selected-reader

Arguments: grid-column

Returns a function that returns whether each of the grid cells in a particular column of a grid-widget is currently selected, or else returns nil to determine the selection status in other ways (see cell-selected). The selected-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 selected status 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 cell is currently considered to be selected, then the function should return true, and otherwise it should return nil. When selected, a grid cell is drawn in special colors, and the application may treat it in some special way.

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 if this facility is not used. The default value is nil.

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

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