Should make it easier to ask just for images.
Change-Id: If821743dc924c4bfbc6b2b2d29b14affde7b3afd
Reviewed-on: https://skia-review.googlesource.com/82684
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
This partially reverts commit
1793e7bb46.
Hide SkEncodedInfo
Bug: skia:7353
Bug: skia:6839
This contains information that is not necessary for clients to know. The
Color enum tells the number of components in the input, but this is only
interesting internally (to the SkSwizzler).
Similarly, the Alpha enum differs from SkAlphaType in that it has
kBinary instead of kPremul. This is useful information only internally
for determining whether the SkColorSpaceXform needs to premultiply.
The bitsPerComponent is potentially useful for a client; Android (in
SkAndroidCodec) uses it to determine the SkColorType. Rather than
exposing bitsPerComponent, make SkAndroidCodec a friend so it can
access the SkEncodedInfo. A future change will change SkCodec to
recommend F16 for bitsPerComponent > 8, but that will be more involved;
it was the reason for the revert of this CL.
Switch conversionSupported to use an SkColorType, which is enough info.
Replace the SkEncodedInfo::Alpha field on SkCodec::FrameInfo with an
SkAlphaType.
SkCodec still needs an SkEncodedInfo, so move its header (which is
already not SK_API) to include/private.
TBR=mtklein@chromium.org,reed@google.com
Change-Id: I928b1f55317602cb37d29da63b53026c8d139cee
Reviewed-on: https://skia-review.googlesource.com/80860
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
This reverts commit c6f7a4ffa9.
Reason for revert: Causing differences in Gold, stemming from the fact that this changes the recommended SkImageInfo for 16 bits-per-component PNG from N32 to F16.
- an F16 bitmap already png-encodes to a 16 bits-per-component PNG, but it does not encode a linear colorspace (possibly a bug?). when we decode this PNG using getInfo(), it fails because it has an F16 color type and non-linear colorspace. (In the encode-srgb-png gm, this results in blank results for F16.) We could correct this on the encoder side, but it seems possible that a 16 bits-per-component PNG could be encoded with a different color space. In that case, we'd want SkCodec to recommend F16/SRGBLinear, but I think we'd want the SkCodec to store the encoded SkColorSpace so that we can Xform between the two. Currently SkCodec only stores one color space, so that will require a refactor.
- When decoding 16-bits-per-component PNGs, we are now decoding them to F16. This shows differences in Gold. The srgb/gpu results now look more like F16. I think this is fine.
Original change's description:
> Hide SkEncodedInfo
>
> Bug: skia:7353
> Bug: skia:6839
>
> This contains information that is not necessary for clients to know. The
> Color enum tells the number of components in the input, but this is only
> interesting internally (to the SkSwizzler).
>
> Similarly, the Alpha enum differs from SkAlphaType in that it has
> kBinary instead of kPremul. This is useful information only internally
> for determining whether the SkColorSpaceXform needs to premultiply.
>
> The bitsPerComponent is potentially useful for a client; Android (in
> SkAndroidCodec) uses it to determine the SkColorType. Rather than
> exposing bitsPerComponent, use it to make the same decision that Android
> would have made - 16 bits per component means to set the info to F16. Add
> a test that computeOutputColorType behaves as expected.
>
> Switch conversionSupported to use an SkColorType, which is enough info.
>
> Replace the SkEncodedInfo::Alpha field on SkCodec::FrameInfo with an
> SkAlphaType.
>
> SkCodec still needs an SkEncodedInfo, so move its header (which is
> already not SK_API) to include/private.
>
> Change-Id: Ie2cf11339bf999ebfd4390c0f448f7edd6feabda
> Reviewed-on: https://skia-review.googlesource.com/79260
> Reviewed-by: Mike Reed <reed@google.com>
> Reviewed-by: Mike Klein <mtklein@chromium.org>
> Commit-Queue: Leon Scroggins <scroggo@google.com>
TBR=mtklein@chromium.org,scroggo@google.com,reed@google.com
Change-Id: I0c5dd1461e1b70d1e55349a8e7ee6b029c3f556e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:7353, skia:6839
Reviewed-on: https://skia-review.googlesource.com/80660
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Bug: skia:7353
Bug: skia:6839
This contains information that is not necessary for clients to know. The
Color enum tells the number of components in the input, but this is only
interesting internally (to the SkSwizzler).
