module Gdk::Paintable

Overview

Gdk::Paintable is a simple interface used by GTK to represent content that can be painted.

The content of a Gdk::Paintable can be painted anywhere at any size without requiring any sort of layout. The interface is inspired by similar concepts elsewhere, such as ClutterContent, HTML/CSS Paint Sources, or SVG Paint Servers.

A Gdk::Paintable can be snapshot at any time and size using Gdk::Paintable#snapshot. How the paintable interprets that size and if it scales or centers itself into the given rectangle is implementation defined, though if you are implementing a Gdk::Paintable and don't know what to do, it is suggested that you scale your paintable ignoring any potential aspect ratio.

The contents that a Gdk::Paintable produces may depend on the #Gdk::Snapshot passed to it. For example, paintables may decide to use more detailed images on higher resolution screens or when OpenGL is available. A Gdk::Paintable will however always produce the same output for the same snapshot.

A Gdk::Paintable may change its contents, meaning that it will now produce a different output with the same snapshot. Once that happens, it will call Gdk::Paintable#invalidate_contents which will emit the [signal@Gdk::Paintable::invalidate-contents] signal. If a paintable is known to never change its contents, it will set the %GDK_PAINTABLE_STATIC_CONTENTS flag. If a consumer cannot deal with changing contents, it may call Gdk::Paintable#current_image which will return a static paintable and use that.

A paintable can report an intrinsic (or preferred) size or aspect ratio it wishes to be rendered at, though it doesn't have to. Consumers of the interface can use this information to layout thepaintable appropriately. Just like the contents, the size of a paintable can change. A paintable will indicate this by calling Gdk::Paintable#invalidate_size which will emit the [signal@Gdk::Paintable::invalidate-size] signal. And just like for contents, if a paintable is known to never change its size, it will set the %GDK_PAINTABLE_STATIC_SIZE flag.

Besides API for applications, there are some functions that are only useful for implementing subclasses and should not be used by applications: Gdk::Paintable#invalidate_contents, Gdk::Paintable#invalidate_size, Gdk::Paintable#new_empty.

Direct including types

Defined in:

lib/gi-crystal/src/auto/gdk-4.0/paintable.cr

Constructors

Class Method Summary

Instance Method Summary

Constructor Detail

def self.cast(obj : GObject::Object) : self #

Cast a GObject::Object to self, throws a TypeCastError if the cast can't be made.


[View source]

Class Method Detail

def self.cast?(obj : GObject::Object) : self | Nil #

[View source]
def self.g_type : UInt64 #

[View source]
def self.new_empty(intrinsic_width : Int32, intrinsic_height : Int32) : Gdk::Paintable #

[View source]

Instance Method Detail

def compute_concrete_size(specified_width : Float64, specified_height : Float64, default_width : Float64, default_height : Float64, concrete_width : Float64, concrete_height : Float64) : Nil #

[View source]
def current_image : Gdk::Paintable #

[View source]
def flags : Gdk::PaintableFlags #

[View source]
def intrinsic_aspect_ratio : Float64 #

[View source]
def intrinsic_height : Int32 #

[View source]
def intrinsic_width : Int32 #

[View source]
def invalidate_contents : Nil #

[View source]
def invalidate_contents_signal #

[View source]
def invalidate_size : Nil #

[View source]
def invalidate_size_signal #

[View source]
def snapshot(snapshot : Gdk::Snapshot, width : Float64, height : Float64) : Nil #

[View source]
abstract def to_unsafe #

[View source]