class Gtk::DrawingArea

Overview

Gtk::DrawingArea is a widget that allows drawing with cairo.

An example Gtk::DrawingArea

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

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

Simple Gtk::DrawingArea usage

WARNING ⚠️ The following code is in c ⚠️

static void
draw_function (Gtk::DrawingArea *area,
               cairo_::t        *cr,
               int             width,
               int             height,
               gpointer        data)
{
  Gdk::RGBA color;
  Gtk::StyleContext *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 ();

  Gtk::Widget *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 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 Gdk::cairo_::set_source_rgba or 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 Gtk::Widget subclass.

Included Modules

Defined in:

lib/gi-crystal/src/auto/gtk-4.0/drawing_area.cr

Constructors

Class Method Summary

Instance Method Summary

Instance methods inherited from module Gtk::ConstraintTarget

to_unsafe to_unsafe

Constructor methods inherited from module Gtk::ConstraintTarget

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::ConstraintTarget

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from module Gtk::Buildable

buildable_id : String | Nil buildable_id, to_unsafe to_unsafe

Constructor methods inherited from module Gtk::Buildable

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::Buildable

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from module Gtk::Accessible

accessible_role : Gtk::AccessibleRole accessible_role, accessible_role=(value : Gtk::AccessibleRole) : Gtk::AccessibleRole accessible_role=, reset_property(property : Gtk::AccessibleProperty) : Nil reset_property, reset_relation(relation : Gtk::AccessibleRelation) : Nil reset_relation, reset_state(state : Gtk::AccessibleState) : Nil reset_state, to_unsafe to_unsafe, update_property(properties : Enumerable(Gtk::AccessibleProperty), values : Enumerable(_)) : Nil update_property, update_relation(relations : Enumerable(Gtk::AccessibleRelation), values : Enumerable(_)) : Nil update_relation, update_state(states : Enumerable(Gtk::AccessibleState), values : Enumerable(_)) : Nil update_state

