Gdk::Paintable Class Reference

An interface for a paintable region. More...

#include <gdkmm/paintable.h>

Inheritance diagram for Gdk::Paintable:

Public Types
enum class	Flags {   Flags::STATIC_SIZE = 1 << 0 ,   Flags::STATIC_CONTENTS = 1 << 1 }
	Flags about a paintable object. More...

Public Member Functions
	Paintable (Paintable &&src) noexcept
Paintable &	operator= (Paintable &&src) noexcept
	~Paintable () noexcept override
GdkPaintable *	gobj ()
	Provides access to the underlying C GObject.
const GdkPaintable *	gobj () const
	Provides access to the underlying C GObject.
void	snapshot (const Glib::RefPtr< Gdk::Snapshot > & snapshot, double width, double height)
	Snapshots the given paintable with the given width and height.
Glib::RefPtr< const Paintable >	get_current_image () const
	Gets an immutable paintable for the current contents displayed by paintable.
Flags	get_flags () const
	Get flags for the paintable.
int	get_intrinsic_width () const
	Gets the preferred width the paintable would like to be displayed at.
int	get_intrinsic_height () const
	Gets the preferred height the paintable would like to be displayed at.
double	get_intrinsic_aspect_ratio () const
	Gets the preferred aspect ratio the paintable would like to be displayed at.
void	compute_concrete_size (double specified_width, double specified_height, double default_width, double default_height, double &concrete_width, double &concrete_height) const
	Compute a concrete size for the Gdk::Paintable.
void	invalidate_contents ()
	Called by implementations of Gdk::Paintable to invalidate their contents.
void	invalidate_size ()
	Called by implementations of Gdk::Paintable to invalidate their size.
Glib::SignalProxy< void()>	signal_invalidate_contents ()
Glib::SignalProxy< void()>	signal_invalidate_size ()

Static Public Member Functions
static void	add_interface (GType gtype_implementer)
static GType	get_type ()
	Get the GType for this class, for use with the underlying GObject type system.

Protected Member Functions
	Paintable ()
	You should derive from this class to use it.
virtual void	snapshot_vfunc (const Glib::RefPtr< Gdk::Snapshot > &snapshot, double width, double height)
virtual Glib::RefPtr< Paintable >	get_current_image_vfunc () const
virtual Flags	get_flags_vfunc () const
virtual int	get_intrinsic_width_vfunc () const
virtual int	get_intrinsic_height_vfunc () const
virtual double	get_intrinsic_aspect_ratio_vfunc () const

Related Symbols
(Note that these are not member symbols.)
Glib::RefPtr< Gdk::Paintable >	wrap (GdkPaintable *object, bool take_copy=false)
	A Glib::wrap() method for this object.

Detailed Description

An interface for a paintable region.

Gdk::Paintable is a simple interface used by GDK and GTK to represent objects that 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 Paintable can be snapshot at any time and size using 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 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 Paintable produces may depend on the Snapshot passed to it. For example, paintables may decide to use more detailed images on higher resolution screens or when OpenGL is available. A Paintable will however always produce the same output for the same snapshot.

A Paintable may change its contents, meaning that it will now produce a different output with the same snpashot. Once that happens, it will call invalidate_contents() which will emit the signal_invalidate_contents() signal.
If a paintable is known to never change its contents, it will set the Flags::STATIC_CONTENTS flag. If a consumer cannot deal with changing contents, it may call get_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 the paintable appropriately. Just like the contents, the size of a paintable can change. A paintable will indicate this by calling invalidate_size() which will emit the signal_invalidate_size() signal. And just like for contents, if a paintable is known to never change its size, it will set the Flags::STATIC_SIZE flag.

See also

Gtk::Image, Gdk::Texture, Gtk::Snapshot

Since gtkmm 3.94:

Constructor & Destructor Documentation

Paintable() [1/2]

Gdk::Paintable::Paintable ( )

protected

You should derive from this class to use it.

Paintable() [2/2]

Gdk::Paintable::Paintable ( Paintable &&  src )

noexcept

~Paintable()

Gdk::Paintable::~Paintable ( )

overridenoexcept

Member Function Documentation

add_interface()

static void Gdk::Paintable::add_interface ( GType  gtype_implementer )

static

compute_concrete_size()

void Gdk::Paintable::compute_concrete_size	(	double	specified_width,
		double	specified_height,
		double	default_width,
		double	default_height,
		double &	concrete_width,
		double &	concrete_height
	)		const

Compute a concrete size for the Gdk::Paintable.

Applies the sizing algorithm outlined in the CSS Image spec to the given paintable. See that link for more details.

It is not necessary to call this function when both specified_width and specified_height are known, but it is useful to call this function in GtkWidget:measure implementations to compute the other dimension when only one dimension is given.

Parameters

specified_width	The width paintable could be drawn into or 0.0 if unknown.
specified_height	The height paintable could be drawn into or 0.0 if unknown.
default_width	The width paintable would be drawn into if no other constraints were given.
default_height	The height paintable would be drawn into if no other constraints were given.
concrete_width	Will be set to the concrete width computed.
concrete_height	Will be set to the concrete height computed.

get_current_image()

Glib::RefPtr< const Paintable > Gdk::Paintable::get_current_image

(

)

const

Gets an immutable paintable for the current contents displayed by paintable.

This is useful when you want to retain the current state of an animation, for example to take a screenshot of a running animation.

If the paintable is already immutable, it will return itself.

Returns

An immutable paintable for the current contents of paintable.

get_current_image_vfunc()

virtual Glib::RefPtr< Paintable > Gdk::Paintable::get_current_image_vfunc ( ) const

protectedvirtual

get_flags()

Flags Gdk::Paintable::get_flags

(

)

const

Get flags for the paintable.

