---
name: "Clutter::Cookbook"
section: "3pm"
platform: "linux"
package: "libclutter-perl"
version: "1.002-1"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/Clutter::Cookbook"
---

# Clutter::Cookbook(3pm)

Examples of how to use Clutter

## NAME

Clutter::Cookbook - Examples of how to use Clutter

## DESCRIPTION

This document tries to provide examples on how to perform some common tasks when building an application or a toolkit using the Clutter Perl bindings.

The original version of this document can be found on the Clutter project main site; the online version is aimed at the C API.

## ACTORS

### Maintaining the aspect ratio when loading a texture

Clutter::Texture already provides a property that maintains the aspect ratio of an image loaded on a texture:

```
  Clutter::Texture:keep-aspect-ratio
    type: boolean
    default: FALSE
```

Usually, you just need to set it to TRUE before setting the image data:

```
  $texture = Clutter::Texture->new();
  $texture->set(keep_aspect_ratio => TRUE);
  $texture->set_from_file($filename);
  $texture->set_width(100);
```

This will set up a texture with the contents of *filename*, a width of 100 pixels and an height maintaining the same aspect ratio of the original image.

Clutter::Texture, like the rest of Clutter's actors, is a *height-for-width actor*. This means that the width will be queried first and then the height set for the given width. If you need to set the height of a texture and maintain the same aspect ratio, you will need to change the texture to be a *width-for-height* actor instead, by using this property:

```
  Clutter::Actor:request-mode
    type: Clutter::RequestMode
    default: CLUTTER_REQUEST_HEIGHT_FOR_WIDTH
```

And then setting the height for the actor:

```
  $texture = Clutter::Texture->new();
  $texture->set(
      keep_aspect_ratio => TRUE,
      request_mode      => 'width-for-height',
  );
  $texture->set_from_file($filename);
  $texture->set_height(100);
```

This will set up a texture with the contents of *filename*, a height of 100 pixels and a width maintaining the same aspect ratio of the original image.

## ANIMATIONS

### Inverting animations

If an animation is composed by two identical parts with the latter part "flipping" the animation of the former one, e.g.:

```
                        / scale from 2.0 to 1.0
  begin                /
  +--------------------|--------------------+------> time
  \                                         end
   \ scale from 1.0 to 2.0
```

Instead of using two different effects or two different behaviours you might simply use the

```
  Clutter::Timeline:direction
    type: Clutter::TimelineDirection
    default: CLUTTER_TIMELINE_FORWARD
```

Property of Clutter::Timeline. Set up the *timeline* duration to be the exact half of the overall animation and connect a callback to the

```
  Clutter::Timeline::completed
```

Signal and change the *direction* property; you will also need to rewind the *timeline* so that the state is reset at the right frame number:

```
  $timeline = Clutter::Timeline->new();
  $timeline->set_duration(250); # 250 msecs
  $timeline->signal_connect(completed => sub {
      $timeline->set_direction('backward');
      $timeline->rewind();
      $timeline->start();
  });
```

When the *timeline* is complete it will be restarted from the end and go backward to the start. Any Clutter::Behaviour attached to the *timeline* will be reversed as well, giving you the desired effect.

## AUTHOR

Emmanuele Bassi \<ebassi@linux.intel.com\>

## COPYRIGHT

Copyright (C) 2008 Intel Corporation

## SEE ALSO

[perl(1)](/perl/1.md), [Clutter(3pm)](/Clutter/3pm.md)