Constructor methods inherited from module Gtk::Accessible

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::Accessible

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from class Gtk::Widget

==(other : self) ==, action_set_enabled(action_name : String, enabled : Bool) : Nil action_set_enabled, activate : Bool activate, activate_action(name : String, args : _ | Nil) : Bool activate_action, activate_default : Nil activate_default, add_controller(controller : Gtk::EventController) : Nil add_controller, add_css_class(css_class : String) : Nil add_css_class, add_mnemonic_label(label : Gtk::Widget) : Nil add_mnemonic_label, add_tick_callback(callback : Gtk::TickCallback) : UInt32 add_tick_callback, allocate(width : Int32, height : Int32, baseline : Int32, transform : Gsk::Transform | Nil) : Nil allocate, allocated_baseline : Int32 allocated_baseline, allocated_height : Int32 allocated_height, allocated_width : Int32 allocated_width, allocation : Gdk::Rectangle allocation, ancestor(widget_type : UInt64) : Gtk::Widget | Nil ancestor, can_focus : Bool can_focus, can_focus=(can_focus : Bool) : Nil can_focus=, can_focus? : Bool can_focus?, can_target : Bool can_target, can_target=(can_target : Bool) : Nil can_target=, can_target? : Bool can_target?, child_focus(direction : Gtk::DirectionType) : Bool child_focus, child_visible : Bool child_visible, child_visible=(child_visible : Bool) : Nil child_visible=, children : Iterator(Widget) children, clipboard : Gdk::Clipboard clipboard, compute_bounds(target : Gtk::Widget) : Graphene::Rect compute_bounds, compute_expand(orientation : Gtk::Orientation) : Bool compute_expand, compute_point(target : Gtk::Widget, point : Graphene::Point) : Graphene::Point compute_point, compute_transform(target : Gtk::Widget) : Graphene::Matrix compute_transform, contains(x : Float64, y : Float64) : Bool contains, create_pango_context : Pango::Context create_pango_context, create_pango_layout(text : String | Nil) : Pango::Layout create_pango_layout, css_classes : Enumerable(String) css_classes, css_classes=(classes : Enumerable(String)) : Nil css_classes=, css_name : String css_name, css_name=(value : String) : String
css_name=(value : Nil) : Nil
css_name=
, css_name? : String | Nil css_name?, cursor : Gdk::Cursor | Nil cursor, cursor=(cursor : Gdk::Cursor | Nil) : Nil cursor=, cursor_from_name=(name : String | Nil) : Nil cursor_from_name=, destroy_signal destroy_signal, direction : Gtk::TextDirection direction, direction=(dir : Gtk::TextDirection) : Nil direction=, direction_changed_signal direction_changed_signal, display : Gdk::Display display, drag_check_threshold(start_x : Int32, start_y : Int32, current_x : Int32, current_y : Int32) : Bool drag_check_threshold, error_bell : Nil error_bell, first_child : Gtk::Widget | Nil first_child, focus_child : Gtk::Widget | Nil focus_child, focus_child=(child : Gtk::Widget | Nil) : Nil focus_child=, focus_on_click : Bool focus_on_click, focus_on_click=(focus_on_click : Bool) : Nil focus_on_click=, focus_on_click? : Bool focus_on_click?, focusable : Bool focusable, focusable=(focusable : Bool) : Nil focusable=, focusable? : Bool focusable?, font_map : Pango::FontMap | Nil font_map, font_map=(font_map : Pango::FontMap | Nil) : Nil font_map=, font_options : Cairo::FontOptions | Nil font_options, font_options=(options : Cairo::FontOptions | Nil) : Nil font_options=, frame_clock : Gdk::FrameClock | Nil frame_clock, grab_focus : Bool grab_focus, halign : Gtk::Align halign, halign=(align : Gtk::Align) : Nil halign=, has_css_class(css_class : String) : Bool has_css_class, has_default : Bool has_default, has_default? : Bool has_default?, has_focus : Bool has_focus, has_focus? : Bool has_focus?, has_tooltip : Bool has_tooltip, has_tooltip=(has_tooltip : Bool) : Nil has_tooltip=, has_tooltip? : Bool has_tooltip?, has_visible_focus : Bool has_visible_focus, hash(hasher) hash, height : Int32 height, height_request : Int32 height_request, height_request=(value : Int32) : Int32 height_request=, hexpand : Bool hexpand, hexpand=(expand : Bool) : Nil hexpand=, hexpand? : Bool hexpand?, hexpand_set : Bool hexpand_set, hexpand_set=(set : Bool) : Nil hexpand_set=, hexpand_set? : Bool hexpand_set?, hide : Nil hide, hide_signal hide_signal, in_destruction : Bool in_destruction, init_template : Nil init_template, insert_action_group(name : String, group : Gio::ActionGroup | Nil) : Nil insert_action_group, insert_after(parent : Gtk::Widget, previous_sibling : Gtk::Widget | Nil) : Nil insert_after, insert_before(parent : Gtk::Widget, next_sibling : Gtk::Widget | Nil) : Nil insert_before, is_ancestor(ancestor : Gtk::Widget) : Bool is_ancestor, is_drawable : Bool is_drawable, is_focus : Bool is_focus, is_sensitive : Bool is_sensitive, is_visible : Bool is_visible, keynav_failed(direction : Gtk::DirectionType) : Bool keynav_failed, keynav_failed_signal keynav_failed_signal, last_child : Gtk::Widget | Nil last_child, layout_manager : Gtk::LayoutManager | Nil layout_manager, layout_manager=(layout_manager : Gtk::LayoutManager | Nil) : Nil layout_manager=, list_mnemonic_labels : GLib::List list_mnemonic_labels, map : Nil map, map_signal map_signal, mapped : Bool mapped, margin_bottom : Int32 margin_bottom, margin_bottom=(margin : Int32) : Nil margin_bottom=, margin_end : Int32 margin_end, margin_end=(margin : Int32) : Nil margin_end=, margin_start : Int32 margin_start, margin_start=(margin : Int32) : Nil margin_start=, margin_top : Int32 margin_top, margin_top=(margin : Int32) : Nil margin_top=, measure(orientation : Gtk::Orientation, for_size : Int32) : Nil measure, mnemonic_activate(group_cycling : Bool) : Bool mnemonic_activate, mnemonic_activate_signal mnemonic_activate_signal, move_focus_signal move_focus_signal, name : String name, name=(name : String) : Nil
name=(value : Nil) : Nil
name=
, name? : String | Nil name?, native : Gtk::Native | Nil native, next_sibling : Gtk::Widget | Nil next_sibling, observe_children : Gio::ListModel observe_children, observe_controllers : Gio::ListModel observe_controllers, opacity : Float64 opacity, opacity=(opacity : Float64) : Nil opacity=, overflow : Gtk::Overflow overflow, overflow=(overflow : Gtk::Overflow) : Nil overflow=, pango_context : Pango::Context pango_context, parent : Gtk::Widget | Nil parent, parent=(parent : Gtk::Widget) : Nil parent=, pick(x : Float64, y : Float64, flags : Gtk::PickFlags) : Gtk::Widget | Nil pick, preferred_size : Gtk::Requisition preferred_size, prev_sibling : Gtk::Widget | Nil prev_sibling, primary_clipboard : Gdk::Clipboard primary_clipboard, query_tooltip_signal query_tooltip_signal, queue_allocate : Nil queue_allocate, queue_draw : Nil queue_draw, queue_resize : Nil queue_resize, realize : Nil realize, realize_signal realize_signal, realized : Bool realized, receives_default : Bool receives_default, receives_default=(receives_default : Bool) : Nil receives_default=, receives_default? : Bool receives_default?, remove_controller(controller : Gtk::EventController) : Nil remove_controller, remove_css_class(css_class : String) : Nil remove_css_class, remove_mnemonic_label(label : Gtk::Widget) : Nil remove_mnemonic_label, remove_tick_callback(id : UInt32) : Nil remove_tick_callback, request_mode : Gtk::SizeRequestMode request_mode, root : Gtk::Root | Nil root, scale_factor : Int32 scale_factor, sensitive : Bool sensitive, sensitive=(sensitive : Bool) : Nil sensitive=, sensitive? : Bool sensitive?, set_size_request(width : Int32, height : Int32) : Nil set_size_request, set_state_flags(flags : Gtk::StateFlags, clear : Bool) : Nil set_state_flags, settings : Gtk::Settings settings, should_layout : Bool should_layout, show : Nil show, show_signal show_signal, size(orientation : Gtk::Orientation) : Int32 size, size_allocate(x : Int32, y : Int32, width : Int32, height : Int32, baseline : Int32)
size_allocate(allocation : Gdk::Rectangle, baseline : Int32) : Nil
size_allocate
, size_request : Nil size_request, snapshot_child(child : Gtk::Widget, snapshot : Gtk::Snapshot) : Nil snapshot_child, state_flags : Gtk::StateFlags state_flags, state_flags_changed_signal state_flags_changed_signal, style_context : Gtk::StyleContext style_context, template_child(widget_type : UInt64, name : String) : GObject::Object
template_child(name : String) : GObject::Object
template_child
, tooltip_markup : String | Nil tooltip_markup, tooltip_markup=(value : String) : String
tooltip_markup=(value : Nil) : Nil
tooltip_markup=(markup : String | Nil) : Nil
tooltip_markup=
, tooltip_markup? : String | Nil tooltip_markup?, tooltip_text : String | Nil tooltip_text, tooltip_text=(value : String) : String
tooltip_text=(value : Nil) : Nil
tooltip_text=(text : String | Nil) : Nil
tooltip_text=
, tooltip_text? : String | Nil tooltip_text?, translate_coordinates(dest_widget : Gtk::Widget, src_x : Float64, src_y : Float64) : Bool translate_coordinates, trigger_tooltip_query : Nil trigger_tooltip_query, unmap : Nil unmap, unmap_signal unmap_signal, unparent : Nil unparent, unrealize : Nil unrealize, unrealize_signal unrealize_signal, unset_state_flags(flags : Gtk::StateFlags) : Nil unset_state_flags, valign : Gtk::Align valign, valign=(align : Gtk::Align) : Nil valign=, vexpand : Bool vexpand, vexpand=(expand : Bool) : Nil vexpand=, vexpand? : Bool vexpand?, vexpand_set : Bool vexpand_set, vexpand_set=(set : Bool) : Nil vexpand_set=, vexpand_set? : Bool vexpand_set?, visible : Bool visible, visible=(visible : Bool) : Nil visible=, visible? : Bool visible?, width : Int32 width, width_request : Int32 width_request, width_request=(value : Int32) : Int32 width_request=

