gecko-dev/image/ImgDrawResult.h
Samathy Barratt d8ba79a56b Bug 1351447 - Rename imagelib's DrawResult to ImgDrawResult r+tnikkel r=tnikkel
Renamed to imgDrawResult

MozReview-Commit-ID: 5ESSgIhhU41

--HG--
rename : image/DrawResult.h => image/ImgDrawResult.h
extra : rebase_source : dbf645574aff7eefe65fa81809d6c07cb5800ec6
2017-12-11 15:37:59 +00:00

107 lines
3.7 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/. */
#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.
*
* 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().
*/
enum class MOZ_MUST_USE_TYPE ImgDrawResult : uint8_t
{
SUCCESS,
INCOMPLETE,
WRONG_SIZE,
NOT_READY,
TEMPORARY_ERROR,
BAD_IMAGE,
BAD_ARGS
};
/**
* 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::BAD_IMAGE && aRight != ImgDrawResult::SUCCESS) {
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