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.
Snippets that possibly generate output for Magnum documentation
###############################################################
"Getting started" image
Displayed by the getting-started executable. Run the app and take screenshot
using Spectacle (including decorations, 880x707). Similarly for the gray
version. The resulting files should be resized to half. pngcrush to them for
smaller file sizes:
Created by Inkscape from doc/artwork/triangulate.svg and line-*.svg by
saving as Optimized SVG. On fresh installations you need the scour package
for it:
enabling all possible options in the dialog, saving
cleaning up the <svg> header (removing version, xmlns) in an editor
converting to a style="", keepingviewBox
adding class="m-image"
removing all layers that have display: none
In case of the line-quad-data-expansion*.svg and
line-quad-data-overlap-*.svg, they're all generated from
doc/artwork/line-quad-expansion.svg and doc/artwork/line-quad-overlap.svg,
each time with different layers shown.
The doc/artwork/line-quad-data-other.svg is derived from
doc/artwork/line-quad-data-neighbor.svg by removing the "neighbor" layer and
making the canvas smaller, the doc/artwork/line-quad-data.svg is then derived
from doc/artwork/line-quad-data-other.svg by removing the "other" layer and
making the canvas smaller yet again.
Vladimír Vondruš
