text: /**
   * $Id: ScrollBar.c 28254 2010-04-18 10:28:37Z campbellbarton $
   * ***** BEGIN GPL LICENSE BLOCK *****
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version 2
   * of the License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
   *
   * The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
   * All rights reserved.
   *
   * The Original Code is: all of this file.
   *
   * Contributor(s): none yet.
   *
   * ***** END GPL LICENSE BLOCK *****
   */
  
  #include <stdlib.h>
  
  #include <math.h>
  
  #include "MEM_guardedalloc.h"
  
  #include "Basic.h"
  #include "ScrollBar.h"
  
  struct _ScrollBar {
  	int		rect[2][2];
  	float	thumbpos, thumbpct;
  	
  	int		inset;
  	int		minthumb;
  
  	int		scrolling;
  	float	scrolloffs;
  };
  
  static int scrollbar_get_thumbH(ScrollBar *sb) {
  	int scrollable_h= rect_height(sb->rect) - 2*sb->inset;
  	
  	return clamp_i(sb->thumbpct*scrollable_h, sb->minthumb, scrollable_h);
  }
  static int scrollbar_get_thumbableH(ScrollBar *sb) {
  	int scrollable_h= rect_height(sb->rect) - 2*sb->inset;
  	int thumb_h= scrollbar_get_thumbH(sb);
  	
  	return scrollable_h - thumb_h;
  }
  
  static float scrollbar_co_to_pos(ScrollBar *sb, int yco) {
  	int thumb_h= scrollbar_get_thumbH(sb);
  	int thumbable_h= scrollbar_get_thumbableH(sb);
  	int thumbable_y= (sb->rect[0][1]+sb->inset) + thumb_h/2;
  
  	return (float) (yco-thumbable_y)/thumbable_h;
  }
  
  /**/
  
  ScrollBar *scrollbar_new(int inset, int minthumb) {
  	ScrollBar *sb= MEM_callocN(sizeof(*sb), "scrollbar_new");
  	sb->inset= inset;
  	sb->minthumb= minthumb;
  	
  	return sb;
  }
  
  void scrollbar_get_thumb(ScrollBar *sb, int thumb_r[2][2]) {
  	int thumb_h= scrollbar_get_thumbH(sb);
  	int thumbable_h= scrollbar_get_thumbableH(sb);
  
  	thumb_r[0][0]= sb->rect[0][0]+sb->inset;
  	thumb_r[1][0]= sb->rect[1][0]-sb->inset;
  
  	thumb_r[0][1]= sb->rect[0][1]+sb->inset + sb->thumbpos*thumbable_h;
  	thumb_r[1][1]= thumb_r[0][1] + thumb_h;
  }
  
  int scrollbar_is_scrolling(ScrollBar *sb) {
  	return sb->scrolling;
  }
  int scrollbar_contains_pt(ScrollBar *sb, int pt[2]) {
  	return rect_contains_pt(sb->rect, pt);
  }
  
  void scrollbar_start_scrolling(ScrollBar *sb, int yco) {
  	int thumb_h_2= scrollbar_get_thumbH(sb)/2;
  	int thumbable_h= scrollbar_get_thumbableH(sb);
  	float npos= scrollbar_co_to_pos(sb, yco);
  
  	sb->scrolloffs= sb->thumbpos - npos;
  	if (fabs(sb->scrolloffs) >= (float) thumb_h_2/thumbable_h) {
  		sb->scrolloffs= 0.0;
  	}
  
  	sb->scrolling= 1;
  	sb->thumbpos= clamp_f(npos + sb->scrolloffs, 0.0, 1.0);
  }
  void scrollbar_keep_scrolling(ScrollBar *sb, int yco) {
  	float npos= scrollbar_co_to_pos(sb, yco);
  
  	sb->thumbpos= clamp_f(npos + sb->scrolloffs, 0.0, 1.0);
  }
  void scrollbar_stop_scrolling(ScrollBar *sb) {
  	sb->scrolling= 0;
  	sb->scrolloffs= 0.0;
  }
  
  void scrollbar_set_thumbpct(ScrollBar *sb, float pct) {
  	sb->thumbpct= pct;
  }
  void scrollbar_set_thumbpos(ScrollBar *sb, float pos) {
  	sb->thumbpos= clamp_f(pos, 0.0, 1.0);
  }
  void scrollbar_set_rect(ScrollBar *sb, int rect[2][2]) {
  	rect_copy(sb->rect, rect);
  }
  
  float scrollbar_get_thumbpct(ScrollBar *sb) {
  	return sb->thumbpct;
  }
  float scrollbar_get_thumbpos(ScrollBar *sb) {
  	return sb->thumbpos;
  }
  void scrollbar_get_rect(ScrollBar *sb, int rect_r[2][2]) {
  	rect_copy(rect_r, sb->rect);
  }
  
  void scrollbar_free(ScrollBar *sb) {
  	MEM_freeN(sb);
  }
  