Similarly, the Alpha enum differs from SkAlphaType in that it has
kBinary instead of kPremul. This is useful information only internally
for determining whether the SkColorSpaceXform needs to premultiply.
The bitsPerComponent is potentially useful for a client; Android (in
SkAndroidCodec) uses it to determine the SkColorType. Rather than
exposing bitsPerComponent, use it to make the same decision that Android
would have made - 16 bits per component means to set the info to F16. Add
a test that computeOutputColorType behaves as expected.
Switch conversionSupported to use an SkColorType, which is enough info.
Replace the SkEncodedInfo::Alpha field on SkCodec::FrameInfo with an
SkAlphaType.
SkCodec still needs an SkEncodedInfo, so move its header (which is
already not SK_API) to include/private.
Change-Id: Ie2cf11339bf999ebfd4390c0f448f7edd6feabda
Reviewed-on: https://skia-review.googlesource.com/79260
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Other browsers (including old Chrome) treat invalid palette indices as
transparent for gifs. And there are gifs in the wild which rely on this.
As an example, if the palette only has 64 entries (0-63) then index 64
is treated as transparent.
BUG=skia:7069
Change-Id: I15e8919a953387506c9ac5945c3ae6a2b90189ab
Reviewed-on: https://skia-review.googlesource.com/51100
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Chris Blume <cblume@google.com>
Make initializeColorXform private, and only call in the base class.
Add virtual method to skip initializeColorXform, for classes that do
not need one.
Change SkCodec::FrameInfo's SkAlphaType to an SkEncodedInfo::Alpha.
This allows proper checking internally whether SkCodec needs to do a
color correct premultiply.
Depends on https://chromium-review.googlesource.com/c/620947, for this
API change.
(Separated from review.skia.org/25746)
Bug: skia:5609
Bug: skia:6839
Change-Id: Icb0d46659c546060c34d32eaf792c86708726c7a
Reviewed-on: https://skia-review.googlesource.com/35880
Reviewed-by: Chris Blume <cblume@chromium.org>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Will need guards for android (at least)
Bug: skia:
Change-Id: I2bb8e656997984489ef1f2e41cd3d301c4e7b947
Reviewed-on: https://skia-review.googlesource.com/26040
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>
This reverts commit 742a3e298f.
Reason for revert: Breaking Android roll:
frameworks/base/core/jni/android/graphics/BitmapFactory.cpp:453:18: error: no member named 'fColorPtr' in 'SkAndroidCodec::AndroidOptions'
codecOptions.fColorPtr = colorPtr;
~~~~~~~~~~~~ ^
frameworks/base/core/jni/android/graphics/BitmapFactory.cpp:454:18: error: no member named 'fColorCount' in 'SkAndroidCodec::AndroidOptions'
codecOptions.fColorCount = colorCount;
~~~~~~~~~~~~ ^
Original change's description:
> Remove support for decoding to kIndex_8
>
> Fix up callsites, and remove tests that no longer make sense.
>
> Bug: skia:6828
> Change-Id: I2548c4b7528b7b1be7412563156f27b52c9d4295
> Reviewed-on: https://skia-review.googlesource.com/21664
> Reviewed-by: Derek Sollenberger <djsollen@google.com>
> Commit-Queue: Leon Scroggins <scroggo@google.com>
TBR=djsollen@google.com,scroggo@google.com
Change-Id: I1bc669441f250690884e75a9a61427fdf75c6907
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:6828
Reviewed-on: https://skia-review.googlesource.com/22120
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Fix up callsites, and remove tests that no longer make sense.
Bug: skia:6828
Change-Id: I2548c4b7528b7b1be7412563156f27b52c9d4295
Reviewed-on: https://skia-review.googlesource.com/21664
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
SkCodec sets fRequiredFrame to be the earliest possible frame that a
given frame can depend on. e.g.
- Frame A fills the screen, Keep
- Frame B does not cover A, Keep
- Frame C covers B but not A, and is opaque
Frame C can depend on either A or B. SkCodec already reports that C
depends on A. This CL allows a client of SkCodec to use either A or
B to create C.
