Interface

GdkPaintable

Description [src] 

interface Gdk.Paintable : GObject.Object

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 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_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 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 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().

Prerequisite

In order to implement Paintable, your type must inherit from GObject.

Implementations

Functions

gdk_paintable_new_empty

Returns a paintable that has the given intrinsic size and draws nothing.

Instance methods

gdk_paintable_compute_concrete_size

Compute a concrete size for the GdkPaintable.

gdk_paintable_get_current_image

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

gdk_paintable_get_flags

Get flags for the paintable.

gdk_paintable_get_intrinsic_aspect_ratio

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

gdk_paintable_get_intrinsic_height

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

gdk_paintable_get_intrinsic_width

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

gdk_paintable_invalidate_contents

Called by implementations of GdkPaintable to invalidate their contents.

gdk_paintable_invalidate_size

Called by implementations of GdkPaintable to invalidate their size.

gdk_paintable_snapshot

Snapshots the given paintable with the given width and height.

Signals

Gdk.Paintable::invalidate-contents

Emitted when the contents of the paintable change.

Gdk.Paintable::invalidate-size

Emitted when the intrinsic size of the paintable changes.

Interface structure 

struct GdkPaintableInterface {
  void (* snapshot) (
    GdkPaintable* paintable,
    GdkSnapshot* snapshot,
    double width,
    double height
  );
  GdkPaintable* (* get_current_image) (
    GdkPaintable* paintable
  );
  GdkPaintableFlags (* get_flags) (
    GdkPaintable* paintable
  );
  int (* get_intrinsic_width) (
    GdkPaintable* paintable
  );
  int (* get_intrinsic_height) (
    GdkPaintable* paintable
  );
  double (* get_intrinsic_aspect_ratio) (
    GdkPaintable* paintable
  );
  
}
Interface members
snapshot 
void (* snapshot) (
    GdkPaintable* paintable,
    GdkSnapshot* snapshot,
    double width,
    double height
  )
 No description available.
get_current_image 
GdkPaintable* (* get_current_image) (
    GdkPaintable* paintable
  )
 No description available.
get_flags 
GdkPaintableFlags (* get_flags) (
    GdkPaintable* paintable
  )
 No description available.
get_intrinsic_width 
int (* get_intrinsic_width) (
    GdkPaintable* paintable
  )
 No description available.
get_intrinsic_height 
int (* get_intrinsic_height) (
    GdkPaintable* paintable
  )
 No description available.
get_intrinsic_aspect_ratio 
double (* get_intrinsic_aspect_ratio) (
    GdkPaintable* paintable
  )
 No description available.

Virtual methods

Gdk.Paintable.get_current_image

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

Gdk.Paintable.get_flags

Get flags for the paintable.

Gdk.Paintable.get_intrinsic_aspect_ratio

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

Gdk.Paintable.get_intrinsic_height

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

Gdk.Paintable.get_intrinsic_width

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

Gdk.Paintable.snapshot

Snapshots the given paintable with the given width and height.