Highlighter color

hello everyone, I buy a license of PDF, I make highlighter color change dynamically.
When I highlight the text and repeatably highlight on same text, then color get darker and darker...
Please, help me it is very important for me.
Early feedback is appreciated.

You're simply applying more and more highlight annotations one on the top of the previous one.

Exactly, u r right sir but my question is how to replace the old highlight color to new color without make it overlap.

it seems you shall modify some codes.
current AddAnnotMarkup implement:
public boolean AddAnnotMarkup( int cindex1, int cindex2, int type )
{
int color = Global.highlight_color;
if( type == 1 ) color = Global.underline_color;
if( type == 2 ) color = Global.strikeout_color;
if( type == 4 ) color = Global.squiggle_color;
return addAnnotMarkup2( hand, cindex1, cindex2, color, type );
}

so, you can add a new method:
public boolean AddAnnotMarkup( int cindex1, int cindex2, int type, int color )
{
return addAnnotMarkup2( hand, cindex1, cindex2, color, type );
}
this way, you shall add parameter to a new wrapping.