/***************************************************************************
  This code is from Dynamic Web Coding at www.dyn-web.com
  Copyright 2004 by Sharon Paine 
  See Terms of Use at www.dyn-web.com/bus/terms.html
  regarding conditions under which you may use this code.
  This notice must be retained in the code as is!
****************************************************************************/
/*
  dw_scroll_aux.js    version date: May 2004  
  integrates scrolling layers code with scrollbar code (dw_scrollbar.js)
*/
// Size dragBar according to layer size?  
dw_scrollObj.prototype.bSizeDragBar = true;
dw_scrollObj.prototype.setUpScrollbar = function(id, trkId, axis, offx, offy) {
	if (!document.getElementById) {
		return;
	}
	var bar = document.getElementById(id);
	var trk = document.getElementById(trkId);
	dw_slidebar.init(bar, trk, axis, offx, offy);
	// connect dw_slidebar with dw_scrollObj
	bar.wn = dw_scrollObjs[this.id];
	// scroll area object this bar connected to
	if (axis == "v") {
		this.vBarId = id;
	} else {
		this.hBarId = id;
	}
	// also called on_load (i.e., when layer loaded), but in case h and v scrollbars, need to call here too
	if (this.bSizeDragBar) {
		this.setBarSize();
	}
	bar.on_drag_start = bar.on_slide_start = dw_scrollObj.getWndoLyrRef;
	bar.on_drag_end = bar.on_slide_end = dw_scrollObj.tossWndoLyrRef;
	bar.on_drag = bar.on_slide = dw_scrollObj.UpdateWndoLyrPos;
};
// for these 3 functions (assigned to bar.on_drag/slide...) "this" refers to bar
// get/discard ref to layer visible in scroll area
dw_scrollObj.getWndoLyrRef = function() {
	this.wnLyr = document.getElementById(this.wn.lyrId);
};
dw_scrollObj.tossWndoLyrRef = function() {
	this.wnLyr = null;
};
// keep position of scrolling layer in synch with slide/drag of bar
dw_scrollObj.UpdateWndoLyrPos = function(x, y) {
	var nx, ny;
	if (this.axis == "v") {
		nx = this.wn.x;
		// floating point values for loaded layer's position held in shiftTo method
		ny = -(y - this.minY) * (this.wn.maxY / (this.maxY - this.minY)) || 0;
	} else {
		ny = this.wn.y;
		nx = -(x - this.minX) * (this.wn.maxX / (this.maxX - this.minX)) || 0;
	}
	this.wn.shiftTo(this.wnLyr, nx, ny);
};
// Keep position of dragBar in sync with position of layer onscroll
dw_scrollObj.prototype.updateScrollbar = function(x, y) {
	var nx, ny;
	if (this.vBarId) {
		if (!this.maxY) {
			return;
		}
		ny = -(y * ((this.vbar.maxY - this.vbar.minY) / this.maxY) - this.vbar.minY);
		ny = Math.min(Math.max(ny, this.vbar.minY), this.vbar.maxY);
		nx = parseInt(this.vbar.style.left);
		this.vbar.style.left = nx + "px";
		this.vbar.style.top = ny + "px";
	}
	if (this.hBarId) {
		if (!this.maxX) {
			return;
		}
		nx = -(x * ((this.hbar.maxX - this.hbar.minX) / this.maxX) - this.hbar.minX);
		nx = Math.min(Math.max(nx, this.hbar.minX), this.hbar.maxX);
		ny = parseInt(this.hbar.style.top);
		this.hbar.style.left = nx + "px";
		this.hbar.style.top = ny + "px";
	}
};
// Restore dragBar to start position when loading new layer
dw_scrollObj.prototype.restoreScrollbars = function() {
	var bar;
	if (this.vBarId) {
		bar = document.getElementById(this.vBarId);
		bar.style.left = bar.minX + "px";
		bar.style.top = bar.minY + "px";
	}
	if (this.hBarId) {
		bar = document.getElementById(this.hBarId);
		bar.style.left = bar.minX + "px";
		bar.style.top = bar.minY + "px";
	}
};
// Size dragBar in proportion to size of content in layer
// called on_load of layer if bSizeDragBar prop true
dw_scrollObj.prototype.setBarSize = function() {
	var bar;
	var lyr = document.getElementById(this.lyrId);
	var wn = document.getElementById(this.id);
	if (this.vBarId) {
		bar = document.getElementById(this.vBarId);
		bar.style.height = (lyr.offsetHeight > wn.offsetHeight) ? bar.trkHt / (lyr.offsetHeight / wn.offsetHeight) + "px" : bar.trkHt - 2 * bar.minY + "px";
		bar.maxY = bar.trkHt - bar.offsetHeight - bar.minY;
		//alert(bar.style.height);
		if (bar.style.height == "408px") {
			document.getElementById("scrollbar").style.display = 'none';
		}
	}
	if (this.hBarId) {
		bar = document.getElementById(this.hBarId);
		bar.style.width = (this.wd > wn.offsetWidth) ? bar.trkWd / (this.wd / wn.offsetWidth) + "px" : bar.trkWd - 2 * bar.minX + "px";
		bar.maxX = bar.trkWd - bar.offsetWidth - bar.minX;
	}
};
// called from load method
dw_scrollObj.prototype.on_load = function() {
	this.restoreScrollbars();
	if (this.bSizeDragBar) {
		this.setBarSize();
	}
};
dw_scrollObj.prototype.on_scroll = dw_scrollObj.prototype.on_slide = function (x, y) {
	this.updateScrollbar(x, y);
};
// obtain and discard references to relevant dragBar
dw_scrollObj.prototype.on_scroll_start = dw_scrollObj.prototype.on_slide_start = function () {
	if (this.vBarId) {
		this.vbar = document.getElementById(this.vBarId);
	}
	if (this.hBarId) {
		this.hbar = document.getElementById(this.hBarId);
	}
};
dw_scrollObj.prototype.on_scroll_end = dw_scrollObj.prototype.on_slide_end = function (x, y) {
	this.updateScrollbar(x, y);
	this.lyr = null;
	this.bar = null;
};