When trying to figure out the correct implementation, we now have a very
strong distinction on plugins that are well suited for sniffing, and
plugins that need a MIME type to be chosen.
Instead of having multiple calls to non-static virtual sniff methods for
each Image decoding plugin, we have 2 static methods for each
implementation:
1. The sniff method, which in contrast to the old method, gets a
ReadonlyBytes parameter and ensures we can figure out the result
with zero heap allocations for most implementations.
2. The create method, which just creates a new instance so we don't
expose the constructor to everyone anymore.
In addition to that, we have a new virtual method called initialize,
which has a per-implementation initialization pattern to actually ensure
each implementation can construct a decoder object, and then have a
correct context being applied to it for the actual decoding.
Error::from_string_literal now takes direct char const*s, while
Error::from_string_view does what Error::from_string_literal used to do:
taking StringViews. This change will remove the need to insert `sv`
after error strings when returning string literal errors once
StringView(char const*) is removed.
No functional changes.
I accidentally skipped this part of the spec in the QOI decoder:
> The alpha value remains unchanged from the previous pixel.
This led to incorrect rendering of some images with transparency,
visible in form of a horizontal line of non-transparent pixels (that
shouldn't exist), e.g. for the following chunk sequence:
- QOI_OP_RGBA with alpha = 0
- QOI_OP_RGB
- QOI_OP_RUN
The QOI_OP_RGB should 'inherit' the alpha value of the previous
QOI_OP_RGBA chunk, instead of always setting it to 255.
I'm unsure why the encoder added the QOI_OP_RGB chunk to the specific
image where the bug was noticed in the first place - they effectively
both had fully transparent color values.
What the component which did the actual decoding is called is not
relevant for the error, and would be rather distracting once we show
decoding error messages e.g. in ImageViewer (instead of just silently
failing).
Also makes them more consistent as many already don't include it - a
mistake which is now turned into a feature :^)
The spec had its first stable release today, so I figured we should
support it as well!
As usual, by using the regular LibGfx image decoder plugin architecture,
we immediately get support for it everywhere: ImageViewer, FileManager
thumbnails, PixelPaint, and (with a small change in the subsequent
commit) even the Browser :^)
