NAME

       SDLx::LayerManager - Extension for managing layers in a 2D world

CATEGORY

       Extension

SYNOPSIS

         use SDLx::Layer;
         use SDLx::LayerManager;

         use SDL::Image;
         use SDL::Surface;
         use SDL::Video;

         # creating layers
         my $layer1 = SDLx::Layer->new( SDL::Image::load('image1.png'), {userdata => '7'} );
         my $layer2 = SDLx::Layer->new( SDL::Image::load('image2.png'), 100, 200, {userdata => '42'} );

         # creating the manager that holds the layers
         my $layermanager = SDLx::LayerManager->new();
         $layermanager->add( $layer1 );
         $layermanager->add( $layer2 );

         my $display = # create your video surface here

         $layermanager->blit( $display );

         # accessing the layer at point(x,y)
         print( $layermanager->by_position( 150, 200 )->data->{userdata} ); # should print '42'

DESCRIPTION

       SDLx::LayerManager is a package to handle a bunch of layers. A layer (see SDLx::Layer) is
       an SDL::Surface, the position of the surface on screen and some additional information.

       The layermanager gives you the opportunity to obtain the layer at a given point on screen
       and get the layers that are ahead or behind a layer.

       You will even be able to attach one or more layers to the mouse, e.g. for simulation some
       drag&drop functionality.

METHODS

   new
         my $layermanager = SDLx::LayerManager->new();

       This creates your layermanager object. It doesn't take any parameters.

   add
         $layermanager->add( $layer );
         $layermanager->add( SDLx::Layer->new( $surface, $x, $y, $options ) );

       Call "add" to push an SDLx::Layer object to the layermanager.

   layers
         my @layers = @{ $layermanager->layers };
         my $first_layer = $layermanager->layers->[0];

       The method "layers" returns all layers that were added before.

   layer
         my $layer = $layermanager->layer( $index );

       To obtain only one layer at index $index use this function. $index ranges from 0 to
       "length - 1".

   length
         my $length = $layermanager->length();

       This method returns the count of the added layers.

   blit
         $layermanager->blit( $surface );

       This method blits all layers to the surface (e.g. your video surface).

   by_position
         my $layer = $layermanager->by_position( $x, $y );

       "by_position" returns the "SDLx::Layer" object at point "$x $y", which is not fully
       transparent at this pixel.

   ahead
         my @layers = @{ $layermanager->ahead( $index ) };

       This method returns all layers that are ahead of the given layer indicated by $index.
       Ahead means that a layer has a higher z-index and is blitted over the given layer.

       Note: This method doesn't check for transparency. This will change in future versions.

   behind
         my @layers = @{ $layermanager->behind( $index ) };

       This method returns all layers that are behind of the given layer indicated by $index.
       Behind means that a layer has a lower z-index and is blitted before the given layer.

       Note: This method doesn't check for transparency. This will change in future versions.

   attach
         $layermanager->attach( $layer,  $x, $y );
         $layermanager->attach( @layers, $x, $y );

       This function makes the given layer(s) sticky to the mouse. If you move the mouse the
       layer(s) will follow.  The layermanager blits these layers at last, so they will appear on
       top of all layers.

       $x and $y should be set to the coords of the mouse, e.g. the coords of the mouse click.
       If you omit $x and $y the layermanager obtains them via SDL::Events::get_mouse_state.

       Note: The z-index is not changed for the given layers.

   detach_xy
         $layermanager->detach_xy( $x, $y );

       "detach_xy" detaches the previously attached layers to the given coords. The upper left
       corner of the backmost layer will be at $x and $y.  The other layers are positioned
       relative to the backmost layer just like before.

   detach_back
         $layermanager->detach_back( );

       "detach_back" detaches the previously attached layers back to the position where they were
       attached.

   foreground
         $layermanager->foreground( $layer );
         $layermanager->foreground( @layers );

       This method moves the given layer(s) to the foreground so that they are blitted on top of
       the other layers.

BUGS

       Report at sdlperl.ath.cx

SUPPORT

       #sdl irc.perl.org

AUTHORS

       See "AUTHORS" in SDL.

COPYRIGHT

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       The full text of the license can be found in the LICENSE file included with this module.

SEE ALSO

       perl(1), SDL(2).