According to the C standard all preprocessor definitions starting
with an underscore are reserved for standard and implementation use,
so don't use those. Also, sort and unique include directives.
This commit updates a *lot* of rather questionable path handling
logic to be robust. Specifically:
* All path operations go through Platform::Path.
* All ad-hoc path handling functions are removed, together with
PATH_SEP. This removes code that was in platform-independent
parts, but had platform-dependent behavior.
* Group::linkFileRel is removed; only an absolute path is stored
in Group::linkFile. However, only Group::linkFileRel is saved,
with the relative path calculated on the fly, from the filename
passed into SaveToFile. This eliminates dependence on global
state, and makes it unnecessary to have separare code paths
for saved and not yet saved files.
* In a departure from previous practice, functions with
platform-independent code but platform-dependent behavior
are all grouped under platform/. This makes it easy to grep
for functions with platform-dependent behavior.
* Similarly, new (GUI-independent) code for all platforms is added
in the same platform.cpp file, guarded with #ifs. It turns out
that implementations for different platforms had a lot of shared
code that tended to go out of sync.
These points can be used for constraining the width of the text
(or to the width of the text).
The main parts of the commit are:
* TtfFont is restructured to be able to return the aspect ratio
for a given string.
* This aspect ratio is written to the savefile, such that even if
the font is missing, the sketch would still be solved correctly.
* The two additional points are constrained via perpendicularly
to the two main points (which form a v vector).
The compatibility features are as follows:
* When the font is missing in old files, 1:1 aspect ratio is used,
which works for the replacement symbol anyhow.
* When the two additional points are missing in old files, their
would-be positions are calculated and they are moved there,
avoiding 'jumping' of underconstrained sketches.
SolveSpace 2.0 used the height of 'A' (i.e. cap height) to determine
the reference height.
SolveSpace 2.1 completely broke that during transition to Freetype,
and used something more or less random, by using FT_Set_Char_Size
with units_per_EM.
SolveSpace 2.2 attempted to fix that, but also used something more
or less random, by using FT_Request_Size with "unit" values.
Turns out that Freetype actually doesn't have a concept of cap height
at all. It is possible to extract it from the TT_OS2 table that is
present in some TrueType fonts, but it is not present in Microsoft
fonts (the msttcorefonts ones), and for those Linux fonts in which
it is present it doesn't appear very reliable.
So instead, use the height of 'A' instead, like version 2.0 did.
This has the advantage that it is quite bulletproof, and also matches
exactly what the old files are measured against.
One downside is that fonts without an 'A' glyph would not render.
We can deal with that when it becomes a problem.
Benefits:
* Much simpler code.
* Handles the entire TTF spec, not just a small subset that
only really worked well on Windows fonts.
* Handles all character sets as well as accented characters.
* Much faster parsing, since Freetype lazily loads and
caches glyphs.
* Support for basically every kind of font that was invented,
not just TTF.
Note that OpenType features, e.g. ligatures, are not yet supported.
This means that Arabic and Devanagari scripts, among others, will
not be rendered in their proper form.
RTL scripts are not supported either, neither in TTF nor in
the text window. Adding RTL support is comparatively easy, but
given that Arabic would not be legibly rendered anyway, this is not
done so far.
