Struct gtk::DrawingArea

pub struct DrawingArea(_, _);

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 Widget::add_events to enable events you wish to receive.)

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

• The 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 gtk_render_background in your ::draw method.

Simple DrawingArea usage

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 gdk::WindowExt::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 Widget::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 gtk_render_focus for one way to draw focus.

Implements

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

Implementations

impl DrawingArea

pub fn new() -> DrawingArea

Creates a new drawing area.

Returns

a new DrawingArea

Trait Implementations

impl Clone for DrawingArea

fn clone(&self) -> DrawingArea

Returns a copy of the value.

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 Eq for DrawingArea

impl Hash for DrawingArea

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

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 IsA<Buildable> for DrawingArea

impl IsA<Widget> for DrawingArea

impl Ord for DrawingArea

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

This method returns an [Ordering] between self and other.

#[must_use]fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

#[must_use]fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

#[must_use]fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

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

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

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

#[must_use]fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

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

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

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

#[must_use]fn lt(&self, other: &Rhs) -> bool

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

#[must_use]fn le(&self, other: &Rhs) -> bool

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

#[must_use]fn gt(&self, other: &Rhs) -> bool

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

#[must_use]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.