Struct gtk4::DrawingArea

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

DrawingArea is a widget that allows drawing with cairo.

It’s essentially a blank widget; you can draw on it. After creating a drawing area, the application may want to connect to:

• 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::DrawingArea::resize signal to take any necessary actions when the widget changes size.

• Call DrawingAreaExtManual::set_draw_func() 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.

Simple GtkDrawingArea usage

⚠️ The following code is in c ⚠️

static void
draw_function (GtkDrawingArea *area,
               cairo_t        *cr,
               int             width,
               int             height,
               gpointer        data)
{
  GdkRGBA color;
  GtkStyleContext *context;

  context = gtk_widget_get_style_context (GTK_WIDGET (area));

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

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

  cairo_fill (cr);
}

int
main (int argc, char **argv)
{
  gtk_init ();

  GtkWidget *area = gtk_drawing_area_new ();
  gtk_drawing_area_set_content_width (GTK_DRAWING_AREA (area), 100);
  gtk_drawing_area_set_content_height (GTK_DRAWING_AREA (area), 100);
  gtk_drawing_area_set_draw_func (GTK_DRAWING_AREA (area),
                                  draw_function,
                                  NULL, NULL);
  return 0;
}

The draw function is normally called when a drawing area first comes onscreen, or when it’s covered by another window and then uncovered. You can also force a redraw by adding to the “damage region” of the drawing area’s window using WidgetExt::queue_draw(). This will cause the drawing area to call the draw function again.

The available routines for drawing are documented in the Cairo documentation; GDK offers additional API to integrate with Cairo, like cairo_set_source_rgba() or cairo_set_source_pixbuf().

To receive mouse events on a drawing area, you will need to use event controllers. 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.

If you need more complex control over your widget, you should consider creating your own Widget subclass.

Implements

DrawingAreaExt, WidgetExt, glib::ObjectExt, AccessibleExt, BuildableExt, ConstraintTargetExt, DrawingAreaExtManual, WidgetExtManual, AccessibleExtManual

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.

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, Self: Sized,

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.

fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + 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 ==.

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.

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

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

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

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

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

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

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<Accessible> for DrawingArea

impl IsA<Buildable> for DrawingArea

impl IsA<ConstraintTarget> for DrawingArea

impl IsA<Widget> for DrawingArea