module Gdk::Paintable

Overview

GdkPaintable is a simple interface used by GTK to represent content that can be painted.

The content of a GdkPaintable 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 GdkPaintable 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 GdkPaintable and don't know what to do, it is suggested that you scale your paintable ignoring any potential aspect ratio.

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

A GdkPaintable 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@GdkPaintable::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@GdkPaintable::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

Class Method Summary

Instance Method Summary

Class Method Detail

def self.g_type : UInt64 #

def self.new_empty(intrinsic_width : Int32, intrinsic_height : Int32) : Gdk::Paintable #

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 #

def current_image : Gdk::Paintable #

def flags : Gdk::PaintableFlags #

def intrinsic_aspect_ratio : Float64 #

def intrinsic_height : Int32 #

def intrinsic_width : Int32 #

def invalidate_contents : Nil #

def invalidate_contents_signal #

def invalidate_size : Nil #

def invalidate_size_signal #

def snapshot(snapshot : Gdk::Snapshot, width : Float64, height : Float64) : Nil #

abstract def to_unsafe #