#!/usr/app/bin/perl

eval 'exec /usr/app/bin/perl  -S $0 ${1+"$@"}'
    if 0; # not running under some shell

#
# Note: Seth has transferred the maintainer `position' to me, so bother me
# instead of him now :-)
#       - Steinar H. Gunderson <sgunderson@bigfoot.com>


# This one's all mine.  Well, its GPL/Artisitic but I'm the author and creator. 
# You need gimp 1.1 or better for this; too much has changed, and I don't think
# 1.0.x had a perspective PDB function anyway 

# Here's the working theory on this:
#  There's a function called spinlayer which will spin from a spinlayer to a
#  destlayer.  It won't touch those 2 layers at all, and will leave its results
#  on the top of the layer stack.
#
#  If the user wants to spin back, it will take 1/2 the layers otherwise required
#  per call to the spin_layer, so that the number of total layers comes out the
#  same.  
#
#  The main function makes a new image, copies the source and destination onto it
#  with appropriate offsets, and passes this image with the bottom 2 layers to
#  spin_layer.  At the end, remove the original 2 layers, since they won't be 
#  needed, and add in some Layer comments for timing your gif.
#
################################################################################
#  Many thanks to Steinar and Marc, for expressing an intrest in the script that
#  kept me going, and to Steinar in particular for helping me track down why the
#  script was crashing gimp (hint - don't make layers of height=0, and if you do
#  make sure you're logging to console since the Gtk messagebox will never show
#  up due to a rapid segfault).
#
#  Just a comment on that: We fixed the bug, so height=0 no longer segfaults, but
#  gives the error message it should. However, if GIMP segfaults, you should try
#  logging to console to make sure you get all applicable error messages. This
#  will make it _much_ easier to find the bug. - Steinar
#
# Revision History:
# 1.0 - Initial (too early) release
# 1.1 - Second (still ugly) release: Made the perspective setting actually do
#       something
# 1.2 - Used some of the convienence functions, and made things a little eaiser
#       from the user's standpoint too.  Also moved it from the 
#       Filters->Animations-> menu to Xtns->Animations.  I think its 
#       clearer whats going on this way.  It also works w/ any 2 layers now.
# 1.5 - Some debugging by Steinar and myself to make it work again.
# 1.6 - Moved some renaming into the main loop, more cleanups.
#
# TODO: Clean it up; allow for other effects (skewing, ripples?) while spinning;        

# Seth Burgess
# <sjburges@gimp.org>

use Gimp;  # No qw(:auto) - Trying to use all OO-styling
use Gimp::Fu;
use Gimp::Util;

# Gimp::set_trace(TRACE_ALL);

sub saw {  # a sawtooth function on PI
    ($val) = @_;
    if ($val < 3.14159/2.0) {
        return ($val/3.14159);
    } elsif ($val < 3.14159) {
        return (-1+$val/3.14159); 
    } elsif ($val < 3.14159+3.14159/2.0) {
        return ($val/3.14159);
    } else {
        return (-1+$val/3.14159); 
    }
} 

sub spin_layer { # the function for actually spinning the layer
    my ($img, $spin, $dest, $numframes, $prp) = @_;

    my $floater,  # The transformed image
       $framelay, # The background color
       $frameno;  # The current frame

    # Now let's spin it!
    $stepsize = 3.14159/$numframes; # in radians 
    $frameno = 0;
    for ($i=0; $i<=3.14159; $i+=$stepsize) {
        Gimp->progress_update ($i/3.14159);

        # create a new layer for spinning
        $framelay = ($i < 3.14159/2.0) ? $spin->copy(1) : $dest->copy(1);
        $img->add_layer($framelay, 0);
        $floater = $framelay->copy(1);
        $img->add_layer($floater, 0);

        # spin it a step
        $img->selection_all();
        @x = $img->selection_bounds();
        $img->selection_none();
 
        # x[1],x[2]                  x[3],x[2]
        # x[1],x[4]                  x[3],x[4]
        my($y1, $y3);
        $y1 = int($x[2]+$spin->height *sin($i)/2);
        $y3 = int($x[4]-$spin->height *sin($i)/2);

