### Interface

# Gdk Paintable

#### 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().

#### 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.

#### Functions

###### gdk_paintable_new_empty

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

#### 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`.