gecko-dev/image/LookupResult.h

118 lines
4.2 KiB
C++

/* -*- 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(Move(aOther.mSurface))
, mMatchType(aOther.mMatchType)
{ }
LookupResult(DrawableSurface&& aSurface, MatchType aMatchType)
: mSurface(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(Move(aSurface))
, mMatchType(aMatchType)
, mSuggestedSize(aSuggestedSize)
{
MOZ_ASSERT(!mSuggestedSize.IsEmpty());
MOZ_ASSERT(!mSurface || aMatchType == MatchType::SUBSTITUTE_BECAUSE_NOT_FOUND,
"Only SUBSTITUTE_BECAUSE_NOT_FOUND make sense with no surface");
MOZ_ASSERT(mSurface || aMatchType == MatchType::NOT_FOUND,
"NOT_FOUND does not make sense with a surface");
}
LookupResult& operator=(LookupResult&& aOther)
{
MOZ_ASSERT(&aOther != this, "Self-move-assignment is not supported");
mSurface = 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;
DrawableSurface mSurface;
MatchType mMatchType;
/// If given, the size the caller should request a decode at. This may or may
/// not match the size the caller requested from the cache.
gfx::IntSize mSuggestedSize;
};
} // namespace image
} // namespace mozilla
#endif // mozilla_image_LookupResult_h