Constructor methods inherited from class Gtk::Widget

new
new(*, accessible_role : Gtk::AccessibleRole | Nil = nil, can_focus : Bool | Nil = nil, can_target : Bool | Nil = nil, css_classes : Enumerable(String) | Nil = nil, css_name : String | Nil = nil, cursor : Gdk::Cursor | Nil = nil, focus_on_click : Bool | Nil = nil, focusable : Bool | Nil = nil, halign : Gtk::Align | Nil = nil, has_default : Bool | Nil = nil, has_focus : Bool | Nil = nil, has_tooltip : Bool | Nil = nil, height_request : Int32 | Nil = nil, hexpand : Bool | Nil = nil, hexpand_set : Bool | Nil = nil, layout_manager : Gtk::LayoutManager | Nil = nil, margin_bottom : Int32 | Nil = nil, margin_end : Int32 | Nil = nil, margin_start : Int32 | Nil = nil, margin_top : Int32 | Nil = nil, name : String | Nil = nil, opacity : Float64 | Nil = nil, overflow : Gtk::Overflow | Nil = nil, parent : Gtk::Widget | Nil = nil, receives_default : Bool | Nil = nil, root : Gtk::Root | Nil = nil, scale_factor : Int32 | Nil = nil, sensitive : Bool | Nil = nil, tooltip_markup : String | Nil = nil, tooltip_text : String | Nil = nil, valign : Gtk::Align | Nil = nil, vexpand : Bool | Nil = nil, vexpand_set : Bool | Nil = nil, visible : Bool | Nil = nil, width_request : Int32 | Nil = nil)
new

Class methods inherited from class Gtk::Widget

default_direction : Gtk::TextDirection default_direction, default_direction=(dir : Gtk::TextDirection) : Nil default_direction=, g_type : UInt64 g_type

Instance methods inherited from module Gtk::ConstraintTarget

to_unsafe to_unsafe

Constructor methods inherited from module Gtk::ConstraintTarget

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::ConstraintTarget

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from module Gtk::Buildable

buildable_id : String | Nil buildable_id, to_unsafe to_unsafe

Constructor methods inherited from module Gtk::Buildable

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::Buildable

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from module Gtk::Accessible

accessible_role : Gtk::AccessibleRole accessible_role, accessible_role=(value : Gtk::AccessibleRole) : Gtk::AccessibleRole accessible_role=, reset_property(property : Gtk::AccessibleProperty) : Nil reset_property, reset_relation(relation : Gtk::AccessibleRelation) : Nil reset_relation, reset_state(state : Gtk::AccessibleState) : Nil reset_state, to_unsafe to_unsafe, update_property(properties : Enumerable(Gtk::AccessibleProperty), values : Enumerable(_)) : Nil update_property, update_relation(relations : Enumerable(Gtk::AccessibleRelation), values : Enumerable(_)) : Nil update_relation, update_state(states : Enumerable(Gtk::AccessibleState), values : Enumerable(_)) : Nil update_state

Constructor methods inherited from module Gtk::Accessible

cast(obj : GObject::Object) : self cast

Class methods inherited from module Gtk::Accessible

cast?(obj : GObject::Object) : self | Nil cast?, g_type : UInt64 g_type

Instance methods inherited from class GObject::InitiallyUnowned

==(other : self) ==, hash(hasher) hash

Constructor methods inherited from class GObject::InitiallyUnowned

new new

Class methods inherited from class GObject::InitiallyUnowned

g_type : UInt64 g_type

Instance methods inherited from class GObject::Object

==(other : self) ==, bind_property(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags) : GObject::Binding bind_property, bind_property_full(source_property : String, target : GObject::Object, target_property : String, flags : GObject::BindingFlags, transform_to : GObject::Closure, transform_from : GObject::Closure) : GObject::Binding bind_property_full, data(key : String) : Pointer(Void) | Nil data, finalize finalize, freeze_notify : Nil freeze_notify, getv(names : Enumerable(String), values : Enumerable(_)) : Nil getv, hash(hasher) hash, notify(property_name : String) : Nil notify, notify_by_pspec(pspec : GObject::ParamSpec) : Nil notify_by_pspec, notify_signal notify_signal, property(property_name : String, value : _) : Nil property, qdata(quark : UInt32) : Pointer(Void) | Nil qdata, ref_count : UInt32 ref_count, run_dispose : Nil run_dispose, set_data(key : String, data : Pointer(Void) | Nil) : Nil set_data, set_property(property_name : String, value : _) : Nil set_property, steal_data(key : String) : Pointer(Void) | Nil steal_data, steal_qdata(quark : UInt32) : Pointer(Void) | Nil steal_qdata, thaw_notify : Nil thaw_notify, to_unsafe : Pointer(Void) to_unsafe, watch_closure(closure : GObject::Closure) : Nil watch_closure

