image/DecoderFlags.h
author Andrew Osmond <aosmond@mozilla.com>
Mon, 04 Jun 2018 08:29:50 -0400
changeset 442380 453d21db2a306f4800e8be4d77f6d61000cb9a0c
parent 436808 e72e07baca921e697a6d79aa8488e2a0aecb1364
child 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1465619 - Part 10. Re-add support for discarding animated image frames. r=tnikkel AnimatedFrameDiscardingQueue subclasses AnimationFrameBuffer to allow a cleaner abstraction over the behaviour change when we cross the threshold of too high a memory footprint for an animated image. The next patch will build on top of this to provide an abstraction to reuse the discarded frames. Differential Revision: https://phabricator.services.mozilla.com/D7515

/* -*- 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,

  /**
   * By default, an animation decoder will produce partial frames that need to
   * be combined with the previously displayed/composited frame by FrameAnimator
   * to produce a complete frame. If this flag is set, the decoder will perform
   * this blending at decode time, and the frames produced are complete.
   */
  BLEND_ANIMATION                = 1 << 5
};
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