Animation

Section: User Contributed Perl Documentation (3)
Updated: 2021-01-27
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NAME

Tk::Animation - Display sequence of Tk::Photo images

SYNOPSIS

  use Tk::Animation
  my $img = $widget->Animation('-format' => 'gif', -file => 'somefile.gif');

  $img->add_frame(@images);

  $img->start_animation;
  $img->start_animation( $period );

  $img->next_image;
  $img->prev_image;
  $img->set_image( 0 .. $#frames );

  $img->pause_animation;
  $img->resume_animation( $period );

  $img->fast_forward( $multiplier );
  $img->fast_reverse( $multiplier );

  $img->stop_animation;

  $img->set_disposal_method( $boolean );

DESCRIPTION

In the simple case when "Animation" is passed a GIF89 style GIF with multiple 'frames', it will build an internal array of "Photo" images.

The "add_frame" method adds images to the sequence. It is provided to allow animations to be constructed from separate images. All images must be "Photo"s and should all be the same size.

"start_animation($period)" then initiates a "repeat" with specified $period to sequence through these images. As for raw "repeat" $period is in milliseconds, for a 50Hz monitor it should be at least 20ms. If $period is omitted it is determined from the GIF metadata (see below), or if this is not possible it defaults to 100 milliseconds.

"stop_animation" cancels the "repeat" and resets the image to the first image in the sequence.

For fine-grained control "next_image" and "prev_image" move one frame forward or backward. "set_image" randomly positions the animation to a particular frame.

"pause_animation" pauses the movie and "resume_animation" continues from the pause point.

"fast_forward" and "fast_reverse" speed through the movie either forwards or backwards. $multiplier specifies how much faster the animation moves.

If Image::Info is installed, then the repeat period time and disposal method of GIF animations are determined from the GIF metadata directly. Otherwise the disposal method must be set manually by using "set_disposal_method" (1 for blanking the previous images, 0 for leaving the previous images as is). The repeat period time may be given in the "start_animation" method.

NOTES

"set_disposal_method" was formerly known as "blank" method, but the naming of this method was a mistake.

If the disposal method is not set correctly, either by "set_disposal_method" or by determining from the GIF metadata, then the following may happen: By default Animation leaves the previous movie frame in the animation photo. Many times overlaying subsequent frames produces a composite that looks blurred.

BUGS

This module should not depend on a module which is not declared as a dependency (Image::Info).

The delays between images may vary in a GIF animation. This cannot be handled by this module yet.

The handling of the various disposal methods is not correct.