CellRenderer


Object Hierarchy:

Object hierarchy for CellRenderer

Description:

public abstract class CellRenderer : InitiallyUnowned

The CellRenderer is a base class of a set of objects used for rendering a cell to a Context.

These objects are used primarily by the TreeView widget, though they aren’t tied to them in any specific way. It is worth noting that CellRenderer is not a Widget and cannot be treated as such.

The primary use of a CellRenderer is for drawing a certain graphical elements on a Context. Typically, one cell renderer is used to draw many cells on the screen. To this extent, it isn’t expected that a CellRenderer keep any permanent state around. Instead, any state is set just prior to use using Objects property system. Then, the cell is measured using get_size. Finally, the cell is rendered in the correct location using render.

There are a number of rules that must be followed when writing a new CellRenderer. First and foremost, it’s important that a certain set of properties will always yield a cell renderer of the same size, barring a Style change. The CellRenderer also has a number of generic properties that are expected to be honored by all children.

Beyond merely rendering a cell, cell renderers can optionally provide active user interface elements. A cell renderer can be “activatable” like CellRendererToggle, which toggles when it gets activated by a mouse click, or it can be “editable” like CellRendererText, which allows the user to edit the text using a widget implementing the CellEditable interface, e.g. Entry. To make a cell renderer activatable or editable, you have to implement the activate or start_editing virtual functions, respectively.

Many properties of CellRenderer and its subclasses have a corresponding “set” property, e.g. “cell-background-set” corresponds to “cell-background”. These “set” properties reflect whether a property has been set or not. You should not set them independently.


Namespace: Gtk
Package: gtk+-3.0

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