dragdropscripts.js

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        var handler = this.get_events().getHandler('dragStart');
        if(handler) handler(this,eventArgs);
        this._recoverFromDomChanges();
        
        this._wireEvents();
        
        this._drag(/* isInitialDrag */ true);
    },
    
    
    _stopDragDrop : function(cancelled) {
        var ev = window._event;
        if (this._activeDragSource != null) {
            this._unwireEvents();
        
            if (!cancelled) {
                // The drag operation is cancelled if there 
                // is no drop target.
                cancelled = (this._underlyingTarget == null);
            }

            if (!cancelled && this._underlyingTarget != null) {
                this._underlyingTarget.drop(this._activeDragSource.get_dragMode(), this._activeDragSource.get_dragDataType(),
                    this._activeDragSource.getDragData(this._activeContext));
            }

            this._activeDragSource.onDragEnd(cancelled);
            var handler = this.get_events().getHandler('dragStop');
            if(handler) handler(this,Sys.EventArgs.Empty);
            
            this._activeDragVisual.style.position = this._activeDragVisual.originalPosition;
        
            this._activeDragSource = null;
            this._activeContext = null;
            this._activeDragVisual = null;
            this._isDragging = false;
            this._potentialTarget = null;
            ev.preventDefault();
        }
    },
    
    _drag : function(isInitialDrag) {
        var ev = window._event;
        var mousePosition = { x: ev.clientX, y: ev.clientY };
        
        // NOTE: We store the event object to be able to determine the current 
        // mouse position in Mozilla in other event handlers such as keydown.
        document._lastPosition = mousePosition;
        
        var scrollOffset = this.getScrollOffset(this._activeDragVisual, /* recursive */ true);
        var position = this.addPoints(this.subtractPoints(mousePosition, this._activeDragVisual.startingPoint), scrollOffset);
        
        // Check if the visual moved at all.
        if (!isInitialDrag && parseInt(this._activeDragVisual.style.left) == position.x && parseInt(this._activeDragVisual.style.top) == position.y) {
            return;
        }
        
        $common.setLocation(this._activeDragVisual, position);
        
        // Monitor DOM changes.
        this._prepareForDomChanges();
        this._activeDragSource.onDrag();
        this._recoverFromDomChanges();
        
        // Find a potential target.
        this._potentialTarget = this._findPotentialTarget(this._activeDragSource, this._activeDragVisual);
        
        var movedToOtherTarget = (this._potentialTarget != this._underlyingTarget || this._potentialTarget == null);
        // Check if we are leaving an underlying target.
        if (movedToOtherTarget && this._underlyingTarget != null) {
            this._leaveTarget(this._activeDragSource, this._underlyingTarget);
        }
        
        if (this._potentialTarget != null) {
            // Check if we are entering a new target.
            if (movedToOtherTarget) {
                this._underlyingTarget = this._potentialTarget;
                
                // Enter the new target.
                this._enterTarget(this._activeDragSource, this._underlyingTarget);
            }
            else {
                this._moveInTarget(this._activeDragSource, this._underlyingTarget);
            }
        }
        else {
            this._underlyingTarget = null;
        }
    },
    
    
    _wireEvents : function() {
        $addHandler(document, "mouseup", this._mouseUpHandler);
        $addHandler(document, "mousemove", this._documentMouseMoveHandler);
        $addHandler(document.body, "dragover", this._documentDragOverHandler);
        
        $addHandler(this._activeDragVisual, "dragstart", this._dragStartHandler);
        $addHandler(this._activeDragVisual, "dragend", this._mouseUpHandler);
        $addHandler(this._activeDragVisual, "drag", this._mouseMoveHandler);
    },
    
    
    _unwireEvents : function() {
        $removeHandler(this._activeDragVisual, "drag", this._mouseMoveHandler);
        $removeHandler(this._activeDragVisual, "dragend", this._mouseUpHandler);
        $removeHandler(this._activeDragVisual, "dragstart", this._dragStartHandler);

        $removeHandler(document.body, "dragover", this._documentDragOverHandler);
        $removeHandler(document, "mousemove", this._documentMouseMoveHandler);
        $removeHandler(document, "mouseup", this._mouseUpHandler);
    },
    
    
    registerDropTarget : function(dropTarget) {
        if (this._dropTargets == null) {
            this._dropTargets = [];
        }
        Array.add(this._dropTargets, dropTarget);
        
        this._wireDropTargetEvents(dropTarget);
    },
    
    
    unregisterDropTarget : function(dropTarget) {
        this._unwireDropTargetEvents(dropTarget);
        if (this._dropTargets) {
            Array.remove(this._dropTargets, dropTarget);
        }
    },
    
    
    _wireDropTargetEvents : function(dropTarget) {
        var associatedElement = dropTarget.get_dropTargetElement();
        associatedElement._dropTarget = dropTarget;
        $addHandler(associatedElement, "dragenter",  this._dragEnterHandler);
        $addHandler(associatedElement, "dragleave",  this._dragLeaveHandler);
        $addHandler(associatedElement, "dragover", this._dragOverHandler);
        $addHandler(associatedElement, "drop", this._dropHandler);
    },
    
