/* -*- Mode: C++; tab-width: 2; 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/. */

/**

 * LookupResult is the return type of SurfaceCache's Lookup*() functions. It

 * combines a surface with relevant metadata tracked by SurfaceCache.

 */

#ifndef mozilla_image_LookupResult_h

#define mozilla_image_LookupResult_h

#include "mozilla/Attributes.h"

#include "mozilla/gfx/Point.h"  // for IntSize

#include "mozilla/Move.h"

#include "ISurfaceProvider.h"

namespace mozilla {

namespace image {

enum class MatchType : uint8_t

{

  NOT_FOUND,  // No matching surface and no placeholder.

  PENDING,    // Found a matching placeholder, but no surface.

  EXACT,      // Found a surface that matches exactly.

  SUBSTITUTE_BECAUSE_NOT_FOUND,  // No exact match, but found a similar one.

  SUBSTITUTE_BECAUSE_PENDING,    // Found a similar surface and a placeholder

                                 // for an exact match.

  /* No exact match, but this should be considered an exact match for purposes

   * of deciding whether or not to request a new decode. This is because the

   * cache has determined that callers require too many size variants of this

   * image. It determines the set of sizes which best represent the image, and

   * will only suggest decoding of unavailable sizes from that set. */

  SUBSTITUTE_BECAUSE_BEST

};

/**

 * LookupResult is the return type of SurfaceCache's Lookup*() functions. It

 * combines a surface with relevant metadata tracked by SurfaceCache.

 */

class MOZ_STACK_CLASS LookupResult

{

public:

  explicit LookupResult(MatchType aMatchType)

    : mMatchType(aMatchType)

  {

    MOZ_ASSERT(mMatchType == MatchType::NOT_FOUND ||

               mMatchType == MatchType::PENDING,

               "Only NOT_FOUND or PENDING make sense with no surface");

  }

  LookupResult(LookupResult&& aOther)

    : mSurface(std::move(aOther.mSurface))

    , mMatchType(aOther.mMatchType)

    , mSuggestedSize(aOther.mSuggestedSize)

  { }

  LookupResult(DrawableSurface&& aSurface, MatchType aMatchType)

    : mSurface(std::move(aSurface))

    , mMatchType(aMatchType)

  {

    MOZ_ASSERT(!mSurface || !(mMatchType == MatchType::NOT_FOUND ||

                              mMatchType == MatchType::PENDING),

               "Only NOT_FOUND or PENDING make sense with no surface");

    MOZ_ASSERT(mSurface || mMatchType == MatchType::NOT_FOUND ||

                           mMatchType == MatchType::PENDING,

               "NOT_FOUND or PENDING do not make sense with a surface");

  }

  LookupResult(DrawableSurface&& aSurface, MatchType aMatchType,

               const gfx::IntSize& aSuggestedSize)

    : mSurface(std::move(aSurface))

    , mMatchType(aMatchType)

    , mSuggestedSize(aSuggestedSize)

  {

    MOZ_ASSERT(!mSurface || !(mMatchType == MatchType::NOT_FOUND ||

                              mMatchType == MatchType::PENDING),

               "Only NOT_FOUND or PENDING make sense with no surface");

    MOZ_ASSERT(mSurface || mMatchType == MatchType::NOT_FOUND ||

                           mMatchType == MatchType::PENDING,

               "NOT_FOUND or PENDING do not make sense with a surface");

  }

  LookupResult& operator=(LookupResult&& aOther)

  {

    MOZ_ASSERT(&aOther != this, "Self-move-assignment is not supported");

    mSurface = std::move(aOther.mSurface);

    mMatchType = aOther.mMatchType;

    mSuggestedSize = aOther.mSuggestedSize;

    return *this;

  }

  DrawableSurface& Surface() { return mSurface; }

  const DrawableSurface& Surface() const { return mSurface; }

  const gfx::IntSize& SuggestedSize() const { return mSuggestedSize; }

  /// @return true if this LookupResult contains a surface.

  explicit operator bool() const { return bool(mSurface); }

  /// @return what kind of match this is (exact, substitute, etc.)

  MatchType Type() const { return mMatchType; }

private:

  LookupResult(const LookupResult&) = delete;

  LookupResult& operator=(const LookupResult& aOther) = delete;

  DrawableSurface mSurface;

  MatchType mMatchType;

  /// mSuggestedSize will be the size of the returned surface if the result is

  /// SUBSTITUTE_BECAUSE_BEST. It will be empty for EXACT, and can contain a

  /// non-empty size possibly different from the returned surface (if any) for

  /// all other results. If non-empty, it will always be the size the caller

  /// should request any decodes at.

  gfx::IntSize mSuggestedSize;

};

} // namespace image

} // namespace mozilla

#endif // mozilla_image_LookupResult_h