Essential for text selection and editing in cases where mapping from the
input text to the actual shaped glyphs is nontrivial. I.e., in case of
HarfBuzzFont; both FreeTypeFont and StbTrueTypeFont perform a 1:1
translation from input (UTF-8) characters to glyphs so there it isn't
as important.
This is going to get called from fillGlyphCache() that takes a string,
and thus should be better than one virtual call per character. The
single-character variant still stays, as it's a nice convenience API.
Eventually glyphSize() will get a similar treatment as well.
In basically all cases it's two independent operations so forcing them
to be done together doesn't really bring any potential efficiency
advantages. On the other hand, splitting them allows allows the caller
to better make use of available memory, as the new
renderGlyphQuadsInto() allows the input and output arrays to be aliased.
Bumping AbstractFont plugin interface versions as this is a breaking
change.
This class won't print the deprecation warning in that case. I'm a bit
disappointed that the Clang changelogs are always so vague, there's
often never a possibility to figure out which version a particular bug
was fixed in apart from testing each and every.
Replaces the previous, grossly inefficient AbstractLayouter which was
performing one virtual call per glyph (!). It's now also reusable,
meaning it doesn't need to be allocated anew for every new shaped text,
and it no longer requires each and every font plugin to implement the
same redundant glyph data fetching from the glyph cache, scaling etc. --
all that is meant to be done by the users of AbstractShaper, i.e.
Renderer. The independency on a glyph cache theorerically also means it
can be used for a completely different, non-texture-based way to render
text (such as direct path drawing directly on the GPU), although I won't
be exploring that path now.
It also exposes an interface for specifying script, language,
direction and typographic features. Such interface will be currently
only implemented in HarfBuzz, but that's the intent -- to provide a
flexible enough interface to support all possible use cases that a font
or a font plugin may support, instead of exposing a least common
denominator and then having no easy way to shape a text in a non-Latin
script or use a fancy OpenType feature the chosen font has.
The old public interface is preserved for backwards compatibility,
marked as deprecated, however the virtual APIs are not, as supporting
that would be too nasty. I don't think any user code ever implemented a
font plugin so this should be okay.
To ensure smooth transition with no regressions, the Renderer class and
MagnumFont tests still use the old API in this commit, and their test
pass the same way as they did before (except for two removed MagnumFont
test cases which tested errors that are now an assertion in the
deprecated layout() API and thus cannot be tested from the plugin
anymore). Porting them away from the deprecated API will be done in
separate commits.
The class now supports incremental filling, multiple fonts, texture
arrays, removes all reliance on STL containers and is finally properly
documented.
To avoid complete breakage of every use, as much as possible was kept as
deprecated APIs -- in particular the reserve() with the nasty
std::vectors, the insert() that assumes a 2D cache and a single font
and textureSize() that returns a 2D vector. Those behave the same as
before, but will assert if the cache is an array or contains more than
one font.
On the other hand, begin() / end() access with std::unordered_map iterators
(ew!) was removed as the internals simply aren't a hashmap anymore. The
image() that returned an Image2D is now used to fill the glyph cache
instead of querying its potentially processed contents, and returns a
MutableImageView3D. I considered keeping it and adding sourceImage()
instead, but such naming turned out to be too inconsistent. For querying
processed image data (such as with the distance field cache) there's a
new processedImage() query, guarded by new GlyphCacheFeature bits -- if
both ImageProcessing and ProcessedImageDownload is set, it can be used
to retrieve the processed image (so, similar as ImageDownload was
before), and if neither is set, the cache contents are queryable
directly through image(), without needing any special support from
the GPU API.
Existing code is updated only in the minimal way possible to ensure that
no serious breakage was introduced by reimplementing the deprecated APIs
on top of the new backend. Porting away from deprecated APIs will be
done in next commits. The GlyphCache and DistanceFieldGlyphCache have
their public API kept intact for now, as a similar rework will be needed
for them as well.
Additionally, the MagnumFont and MagnumFontConverter plugins aren't
compiling yet as they require substantial changes to deal with the new
glyph cache features. That is not the case with other plugins in the
magnum-plugins repository tho, for those the backwards compatibility
"just works". On the other hand, since layout of the AbstractGlyphChange
changed, I'm bumping the AbstractFont plugin interface version to
force-trigger a rebuild of dependent projects. Because I ran a stale
magnum-player binary, it worked without crashing or GL errors but just
didn't show ANY text whatsoever due to ABI differences, and I wasted
some precious minutes before realizing that a simple rebuild would fix
it.
It won't contain just font metrics anymore. Also don't require the
struct to be zero-initialized if opening fails -- simply allow the
plugins to return garbage in that case and save the values only if
opening actually succeeded.
Strictly speaking this isn't an ABI change as the return value isn't
part of the function signature and the struct is still the same, so the
plugin interface version isn't bumped for this change.
All std::string arguments are now a StringView, what returned a
std::pair is now a Pair. STL compatibility headers are included on
deprecated builds to ease porting, as usual.
The only *really* breaking changes are in the internals, where an
ArrayView<const char32_t> is used instead of std::u32string, which is in
line with the change done in Utility::Unicode::utf32(); and a Triple is
returned instead of a std::tuple. Behaviorally nothing changed except
that fillGlyphCache() now asserts if the input string contains invalid
UTF-8 (which is also in line with the cahnge done in Utility::Unicode).
This means I (and people making their own plugins) don't need to go and
update each and every plugin once the version in the interface string
gets bumped after a (silent) ABI break. Such as when new virtual
functions get added, as those often lead to strange crashes if the
plugins don't get rebuilt after.
The plugins will now use this macro, which means they'll
automatically embed an interface string that was present in the base
class header at build time. However, when the base class updates, the
previous string is still embedded in the plugin binary, which will then
fail to load -- this being automatic doesn't mean the original purpose
is lost. Subsequently rebuilding the plugins from source will make them
pick up the updated interface string again.
Originally I copied this over from SceneGraph template classes, where it
was used to prevent the compiler from needlessly instantiating a
template that was already available elsewhere. But this is a different
case, the extern template is not preventing any instatiation of
anything, no code is inline, so it apparently should not have been there
at all, instead of being disabled for ḾinGW GCC and clang-cl, and then
subsequently discovering it also breaks MinGW Clang.
Since I'm not testing with MinGW Clang on the CI (only with MinGW GCC),
this went unnoticed for a while -- sorry.
It's more useful if the Error class is directly referenced than saying
just "error output" -- so people can grab it, redirect it, etc. Also
drop the useless "does what it is expected to do on success" sentences
that add no value whatsoever.
I wanted to avoid including extra stuff with the Manager.hpp split, but
this would make it even worse than having Array and String included
unconditionally. Fortunately it's enough to simply not even have the
declaration.
This makes it much less annoying to pass arbitrarily typed data, such as
std::uint8_t or char8_t and what not. It was already done like this for
the new shader converter plugins, where the input is often 32-bit ints
for SPIR-V.
OTOH the internal virtual API is kept with ArrayView<const char>, as
that makes it easier to operate on by the implementations.
Should make new things more discoverable, avoid confusion when a
documented API isn't there and reduce the need for maintaining multiple
separate versions of the docs.
Vladimír Vondruš