endif // MOZILLA_SVGCONTEXT_H_