// Make an HTML element fly in from the top or bottom.

// Includes inertia!

// vB, don't even try. It's GPL like the rest of Enano. I know you're jealous. >:)

var fly_in_cache = new Object();

var FI_TOP = 1;

var FI_BOTTOM = 2;

var FI_IN = 1;

var FI_OUT = 2;

var FI_UP = 1;

var FI_DOWN = 2;

/**

 * You can thank Robert Penner for the math used here. Ported from an ActionScript class.

 * License: Modified BSD license <http://www.robertpenner.com/easing_terms_of_use.html>

 */

// Effects code - don't bother changing these formulas

var Back = {

  easeOut: function(t, b, c, d, s)

  {

    if (s == undefined) s = 1.70158;

    return c * ( ( t=t/d-1 ) * t * ( ( s + 1 ) * t + s) + 1) + b;

  },

  easeIn: function (t, b, c, d, s)

  {

    if (s == undefined) s = 1.70158;

    return c * ( t/=d ) * t * ( ( s + 1 ) * t - s) + b;

  },

  easeInOut: function (t, b, c, d, s)

  {

    if (s == undefined) s = 1.70158; 

    if ((t /= d/2) < 1) 

    {

      return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;

    }

    return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;

  }

}

// This should be set to the class name of the effect you want.

var GlideEffect = Back;

// Placeholder functions, to make organization a little easier :-)

function fly_in_top(element, nofade, height_taken_care_of)

{

  return fly_core(element, nofade, FI_TOP, FI_IN, height_taken_care_of);

}

function fly_in_bottom(element, nofade, height_taken_care_of)

{

  return fly_core(element, nofade, FI_BOTTOM, FI_IN, height_taken_care_of);

}

function fly_out_top(element, nofade, height_taken_care_of)

{

  return fly_core(element, nofade, FI_TOP, FI_OUT, height_taken_care_of);

}

function fly_out_bottom(element, nofade, height_taken_care_of)

{

  return fly_core(element, nofade, FI_BOTTOM, FI_OUT, height_taken_care_of);

}

function fly_core(element, nofade, origin, direction, height_taken_care_of)

{

  if ( !element || typeof(element) != 'object' )

    return false;

  // target dimensions

  var top, left;

  // initial dimensions

  var topi, lefti;

  // current dimensions

  var topc, leftc;

  // screen dimensions

  var w = getWidth();

  var h = getHeight();

  var y = parseInt ( getScrollOffset() );

  // temp vars

  var dim, off, diff, dist, ratio, opac_factor;

  // setup element

  element.style.position = 'absolute';

  if ( height_taken_care_of )

  {

    top = off[0];

    left = off[1];

  }

  else

  {

    top  = Math.round(( h / 2 ) - ( dim[0] / 2 )) + y; // - ( h / 4 ));

    left = Math.round(( w / 2 ) - ( dim[1] / 2 ));

  }

  // you can change this around to get it to fly in from corners or be on the left/right side

  lefti = left;

  // calculate first frame Y position

  if ( origin == FI_TOP && direction == FI_IN )

  {

    topi = 0 - dim[0] + y;

  }

  else if ( origin == FI_TOP && direction == FI_OUT )

  {

    topi = top;

    top = 0 - dim[0] + y;

  }

  else if ( origin == FI_BOTTOM && direction == FI_IN )

  {

    topi = h + y;

  }

  else if ( origin == FI_BOTTOM && direction == FI_OUT )

  {

    topi = top;

    top = h + y;

  }

  var abs_dir = ( ( origin == FI_TOP && direction == FI_IN ) || ( origin == FI_BOTTOM && direction == FI_OUT ) ) ? FI_DOWN : FI_UP;

  var diff_top = top - topi;

  var diff_left = left - lefti;

  var frames = 100;

  var timeout = 0;

  var timerstep = 8;

  // cache element so it can be changed from within setTimeout()

  var rand_seed = Math.floor(Math.random() * 1000000);

  fly_in_cache[rand_seed] = element;

  for ( var i = 0; i < frames; i++ )

  {

    topc = GlideEffect.easeInOut(i, topi, diff_top, frames);

    leftc = GlideEffect.easeInOut(i, lefti, diff_left, frames);

    var code = 'var o = fly_in_cache['+rand_seed+']; o.style.top=\''+topc+'px\';';

    if ( !height_taken_care_of )

      code += ' o.style.left=\''+leftc+'px\'';

    code += ';';

    setTimeout(code, timeout);

    timeout += timerstep;

    var ratio = i / frames;

    if ( !nofade )

    {

      // handle fade

      var opac_factor = ratio * 100;

      if ( direction == FI_OUT )

        opac_factor = 100 - opac_factor;

      setTimeout('var o = fly_in_cache['+rand_seed+']; domObjChangeOpac('+opac_factor+', o);', timeout);

    }

  }

  // old framestepper code removed from here in Loch Ness

  timeout += timerstep;

  return timeout;

}

function abs(i)

{

  if ( isNaN(i) )

    return i;

  return ( i < 0 ) ? ( 0 - i ) : i;

}