/*
	Class 		: scrollable_statictext
	SuperClass 	: statictext

	Author		: Cathy Waite
			  Turing Institute

	Date		: Mon Jan 28 12:23:11 GMT 1991


	Funtionality    : Can display and format several lines of text.
			  The text is scrollable.
*/

#include <ol.h>
#include "statictext.h"

#define SCROLLGAP	4
int scroll_width = OLScrollW + SCROLLGAP;

/* Compute area available for actual text, treaking into account the
   scroll bar
*/

int textarea_width()
{
    return w - margin2 - scroll_width;
}

int boxarea_width()
{
    return w - scroll_width;
}

/***********************************************************************

  			Scrolling Procedures

***********************************************************************/

/* Set the given line to be the first line displayed (i.e. */
/* display_to_line) and repaint the appropropriate lined */

/* Sets top line, without notify scrollbar, thus avoiding cyclic */
/* update messages.  This is the version the scrollbar should use all */
/* other methods should use "set_top_line" */

void set_top_line(int new_top)
{
    if (new_top == display_top_line)
	return;
    gexeca(/do_set_top_line,[new_top]);
     if (promoted(/@scroll))
	Send changevalue(display_top_line) to /@scroll;
}

void do_set_top_line(int new_top)
{
    int new_bottom, old_top, old_bottom;
    int line_height;

    if ((new_top >= 0) && (new_top <= total_display_lines))
	{
	    new_bottom = min(total_display_lines,max(0,new_top+max_display_lines-1));
	    if ((new_bottom < display_top_line) ||  (new_top >
						    display_bottom_line))
		{
		    display_top_line = new_top;
		    display_bottom_line = new_bottom;
		    
		    /*need to redisplay all lines */
		    gexeca(/paint_text_from_line,[display_top_line]);
		}
	    
	    else /* scrolling to a line already visible, use copyarea */
		{
		    line_height = fontheight(textfont)+line_gap;
		    
		    if (new_top < display_top_line)
			{
			   rectpath(margin,ypos_from_line(new_bottom),textarea_width,(new_bottom-display_top_line+1)*line_height);
			   
			    copyarea(0,(new_top-display_top_line)*line_height); 
			    old_top = display_top_line;
			    display_top_line = new_top;
			    display_bottom_line = new_bottom;
			    paint_text_from_line_to(display_top_line,old_top-1);
			 
			}
		    else
			{
			    rectpath(margin,ypos_from_line(display_bottom_line),textarea_width,(display_bottom_line-max(0,new_top-1))*line_height);
			   
			    copyarea(0,(new_top-display_top_line)*line_height);
			    display_top_line = new_top;
			    old_bottom = display_bottom_line;
			    display_bottom_line = new_bottom;
			    paint_text_from_line(old_bottom+1);
			}
		}
	}
}

void scroll_up_line()
{
    if (display_top_line > 0)
      set_top_line(display_top_line-1);
}

void scroll_down_line()
{
    /* Don't allow to scroll past  total_display_line - 1, so last line
       is visible */
    if (display_top_line < total_display_lines)
      set_top_line(display_top_line+1);
}

void scroll_up_page()
{
    set_top_line(max(display_top_line-max_display_lines+1,0));
}

void scroll_down_page()
{
    set_top_line(min(display_top_line+max_display_lines-1,total_display_lines));
}

void scroll_to_top()
{
    set_top_line(0);
}

void scroll_to_bottom()
{
    set_top_line(max(0,total_display_lines));
}


void create_scrollbar()
{
    olscrollbar s;

    s = (olscrollbar)newmember(/olscrollbar);
    s.rename(/@scroll);
    s.setscript("","/Preview {
       [exch] /set_top_line @parent Send } def
			    /Action /pop load def ");
    s.setposition(null,0,0,0);
    s.map();
}

void OnInit()
{
    super.OnInit();
    
   if (!promoted(/@scroll))
       create_scrollbar();
}

/* When the display map changes, the number of display lines may ahve */
/* changed, so the scrollbar sohuld be told */
void compute_display_map_from(int line_no, int char_count, char *rest_of_text)
{
    super.compute_display_map_from(line_no,char_count,rest_of_text);
   
    Send setparameters(display_top_line,max_display_lines,total_display_lines)
	to /@scroll; 
}
   
void compute_display_map()
{
    if (length(value) == 0)
      {
	  display_top_line = 0;
	  display_bottom_line = 0;
	  total_display_lines = 0;
	  display_map = [0,0]; 
	  Send setparameters(display_top_line,max_display_lines,total_display_lines)
	      to /@scroll; 
	  return;
      }
    compute_display_map_from(0,0,value);
}
    
/*
void set_scrollbar(boolean flag)
{
    DEBUG(flag);
    
    if ( flag && (!promoted(/@scroll)))
	{
	    create_scrollbar();
	    scroll_width = OLScrollW + SCROLLGAP;
	    compute_display_map();
	    paint();
	}
    else if (promoted(/@scroll))
	{
	    ((olscrollbar)find_object(/@scroll)).unmap();
	    unpromote(/@scroll);
	    
	    scroll_width = 0;
	    compute_display_map();
	    paint();
	}
}	    
*/


float minwidth()
{
    return(super.minwidth()+ scroll_width);
}