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A.4.5.32 AreaLabel Form

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

Example AreaLabel plot

AreaLabel form configuration panel

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.


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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