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/*
* drag.js - click & drag DOM elements
*
* originally based on Youngpup's dom-drag.js, www.youngpup.net
*/
var Drag = {
BIG_Z_INDEX : 10000,
group : null,
isDragging : false,
makeDraggable : function(group) {
group.handle = group;
group.handle.group = group;
group.minX = null;
group.minY = null;
group.maxX = null;
group.maxY = null;
group.threshold = 0;
group.thresholdY = 0;
group.thresholdX = 0;
group.onDragStart = new Function();
group.onDragEnd = new Function();
group.onDrag = new Function();
// TODO: use element.prototype.myFunc
group.setDragHandle = Drag.setDragHandle;
group.setDragThreshold = Drag.setDragThreshold;
group.setDragThresholdX = Drag.setDragThresholdX;
group.setDragThresholdY = Drag.setDragThresholdY;
group.constrain = Drag.constrain;
group.constrainVertical = Drag.constrainVertical;
group.constrainHorizontal = Drag.constrainHorizontal;
group.onmousedown = Drag.onMouseDown;
},
constrainVertical : function() {
var nwOffset = Coordinates.northwestOffset(this, true);
this.minX = nwOffset.x;
this.maxX = nwOffset.x;
},
constrainHorizontal : function() {
var nwOffset = Coordinates.northwestOffset(this, true);
this.minY = nwOffset.y;
this.maxY = nwOffset.y;
},
constrain : function(nwPosition, sePosition) {
this.minX = nwPosition.x;
this.minY = nwPosition.y;
this.maxX = sePosition.x;
this.maxY = sePosition.y;
},
setDragHandle : function(handle) {
if (handle && handle != null)
this.handle = handle;
else
this.handle = this;
this.handle.group = this;
this.onmousedown = null;
this.handle.onmousedown = Drag.onMouseDown;
},
setDragThreshold : function(threshold) {
if (isNaN(parseInt(threshold))) return;
this.threshold = threshold;
},
setDragThresholdX : function(threshold) {
if (isNaN(parseInt(threshold))) return;
this.thresholdX = threshold;
},
setDragThresholdY : function(threshold) {
if (isNaN(parseInt(threshold))) return;
this.thresholdY = threshold;
},
onMouseDown : function(event) {
event = Drag.fixEvent(event);
Drag.group = this.group;
var group = this.group;
var mouse = event.windowCoordinate;
var nwOffset = Coordinates.northwestOffset(group, true);
var nwPosition = Coordinates.northwestPosition(group);
var sePosition = Coordinates.southeastPosition(group);
var seOffset = Coordinates.southeastOffset(group, true);
group.originalOpacity = group.style.opacity;
group.originalZIndex = group.style.zIndex;
group.initialWindowCoordinate = mouse;
// TODO: need a better name, but don't yet understand how it
// participates in the magic while dragging
group.dragCoordinate = mouse;
Drag.showStatus(mouse, nwPosition, sePosition, nwOffset, seOffset);
group.onDragStart(nwPosition, sePosition, nwOffset, seOffset);
// TODO: need better constraint API
if (group.minX != null)
group.minMouseX = mouse.x - nwPosition.x +
group.minX - nwOffset.x;
if (group.maxX != null)
group.maxMouseX = group.minMouseX + group.maxX - group.minX;
if (group.minY != null)
group.minMouseY = mouse.y - nwPosition.y +
group.minY - nwOffset.y;
if (group.maxY != null)
group.maxMouseY = group.minMouseY + group.maxY - group.minY;
group.mouseMin = new Coordinate(group.minMouseX, group.minMouseY);
group.mouseMax = new Coordinate(group.maxMouseX, group.maxMouseY);
document.onmousemove = Drag.onMouseMove;
document.onmouseup = Drag.onMouseUp;
return false;
},
showStatus : function(mouse, nwPosition, sePosition, nwOffset, seOffset) {
window.status =
"mouse: " + mouse.toString() + " " +
"NW pos: " + nwPosition.toString() + " " +
"SE pos: " + sePosition.toString() + " " +
"NW offset: " + nwOffset.toString() + " " +
"SE offset: " + seOffset.toString();
},
onMouseMove : function(event) {
event = Drag.fixEvent(event);
var group = Drag.group;
var mouse = event.windowCoordinate;
var nwOffset = Coordinates.northwestOffset(group, true);
var nwPosition = Coordinates.northwestPosition(group);
var sePosition = Coordinates.southeastPosition(group);
var seOffset = Coordinates.southeastOffset(group, true);
Drag.showStatus(mouse, nwPosition, sePosition, nwOffset, seOffset);
if (!Drag.isDragging) {
if (group.threshold > 0) {
var distance = group.initialWindowCoordinate.distance(
mouse);
if (distance < group.threshold) return true;
} else if (group.thresholdY > 0) {
var deltaY = Math.abs(group.initialWindowCoordinate.y - mouse.y);
if (deltaY < group.thresholdY) return true;
} else if (group.thresholdX > 0) {
var deltaX = Math.abs(group.initialWindowCoordinate.x - mouse.x);
if (deltaX < group.thresholdX) return true;
}
Drag.isDragging = true;
group.style["zIndex"] = Drag.BIG_Z_INDEX;
group.style["opacity"] = 0.75;
}
// TODO: need better constraint API
var adjusted = mouse.constrain(group.mouseMin, group.mouseMax);
nwPosition = nwPosition.plus(adjusted.minus(group.dragCoordinate));
nwPosition.reposition(group);
group.dragCoordinate = adjusted;
// once dragging has started, the position of the group
// relative to the mouse should stay fixed. They can get out
// of sync if the DOM is manipulated while dragging, so we
// correct the error here
//
// TODO: what we really want to do is find the offset from
// our corner to the mouse coordinate and adjust to keep it
// the same
var offsetBefore = Coordinates.northwestOffset(group);
group.onDrag(nwPosition, sePosition, nwOffset, seOffset);
var offsetAfter = Coordinates.northwestOffset(group);
if (!offsetBefore.equals(offsetAfter)) {
var errorDelta = offsetBefore.minus(offsetAfter);
nwPosition = Coordinates.northwestPosition(group).plus(errorDelta);
nwPosition.reposition(group);
}
return false;
},
onMouseUp : function(event) {
event = Drag.fixEvent(event);
var group = Drag.group;
var mouse = event.windowCoordinate;
var nwOffset = Coordinates.northwestOffset(group, true);
var nwPosition = Coordinates.northwestPosition(group);
var sePosition = Coordinates.southeastPosition(group);
var seOffset = Coordinates.southeastOffset(group, true);
document.onmousemove = null;
document.onmouseup = null;
group.onDragEnd(nwPosition, sePosition, nwOffset, seOffset);
if (Drag.isDragging) {
// restoring zIndex before opacity avoids visual flicker in Firefox
group.style["zIndex"] = group.originalZIndex;
group.style["opacity"] = group.originalOpacity;
}
Drag.group = null;
Drag.isDragging = false;
return false;
},
fixEvent : function(event) {
if (typeof event == 'undefined') event = window.event;
Coordinates.fixEvent(event);
return event;
}
};
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