Also expose the DisposalMethod. Since any frame between A and C can
be used to create C except for DisposePrevious frames, the client
needs to be able to know the disposal method so they do not try to
use such a frame to create C.
Further, the disposal method can be used to give the client a better
idea whether they will continue to need a frame. (e.g. if frame i is
DisposePrevious and depends on i-1, the client may not want to steal
i-1 to create i, since i+1 may also depend on i-1.)
TODO: Share code for decoding prior frames between GIF and WEBP
Change-Id: I91a5ae22ba3d8dfbe0bde833fa67ae3da0d81ed6
Reviewed-on: https://skia-review.googlesource.com/13722
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Chris Blume <cblume@chromium.org>
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
- Call conversion_possible with the proper alpha type for the frame.
- Always use kUnpremul for the transform. Previously we used the alpha
type for the first frame. If it was opaque and a later frame was not,
this would be incorrect.
Also fix Codec_frames test. Most of the tests were not running due to
a return statement in a loop. Change that to continue, and correct
errors in the test. Provide better debugging information.
Change-Id: Icd40c09526b1d599168bfe90d93d8ddcdd9ca20f
Reviewed-on: https://skia-review.googlesource.com/18935
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
TBR=reed@google.com
(No change to the public API, but changed a header file)
SkWebpCodec:
- Implement onGetFrameCount, onGetFrameInfo, and onGetRepetitionCount
- Respect the alpha reported by libwebp. Although the spec states that
it is only a hint, the libwebp encoder uses it properly. Respecting
allows us to draw opaque images faster and decode them to 565. This
also matches other SkCodecs (and Chromium).
- onGetPixels:
- Decode the frame requested, recursively decoding required frame if
necessary
- When blending with a prior frame, use SkRasterPipeline
SkCodec:
- Move check for negative index to getFrameInfo
- Reset the colorXform if one is not needed
SkCodecAnimation:
- Add new blend enum, for WebP's (and APNG's) non-blending option
SkFrameHolder:
- New base classes for frames and the owner of the frames, allowing
code sharing between SkWebpCodec and SkGifCodec (particularly for
determining whether a frame has alpha and what frame it depends on)
- When moving items from SkGIFFrameContext, use Skia conventions (i.e.
int instead of unsigned)
- Rename "delay time" to "duration", to match e.g. SkFrameInfo::
fDuration
SkGifImageReader:
- Move pieces to SkFrameHolder, and adapt to changes made in the
process
- Make setAlphaAndRequiredFrame (now on the base class SkFrameHolder)
more general to support webp, and add support for frames that do not
blend
- Change SkGIFFrameContext from a struct to a class, to match how we
use the distinction elsewhere (i.e. struct is a small object with
public fields)
- Rework hasTransparentPixel (now hasTransparency, since it returns true
in some cases where there is not a transparent pixel) to better fit
with the modified setAlphaAndRequiredFrame. Also be more consistent
when there is no transparent pixel but no color map.
- Simplify an if condition that was previously simplified in 2d61e717
but accidentally got reverted in a4db9be6
CodecAnimTest:
- Test new animated webp files
- Rearrange the test to more cleanly print alpha type mismatches for
the first frame
resources:
- webp-animated.webp
- animated webp from Chromium
- blendBG.webp
- new webp file using bits of webp-animated-semitransparent4.webp
from Chromium
- tests required frame and alpha when using the non-blending mode
- frames have the following properties:
- Frame 0: no alpha, fills screen
- Frame 1: alpha, fills screen
- Frame 2: no alpha, fills screen
- Frame 3: alpha, fills screen, blendBG
- Frame 4: no alpha, fills screen, blendBG
- Frame 5: alpha, blendBG
- Frame 6: covers 4, has alpha, blendBG
- also used to test decoding to 565 if the new frame data has alpha
but blends onto an opaque frame
DM.cpp:
- Test animated images to non-native 8888 and unpremul
DMSrcSink.cpp:
- Do not test non-native 8888 decodes to f16 dst
- Test unpremul decodes to f16
- Copy a frame of an animated image prior to drawing, since in unpremul
mode, the DM code will premultiply first.
Bug: skia: 3315
Change-Id: I4e55ae2ee5bc095b37a743bdcfac644be603b980
Reviewed-on: https://skia-review.googlesource.com/16707
Commit-Queue: Mike Reed <reed@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
This reverts commit d4a338f4d0.