Constructor methods inherited from class GObject::Object

cast(obj : GObject::Object) : self cast, new(pointer : Pointer(Void), transfer : GICrystal::Transfer)
new
new
, newv(object_type : UInt64, parameters : Enumerable(GObject::Parameter)) : self newv

Class methods inherited from class GObject::Object

cast?(obj : GObject::Object) : self | Nil cast?, compat_control(what : UInt64, data : Pointer(Void) | Nil) : UInt64 compat_control, g_type : UInt64 g_type, interface_find_property(g_iface : GObject::TypeInterface, property_name : String) : GObject::ParamSpec interface_find_property, interface_list_properties(g_iface : GObject::TypeInterface) : Enumerable(GObject::ParamSpec) interface_list_properties

Macros inherited from class GObject::Object

previous_vfunc(*args) previous_vfunc, previous_vfunc!(*args) previous_vfunc!, signal(signature) signal

Constructor Detail

def self.new : self #

Creates a new drawing area.


[View source]
def self.new(*, accessible_role : Gtk::AccessibleRole | Nil = nil, can_focus : Bool | Nil = nil, can_target : Bool | Nil = nil, content_height : Int32 | Nil = nil, content_width : Int32 | Nil = nil, css_classes : Enumerable(String) | Nil = nil, css_name : String | Nil = nil, cursor : Gdk::Cursor | Nil = nil, focus_on_click : Bool | Nil = nil, focusable : Bool | Nil = nil, halign : Gtk::Align | Nil = nil, has_default : Bool | Nil = nil, has_focus : Bool | Nil = nil, has_tooltip : Bool | Nil = nil, height_request : Int32 | Nil = nil, hexpand : Bool | Nil = nil, hexpand_set : Bool | Nil = nil, layout_manager : Gtk::LayoutManager | Nil = nil, margin_bottom : Int32 | Nil = nil, margin_end : Int32 | Nil = nil, margin_start : Int32 | Nil = nil, margin_top : Int32 | Nil = nil, name : String | Nil = nil, opacity : Float64 | Nil = nil, overflow : Gtk::Overflow | Nil = nil, parent : Gtk::Widget | Nil = nil, receives_default : Bool | Nil = nil, root : Gtk::Root | Nil = nil, scale_factor : Int32 | Nil = nil, sensitive : Bool | Nil = nil, tooltip_markup : String | Nil = nil, tooltip_text : String | Nil = nil, valign : Gtk::Align | Nil = nil, vexpand : Bool | Nil = nil, vexpand_set : Bool | Nil = nil, visible : Bool | Nil = nil, width_request : Int32 | Nil = nil) #

[View source]

Class Method Detail

def self.g_type : UInt64 #

Returns the type id (GType) registered in GLib type system.


[View source]

Instance Method Detail

def ==(other : self) #
Description copied from class Reference

Returns true if this reference is the same as other. Invokes same?.


def content_height : Int32 #

Retrieves the content height of the Gtk::DrawingArea.


[View source]
def content_height=(height : Int32) : Nil #

Sets the desired height of the contents of the drawing area.

Note that because widgets may be allocated larger sizes than they requested, it is possible that the actual height passed to your draw function is larger than the height set here. You can use Gtk::Widget#valign= to avoid that.

If the height is set to 0 (the default), the drawing area may disappear.


[View source]
def content_width : Int32 #

Retrieves the content width of the Gtk::DrawingArea.


[View source]
def content_width=(width : Int32) : Nil #

Sets the desired width of the contents of the drawing area.

Note that because widgets may be allocated larger sizes than they requested, it is possible that the actual width passed to your draw function is larger than the width set here. You can use Gtk::Widget#halign= to avoid that.

If the width is set to 0 (the default), the drawing area may disappear.


[View source]
def draw_func=(draw_func : Gtk::DrawingAreaDrawFunc | Nil) : Nil #

Setting a draw function is the main thing you want to do when using a drawing area.

The draw function is called whenever GTK needs to draw the contents of the drawing area to the screen.

The draw function will be called during the drawing stage of GTK. In the drawing stage it is not allowed to change properties of any GTK widgets or call any functions that would cause any properties to be changed. You should restrict yourself exclusively to drawing your contents in the draw function.

If what you are drawing does change, call Gtk::Widget#queue_draw on the drawing area. This will cause a redraw and will call draw_func again.


[View source]
def hash(hasher) #
Description copied from class Reference

See Object#hash(hasher)


def resize_signal #

[View source]