Package ca.cgjennings.ui.dnd

Class DragManager<T>

  • public final class DragManager<T>
extends java.lang.Object
    The drag manager is the core of the draggable token framework. This is a small set of classes that can be used to implement drag-and-drop functionality independently of AWT/Swing drag support. It can therefore display drag operations in a way that is consistent across platforms, and also avoids platform-specific drag bugs. However, unlike AWT/Swing, this framework does not interact with the native platform's drag support. It is only intended to be used to drag objects within a single virtual machine.

    To use the framework, you must implement a DragHandler and DropHandler to provide the logic necessary to select an object when a drag starts and do something with it when it is dropped. (Both can be implemented in a single object using AbstractDragAndDropHandler.) Then create a manager for the handlers and add the source components that be dragged from and the target components that can be dragged to. In the simplest case, you simply want the user to be able to drag objects from one component and drop them on another. In this case, the drag handler detects the object being dragged and packages it as a DragToken, and the drop handler fetches the object from the drag token and adds it to the target container.

    Since:
    3.0
    Author:
    Chris Jennings

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void addDragSource​(javax.swing.JComponent source)
      Adds a new source component in which the user can initiate drags.
      void addDropTarget​(javax.swing.JComponent target)
      Adds a new target that the user can drag dragged objects upon.
      void cancelDrag()
      Cancels the active drag operation, if any.
      java.awt.Cursor getDropCursor()
      Returns the cursor displayed for the token when a drag is allowed.
      java.awt.Cursor getNoDropCursor()
      Returns the cursor displayed for the token when a drag is not allowed.
      boolean isTokenVisible()
      Returns true if drag token images are displayed.
      void removeDragSource​(javax.swing.JComponent source)
      Removes a component from the set of drag sources.
      void removeDropTarget​(javax.swing.JComponent target)
      Removes a component from the set of drop targets.
      void setDropCursor​(java.awt.Cursor dropCursor)
      Sets the cursor displayed for the token when a drag is allowed.
      void setNoDropCursor​(java.awt.Cursor noDropCursor)
      Sets the cursor displayed for the token when a drag is not allowed.
      void setTokenVisible​(boolean visible)
      Sets whether drag token images are displayed.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Method Detail

      • addDragSource

        public void addDragSource​(javax.swing.JComponent source)
        Adds a new source component in which the user can initiate drags.
        Parameters:
        source - the new drag source to add

      • removeDragSource

        public void removeDragSource​(javax.swing.JComponent source)
        Removes a component from the set of drag sources.
        Parameters:
        source - the source to remove

      • addDropTarget

        public void addDropTarget​(javax.swing.JComponent target)
        Adds a new target that the user can drag dragged objects upon.
        Parameters:
        target - the target component to add

      • removeDropTarget

        public void removeDropTarget​(javax.swing.JComponent target)
        Removes a component from the set of drop targets.
        Parameters:
        target - the target to remove

      • getDropCursor

        public java.awt.Cursor getDropCursor()
        Returns the cursor displayed for the token when a drag is allowed.
        Returns:
        the drop cursor

      • setDropCursor

        public void setDropCursor​(java.awt.Cursor dropCursor)
        Sets the cursor displayed for the token when a drag is allowed.
        Parameters:
        dropCursor - the new drop cursor to use

      • getNoDropCursor

        public java.awt.Cursor getNoDropCursor()
        Returns the cursor displayed for the token when a drag is not allowed.
        Returns:
        the drop cursor

      • setNoDropCursor

        public void setNoDropCursor​(java.awt.Cursor noDropCursor)
        Sets the cursor displayed for the token when a drag is not allowed.
        Parameters:
        noDropCursor - the new cursor to use; null for default cursor

      • isTokenVisible

        public boolean isTokenVisible()
        Returns true if drag token images are displayed.
        Returns:
        true if the images associated with tokens are visible

      • setTokenVisible

        public void setTokenVisible​(boolean visible)
        Sets whether drag token images are displayed. Some platforms may not support changing the token's visibility while a drag is active. On these platforms, the method will only affect subsequent tokens and not the currently displayed token.
        Parameters:
        visible - true if the images associated with tokens are visible

      • cancelDrag

        public void cancelDrag()
        Cancels the active drag operation, if any.

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object