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.
Adjusting the size of the parent (container) view to the views it
contains will be useful for automatic layout and knowing how large the
view is for scrolling. New tests added so testing both with and without
the option is still possible.
This should be suitable for laying out text objects with word-wrap,
where each view is a "word" or break between "words". This should be
useful for any other objects that could benefit from similar layout
rules. All eight flows are supported left-right-top-down (English and
most European languages), right-left-top-down (Arabic and similar),
top-down-right-left (Chinese, Japanese, Korean), top-down-left-right,
as well as bottom-up variants of those four.
More work is needed for support of things like views being centered on
the flow line rather than on one edge (depends on flow direction),
offset views, and others. Suppression of "spaces" at the beginning of a
line is supported but not tested.
