Struct gtk::DrawingArea [−][src]
pub struct DrawingArea(_);
Expand description
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::realizesignal 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-allocatesignal to take any necessary actions when the widget changes size. -
The
signal::Widget::drawsignal 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
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
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
Returns the type identifier of Self.
Auto Trait Implementations
impl RefUnwindSafe for DrawingAreaimpl !Send for DrawingAreaimpl !Sync for DrawingAreaimpl Unpin for DrawingAreaimpl UnwindSafe for DrawingAreaBlanket Implementations
Mutably borrows from an owned value. Read more
Upcasts an object to a superclass or interface T. Read more
Upcasts an object to a reference of its superclass or interface T. Read more
Tries to downcast to a subclass or interface implementor T. Read more
Tries to downcast to a reference of its subclass or interface implementor T. Read more
Tries to cast to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Tries to cast to reference to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Casts to T unconditionally. Read more
Casts to &T unconditionally. Read more
Returns true if the object is an instance of (can be cast to) T.
pub fn set_properties_from_value(
&self,
property_values: &[(&str, Value)]
) -> Result<(), BoolError>pub fn set_property<'a, N, V>(
&self,
property_name: N,
value: V
) -> Result<(), BoolError> where
V: ToValue,
N: Into<&'a str>, pub fn set_property_from_value<'a, N>(
&self,
property_name: N,
value: &Value
) -> Result<(), BoolError> where
N: Into<&'a str>, Safety Read more
Safety Read more
Safety Read more
Safety Read more
pub fn connect_notify<F>(&self, name: Option<&str>, f: F) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec) + Send + Sync, pub fn connect_notify_local<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec), pub unsafe fn connect_notify_unsafe<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: Fn(&T, &ParamSpec), pub fn has_property<'a, N>(&self, property_name: N, type_: Option<Type>) -> bool where
N: Into<&'a str>, pub fn find_property<'a, N>(&self, property_name: N) -> Option<ParamSpec> where
N: Into<&'a str>, pub fn connect<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value> + Send + Sync + 'static,
N: Into<&'a str>, Same as connect but takes a SignalId instead of a signal name.
pub fn connect_local<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value> + 'static,
N: Into<&'a str>, Same as connect_local but takes a SignalId instead of a signal name.
pub unsafe fn connect_unsafe<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
F: Fn(&[Value]) -> Option<Value>,
N: Into<&'a str>, Same as connect_unsafe but takes a SignalId instead of a signal name.
Emit signal by signal id.
Emit signal with details by signal id.
Emit signal by it’s name.
pub fn bind_property<'a, O, N, M>(
&'a self,
source_property: N,
target: &'a O,
target_property: M
) -> BindingBuilder<'a> where
O: ObjectType,
N: Into<&'a str>,
M: Into<&'a str>, Same as emit but takes Value for the arguments.
Same as emit_by_name but takes Value for the arguments.
Returns a SendValue clone of self.
impl<'a, T, C> FromValueOptional<'a> for T where
C: ValueTypeChecker<Error = ValueTypeMismatchOrNoneError>,
T: FromValue<'a, Checker = C>,