Previously, getFrameInfo might report a frame that was truncated prior
to setting its requiredFrame. As a result, fRequiredFrame may be
different depending on how much data has already been received.
If there is a local color table, do not report the frame until the
color table has been received, since that is used to determine
fRequiredFrame. If there is no local color table, set fRequiredFrame
and report the frame after reading the header.
Add a test.
Replace make_from_resource with GetResourceAsData
Change-Id: I1b697f766c1d0e1e12ab2ae1d27167af5193395d
Reviewed-on: https://skia-review.googlesource.com/7756
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
If a frame does not have a valid transparent index and it covers the
prior frame, it does not really depend on that frame. Instead, it
depends on the frame that the prior frame depends on.
Determine this once we have parsed the local color map (if any), so a
transparent index out of range of the color map is not considered
valid.
Share code that determines whether a frame has a transparent pixel.
Add a test that we compute the dependencies correctly. randPixelsAnim.gif
has 13 frames. After the first, the frames cover all combinations of
- Whether the prior frame was keep, restoreBG or restoreToPrevious
- Whether the new frame covers the prior frame
- Whether the new frame has a transparent pixel
(It only does so when using a global color table. It may make sense to
expand the test to also cover using local color tables.)
The test caught a bug where we incorrectly reused an existing
SkColorTable for a different frame. Fix that bug by keeping track of
the transparent index associated with the current SkColorTable.
Change-Id: I3cf6be7f612990fa7a00d9e74d116d31bd227526
Reviewed-on: https://skia-review.googlesource.com/6402
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
std::vector needs to be able to assign objects contained inside it. With
const member variables, this isn't possible. Remove the consts so
SkGIFLZWBlock can be assigned.
BUG=skia:6072
Change-Id: I990dc80fb1c49fbd584712c6d0c1154c2da36e85
Reviewed-on: https://skia-review.googlesource.com/6362
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
If the input SkStream has a length and position, do not copy and store
LZW blocks or ColorMaps. Instead, mark the position and size, and read
from the stream when necessary.
This will save memory in Chromium's use case, which has already
buffered all of its data.
In the case where we *do* need to copy, store it on the SkStreamBuffer.
This allows SkGifImageReader to have simpler code.
Add tests.
Change-Id: Ic65fa766328ae2e5974b2084bc2099e19aced731
Reviewed-on: https://skia-review.googlesource.com/6157
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
If there is enough data in the stream to read the reported canvas size,
but not enough to read the first image's header, we do not know the
true canvas size, since we may expand it to fit the first frame. In
that case, return nullptr from NewFromStream.
Add a test.
SkGifCodec.cpp:
Correct a comment - parse returns false if there is a fatal error.
parse() returning true does not guarantee that the size was found.
Instead of checking the width and height, check to see whether the
first frame exists and has its header defined. If not, we do not yet
know the true canvas size. Assert that the canvas size is non-zero,
which is a fatal error from parse.
SkGifImageReader.cpp:
Move the code to set the header defined before the SkGIFSizeQuery exit
condition. This allows SkGifCodec to check the first frame's header to
determine whether the size is known.
GifTest.cpp:
Add a test which truncates the file just before the image header (and
after the global header). Prior to the other changes, this would create
an SkCodec. For an image that needs its canvas size expanded, the
SkCodec would have an incorrect size.
CodecPartialTest.cpp:
randPixels.gif now needs more than half of its data to create an
SkCodec, so set a minimum for test_partial.
Change-Id: I40482f524128b2f1fe59b8f27dd64c7cbe793079
Reviewed-on: https://skia-review.googlesource.com/5701
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
SkGIFFrameContext::decode() and SkGIFLZWContext::prepareToDecode() do
not need (or use) the global color map, so stop passing it as a
parameter. The parameter was used prior to
https://skia-review.googlesource.com/c/4379/ (different issue!), but we
overlooked removing it then.
Change-Id: I0f477e9db11f7650938d6b868baef69e3b37d86b
Reviewed-on: https://skia-review.googlesource.com/5609
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
This stems from a behavior difference between Skia and Chrome.
In Skia, we want to write transparent pixels as often as possible.
(It's faster than checking if we should skip each pixel.)
In Chrome, they avoid writing transparent pixels unless
absolutely necessary.
We were cautious about changing behavior when this first landed,
but this is easier to think about in a smaller change (right now).
(1) We can always write transparent pixels when we are writing
an independent frame.
(2) There is no need for the progressiveDisplay() check. We
only ever use progressive display methods on the first
frame - and the first frame is always independent.
BUG=skia:
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Change-Id: I82048a08e2003aac216f483c7db8df997b687149
Reviewed-on: https://skia-review.googlesource.com/4379
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Add a new accessor to retrieve the repetition count.
Remove constants (and corresponding copyright) in SkCodecAnimation.
These may make sense for the calling code, but are not needed here.
kRepetitionCountInfinite corresponds to Blink's kAnimationLoopInfinite.
Move cLoopCountNotSeen to private. It is used to determine whether we
still need to parse. Add a new enum to the parse query - only parse
enough to determine the repetition count.
Unlike Chromium, SkGifCodec does not account for deleting the reader
(which SkGifCodec does not do) or failed decodes.
Add a test.
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When checking to see whether a GIF has transparency to determine its
alpha type, treat an empty color table as having alpha, since we
will draw it as a transparent image.
