image/DecoderFlags.h
author Andrew Osmond <aosmond@mozilla.com>
Tue, 05 Sep 2017 07:58:45 -0400
changeset 378983 c856f513264340a2d6c2b70f71f345b5e4c8d6c0
parent 257946 3a12957a6bd3166c3c0f6b5667264ddd040e6318
child 436830 1b1e25b0b345cf3774ae7d186dc082430420e056
permissions -rw-r--r--
Bug 1370412 - Part 8a. Add "substitutable" flag to ISurfaceProvider state to indicate when the caller won't accept substitutes. r=tnikkel When SurfaceCache::Lookup is called to access surface data, it indicates that the caller will not accept substitutes as in the case of SurfaceCache::LookupBestMatch. As such, we need to be careful not to remove those surfaces from our cache when pruning (in part 8b). This is the marker used to track that, at some point, there was a caller which got this surface that would accept no other (e.g. factor of 2 mode must make an accept for this particular surface).

/* -*- 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/. */

#ifndef mozilla_image_DecoderFlags_h
#define mozilla_image_DecoderFlags_h

#include "mozilla/TypedEnumBits.h"

namespace mozilla {
namespace image {

/**
 * Flags that influence decoder behavior. Note that these flags *don't*
 * influence the logical content of the surfaces that the decoder generates, so
 * they're not in a factor in SurfaceCache lookups and the like. These flags
 * instead either influence which surfaces are generated at all or the tune the
 * decoder's behavior for a particular scenario.
 */
enum class DecoderFlags : uint8_t
{
  FIRST_FRAME_ONLY               = 1 << 0,
  IS_REDECODE                    = 1 << 1,
  IMAGE_IS_TRANSIENT             = 1 << 2,
  ASYNC_NOTIFY                   = 1 << 3,

  /**
   * By default, a surface is considered substitutable. That means callers are
   * willing to accept a less than ideal match to display. If a caller requires
   * a specific size and won't accept alternatives, then this flag should be
   * set.
   */
  CANNOT_SUBSTITUTE              = 1 << 4
};
MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(DecoderFlags)

/**
 * @return the default set of decode flags.
 */
inline DecoderFlags
DefaultDecoderFlags()
{
  return DecoderFlags();
}

} // namespace image
} // namespace mozilla

#endif // mozilla_image_DecoderFlags_h