Prior to this CL, each SkCodec subclass that allows sampling does an
extra check in onStartScanlineDecode to determine whether the X dimension
is supported for sampling. Remove this check, and provide a way for
SkScaledCodec to directly access the SkSwizzler, and update it to do
sampling. This way, the SkCodec knows nothing of sampling, but we can
still save the extra step of sampling afterwards.
FIXME: SkBmpRLECodec still calls SkScaledCodec::DimensionsSupported. It
seems like it could directly support sampling, rather than dealing with
SkScaledCodec (partially).
Add a new base class for SkSwizzler. It allows updating the swizzler
after it was created, which is done by SkScaledCodec. Modify SkSwizzler's
constructor/factory function to stop taking any info about sampling,
assume the sample size is one, and move modifying that into a virtual
function overridden from the base class.
BUG=skia:4284
Review URL: https://codereview.chromium.org/1372973002
Rather than calling it in each subclass, call it once in the base
class. Call it first, since other steps may modify internal structures
which would be replaced by a call to onRewind.
BUG=skia:4284
Review URL: https://codereview.chromium.org/1381483002
Benefits:
- This mimics other decoding APIs (including the ones SkCodec relies
on, e.g. a png_struct, which can be used to decode an entire image or
one line at a time).
- It allows a client to ask us to do what we can do efficiently - i.e.
start from encoded data and either decode the whole thing or scanlines.
- It removes the duplicate methods which appeared in both SkCodec and
SkScanlineDecoder (some of which, e.g. in SkJpegScanlineDecoder, just
call fCodec->sameMethod()).
- It simplifies moving more checks into the base class (e.g. the
examples in skbug.com/4284).
BUG=skia:4175
BUG=skia:4284
=====================================================================
SkScanlineDecoder.h/.cpp:
Removed.
SkCodec.h/.cpp:
Add methods, enums, and variables which were previously in
SkScanlineDecoder.
Default fCurrScanline to -1, as a sentinel that start has not been
called.
General changes:
Convert SkScanlineDecoders to SkCodecs.
General changes in SkCodec subclasses:
Merge SkScanlineDecoder implementation into SkCodec. Most (all?) owned
an SkCodec, so they now call this-> instead of fCodec->.
SkBmpCodec.h/.cpp:
Replace the unused rowOrder method with an override for
onGetScanlineOrder.
Make getDstRow const, since it is called by onGetY, which is const.
SkCodec_libpng.h/.cpp:
Make SkPngCodec an abstract class, with two subclasses which handle
scanline decoding separately (they share code for decoding the entire
image). Reimplement onReallyHasAlpha so that it can return the most
recent result (e.g. after a scanline decode which only decoded part
of the image) or a better answer (e.g. if the whole image is known to
be opaque).
Compute fNumberPasses early, so we know which subclass to instantiate.
Make SkPngInterlaceScanlineDecoder use the base class' fCurrScanline
rather than a separate variable.
CodexTest.cpp:
Add tests for the state changes in SkCodec (need to call start before
decoding scanlines; calling getPixels means that start will need to
be called again before decoding more scanlines).
Add a test which decodes in stripes, currently only used for an
interlaced PNG.
TODO: Add tests for onReallyHasAlpha.
Review URL: https://codereview.chromium.org/1365313002
SkTemplates.h contains a number of Skia specific utilities which are
not designed for external use. In addition to reducing the external
support burden, this will allow Skia to freely refactor this file.
Review URL: https://codereview.chromium.org/1272293004
We don't want to test small images on Gold because they are
not interested to look at. Instead, I wrote a unit test to
verify that scaling small images does not cause crashes.
BUG=skia:
Review URL: https://codereview.chromium.org/1287863004
Previously, many of our codec implementations followed the same
pattern (often in a function named handleRewind):
switch (this->rewindIfNeeded()) {
case CouldNotRewind:
return CouldNotRewind;
case NoRewindNecessary:
// keep going
break;
case Rewound:
<re-read header etc>
break;
}
In this CL, remove the enum, and put the piece that happens in the
Rewound case into a virtual function, onRewind. rewindIfNeeded now
contains the common pieces from various functions named handleRewind.
In SkBmpCodec, add a function that returns whether the BMP is in ICO,
so it can have a common implementation for onRewind.
