The Yoix^® Scripting Language

DropTargetEvent is one of three special drag and drop events that currently do not behave like the AWT and Swing events that you may be familiar with. For example, Swing provides automatic drag handling for some components that must be disabled by storing NULL in the component's transferhandler field before the drag and drop event handlers will start working. A DropTargetEvent also can not be assigned to an Event object or posted to a component using postEvent. There are no special fields in a DropTargetEvent that event handlers change when they want to affect a drag and drop operation, however most return TRUE or FALSE to indicate the success or failure of a drop or their ability to handle the data that is being transferred by the drag and drop operation. The fields in a DropTargetEvent are:

action	An int that describes what is currently supposed to happen in this drag operation, which can vary depending on the modifier keys that the user may or may not be holding down. The value will be one of COPY, MOVE, LINK, or NONE, which are all defined in yoix.awt and yoix.swing.
coordinates	A Point that indicates where the cursor's hotspot was at the time of the event. The coordinates and location fields may or may not match, but coordinates should only be used by event handlers that are defined in drawable objects (i.e., components that define a graphics field). In that case coordinates will be the location of the cursor's hotspot in the coordinate system described by the drawable object's graphics.CTM at the time the event arrived, otherwise coordinates and location will match.
dragowner	An int that is 1 if the component that receives this event started the drag and 0 if it did not.
id	An Object that must be an int or String, that identifies the type of this event. A value that is a String must be the name of an event handler that can process this event. A value that is an int must be a number that the yoix.event.HandlerID dictionary associates with an event handler that can process this event.
location	A Point that indicates where the cursor's hotspot was at the time of the event. location always describes a point in the component that requested the event in a coordinate system that has its origin at that component's upper left corner, positive x to the right, positive y down, and a resolution of 72 dots per inch.
mimetypes	An Array that will be NULL or a list of Strings that are the MIME types that can be supplied when the user decides to end the drag and drop operation with a drop. An event handler like dragEnter can use mimetypes to decide if it should accept the data that is being transferred by the drag and drop operation. Using transferable to make the decision is much easier, but only works on Java 1.5.0 and later.
screenlocation	A Point that indicates where on the screen the cursor's hotspot was at the time of the event. screenlocation always describes a point on the screen in a coordinate system that has its origin at upper left corner of the screen, positive x to the right, positive y down, and a resolution of 72 dots per inch.
transferable	An Object that is the data that the drag and drop operation would like to transfer into the component or NULL if the value is not available. Right now drop is the only event handler that can count on finding a non-null value in transferable, however dragEnter, dragOver, and dropActionChanged can use transferable to make decisions if they are running under Java 1.5.0 or later.

Event Handlers:	dragEnter, dragExit, dragOver, drop, dropActionChanged
Example:	The program, import yoix.*.*; JFrame colorframe = { Dimension size = NULL; double border = 72/8; int initialized = FALSE; Array layout = { new JColorChooser { Color color = Color.red; int dragenabled = TRUE; }, }; }; JFrame textframe = { double border = 72/4; Dimension size = { double width = 5*72; double height = 3*72; }; Point location = { double x = VM.screen.width - size.width - 72/2; double y = (VM.screen.height - size.height)/2; }; Array layout = { new JTextArea { String text = "Now is the time\n\tfor all good men..."; Object transferhandler = NULL; int edit = TRUE; int scroll = NONE; dragGestureRecognized(DragGestureEvent e) { Array ends = selectedends; int index = viewToModel(e.location); // // We only start the drag (by returning a non // NULL value) if the event happen inside the // the current selection. // if ((ends = selectedends) != NULL) { if (index >= ends[0] && index < ends[1]) e.visual = selected; } return(e.visual); } dragEnter(DropTargetEvent e) { // // Return value means we won't accept anything // if we started the drag. // if (e.transferable instanceof Color) caretmodel = 1; else caretmodel = 0; return(!e.dragowner); } drop(DropTargetEvent e) { int succeeded = TRUE; if (e.transferable instanceof String) insertText(this, e.transferable, viewToModel(e.location)); else if (e.transferable instanceof Color) foreground = e.transferable; else succeeded = FALSE; return(succeeded); } }, }; }; textframe.visible = TRUE; colorframe.visible = TRUE; lets you drag colors from a JColorChooser using Java's automatic drag handling and uses custom drag and drop event handlers in a JTextArea to handle text and colors. As usual we were forced to set the field in the JTextArea to NULL before the drag and drop event handlers start working.
See Also:	ActionEvent, AdjustmentEvent, CaretEvent, ChangeEvent, ComponentEvent, DragGestureEvent, DragSourceEvent, Event, FocusEvent, HyperlinkEvent, InvocationEvent, invokeLater, isDispatchThread, ItemEvent, KeyEvent, ListSelectionEvent, MouseEvent, MouseWheelEvent, PaintEvent, postEvent, TextEvent, TreeSelectionEvent, WindowEvent