Interfacing Raku to Gnome GTK+

Gnome::Gtk3::Image

A widget displaying an image

Description

The Gnome::Gtk3::Image widget displays an image. Various kinds of object can be displayed as an image; most typically, you would load a Gnome::Gdk3::Pixbuf (“pixel buffer”) from a file, and then display that. There’s a convenience function to do this, set_from_file(), used as follows:

my Gnome::Gtk3::Image $image .= new;
$image.set-from-file("myfile.png");

To make it shorter;

my Gnome::Gtk3::Image $image .= new(:file<myfile.png>);

If the file isn’t loaded successfully, the image will contain a “broken image” icon similar to that used in many web browsers. If you want to handle errors in loading the file yourself, for example by displaying an error message, then load the image like next example

my Gnome::Gdk3::Pixbuf $pixbuf .= new(:$file);
die $e.message if $pixbuf.last-error.is-valid;
my Gnome::Gtk3::Image $image .= new(:$pixbuf);

The image file may contain an animation, if so the Gnome::Gtk3::Image will display an animation

Gnome::Gtk3::Image is a “no window” widget (has no Gnome::Gdk3::Window of its own), so by default does not receive events. If you want to receive events on the image, such as button clicks, place the image inside a Gnome::Gtk3::EventBox, then connect to the event signals on the event box.

When handling events on the event box, keep in mind that coordinates in the image may be different from event box coordinates due to the alignment and padding settings on the image (see Gnome::Gtk3::Misc). The simplest way to solve this is to set the alignment to 0.0 (left/top), and set the padding to zero. Then the origin of the image will be the same as the origin of the event box.

A note: Gnome::Gtk3::Misc is almost completely deprecated. It exists only to support the inheritance tree below the Misc class. For alignment and padding look for the methods in Gnome::Gtk3::Widget.

Css Nodes

Gnome::Gtk3::Image has a single CSS node with the name image.

Synopsis

Declaration

unit class Gnome::Gtk3::Image;
also is Gnome::Gtk3::Misc;

Uml Diagram

Inheriting this class

Inheriting is done in a special way in that it needs a call from new() to get the native object created by the class you are inheriting from.

use Gnome::Gtk3::Image;

unit class MyGuiClass;
also is Gnome::Gtk3::Image;

submethod new ( |c ) {
  # let the Gnome::Gtk3::Image class process the options
  self.bless( :GtkImage, |c);
}

submethod BUILD ( ... ) {
  ...
}

Example

Handling button press events on a Gnome::Gtk3::Image.

# Define a button press event handler
method button-press-handler (
  N-GdkEventButton $event, Gnome::Gtk3::EventBox :widget($event-box)
  --> Bool
) {
  say "Event box clicked at coordinates $event.x(), $event.y()");

  # Returning True means we handled the event, so the signal
  # emission should be stopped (don’t call any further callbacks
  # that may be connected). Return False to continue invoking callbacks.
  True
}

# Create an image and setup a button click event on the image.
# Return the result image object
method create-image ( Str $image-file --> Gnome::Gtk3::Image ) {
  my Gnome::Gtk3::Image $image .= new(:filename($image-file));
  my Gnome::Gtk3::EventBox $eb .= new;
  $eb.add($image);
  $eb.register-signal( self, button-press-handler, 'button_press_event');

  $image
}

Types

enum GtkImageType

Describes the image data representation used by a Gnome::Gtk3::Image. If you want to get the image from the widget, you can only get the currently-stored representation. e.g. if the gtk_image_get_storage_type() returns GTK_IMAGE_PIXBUF, then you can call gtk_image_get_pixbuf() but not gtk_image_get_stock(). For empty images, you can request any storage type (call any of the “get” functions), but they will all return Any values.

