Image metadata is usually a serialized string representing an array.
Passing the string around internally and having everything unserialize
it is an awkward convention.
Also, many image handlers were reading the file twice: once for
getMetadata() and again for getImageSize(). Often getMetadata()
would actually read the width and height and then throw it away.
So, in filerepo:
* Add File::getMetadataItem(), which promises to allow partial
loading of metadata per my proposal on T275268 in a future commit.
* Add File::getMetadataArray(), which returns the unserialized array.
Some file handlers were returning non-serializable strings from
getMetadata(), so I gave them a legacy array form ['_error' => ...]
* Changed MWFileProps to return the array form of metadata.
* Deprecate the weird File::getImageSize(). It was apparently not
called by anything, but was overridden by UnregisteredLocalFile.
* Wrap serialize/unserialize with File::getMetadataForDb() and
File::loadMetadataFromDb() in preparation for T275268.
In MediaHandler:
* Merged MediaHandler::getImageSize() and MediaHandler::getMetadata()
into getSizeAndMetadata(). Deprecated the old methods.
* Instead of isMetadataValid() we now have isFileMetadataValid(), which
only gets a File object, so it can decide what data it needs to load.
* Simplified getPageDimensions() by having it return false for non-paged
media. It was not called in that case, but was implemented anyway.
In specific handlers:
* Rename DjVuHandler::getUnserializedMetadata() and
extractTreesFromMetadata() for clarity. "Metadata" in these function
names meant an XML string.
* Updated DjVuImage::getImageSize() to provide image sizes in the new
style.
* In ExifBitmapHandler, getRotationForExif() now takes just the
Orientation tag, rather than a serialized string. Also renamed for
clarity.
* In GIFMetadataExtractor, return the width, height and bits per channel
instead of throwing them away. There was some conflation in
decodeBPP() which I picked apart. Refer to GIF89a section 18.
* In JpegMetadataExtractor, process the SOF0/SOF2 segment to extract
bits per channel, width, height and components (channel count). This
is essentially a port of PHP's getimagesize(), so should be bugwards
compatible.
* In PNGMetadataExtractor, return the width and height, which were
previously assigned to unused local variables. I verified the
implementation by referring to the specification.
* In SvgHandler, retain the version validation from unpackMetadata(),
but rename the function since it now takes an array as input.
In tests:
* In ExifBitmapTest, refactored some tests by using a provider.
* In GIFHandlerTest and PNGHandlerTest, I removed the tests in which
getMetadata() returns null, since it doesn't make sense when ported to
getMetadataArray(). I added tests for empty arrays instead.
* In tests, I retained serialization of input data since I figure it's
useful to confirm that existing database rows will continue to be read
correctly. I removed serialization of expected values, replacing them
with plain data.
* In tests, I replaced access to private class constants like
BROKEN_FILE with string literals, since stability is essential. If
the class constant changes, the test should fail.
Elsewhere:
* In maintenance/refreshImageMetadata.php, I removed the check for
shrinking image metadata, since it's not easy to implement and is
not future compatible. Image metadata is expected to shrink in
future.
Bug: T275268
Change-Id: I039785d5b6439d71dcc21dcb972177dba5c3a67d
b4849e03b7