|Text-Graphic Object Notation
Pattern structure is shown by the "spider webs" = . They can be turned off and on and are not part
of the image. Empty patterns show as just the terminating ground
sign = from the end of the horizontal
bars. And notationally speaking, the ground sign terminator is not
necessary, so may be omitted for clarity, as for example with the
Sometimes pattern order may be important, and sometimes
not, in which case patterns function as sets.
Stroke lines have varying width over a path.
Separation of Space and Tree
In a diagram, each text
graphic object has a spatial location
independent from its pattern membership, but usually related in
conventional ways. These conventions are part of the visual
language that humans use in interpreting diagrams of that kind.
text, binary trees, and bar charts are all examples of
conventions which relate spatial arrangement to underlying tree
structure. A spatial parser has been written which can handle the
latter two (among others). The parser takes two inputs: a
machine readable visual grammar for the target visual language,
and a region on the screen in which atomic elements from an
expression in the target language are spatially arranged according
to the conventions of that language. Using the former it then
parses the latter, returning a complex pattern in which copies of
the visual atoms from the region are arranged in the structure
denoted by the grammar.
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