  • GTK_IMAGE_EMPTY: there is no image displayed by the widget

  • GTK_IMAGE_PIXBUF: the widget contains a Gnome::Gdk3::Pixbuf

  • GTK_IMAGE_STOCK: the widget contains a [stock item name][gtkstock]

  • GTK_IMAGE_ICON_SET: the widget contains a Gnome::Gtk3::IconSet

  • GTK_IMAGE_ANIMATION: the widget contains a Gnome::Gdk3::PixbufAnimation

  • GTK_IMAGE_ICON_NAME: the widget contains a named icon. This image type was added in GTK+ 2.6

  • GTK_IMAGE_GICON: the widget contains a GIcon. This image type was added in GTK+ 2.14

  • GTK_IMAGE_SURFACE: the widget contains a cairo_surface_t. This image type was added in GTK+ 3.10

Methods

new

default, no options

Create a new plain object without an image.

multi method new ( )

:file

Creates a new Gnome::Gtk3::Image displaying the file filename. If the file isn’t found or can’t be loaded, the resulting Gnome::Gtk3::Image will display a “broken image” icon.

If the file contains an animation, the image will contain an animation.

If you need to detect failures to load the file, use gdk_pixbuf_new_from_file() to load the file yourself, then create the Gnome::Gtk3::Image from the pixbuf.

The storage type (gtk_image_get_storage_type()) of the returned image is not defined, it will be whatever is appropriate for displaying the file. Create a new object and load an image from file.

multi method new ( Str :$file! )

:icon-name, :size

Creates a Gnome::Gtk3::Image displaying an icon from the current icon theme. If the icon name isn’t known, a “broken image” icon will be displayed instead. If the current icon theme is changed, the icon will be updated appropriately. You can use the program gtk3-icon-browser to get the available names in the current selected theme.

multi method new (
  Str:D :$icon-name!, GtkIconSize :$size = GTK_ICON_SIZE_BUTTON
)

  • Str $icon_name; an icon name

  • GtkIconSize $size; a stock icon size (an enum GtkIconSize)

:pixbuf

Creates a new Gnome::Gtk3::Image displaying $pixbuf. The Gnome::Gtk3::Image does not assume a reference to the pixbuf; you still need to unref it if you own references. Gnome::Gtk3::Image will add its own reference rather than adopting yours.

Note that this function just creates an Gnome::Gtk3::Image from the pixbuf. The Gnome::Gtk3::Image created will not react to state changes. Should you want that, you should use gtk_image_new_from_icon_name().

multi method new ( N-GObject :$pixbuf! )

:resource-path

Creates a new Gnome::Gtk3::Image displaying the resource file $resource-path. If the file isn’t found or can’t be loaded, the resulting Gnome::Gtk3::Image will display a “broken image” icon. This function never returns Any, it always returns a valid Gnome::Gtk3::Image widget.

If the file contains an animation, the image will contain an animation.

If you need to detect failures to load the file, use gdk_pixbuf_new_from_file() to load the file yourself, then create the Gnome::Gtk3::Image from the pixbuf. (Or for animations, use gdk_pixbuf_animation_new_from_file()).

The storage type (gtk_image_get_storage_type()) of the returned image is not defined, it will be whatever is appropriate for displaying the file.

multi method new ( Str :$resource-path! )

:surface

Creates a new Gnome::Gtk3::Image displaying surface. The Gnome::Gtk3::Image does not assume a reference to the surface; you still need to unref it if you own references. Gnome::Gtk3::Image will add its own reference rather than adopting yours.

multi method new ( cairo_surface_t:D :$surface! )

:native-object

Create a Image object using a native object from elsewhere. See also Gnome::N::TopLevelClassSupport.

multi method new ( N-GObject :$native-object! )

:build-id

Create a Image object using a native object returned from a builder. See also Gnome::GObject::Object.

multi method new ( Str :$build-id! )

clear

Resets the image to be empty.

method clear ( )

get-icon-name

Gets the icon name and size being displayed by the Gnome::Gtk3::Image. The storage type of the image must be GTK-IMAGE-EMPTY or GTK-IMAGE-ICON-NAME (see get-storage-type()). The returned string is owned by the Gnome::Gtk3::Image and should not be freed.

method get-icon-name ( --> List )

  • CArray[Str] $icon_name; place to store an icon name, or undefined

  • GtkIconSize $size; (type int): place to store an icon size (Gnome::Gtk3::IconSize), or undefined

get-pixbuf

Gets the Gnome::Gtk3::Pixbuf being displayed by the Gnome::Gtk3::Image. The storage type of the image must be GTK-IMAGE-EMPTY or GTK-IMAGE-PIXBUF (see get-storage-type()). The caller of this function does not own a reference to the returned pixbuf.