This is oftentimes useful for optimizations.

See Gdk::PaintableFlags for the flags and what they mean.

Returns

The Gdk::PaintableFlags for this paintable.

get_flags_vfunc()

virtual Flags Gdk::Paintable::get_flags_vfunc ( ) const

protectedvirtual

get_intrinsic_aspect_ratio()

double Gdk::Paintable::get_intrinsic_aspect_ratio

(

)

const

Gets the preferred aspect ratio the paintable would like to be displayed at.

The aspect ratio is the width divided by the height, so a value of 0.5 means that the paintable prefers to be displayed twice as high as it is wide. Consumers of this interface can use this to preserve aspect ratio when displaying the paintable.

This is a purely informational value and does not in any way limit the values that may be passed to snapshot().

Usually when a paintable returns nonzero values from get_intrinsic_width() and get_intrinsic_height() the aspect ratio should conform to those values, though that is not required.

If the paintable does not have a preferred aspect ratio, it returns 0. Negative values are never returned.

Returns

The intrinsic aspect ratio of paintable or 0 if none.

get_intrinsic_aspect_ratio_vfunc()

virtual double Gdk::Paintable::get_intrinsic_aspect_ratio_vfunc ( ) const

protectedvirtual

get_intrinsic_height()

int Gdk::Paintable::get_intrinsic_height

(

)

const

Gets the preferred height the paintable would like to be displayed at.

Consumers of this interface can use this to reserve enough space to draw the paintable.

This is a purely informational value and does not in any way limit the values that may be passed to snapshot().

If the paintable does not have a preferred height, it returns 0. Negative values are never returned.

Returns

The intrinsic height of paintable or 0 if none.

get_intrinsic_height_vfunc()

virtual int Gdk::Paintable::get_intrinsic_height_vfunc ( ) const

protectedvirtual

get_intrinsic_width()

int Gdk::Paintable::get_intrinsic_width

(

)

const

Gets the preferred width the paintable would like to be displayed at.

Consumers of this interface can use this to reserve enough space to draw the paintable.

This is a purely informational value and does not in any way limit the values that may be passed to snapshot().

If the paintable does not have a preferred width, it returns 0. Negative values are never returned.

Returns

The intrinsic width of paintable or 0 if none.

get_intrinsic_width_vfunc()

virtual int Gdk::Paintable::get_intrinsic_width_vfunc ( ) const

protectedvirtual

get_type()

static GType Gdk::Paintable::get_type ( )

static

Get the GType for this class, for use with the underlying GObject type system.

gobj() [1/2]

GdkPaintable * Gdk::Paintable::gobj ( )

inline

Provides access to the underlying C GObject.

gobj() [2/2]

const GdkPaintable * Gdk::Paintable::gobj ( ) const

inline

Provides access to the underlying C GObject.

invalidate_contents()

void Gdk::Paintable::invalidate_contents

(

)

Called by implementations of Gdk::Paintable to invalidate their contents.

Unless the contents are invalidated, implementations must guarantee that multiple calls of snapshot() produce the same output.

This function will emit the signal_invalidate_contents() signal.

If a paintable reports the Gdk::Paintable::Flags::STATIC_CONTENTS flag, it must not call this function.

invalidate_size()

void Gdk::Paintable::invalidate_size

(

)

Called by implementations of Gdk::Paintable to invalidate their size.

As long as the size is not invalidated, paintable must return the same values for its intrinsic width, height and aspect ratio.

This function will emit the signal_invalidate_size() signal.

If a paintable reports the Gdk::Paintable::Flags::STATIC_SIZE flag, it must not call this function.

operator=()

Paintable & Gdk::Paintable::operator= ( Paintable &&  src )

noexcept

signal_invalidate_contents()

Glib::SignalProxy< void()> Gdk::Paintable::signal_invalidate_contents

(

)

Slot Prototype:

void on_my_invalidate_contents()

Flags: Run Last

Emitted when the contents of the paintable change.

Examples for such an event would be videos changing to the next frame or the icon theme for an icon changing.

signal_invalidate_size()

Glib::SignalProxy< void()> Gdk::Paintable::signal_invalidate_size

(

)

Slot Prototype:

void on_my_invalidate_size()

Flags: Run Last

Emitted when the intrinsic size of the paintable changes.

This means the values reported by at least one of Gdk::Paintable::get_intrinsic_width(), Gdk::Paintable::get_intrinsic_height() or Gdk::Paintable::get_intrinsic_aspect_ratio() has changed.

Examples for such an event would be a paintable displaying the contents of a toplevel surface being resized.

snapshot()

void Gdk::Paintable::snapshot	(	const Glib::RefPtr< Gdk::Snapshot > &	snapshot,
		double	width,
		double	height
	)

Snapshots the given paintable with the given width and height.

The paintable is drawn at the current (0,0) offset of the snapshot. If width and height are not larger than zero, this function will do nothing.

Parameters

snapshot	A Gdk::Snapshot to snapshot to.
width	Width to snapshot in.
height	Height to snapshot in.

snapshot_vfunc()

virtual void Gdk::Paintable::snapshot_vfunc ( const Glib::RefPtr< Gdk::Snapshot > &  snapshot, double  width, double  height  )

protectedvirtual

Friends And Related Symbol Documentation

wrap()

Glib::RefPtr< Gdk::Paintable > wrap ( GdkPaintable *  object, bool  take_copy = false  )

related

A Glib::wrap() method for this object.

Parameters

object	The C instance.
take_copy	False if the result should take ownership of the C instance. True if it should take a new copy or ref.

Returns

A C++ instance that wraps this C instance.