## GtkCellRenderer

GtkCellRenderer — An object for rendering a single cell on a GdkDrawable

## Synopsis

    #include <gtk/gtk.h>

    enum        GtkCellRendererState;
    enum        GtkCellRendererMode;
    struct      GtkCellRenderer;
    void        gtk_cell_renderer_get_size      (GtkCellRenderer *cell,
                                                 GtkWidget *widget,
                                                 GdkRectangle *cell_area,
                                                 gint *x_offset,
                                                 gint *y_offset,
                                                 gint *width,
                                                 gint *height);
    void        gtk_cell_renderer_render        (GtkCellRenderer *cell,
                                                 GdkWindow *window,
                                                 GtkWidget *widget,
                                                 GdkRectangle *background_area,
                                                 GdkRectangle *cell_area,
                                                 GdkRectangle *expose_area,
                                                 GtkCellRendererState flags);
    gboolean    gtk_cell_renderer_activate      (GtkCellRenderer *cell,
                                                 GdkEvent *event,
                                                 GtkWidget *widget,
                                                 const gchar *path,
                                                 GdkRectangle *background_area,
                                                 GdkRectangle *cell_area,
                                                 GtkCellRendererState flags);
    GtkCellEditable* gtk_cell_renderer_start_editing
                                                (GtkCellRenderer *cell,
                                                 GdkEvent *event,
                                                 GtkWidget *widget,
                                                 const gchar *path,
                                                 GdkRectangle *background_area,
                                                 GdkRectangle *cell_area,
                                                 GtkCellRendererState flags);
    void        gtk_cell_renderer_get_fixed_size
                                                (GtkCellRenderer *cell,
                                                 gint *width,
                                                 gint *height);
    void        gtk_cell_renderer_set_fixed_size
                                                (GtkCellRenderer *cell,
                                                 gint width,
                                                 gint height);

## Object Hierarchy

      GObject
       +----GtkObject
             +----GtkCellRenderer
                   +----GtkCellRendererPixbuf
                   +----GtkCellRendererText
                   +----GtkCellRendererToggle

## Properties

      "cell-background"      gchararray           : Write
      "cell-background-gdk"  GdkColor             : Read / Write
      "cell-background-set"  gboolean             : Read / Write
      "height"               gint                 : Read / Write
      "is-expanded"          gboolean             : Read / Write
      "is-expander"          gboolean             : Read / Write
      "mode"                 GtkCellRendererMode  : Read / Write
      "visible"              gboolean             : Read / Write
      "width"                gint                 : Read / Write
      "xalign"               gfloat               : Read / Write
      "xpad"                 guint                : Read / Write
      "yalign"               gfloat               : Read / Write
      "ypad"                 guint                : Read / Write

## Signal Prototypes

    "editing-canceled"
                void        user_function      (GtkCellRenderer *,
                                                gpointer user_data);

## Description

The GtkCellRenderer is a base class of a set of objects used for rendering a cell to a GdkDrawable. 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 GdkDrawable. 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 GObjects property system. Then, the cell is measured using `gtk_cell_renderer_get_size`. Finally, the cell is rendered in the correct location using `gtk_cell_renderer_render`.

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

## Details

### enum GtkCellRendererState

    typedef enum
    {
      GTK_CELL_RENDERER_SELECTED    = 1 << 0,
      GTK_CELL_RENDERER_PRELIT      = 1 << 1,
      GTK_CELL_RENDERER_INSENSITIVE = 1 << 2,
      /* this flag means the cell is in the sort column/row */
      GTK_CELL_RENDERER_SORTED      = 1 << 3,
      GTK_CELL_RENDERER_FOCUSED     = 1 << 4
    } GtkCellRendererState;

Tells how a cell is to be rendererd.

`GTK_CELL_RENDERER_SELECTED` | The cell is currently selected, and probably has a selection colored background to render to.
`GTK_CELL_RENDERER_PRELIT` | The mouse is hovering over the cell.
`GTK_CELL_RENDERER_INSENSITIVE` | The cell is drawn in an insensitive manner
`GTK_CELL_RENDERER_SORTED` | The cell is in a sorted row
`GTK_CELL_RENDERER_FOCUSED` |

### enum GtkCellRendererMode

    typedef enum
    {
      GTK_CELL_RENDERER_MODE_INERT,
      GTK_CELL_RENDERER_MODE_ACTIVATABLE,
      GTK_CELL_RENDERER_MODE_EDITABLE
    } GtkCellRendererMode;

Identifies how the user can interact with a particular cell.

`GTK_CELL_RENDERER_MODE_INERT` | The cell is just for display and cannot be interacted with. Note that this doesn't mean that eg. the row being drawn can't be selected -- just that a particular element of it cannot be individually modified.
`GTK_CELL_RENDERER_MODE_ACTIVATABLE` | The cell can be clicked.
`GTK_CELL_RENDERER_MODE_EDITABLE` | The cell can be edited or otherwise modified.

### struct GtkCellRenderer

    struct GtkCellRenderer;

### gtk_cell_renderer_get_size ()

    void        gtk_cell_renderer_get_size      (GtkCellRenderer *cell,
                                                 GtkWidget *widget,
                                                 GdkRectangle *cell_area,
                                                 gint *x_offset,
                                                 gint *y_offset,
                                                 gint *width,
                                                 gint *height);

Obtains the width and height needed to render the cell. Used by view widgets to determine the appropriate size for the cell_area passed to `gtk_cell_renderer_render()`. If `cell_area` is not `NULL`, fills in the x and y offsets (if set) of the cell relative to this location. Please note that the values set in `width` and `height`, as well as those in `x_offset` and `y_offset` are inclusive of the xpad and ypad properties.