Returns: the displayed pixbuf, or undefined if the image is empty

method get-pixbuf ( --> N-GObject )

get-pixel-size

Gets the pixel size used for named icons.

Returns: the pixel size used for named icons.

method get-pixel-size ( --> Int )

get-storage-type

Gets the type of representation being used by the Gnome::Gtk3::Image to store image data. If the Gnome::Gtk3::Image has no image data, the return value will be GTK-IMAGE-EMPTY.

Returns: image representation being used

method get-storage-type ( --> GtkImageType )

set-from-file

See new-from-file() for details.

method set-from-file ( Str $filename )
  • Str $filename; a filename or undefined

set-from-icon-name

See new-from-icon-name() for details.

method set-from-icon-name ( Str $icon_name, GtkIconSize $size )

  • Str $icon_name; an icon name or undefined

  • GtkIconSize $size; an icon size

set-from-pixbuf

See new-from-pixbuf() for details.

method set-from-pixbuf ( N-GObject $pixbuf )
  • N-GObject $pixbuf; a Gnome::Gtk3::Pixbuf or undefined

set-from-resource

See new-from-resource() for details.

method set-from-resource ( Str $resource_path )
  • Str $resource_path; a resource path or undefined

set-from-surface

See new-from-surface() for details.

method set-from-surface ( cairo_surface_t $surface )
  • cairo_surface_t $surface; a cairo-surface-t or undefined

set-pixel-size

Sets the pixel size to use for named icons. If the pixel size is set to a value != -1, it is used instead of the icon size set by set-from-icon-name().

method set-pixel-size ( Int() $pixel_size )
  • Int() $pixel_size; the new pixel size

Properties

An example of using a string type property of a Gnome::Gtk3::Label object. This is just showing how to set/read a property, not that it is the best way to do it. This is because a) The class initialization often provides some options to set some of the properties and b) the classes provide many methods to modify just those properties. In the case below one can use new(:label(‘my text label’)) or .set-text(‘my text label’).

my Gnome::Gtk3::Label $label .= new;
my Gnome::GObject::Value $gv .= new(:init(G_TYPE_STRING));
$label.get-property( 'label', $gv);
$gv.set-string('my text label');

Supported properties

Filename: file

Filename to load and display Default value: Any

The Gnome::GObject::Value type of property file is G_TYPE_STRING.

Icon Name: icon-name

The name of the icon in the icon theme. If the icon theme is changed, the image will be updated automatically.

The Gnome::GObject::Value type of property icon-name is G_TYPE_STRING.

Pixbuf: pixbuf

A GdkPixbuf to display Widget type: GDK-TYPE-PIXBUF

The Gnome::GObject::Value type of property pixbuf is G_TYPE_OBJECT.

Resource: resource

A path to a resource file to display.

The Gnome::GObject::Value type of property resource is G_TYPE_STRING.

Storage type: storage-type

The representation being used for image data Default value: False

The Gnome::GObject::Value type of property storage-type is G_TYPE_ENUM.

Surface: surface

The Gnome::GObject::Value type of property surface is G_TYPE_BOXED.

Use Fallback: use-fallback

Whether the icon displayed in the GtkImage will use standard icon names fallback. The value of this property is only relevant for images of type GTK-IMAGE-ICON-NAME and GTK-IMAGE-GICON.

The Gnome::GObject::Value type of property use-fallback is G_TYPE_BOOLEAN.