gecko-dev/image/ImgDrawResult.h
Andrew Osmond 29af4ed6a2 Bug 1446309 - Part 3. Properly handle ImgDrawResult for WebRender display list generation. r=tnikkel
When generating display lists for WebRender, we were not caching the
draw result via nsDisplayItemGenericImageGeometry::UpdateDrawResult (or
similar) after completing CreateWebRenderCommands. This is important
because reftests use this to force sync decoding for images; it may be a
reason for image-related intermittent failures on *-qr builds.

Additionally, we may have been requesting fallback in cases where fallback
could not do anything more than WebRender could. For example, if we can't
get an image container yet, there is no point in requesting fallback
because it might just be we haven't started decoding yet. We should just
return the actual draw result in such cases.
2018-09-13 19:48:27 -04:00

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4.4 KiB
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/* -*- 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