WebDragDropExtender component provides robust event-driven messaging architecture to handle the drag-drop communication throughout the entire page life cycle. Unlike other Web-based drag-drop client scripts available in the industry, WebDragDropExtender encapsulates all drag-drop mechanism and behaviors into an elegant object model. This enables any developers to easily understand and utilize drag-drop behaviors without extensive knowledge of complex drag-drop mechanism.
 |
WebDragDropExtender requires very little effort and almost no code to add drag-drop behavior into your Web application. All that you need to do is basically handling the OnDragDrop event to perform the actions and business-related logics upon a successful drag-drop operation. If you wanted to add some more interactivity, such as providing feedbacks to users when you hover on a drop element, you simply handle the OnDragOver event and assign the Effect available in the drag event arguments. |
WebDragDropExtender is designed with high customization and extensibility as one of the key objectives. The following list describes the available client side events and the life cycle in order:
- OnDragStart
When you started a drag operation by holding down left mouse button and move your mouse, this is the first event invoked by WebDragDropExtender. - OnDragEnter
At the first time you hover on a valid drop element, this event will be invoked against the target drop element. - OnDragOver
After you entered on a valid drop element and keep moving your mouse over the same element, the WebDragDropExtender control will invoke this event. Since this event will be called repetitively as you move your mouse in the drop area, please handle this event effectively and avoid heavy or long-progress code executions. - OnDragLeave
When you have entered a valid drop element and move your mouse out from the drop element, this indicates that the drag has leaved the drop element and this event will be invoked. - OnDragEnd
When you release the left mouse button outside of a valid drop element, this event will be invoked to indicate the end of drag operation. - OnDragDrop
When you release the left mouse button inside of a valid drop element, this event will be invoked to indicate a successful drag-drop operation.
In addition to the drag-drop events above, there are two additional client side events:
- OnInitialize
This event is invoked during WebDragDropExtender initialization. - OnShadowCreate
This event is invoked when WebDragDropExtender is about to create shadow element for the drag control. The shadow is usually created only the first time when the drag operation is initiated. This event allows you to create your own custom shadow in addition to the predefined visual shadow provided in DragSettings.DragVisualHint.