BUG=skia:3257
Review URL: https://codereview.chromium.org/1288483002
Prior to this CL, if a client wanted to decode scanlines, they had to
create an SkCodec in order to get an SkScanlineDecoder. This introduces
complications if input data is not easily shared between the two
objects.
Instead, add methods to SkScanlineDecoder for creating a new one from
input data, and remove the creation functions from SkCodec.
Update DM and tests.
Review URL: https://codereview.chromium.org/1267583002
This allows codecs that support subsets natively (i.e. WEBP) to do so.
Add a field on SkCodec::Options representing the subset.
Add a method on SkCodec to find a valid subset which approximately
matches a desired subset.
Implement subset decodes in SkWebpCodec.
Add a test in DM for decoding subsets.
Notice that we only start on even boundaries. This is due to the
way libwebp's API works. SkWEBPImageDecoder does not take this into
account, which results in visual artifacts.
FIXME: Subsets with scaling are not pixel identical, but close. (This
may be fine, though - they are not perceptually different. We'll just
need to mark another set of images in gold as valid, once
https://skbug.com/4038 is fixed, so we can tests scaled webp without
generating new images on each run.)
Review URL: https://codereview.chromium.org/1240143002
Make getScanlineDecoder return a new object each time, which is
owned by the caller, and independent from any existing scanline
decoders and the SkCodec itself.
Since the SkCodec already contains the entire state machine, and it
is used by the scanline decoders, simply create a new SkCodec which
is now owned by the scanline decoder.
Move code that cleans up after using a scanline decoder into its
destructor
One side effect is that creating the first scanline decoder requires
a duplication of the stream and re-reading the header. (With some
more complexity/changes, we could pass the state machine to the
scanline decoder and make the SkCodec recreate its own state machine
instead.) The typical client of the scanline decoder (region decoder)
uses an SkMemoryStream, so the duplication is cheap, although we
should consider the extra time to reread the header/recreate the state
machine. (If/when we use the scanline decoder for other purposes,
where the stream may not be cheaply duplicated, we should consider
passing the state machine.)
One (intended) result of this change is that a client can create a
new scanline decoder in a new thread, and decode different pieces of
the image simultaneously.
In SkPngCodec::decodePalette, use fBitDepth rather than a parameter.
Review URL: https://codereview.chromium.org/1230033004
SkImageGenerator makes some assumptions that are not necessarily valid
for SkCodec. For example, SkCodec does not assume that it can always be
rewound.
We also have an ongoing question of what an SkCodec should report as
its default settings (i.e. the return from getInfo). It makes sense for
an SkCodec to report that its pixels are unpremultiplied, if that is
the case for the underlying data, but if a client of SkImageGenerator
uses the default settings (as many do), they will receive
unpremultiplied pixels which cannot (currently) be drawn with Skia. We
may ultimately decide to revisit SkCodec reporting an SkImageInfo, but
I have left it unchanged for now.
Import features of SkImageGenerator used by SkCodec into SkCodec.
I have left SkImageGenerator unchanged for now, but it no longer needs
Result or Options. This will require changes to Chromium.
Manually handle the lifetime of fScanlineDecoder, so SkScanlineDecoder.h
can include SkCodec.h (where Result is), and SkCodec.h does not need
to include it (to delete fScanlineDecoder).
In many places, make the following simple changes:
- Now include SkScanlineDecoder.h, which is no longer included by
SkCodec.h
- Use the enums in SkCodec, rather than SkImageGenerator
- Stop including SkImageGenerator.h where no longer needed
Review URL: https://codereview.chromium.org/1220733013
the bottom of the image. In our code before this patch,
this would result in cleanup code in onFinish() never being
called.
We can allow subclasses to take ownership of the
SkScanlineDecoder in order to make sure that it is
finished/deleted before deleting the decode manager.
BUG=skia:
Review URL: https://codereview.chromium.org/1212593003
This mirrors the behavior in onGetPixels, and allows the implementation
to share code for handling calls to rewindIfNeeded.
This also fixes a bug where getScanlineDecoder was calling
rewindIfNeeded and treating the result as a bool.
