DrawingArea
GtkDrawingArea 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@Gtk.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@Gtk.DrawingArea::resize signal to take any necessary actions when the widget changes size.
Call method@Gtk.DrawingArea.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
static void
draw_function (GtkDrawingArea *area,
cairo_t *cr,
int width,
int height,
gpointer data)
{
GdkRGBA color;
cairo_arc (cr,
width / 2.0, height / 2.0,
MIN (width, height) / 2.0,
0, 2 * G_PI);
gtk_widget_get_color (GTK_WIDGET (area),
&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 method@Gtk.Widget.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 func@Gdk.cairo_set_source_rgba or func@Gdk.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 GtkWidget subclass.
Constructors
Properties
The accessible role of the given GtkAccessible implementation.
The content height.
The content width.
A list of css classes applied to this widget.
Whether the widget should grab focus when it is clicked with the mouse.
Enables or disables the emission of the ::query-tooltip signal on @widget.
Whether to use the hexpand property.
The GtkLayoutManager instance to use to compute the preferred size of the widget, and allocate its children.
Margin on bottom side of widget.
Margin on start of widget, horizontally.
Whether the widget will receive the default action when it is focused.
The scale factor of the widget.
Sets the text of tooltip to be the given string, which is marked up with Pango markup.
Sets the text of tooltip to be the given string.
Whether to use the vexpand property.
Functions
Enable or disable an action installed with gtk_widget_class_install_action().
Looks up the action in the action groups associated with
Activates the default.activate action from @widget.
For widgets that can be “activated” (buttons, menu items, etc.), this function activates them.
Adds @controller to @widget so that it will receive events.
Adds a style class to @widget.
Adds a widget to the list of mnemonic labels for this widget.
Queues an animation frame update and adds a callback to be called before each frame.
This function is only used by GtkWidget subclasses, to assign a size, position and (optionally) baseline to their child widgets.
Requests the user's screen reader to announce the given message.
Called by widgets as the user moves around the window using keyboard shortcuts.
Computes the bounds for @widget in the coordinate space of @target.
Computes whether a container should give this widget extra space when possible.
Translates the given @point in @widget's coordinates to coordinates relative to @target’s coordinate system.
Computes a matrix suitable to describe a transformation from
Signals that all holders of a reference to the widget should release the reference that they hold.
Emitted when the text direction of a widget changes.
Emitted when @widget is hidden.
Emitted if keyboard navigation fails.
Emitted when @widget is going to be mapped.
Emitted when a widget is activated via a mnemonic.
Emitted when the focus is moved.
Emitted when the widget’s tooltip is about to be shown.
Emitted when @widget is associated with a GdkSurface.
Emitted once when the widget is realized, and then each time the widget is changed while realized.
Emitted when @widget is shown.
Emitted when the widget state changes.
Emitted when @widget is going to be unmapped.
Emitted when the GdkSurface associated with @widget is destroyed.
Creates a new PangoContext with the appropriate font map, font options, font description, and base direction for drawing text for this widget.
Creates a new PangoLayout with the appropriate font map, font description, and base direction for drawing text for this widget.
Clears the template children for the given widget.
Checks to see if a drag movement has passed the GTK drag threshold.
Retrieves the accessible parent for an accessible object.
Retrieves the accessible role of an accessible object.
Returns the baseline that has currently been allocated to @widget.
Returns the height that has currently been allocated to @widget.
Returns the width that has currently been allocated to @widget.
Gets the first ancestor of @widget with type @widget_type.
Retrieves the accessible implementation for the given GtkAccessible.
Returns the baseline that has currently been allocated to @widget.
Gets the ID of the @buildable object.
Gets the value set with gtk_widget_set_child_visible().
Gets the clipboard object for @widget.
Gets the reading direction for a particular widget.
Get the GdkDisplay for the toplevel window associated with this widget.
Retrieves the first accessible child of an accessible object.
Returns the widget’s first child.
Returns the current focus child of @widget.
Gets the font map of @widget.
Obtains the frame clock for a widget.
Returns the widget’s last child.
Retrieves the next accessible sibling of an accessible object
Returns the widget’s next sibling.
Gets a PangoContext with the appropriate font map, font description, and base direction for this widget.
Query a platform state, such as focus.
Retrieves the minimum and natural size of a widget, taking into account the widget’s preference for height-for-width management.
Returns the widget’s previous sibling.
Gets the primary clipboard of @widget.
Determines whether @widget is realized.
Gets whether the widget prefers a height-for-width layout or a width-for-height layout.
Returns the widget’s sensitivity.
Gets the settings object holding the settings used for this widget.
Returns the content width or height of the widget.
Returns the widget state as a flag set.
Returns the style context associated to @widget.
Fetch an object build from the template XML for @widget_type in this @widget instance.
Determines whether the widget is visible.
Returns whether @css_class is currently applied to @widget.
Determines whether @widget is the current default widget within its toplevel.
Determines if the widget should show a visible indication that it has the global input focus.
Returns whether the widget is currently being destroyed.
Creates and initializes child widgets defined in templates.
Inserts @group into @widget.
Inserts @widget into the child widget list of @parent.
Inserts @widget into the child widget list of @parent.
Determines whether @widget is somewhere inside @ancestor, possibly with intermediate containers.
Determines whether @widget can be drawn to.
Returns the widget’s effective sensitivity.
Emits the ::keynav-failed signal on the widget.
Returns the widgets for which this widget is the target of a mnemonic.
Emits the ::mnemonic-activate signal.
Returns a GListModel to track the children of @widget.
Returns a GListModel to track the class@Gtk.EventControllers of @widget.
Flags the widget for a rerun of the vfunc@Gtk.Widget.size_allocate function.
Flags a widget to have its size renegotiated.
Removes @controller from @widget, so that it doesn't process events anymore.
Removes a style from @widget.
Removes a widget from the list of mnemonic labels for this widget.
Removes a tick callback previously registered with gtk_widget_add_tick_callback().
Resets the accessible @property to its default value.
Resets the accessible @relation to its default value.
Resets the accessible @state to its default value.
Sets the parent and sibling of an accessible object.
Sets whether @widget should be mapped along with its parent.
Sets a named cursor to be shown when pointer devices point towards @widget.
Sets the reading direction on a particular widget.
Setting a draw function is the main thing you want to do when using a drawing area.
Set @child as the current focus child of @widget.
Sets the font map to use for Pango rendering.
Set all margins to the same value.
Set start and end margin to horizontal and top and bottom margin to vertical
Set margins.
Sets the sensitivity of a widget.
Sets the minimum size of a widget.
Turns on flag values in the current widget state.
Sets the visibility state of @widget.
Returns whether @widget should contribute to the measuring and allocation of its parent.
Triggers a tooltip query on the display where the toplevel of @widget is located.
Turns off flag values for the current widget state.
Updates the next accessible sibling of @self.