While "set" is a tad strong (there's just the one component for now), I
had missed the changes when adding ECS systems. Fixes the segfault at
the end of demo1 (ie, when any center text is printed).
There's now a main ecs.h file that includes the sub-system headers,
removing the need to explicitly include several header files, but the
sub-systems are a less cluttered.
This means that the component id used for hierarchy references must be
passed to Hierarchy_New and Hierarchy_Copy, but does all an entity to
have more than one hierarchy, which is useful for canvases (hierarchies
of views) in the 3d world (the canvas root would have a 3d hierarchy
reference and a 2d (view) hierarchy reference).
Passage_Delete needs to check if the hierarchy is valid as no text may
have been added, which results in a null pointer for the hierarchy.
Text shaping needs to set language etc every time it resets the buffer.
The text object covering the whole passage was not being initialized,
thus center print tried to print rubbish when (incorrectly) printing the
entire message.
It's not quite complete in that entities need to be created for the
objects, and passage text object might get additional components in the
hierarchy, but the direct use of views has been replaced by the use of a
hierarchy object with the same tree structure, and now has text objects
for paragraphs and the entire passage.
A passage object has a list of all the text objects in the given string,
where the objects represent either white space or "words", as well as a
view_t object representing the entire passage, with paragraphs split
into child views of the passage view, and each paragraph has a child
view for every text/space object in the paragraph.
Paragraphs are split by '\n' (not included in any object).
White space is grouped into clumps such that multiple adjacent spaces
form a single object. The standard ASCII space (0x20) and all of the
Unicode characters marked "WS;<compat> 0020" are counted as white space.
Unless a white space object is the first in the paragraph, its view is
marked for suppression by the view flow code.
Contiguous non-white space characters are grouped into single objects,
and their views are not suppressed.
All text object views (both white space and "word") have their data
pointer set to the psg_text_t object representing the text for that
view. This should be suitable for simple text-mode unattributed display.
More advanced rendering would probably want to create suitable objects
and set the view data pointers to those objects.
No assumption is made about text direction.
Passage and paragraph views need to have their primary axis sizes set
appropriately, as well as their resize flags. Their xlen and ylen are
both set to 10, and xpos,ypos is 0,0. Paragraph views need their
setgeometry pointer set to the appropriate view_flow_* function.
However, they are set up to have their secondary axis set automatically
when flowed.
Text object views are set up for automatic flowing: grav_flow, 0,0 for
xpos,ypos. However, xlen and ylen are also both 0, so need to be set by
the renderer before attempting to flow the text.