(This is a separate bug from skbug.com/5883, but the image I used to
verify that bug was drawn to 565 as black. The fix is to not support
565 in that case, by changing its recommended alpha type.)
BUG=skia:5883
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565 cannot take the !writeTransparentPixels path, so disable it for
cases where we might have to take that path.
This only affects frames beyond the first. If the first frame has
a transparent pixel, it will be marked as non-opaque, so we cannot
decode to 565 anyway.
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Add an interface to decode frames beyond the first in SkCodec, and
add an implementation for SkGifCodec.
Add getFrameData to SkCodec. This method reads ahead in the stream
to return a vector containing meta data about each frame in the image.
This is not required in order to decode frames beyond the first, but
it allows a client to learn extra information:
- how long the frame should be displayed
- whether a frame should be blended with a prior frame, allowing the
client to provide the prior frame to speed up decoding
Add a new fields to SkCodec::Options:
- fFrameIndex
- fHasPriorFrame
The API is designed so that SkCodec never caches frames. If a
client wants a frame beyond the first, they specify the frame in
Options.fFrameIndex. If the client does not have the
frame's required frame (the frame that this frame must be blended on
top of) cached, they pass false for
Options.fHasPriorFrame. Unless the frame is
independent, the codec will then recursively decode all frames
necessary to decode fFrameIndex. If the client has the required frame
cached, they can put it in the dst they pass to the codec, and the
codec will only draw fFrameIndex onto it.
Replace SkGifCodec's scanline decoding support with progressive
decoding, and update the tests accordingly.
Implement new APIs in SkGifCodec. Instead of using gif_lib, use
GIFImageReader, imported from Chromium (along with its copyright
headers) with the following changes:
- SkGifCodec is now the client
- Replace blink types
- Combine GIFColorMap::buildTable and ::getTable into a method that
creates and returns an SkColorTable
- Input comes from an SkStream, instead of a SegmentReader. Add
SkStreamBuffer, which buffers the (potentially partial) stream in
order to decode progressively.
(FIXME: This requires copying data that previously was read directly
from the SegmentReader. Does this hurt performance? If so, can we
fix it?)
- Remove UMA code
- Instead of reporting screen width and height to the client, allow the
client to query for it
- Fail earlier if the first frame AND screen have size of zero
- Compute required previous frame when adding a new one
- Move GIFParseQuery from GIFImageDecoder to GIFImageReader
- Allow parsing up to a specific frame (to skip parsing the rest of the
stream if a client only wants the first frame)
- Compute whether the first frame has alpha and supports index 8, to
create the SkImageInfo. This happens before reporting that the size
has been decoded.
Add GIFImageDecoder::haveDecodedRow to SkGifCodec, imported from
Chromium (along with its copyright header), with the following changes:
- Add support for sampling
- Use the swizzler
- Keep track of the rows decoded
- Do *not* keep track of whether we've seen alpha
Remove SkCodec::kOutOfOrder_SkScanlineOrder, which was only used by GIF
scanline decoding.
Call onRewind even if there is no stream (SkGifCodec needs to clear its
decoded state so it will decode from the beginning).
Add a method to SkSwizzler to access the offset into the dst, taking
subsetting into account.
Add a GM that animates a GIF.
Add tests for the new APIs.
*** Behavior changes:
* Previously, we reported that an image with a subset frame and no transparent
index was opaque and used the background index (if present) to fill the
background. This is necessary in order to support index 8, but it does not
match viewers/browsers I have seen. Examples:
- Chromium and Gimp render the background transparent
- Firefox, Safari, Linux Image Viewer, Safari Preview clip to the frame (for
a single frame image)
This CL matches Chromium's behavior and renders the background transparent.
This allows us to have consistent behavior across products and simplifies
the code (relative to what we would have to do to continue the old behavior
on Android). It also means that we will no longer support index 8 for some
GIFs.
* Stop checking for GIFSTAMP - all GIFs should be either 89a or 87a.
This matches Chromium. I suspect that bugs would have been reported if valid
GIFs started with "GIFVER" instead of "GIF89a" or "GIF87a" (but did not decode
in Chromium).
*** Future work not included in this CL:
* Move some checks out of haveDecodedRow, since they are the same for the
entire frame e.g.
- intersecting the frameRect with the full image size
- whether there is a color table
* Change when we write transparent pixels
- In some cases, Chromium deemed this unnecessary, but I suspect it is slower
than the fallback case. There will continue to be cases where we should
*not* write them, but for e.g. the first pass where we have already
cleared to transparent (which we may also be able to skip) writing the
transparent pixels will not make anything incorrect.
* Report color type and alpha type per frame
- Depending on alpha values, disposal methods, frame rects, etc, subsequent
frames may have different properties than the first.
* Skip copies of the encoded data
- We copy the encoded data in case the stream is one that cannot be rewound,
so we can parse and then decode (possibly not immediately). For some input
streams, this is unnecessary.
- I was concerned this cause a performance regression, but on average the
new code is faster than the old for the images I tested [1].
- It may cause a performance regression for Chromium, though, where we can
always move back in the stream, so this should be addressed.
Design doc:
https://docs.google.com/a/google.com/document/d/12Qhf9T92MWfdWujQwCIjhCO3sw6pTJB5pJBwDM1T7Kc/
[1] https://docs.google.com/a/google.com/spreadsheets/d/19V-t9BfbFw5eiwBTKA1qOBkZbchjlTC5EIz6HFy-6RI/
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