image/ImgDrawResult.h
author Henrik Skupin <mail@hskupin.info>
Fri, 30 Nov 2018 13:27:22 +0000
changeset 448968 cd370c35d88d82c719e7b3d70ae1da003c8cb7f6
parent 448947 6f3709b3878117466168c40affa7bca0b60cf75b
permissions -rw-r--r--
Bug 1511311 - [marionette] GeckoInstance classes should not overwrite already set custom preferences. r=automatedtester Custom preferences as passed into both classes via the constructor are getting set in the base GeckoInstance class. But both the DesktopInstance and FennecInstance classes could override those custom preferences if they have the same preference set as required preference. As such the custom preference doesn't have any effect. This patch allows both classes to override required prefs with a different value. Differential Revision: https://phabricator.services.mozilla.com/D13522

/* -*- 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_ImgDrawResult_h
#define mozilla_image_ImgDrawResult_h

#include <cstdint>  // for uint8_t
#include "mozilla/Attributes.h"
#include "mozilla/Likely.h"

namespace mozilla {
namespace image {

/**
 * An enumeration representing the result of a drawing operation.
 *
 * Most users of ImgDrawResult will only be interested in whether the value is
 * SUCCESS or not. The other values are primarily useful for debugging and error
 * handling.
 *
 * SUCCESS: We successfully drew a completely decoded frame of the requested
 * size. Drawing again with FLAG_SYNC_DECODE would not change the result.
 *
 * SUCCESS_NOT_COMPLETE: The image was drawn successfully and completely, but
 * it hasn't notified about the sync-decode yet. This can only happen when
 * layout pokes at the internal image state beforehand via
 * nsStyleImage::StartDecoding. This should probably go away eventually,
 * somehow, see bug 1471583.
 *
 * INCOMPLETE: We successfully drew a frame that was partially decoded. (Note
 * that successfully drawing a partially decoded frame may not actually draw any
 * pixels!) Drawing again with FLAG_SYNC_DECODE would improve the result.
 *
 * WRONG_SIZE: We successfully drew a wrongly-sized frame that had to be scaled.
 * This is only returned if drawing again with FLAG_SYNC_DECODE would improve
 * the result; if the size requested was larger than the intrinsic size of the
 * image, for example, we would generally have to scale whether FLAG_SYNC_DECODE
 * was specified or not, and therefore we would not return WRONG_SIZE.
 *
 * NOT_READY: We failed to draw because no decoded version of the image was
 * available. Drawing again with FLAG_SYNC_DECODE would improve the result.
 * (Though FLAG_SYNC_DECODE will not necessarily work until after the image's
 * load event!)
 *
 * TEMPORARY_ERROR: We failed to draw due to a temporary error. Drawing may
 * succeed at a later time.
 *
 * BAD_IMAGE: We failed to draw because the image has an error. This is a
 * permanent condition.
 *
 * BAD_ARGS: We failed to draw because bad arguments were passed to draw().
 *
 * NOT_SUPPORTED: The requested operation is not supported, but the image is
 *                otherwise valid.
 */
enum class MOZ_MUST_USE_TYPE ImgDrawResult : uint8_t {
  SUCCESS,
  SUCCESS_NOT_COMPLETE,
  INCOMPLETE,
  WRONG_SIZE,
  NOT_READY,
  TEMPORARY_ERROR,
  BAD_IMAGE,
  BAD_ARGS,
  NOT_SUPPORTED
};

/**
 * You can combine ImgDrawResults with &. By analogy to bitwise-&, the result is
 * ImgDrawResult::SUCCESS only if both operands are ImgDrawResult::SUCCESS.
 * Otherwise, a failing ImgDrawResult is returned; we favor the left operand's
 * failure when deciding which failure to return, with the exception that we
 * always prefer any other kind of failure over ImgDrawResult::BAD_IMAGE, since
 * other failures are recoverable and we want to know if any recoverable
 * failures occurred.
 */
inline ImgDrawResult operator&(const ImgDrawResult aLeft,
                               const ImgDrawResult aRight) {
  if (MOZ_LIKELY(aLeft == ImgDrawResult::SUCCESS)) {
    return aRight;
  }

  if (aLeft == ImgDrawResult::NOT_SUPPORTED ||
      aRight == ImgDrawResult::NOT_SUPPORTED) {
    return ImgDrawResult::NOT_SUPPORTED;
  }

  if ((aLeft == ImgDrawResult::BAD_IMAGE ||
       aLeft == ImgDrawResult::SUCCESS_NOT_COMPLETE) &&
      aRight != ImgDrawResult::SUCCESS &&
      aRight != ImgDrawResult::SUCCESS_NOT_COMPLETE) {
    return aRight;
  }
  return aLeft;
}

inline ImgDrawResult& operator&=(ImgDrawResult& aLeft,
                                 const ImgDrawResult aRight) {
  aLeft = aLeft & aRight;
  return aLeft;
}

/**
 * A struct used during painting to provide input flags to determine how
 * imagelib draw calls should behave and an output ImgDrawResult to return
 * information about the result of any imagelib draw calls that may have
 * occurred.
 */
struct imgDrawingParams {
  explicit imgDrawingParams(uint32_t aImageFlags = 0)
      : imageFlags(aImageFlags), result(ImgDrawResult::SUCCESS) {}

  const uint32_t imageFlags;  // imgIContainer::FLAG_* image flags to pass to
                              // image lib draw calls.
  ImgDrawResult result;       // To return results from image lib painting.
};

}  // namespace image
}  // namespace mozilla

#endif  // mozilla_image_ImgDrawResult_h