CellRenderer


Object Hierarchy:

Object hierarchy for CellRenderer

Description:

[ CCode ( type_id = "gtk_cell_renderer_get_type ()" ) ]
public abstract class CellRenderer : InitiallyUnowned

An object for rendering a single cell

The `GtkCellRenderer` is a base class of a set of objects used for rendering a cell to a `cairo_t`. These objects are used primarily by the `GtkTreeView` widget, though they aren’t tied to them in any specific way. It is worth noting that `GtkCellRenderer` is not a `GtkWidget` and cannot be treated as such.

The primary use of a `GtkCellRenderer` is for drawing a certain graphical elements on a `cairo_t`. 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 `GObject`s property system. Then, the cell is measured using get_preferred_size. Finally, the cell is rendered in the correct location using snapshot.

There are a number of rules that must be followed when writing a new `GtkCellRenderer`. 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 `GtkCellRenderer` 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 `GtkCellRenderer`Toggle, which toggles when it gets activated by a mouse click, or it can be “editable” like `GtkCellRenderer`Text, which allows the user to edit the text using a widget implementing the `GtkCellEditable` interface, e.g. `GtkEntry`. To make a cell renderer activatable or editable, you have to implement the `GtkCellRenderer`Class.activate or `GtkCellRenderer`Class.start_editing virtual functions, respectively.

Many properties of `GtkCellRenderer` 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: gtk4

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