Struct gtk::DrawingArea

#[repr(transparent)]
pub struct DrawingArea { /* private fields */ }

The DrawingArea widget is used for creating custom user interface elements. It’s essentially a blank widget; you can draw on it. After creating a drawing area, the application may want to connect to:

• Mouse and button press signals to respond to input from the user. (Use WidgetExtManual::add_events() to enable events you wish to receive.)

• The signal::Widget::realize signal to take any necessary actions when the widget is instantiated on a particular display. (Create GDK resources in response to this signal.)

• The signal::Widget::size-allocate signal to take any necessary actions when the widget changes size.

• The signal::Widget::draw signal to handle redrawing the contents of the widget.

The following code portion demonstrates using a drawing area to display a circle in the normal widget foreground color.

Note that GDK automatically clears the exposed area before sending the expose event, and that drawing is implicitly clipped to the exposed area. If you want to have a theme-provided background, you need to call render_background() in your ::draw method.

Simple GtkDrawingArea usage

⚠️ The following code is in C ⚠️

gboolean
draw_callback (GtkWidget *widget, cairo_t *cr, gpointer data)
{
  guint width, height;
  GdkRGBA color;
  GtkStyleContext *context;

  context = gtk_widget_get_style_context (widget);

  width = gtk_widget_get_allocated_width (widget);
  height = gtk_widget_get_allocated_height (widget);

  gtk_render_background (context, cr, 0, 0, width, height);

  cairo_arc (cr,
             width / 2.0, height / 2.0,
             MIN (width, height) / 2.0,
             0, 2 * G_PI);

  gtk_style_context_get_color (context,
                               gtk_style_context_get_state (context),
                               &color);
  gdk_cairo_set_source_rgba (cr, &color);

  cairo_fill (cr);

 return FALSE;
}
[...]
  GtkWidget *drawing_area = gtk_drawing_area_new ();
  gtk_widget_set_size_request (drawing_area, 100, 100);
  g_signal_connect (G_OBJECT (drawing_area), "draw",
                    G_CALLBACK (draw_callback), NULL);

Draw signals are normally delivered when a drawing area first comes onscreen, or when it’s covered by another window and then uncovered. You can also force an expose event by adding to the “damage region” of the drawing area’s window; WidgetExt::queue_draw_area() and Window::invalidate_rect() are equally good ways to do this. You’ll then get a draw signal for the invalid region.

The available routines for drawing are documented on the [GDK Drawing Primitives][gdk3-Cairo-Interaction] page and the cairo documentation.

To receive mouse events on a drawing area, you will need to enable them with WidgetExtManual::add_events(). To receive keyboard events, you will need to set the “can-focus” property on the drawing area, and you should probably draw some user-visible indication that the drawing area is focused. Use WidgetExt::has_focus() in your expose event handler to decide whether to draw the focus indicator. See render_focus() for one way to draw focus.

Implements

WidgetExt, glib::ObjectExt, BuildableExt, WidgetExtManual, BuildableExtManual

Implementations

impl DrawingArea

pub const NONE: Option<&'static DrawingArea> = None

pub fn new() -> DrawingArea

Creates a new drawing area.

Returns

a new DrawingArea

pub fn builder() -> DrawingAreaBuilder

Creates a new builder-pattern struct instance to construct DrawingArea objects.

This method returns an instance of DrawingAreaBuilder which can be used to create DrawingArea objects.

Trait Implementations

impl Clone for DrawingArea

fn clone(&self) -> Self

Returns a copy of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for DrawingArea

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DrawingArea

fn default() -> Self

Returns the “default value” for a type.

impl Display for DrawingArea

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Hash for DrawingArea

fn hash<H>(&self, state: &mut H)where
    H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,

Feeds a slice of this type into the given Hasher.

impl<T: DrawingAreaImpl> IsSubclassable<T> for DrawingArea

fn class_init(class: &mut Class<Self>)

Override the virtual methods of this class for the given subclass and do other class initialization.

fn instance_init(instance: &mut InitializingObject<T>)

Instance specific initialization.

impl Ord for DrawingArea

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

const fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

const fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

const fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: PartialOrd<Self>,

Restrict a value to a certain interval.

impl ParentClassIs for DrawingArea

type Parent = Widget

impl<OT: ObjectType> PartialEq<OT> for DrawingArea

fn eq(&self, other: &OT) -> bool

This method tests for self and other values to be equal, and is used by ==.

const fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<OT: ObjectType> PartialOrd<OT> for DrawingArea

fn partial_cmp(&self, other: &OT) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

const fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

const fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

const fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

const fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl StaticType for DrawingArea

fn static_type() -> Type

Returns the type identifier of Self.

impl Eq for DrawingArea

impl IsA<Buildable> for DrawingArea

impl IsA<Widget> for DrawingArea