font-reader

Arguments: grid-column

Returns a function that returns the font to use when drawing each grid cell of a a particular column, or else returns nil to determine the font in other ways. This function is called by the default cell-font method, which in turn is typically called by a draw-cell method (including those supplied by editable-text-column-mixin and other mixins). A font-reader may be nil rather than a function if this facility is not used. The default value is nil.

The font-reader function is a property of a particular grid-column, and is called once for each grid-row that intersects that column, to determine the font of the cell at the intersection of that row and column. The function should take one argument, which is the data-object of the grid-row. If the font for a particular cell should be determined by the font-reader function, then it should return the font to use, and otherwise it should return nil.

This property value may be specified as either a function name symbol (which would be more debuggable), or a function object (which may be slightly faster, though probably insignificantly), or nil.

An application does not call the font-reader function; it supplies the font-reader function by calling (setf font-reader) or by passing the :font-reader initarg when calling make-instance to create a grid-column, and the specified function is then called automatically by the system as needed.

See the grid-widget class for an overview of writing grid-widget code.

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This page was not revised from the 10.0 page.
Created 2019.8.20.