`cell` : | a GtkCellRenderer
`widget` : | the widget the renderer is rendering to
`cell_area` : | The area a cell will be allocated, or `NULL`
`x_offset` : | location to return x offset of cell relative to `cell_area`, or `NULL`
`y_offset` : | location to return y offset of cell relative to `cell_area`, or `NULL`
`width` : | location to return width needed to render a cell, or `NULL`
`height` : | location to return height needed to render a cell, or `NULL`

### gtk_cell_renderer_render ()

    void        gtk_cell_renderer_render        (GtkCellRenderer *cell,
                                                 GdkWindow *window,
                                                 GtkWidget *widget,
                                                 GdkRectangle *background_area,
                                                 GdkRectangle *cell_area,
                                                 GdkRectangle *expose_area,
                                                 GtkCellRendererState flags);

Invokes the virtual render function of the GtkCellRenderer. The three passed-in rectangles are areas of `window`. Most renderers will draw within `cell_area`; the xalign, yalign, xpad, and ypad fields of the GtkCellRenderer should be honored with respect to `cell_area`. `background_area` includes the blank space around the cell, and also the area containing the tree expander; so the `background_area` rectangles for all cells tile to cover the entire `window`. `expose_area` is a clip rectangle.

`cell` : | a GtkCellRenderer
`window` : | a GdkDrawable to draw to
`widget` : | the widget owning `window`
`background_area` : | entire cell area (including tree expanders and maybe padding on the sides)
`cell_area` : | area normally rendered by a cell renderer
`expose_area` : | area that actually needs updating
`flags` : | flags that affect rendering

### gtk_cell_renderer_activate ()

    gboolean    gtk_cell_renderer_activate      (GtkCellRenderer *cell,
                                                 GdkEvent *event,
                                                 GtkWidget *widget,
                                                 const gchar *path,
                                                 GdkRectangle *background_area,
                                                 GdkRectangle *cell_area,
                                                 GtkCellRendererState flags);

Passes an activate event to the cell renderer for possible processing. Some cell renderers may use events; for example, GtkCellRendererToggle toggles when it gets a mouse click.

`cell` : | a GtkCellRenderer
`event` : | a GdkEvent
`widget` : | widget that received the event
`path` : | widget-dependent string representation of the event location; e.g. for GtkTreeView, a string representation of GtkTreePath
`background_area` : | background area as passed to `gtk_cell_renderer_render`
`cell_area` : | cell area as passed to `gtk_cell_renderer_render`
`flags` : | render flags
Returns : | `TRUE` if the event was consumed/handled

### gtk_cell_renderer_start_editing ()

    GtkCellEditable* gtk_cell_renderer_start_editing
                                                (GtkCellRenderer *cell,
                                                 GdkEvent *event,
                                                 GtkWidget *widget,
                                                 const gchar *path,
                                                 GdkRectangle *background_area,
                                                 GdkRectangle *cell_area,
                                                 GtkCellRendererState flags);

Passes an activate event to the cell renderer for possible processing.

`cell` : | a GtkCellRenderer
`event` : | a GdkEvent
`widget` : | widget that received the event
`path` : | widget-dependent string representation of the event location; e.g. for GtkTreeView, a string representation of GtkTreePath
`background_area` : | background area as passed to `gtk_cell_renderer_render`
`cell_area` : | cell area as passed to `gtk_cell_renderer_render`
`flags` : | render flags
Returns : | A new GtkCellEditable, or `NULL`

### gtk_cell_renderer_get_fixed_size ()

    void        gtk_cell_renderer_get_fixed_size
                                                (GtkCellRenderer *cell,
                                                 gint *width,
                                                 gint *height);

Fills in `width` and `height` with the appropriate size of `cell`.

`cell` : | A GtkCellRenderer
`width` : | location to fill in with the fixed width of the widget, or `NULL`
`height` : | location to fill in with the fixed height of the widget, or `NULL`

### gtk_cell_renderer_set_fixed_size ()

    void        gtk_cell_renderer_set_fixed_size
                                                (GtkCellRenderer *cell,
                                                 gint width,
                                                 gint height);

Sets the renderer size to be explicit, independent of the properties set.

`cell` : | A GtkCellRenderer
`width` : | the width of the cell renderer, or -1
`height` : | the height of the cell renderer, or -1

## Properties

"`cell-background`" (gchararray : Write) | Cell background color as a string.
"`cell-background-gdk`" (GdkColor : Read / Write) | Cell background color as a GdkColor.
"`cell-background-set`" (gboolean : Read / Write) | Whether this tag affects the cell background color.
"`height`" (gint : Read / Write) | The fixed height.
"`is-expanded`" (gboolean : Read / Write) | Row is an expander row, and is expanded.
"`is-expander`" (gboolean : Read / Write) | Row has children.
"`mode`" (GtkCellRendererMode : Read / Write) | Editable mode of the CellRenderer.
"`visible`" (gboolean : Read / Write) | Display the cell.
"`width`" (gint : Read / Write) | The fixed width.
"`xalign`" (gfloat : Read / Write) | The x-align.
"`xpad`" (guint : Read / Write) | The xpad.
"`yalign`" (gfloat : Read / Write) | The y-align.
"`ypad`" (guint : Read / Write) | The ypad.

## Signals

### The "editing-canceled" signal

    void        user_function                  (GtkCellRenderer *,
                                                gpointer user_data);

This signal gets emitted when the user cancels the process of editing a cell. For example, an editable cell renderer could be written to cancel editing when the user presses Escape.

See also: `gtk_cell_renderer_editing_canceled()`

`user_data` : | user data set when the signal handler was connected.

Since 2.4

## See Also

GtkCellRendererText,GtkCellRendererPixbuf,GtkCellRendererToggle