Nearly all Leo themes use a monospaced typeface for the body font. This is
what you want for programming, but for documentation and other non-code
writing, many people would prefer a non-monospaced font. Some might event
wish for a serif style typeface.
The attached script installs a global script that changes the font for
nodes that use an @language directive of rest, md, asciidoc, text, or plain.
By default the alternate font is either Verdana or Sans-serif, but any font
name installed on the system can be used. If the body does not have an
@language
directive, the command looks up the tree to find what language is in effect.
The change comes into effect the next time a node receives focus after the
command is run. So after you run it, you will not see any effect on the
currently focused node until you navigate away and return to it. The
command is global in scope, so it will affect all outlines.
If you want to use a different font or font size, just edit the values in
the script. If you have a text node but you temporarily want to see it in
the theme's font instead, temporarily add an @language python (or some
other programming language name) at or near the top of the node. Navigate
away then back to the node.
This font-changing behavior will remain in effect until Leo is restarted.
Create a new node in, say, workbook.leo and paste the contents of the
attached file into it. Run it with the usual <CTRL-b>
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@language python
"""Change the body font of a node.
Called when the selected node changes. If the language directive
in effect is one of the specified ones, change the font family to
one of the specified fonts. Also change the font if the body
contains lines near the start that begin with ":id:" or ":ref:".
Otherwise change it back to the normal font."""
NOSTYLE = 'LeoQTextBrowser {}'
STYLE = ('LeoQTextBrowser {font-family: Verdana, "Sans-serif";'
'font-size: 10pt;}')
LANGS = ('@language rest', '@language md', '@language asciidoc',
'@language text', '@language plain')
LANGTAGS = ('@rest', '@md', '@rst', '@adoc')
TAGS = (':id:', ':ref:')
def qualifies(b, h):
"""See if we have a qualifying language or tag.
RETURNS
-- True if headline h starts with one of the LANGTAGS.
-- True if body b has a line starting with a qualifying tag or
language directive.
-- -1 if body b has a line starting with "@language" but
the language is not a qualifying one.
-- False otherwise.
"""
if h.startswith(LANGTAGS):
return True
lines = b[:300].splitlines()
lines = [l for l in lines if l.strip()]
for line in lines:
if line.startswith('@language'):
if line.startswith(LANGS):
return True
else:
return -1 # Tri-state logic; not a mistake
else:
if line.startswith(TAGS):
return True
return False
def set_alt_body_font(tag, keys):
"""Set body font if this node is one of the qualifying node kinds.
Looks up the tree until a qualifying node is found. Then sets the
CSS style based on the qualified language or tag.
Expected to be called by a hook procedure.
"""
c = keys['c']
css = NOSTYLE
# Check if language or special tags qualify
for p in c.p.self_and_parents():
found = qualifies(p.b, p.h)
if found is True:
css = STYLE
break
elif found is not False: # Tri-state logic!
break
editor = c.frame.body.wrapper.widget
editor.setStyleSheet(css)
ud = g.user_dict
ud['alt_body_font_proc'] = set_alt_body_font
g.registerHandler('select3', ud['alt_body_font_proc'])
