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The AreaLabel form ()
is available from the
Area layer control,
and draws a text label near the nominal center of each plotted area.
The effect is just the same as for the Label form,
but it can be used from the Area layer control rather than
having to specify positional coordinates separately.
The plotted position is determined by the plotting code from the
shape information; it may or may not correspond to the shape's actual center.
Example AreaLabel plot
AreaLabel form configuration panel
The configuration options are:
-
Text
- A column or expression from the table supplying the text to
write on the plot. Any data type (string or numeric) is permitted.
-
Text Syntax
- How to turn the text into characters on the screen.
Plain and Antialias both take the
text at face value, but Antialias smooths the characters.
Antialiased text usually looks nicer, but can be perceptibly slower to plot.
At time of writing, on MacOS antialiased text seems to be required to
stop the writing coming out upside-down for non-horizontal text.
LaTeX interprets the text as LaTeX source code
and typesets it accordingly.
-
Font Size
- Size of the font in points.
-
Font Style
- Style of the font - standard, serif or monospaced.
-
Font Weight
- Whether the font is plain, bold or italic.
-
Anchor
- The position of the text relative to the data position.
-
Spacing Threshold
-
Crowding Limit
- These two options control how closely spaced labels can be.
Labels which are too closely crowded together will simply not be shown,
since overplotting many labels together ends up with them being illegible.
The Spacing Threshold slider controls the smallest
area that a group of labels can have to themselves - if there are too
many in the same area, none will be drawn. Sliding it left allows more
crowding and right allows less. The Crowding Limit
controls the largest number of labels that can be in a group.
Setting it to 2 for instance is useful if you want to see pairs of
labels, even if the pair is close.
Next Previous Up Contents
Next: Lines Form
Up: Plot Forms
Previous: Central Form
TOPCAT - Tool for OPerations on Catalogues And Tables
Starlink User Note253
TOPCAT web page:
http://www.starlink.ac.uk/topcat/
Author email:
m.b.taylor@bristol.ac.uk
Mailing list:
topcat-user@jiscmail.ac.uk