    
    _unwireDropTargetEvents : function(dropTarget) {
        var associatedElement = dropTarget.get_dropTargetElement();
        // make sure that the handlers are not removed twice
        if(associatedElement._dropTarget)
        {
            associatedElement._dropTarget = null;
            $removeHandler(associatedElement, "dragenter",  this._dragEnterHandler);
            $removeHandler(associatedElement, "dragleave",  this._dragLeaveHandler);
            $removeHandler(associatedElement, "dragover", this._dragOverHandler);
            $removeHandler(associatedElement, "drop", this._dropHandler);
        }
    },
    
    
    _onDragStart : function(ev) {
        window._event = ev;
        document.selection.empty();
        
        var dt = ev.dataTransfer;
        if(!dt && ev.rawEvent) dt = ev.rawEvent.dataTransfer;
        
        var dataType = this._activeDragSource.get_dragDataType().toLowerCase();
        var data = this._activeDragSource.getDragData(this._activeContext);
        
        if (data) {
            // TODO: How do we want to deal with 'non-compatible types'?
            if (dataType != "text" && dataType != "url") {
                dataType = "text";
                
                if (data.innerHTML != null) {
                    data = data.innerHTML;
                }
            }
            
            dt.effectAllowed = "move";
            dt.setData(dataType, data.toString());
        }
    },
    
    _onMouseUp : function(ev) {
        window._event = ev;
        this._stopDragDrop(false);
    },
    
    _onDocumentMouseMove : function(ev) {
        window._event = ev;
        this._dragDrop();
    },

    _onDocumentDragOver : function(ev) {
        window._event = ev;
        if(this._potentialTarget) ev.preventDefault();
        //ev.returnValue = (_potentialTarget == null);
    },
    
    _onMouseMove : function(ev) {
        window._event = ev;
        this._drag();
    },
    
    _onDragEnter : function(ev) {
        window._event = ev;
        if (this._isDragging) {
            ev.preventDefault();
            //ev.returnValue = false;
        }
        else {
            // An external object is dragged to the drop target.
            var dataObjects = AjaxControlToolkit.IEDragDropManager._getDataObjectsForDropTarget(this._getDropTarget(ev.target));
            for (var i = 0; i < dataObjects.length; i++) {
                this._dropTarget.onDragEnterTarget(AjaxControlToolkit.DragMode.Copy, dataObjects[i].type, dataObjects[i].value);
            }
        }
    },
    
    _onDragLeave : function(ev) {
        window._event = ev;
        if (this._isDragging) {
            ev.preventDefault();
            //ev.returnValue = false;
        }
        else {
            // An external object is dragged to the drop target.
            var dataObjects = AjaxControlToolkit.IEDragDropManager._getDataObjectsForDropTarget(this._getDropTarget(ev.target));
            for (var i = 0; i < dataObjects.length; i++) {
                this._dropTarget.onDragLeaveTarget(AjaxControlToolkit.DragMode.Copy, dataObjects[i].type, dataObjects[i].value);
            }
        }
    },
    
    _onDragOver : function(ev) {
        window._event = ev;
        if (this._isDragging) {
            ev.preventDefault();
            //ev.returnValue = false;
        }
        else {
            // An external object is dragged over the drop target.
            var dataObjects = AjaxControlToolkit.IEDragDropManager._getDataObjectsForDropTarget(this._getDropTarget(ev.target));
            for (var i = 0; i < dataObjects.length; i++) {
                this._dropTarget.onDragInTarget(AjaxControlToolkit.DragMode.Copy, dataObjects[i].type, dataObjects[i].value);
            }
        }
    },
    
    _onDrop : function(ev) {
        window._event = ev;
        if (!this._isDragging) {
            // An external object is dropped on the drop target.
            var dataObjects = AjaxControlToolkit.IEDragDropManager._getDataObjectsForDropTarget(this._getDropTarget(ev.target));
            for (var i = 0; i < dataObjects.length; i++) {
                this._dropTarget.drop(AjaxControlToolkit.DragMode.Copy, dataObjects[i].type, dataObjects[i].value);
            }
        }
        ev.preventDefault();
        //ev.returnValue = false;
    },
    
    _getDropTarget : function(element) {
        while (element) {
            if (element._dropTarget != null) {
                return element._dropTarget;
            }
            element = element.parentNode;
        }
        return null;
    },
    
    _dragDrop : function() {
        if (this._isDragging) {
            return;
        }
        
        this._isDragging = true;
        this._activeDragVisual.dragDrop();
        document.selection.empty();
    },
    
    _moveInTarget : function(dragSource, dropTarget) {
        // Monitor DOM changes.
        this._prepareForDomChanges();
        dropTarget.onDragInTarget(dragSource.get_dragMode(), dragSource.get_dragDataType(), dragSource.getDragData(this._activeContext));
        this._recoverFromDomChanges();
    },