Reason for revert: Looks like I missed something I was supposed to delete in Android.
Original change's description:
> Delete copyTo(Allocator), hide copyTo() behind flag
>
> Replace uses of copyTo() in Skia.
>
> Bug: skia:6464
> Change-Id: I921dc53a1c29a5176d18f05741f7c0b5a008e548
> Reviewed-on: https://skia-review.googlesource.com/14502
> Commit-Queue: Matt Sarett <msarett@google.com>
> Reviewed-by: Mike Reed <reed@google.com>
>
TBR=msarett@google.com,reed@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Change-Id: I4d252940cc6a2462b030007055ea6c229471fc6e
Reviewed-on: https://skia-review.googlesource.com/14602
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Matt Sarett <msarett@google.com>
Replace uses of copyTo() in Skia.
Bug: skia:6464
Change-Id: I921dc53a1c29a5176d18f05741f7c0b5a008e548
Reviewed-on: https://skia-review.googlesource.com/14502
Commit-Queue: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
This matches other Skia APIs. size_t was adopted from blink/
GIFImageReader.
Change-Id: Ic83e59f0942f597c4fb834e623acd9886ad483fe
Reviewed-on: https://skia-review.googlesource.com/13274
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Reviewed-by: Chris Blume <cblume@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Prior to e132e7be5f, calling getFrameInfo
on an SkGifCodec which was truncated before fully parsing the local
color map of the first frame would hit an assert. Add a test to verify
that the problem has been fixed.
Modify box.gif to use a local color map for the first (and only) frame.
Change-Id: I905afe60c0c6ecc82e251e00ef82b2e5b22975a3
Reviewed-on: https://skia-review.googlesource.com/13320
Reviewed-by: Chris Blume <cblume@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Add a version of getFrameInfo that returns information about a single
frame, allowing a client to skip creating the entire vector.
Add getFrameCount, for determining the number of frames in the image.
Reimplement std::vector<FrameInfo> getFrameInfo with the new methods.
Updates to the test:
- getFrameInfo(size_t, FrameInfo*) fails before parsing
- Test both versions of getFrameInfo
- Recreate the codec between tests, to test parsing
Change-Id: I77c19087f2f8dcf2c536d80167b18ad1ca96ae94
Reviewed-on: https://skia-review.googlesource.com/13190
Reviewed-by: Matt Sarett <msarett@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Chris Blume <cblume@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
Add SkCodec::FrameInfo::fAlphaType. The SkImageInfo for the SkCodec
specifies the SkAlphaType for the first frame, but the opacity can vary
from frame to frame.
When determining the required frame, also compute whether a frame has
alpha. Update how we determine the required frame, which had bugs.
(Update a test that had an incorrect required frame as a result.)
Add new test images covering cases that have been fixed:
- randPixelsAnim2.gif
It has the following frames:
A (keep)
B (keep) (subset)
C (disposePrevious) (covers B)
D (any) (does *not* cover B)
B and C depend on A, but D depends on B, since after disposing C, B
should be visible again.
- alphabetAnim.gif
Includes frames which fill the image size, with different disposal
methods and transparencies.
Change-Id: Ie086167711c4cac4931ed8c4ddaeb9c9b0b91fdb
Reviewed-on: https://skia-review.googlesource.com/9810
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Matt Sarett <msarett@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>
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.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2447863002
Review-Url: https://codereview.chromium.org/2447863002
While investigating skbug.com/5883 I noticed that we use the color
table for the current frame even while recursively decoding frames that
the current frame depends on.
This CL updates fCurrColorTable, fCurrColorTableIsReal and fSwizzler
before decoding prior frames, and then sets them back afterwards.
Move telling the client about the color table into prepareToDecode,
since the other callers do not need to do so. (That is only necessary
for decoding to index 8, which is unsupported for frames with
dependencies.)
Add a test that exposes the bug. colorTables.gif has a local color
table in its second frame that does not match the global table used by
the first frame.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=4208
Change-Id: Id2dc9e3283adfd92801d2f38726afa74574b1955
Reviewed-on: https://skia-review.googlesource.com/4208
Reviewed-by: Joost Ouwerling <joostouwerling@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
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/
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=2045293002
Review-Url: https://codereview.chromium.org/2045293002