In SkPngCodec, factor out the code to call rewindIfNeeded, and call it
in both onGetPixels and onGetScanlineDecoder.
Update the test to include testing the scanline decoder. Rename "gen"
to "codec" now that it must be an SkCodec.
BUG=skia:3257
Depends on https://codereview.chromium.org/1048423003/ (DIFFERENT ISSUE).
Review URL: https://codereview.chromium.org/1050893002
Add an interface for decoding scanlines, and implement that interface
in the PNG decoder.
Use a separate method to determine whether an image that used a type
with alpha was actually opaque.
SkScanlineDecoder.h:
New interface for decoding scanlines.
SkCodec.h:
Add getScanlineDecoder.
Add a virtual function (with non-virtual caller) for determining
whether the image truly had alpha. The client can call this to
determine if the image was actually opaque if it reported having alpha.
Remove code to sneakily change the passed in alpha type.
SkCodec_libpng.*:
Split up code onGetPixels into helper functions that can be shared with
the scanline decoder.
Implement scanline decoding.
Implement onReallyHasAlpha.
SkSwizzler.*:
Add a new SrcConfig as a default, which is invalid.
Add a function for setting fDstRow directly.
Assert fDstRow is not NULL.
BUG=skia:3257
Review URL: https://codereview.chromium.org/1010903003
DM:
Add a flag to use SkCodec instead of SkImageDecoder.
SkCodec:
Base class for codecs, allowing creation from an SkStream or an SkData.
An SkCodec, on creation, knows properties of the data like its width and height. Further calls can be used to generate the image.
TODO: Add scanline iterator
SkPngCodec:
New decoder for png. Wraps libpng. The code has been repurposed from SkImageDecoder_libpng.
TODO: Handle other destination colortypes
TODO: Substitute the transpose color
TODO: Allow silencing warnings
TODO: Use RGB instead of filler?
TODO: sRGB
SkSwizzler:
Simplified version of SkScaledSampler. Unlike the sampler, this object does no sampling.
TODO: Implement other swizzles.
Requires a gclient sync to pull down libpng.
BUG=skia:3257
Committed: https://skia.googlesource.com/skia/+/ca358852b4fed656d11107b2aaf28318a4518b49
(and then reverted)
Review URL: https://codereview.chromium.org/930283002
Reason for revert:
Breaking windows bots all over the place :(
Original issue's description:
> Add SkCodec, including PNG implementation.
>
> DM:
> Add a flag to use SkCodec instead of SkImageDecoder.
>
> SkCodec:
> Base class for codecs, allowing creation from an SkStream or an SkData.
> An SkCodec, on creation, knows properties of the data like its width and height. Further calls can be used to generate the image.
> TODO: Add scanline iterator
>
> SkPngCodec:
> New decoder for png. Wraps libpng. The code has been repurposed from SkImageDecoder_libpng.
> TODO: Handle other destination colortypes
> TODO: Substitute the transpose color
> TODO: Allow silencing warnings
> TODO: Use RGB instead of filler?
> TODO: sRGB
>
> SkSwizzler:
> Simplified version of SkScaledSampler. Unlike the sampler, this object does no sampling.
> TODO: Implement other swizzles.
>
> BUG=skia:3257
>
> Committed: https://skia.googlesource.com/skia/+/ca358852b4fed656d11107b2aaf28318a4518b49TBR=reed@google.com,djsollen@google.com,msarett@google.com,mtklein@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:3257
Review URL: https://codereview.chromium.org/972743003
DM:
Add a flag to use SkCodec instead of SkImageDecoder.
SkCodec:
Base class for codecs, allowing creation from an SkStream or an SkData.
An SkCodec, on creation, knows properties of the data like its width and height. Further calls can be used to generate the image.
TODO: Add scanline iterator
SkPngCodec:
New decoder for png. Wraps libpng. The code has been repurposed from SkImageDecoder_libpng.
TODO: Handle other destination colortypes
TODO: Substitute the transpose color
TODO: Allow silencing warnings
TODO: Use RGB instead of filler?
TODO: sRGB
SkSwizzler:
Simplified version of SkScaledSampler. Unlike the sampler, this object does no sampling.
TODO: Implement other swizzles.
BUG=skia:3257
Review URL: https://codereview.chromium.org/930283002