	# height must be != 0
        $y3++ if ($y1 == $y3);

        $floater = Gimp->perspective($floater, 1,
                       $x[1]+saw($i)*$prp*$framelay->width,$y1,  
                       $x[3]-saw($i)*$prp*$framelay->width,$y1,
                       $x[1]-saw($i)*$prp*$framelay->width,$y3,  
                       $x[3]+saw($i)*$prp*$framelay->width,$y3);
        $framelay->fill(1); # BG-IMAGE-FILL

	# merge the two layers together before we continue
        $img->set_visible($floater, $framelay);
        $framelay = $img->merge_visible_layers(0);

	$frameno++;
	$framelay->set_name("Spin Layer $frameno (50ms)");
    }
}

register "seth_spin",
         "Seth Spin",
         "Take one image.  Spin it about the horizontal axis, and end up with another image.  I made it for easy web buttons.",
         "Seth Burgess",
         "Seth Burgess <sjburges\@gimp.org>",
         "1.6",
         N_"<Toolbox>/Xtns/Animation/Seth Spin...",
         "*",
         [
          [PF_DRAWABLE, "source", "What drawable to spin from?"],
          [PF_DRAWABLE, "destination","What drawable to spin to?"],
          [PF_INT8, "frames", "How many frames to use?", 16],
          [PF_COLOR, "background", "What color to use for background if not transparent", [0,0,0]],
          [PF_SLIDER, "perspective", "How much perspective effect to get", 40, [0,255,5]],
          [PF_TOGGLE, "spin_back", "Also spin back?" , 1],
          [PF_TOGGLE, "convert_indexed", "Convert to indexed?", 1],
         ],
         [],
         ['gimp-1.1'],
         sub {
    my($src,$dest,$frames,$color,$perspective,$spinback,$indexed) = @_;
    
    $oldbackground = Gimp->palette_get_background();
    Gimp->palette_set_background($color);

    $perspective = $perspective/255.0; # PF_SLIDER doesn't work right for < 1

    Gimp->progress_init(__"Seth Spin...",-1);

    # Copy souce and destination to new image
    
    $maxwide = ($src->width > $dest->width) ? $src->width : $dest->width;
    $maxhigh = ($src->height > $dest->height) ? $src->height: $dest->height;

    $img = Gimp->image_new($maxwide, $maxhigh, RGB);
    $tmpimglayer = $img->add_new_layer(0,3,1); # have to have a layer before displaying
    $img->display_new;

    $src->edit_copy();
    $spinlayer = $tmpimglayer->edit_paste(1);
    $spinlayer->floating_sel_to_layer();

    $dest->edit_copy();
    $destlayer = $tmpimglayer->edit_paste(1);
    $destlayer->floating_sel_to_layer();

    $tmpimglayer->remove_layer;                # remove temporary layer.

    # set the layer size to be the full layer for each copied layer
    $spinlayer->resize($maxwide, $maxhigh, $spinlayer->offsets);
    $destlayer->resize($maxwide, $maxhigh, $destlayer->offsets);

    # need an even number of frames for spinback
    if ($frames%2 && $spinback) {
        $frames++;
        Gimp->message(__"An even number of frames is needed for spin back.\nAdjusted frames up to $frames");
    }

    spin_layer($img, $spinlayer, $destlayer, $spinback ? $frames/2 : $frames, $perspective);
   
    # go back from destination to spinlayer if spinning back 
    if ($spinback) { 
        @layerlist = $img->get_layers();
        spin_layer($img, $destlayer, $spinlayer, $frames/2, $perspective);
    }    
 
    # remove the original 2 pasted layers
    $img->remove_layer($destlayer);
    $img->remove_layer($spinlayer);

    # unhide and name layers (Give timings)
    @all_layers = $img->get_layers;
    $img->set_visible(@all_layers);

    if ($spinback) {
        $all_layers[$frames/2-1]->set_name(__"Spin Layer DEST (250ms)");
    }
    $all_layers[$frames-1]->set_name(__"Spin Layer SRC (250ms)");  

    # indexed conversion wants a display for some reason
    if ($indexed) { 
        $img->convert_indexed(1,MAKE_PALETTE,255,0,1,"buffy" ); 
    } 

    Gimp->palette_set_background($oldbackground);
    return();
};

exit main;

