The Yoix^® Scripting Language

DragSourceEvent 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 DragSourceEvent also can not be assigned to an Event object or posted to a component using postEvent. In addition, any event handler that gets a DragSourceEvent can change the cursor field in its event argument and expect to see the new cursor used by the drag and drop operation. The fields in a DragSourceEvent 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 or NULL if the location is not available, which always happens with versions of Java that are older than 1.4.0. 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.
cursor	An Object that can be an int, Image, or String that represents the cursor shown during the drag and drop operation. A NULL value is special and means Java's drag and drop machinery picks the cursor. A cursor that is an int should be one of the cursors defined in the yoix.awt.Cursor dictionary. A cursor that is an Image can describe the cursor using its size and hotspot fields and often draws it using its paint function. A cursor that is a String should be the name of a cursor that is already defined in yoix.awt.Cursor or the name a local a file or URL that contains a GIF or JPEG image that will be used as the cursor. The cursor field in the DragSourceEvent that is received by an event handler describes the current cursor, but the event handler can change it and the drag and drop operation will start using the new cursor when the event handler finishes its work.
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 or NULL if the location is not available, which always happens with versions of Java that are older than 1.4.0. A non-null 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.
screenlocation	A Point that indicates where on the screen the cursor's hotspot was at the time of the event or NULL if the location is not available, which always happens with versions of Java that are older than 1.4.0. A non-null 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.
succeeded	An int that is 1 if the drag and drop operation ended in a successful drop 0 if it failed or has not ended yet. dragDropEnd, which is called at the end of a drag operation, is the only event handler that should be interested in this field.

Event Handlers:	dragDropEnd, dragEnter, dragExit, dragMouseMoved, dragOver, dropActionChanged
Example:	Our only example does not transfer anything, but instead illustrates cursor animation using dragOver and a small collection of custom cursors. It looks harder than it really is, because the first half of the program builds and installs the custom cursors that the two frames use for their drag and drop cursor animation. Run the program import yoix.*.*; PaintScrew(double angle) { Image image = { int type = TYPE_RGBA; Dimension size = { double width = 72/3; double height = 72/3; }; Graphics graphics = { int rendering = 1; // probably no help int antialiasing = 1; }; double angle = angle; paint(Rectangle r) { Rectangle bbox; double thickness; double radius; double alpha; double cx; double cy; graphics { gsave(); initclip(); clippath(); bbox = pathbbox(); newpath(); cx = bbox.width/2; cy = bbox.height/2; thickness = cx/4.0; radius = cx - thickness - 1; alpha = 180*atan2(thickness/2, radius)/PI; translate(cx, cy); rotate(angle); moveto(0, thickness/2); arc(0, 0, radius, alpha, 180 - alpha); closepath(); moveto(0, -thickness/2); arc(0, 0, radius, 180 + alpha, 360 - alpha); closepath(); moveto(radius + thickness, 0); arc(0, 0, radius + thickness, 0, 360); closepath(); gsave(); setrgbcolor(0, 0, 1); eofill(); grestore(); setlinewidth(1); setrgbcolor(1, 1, 0); stroke(); grestore(); hotspot = new Point { double x = cx; double y = cy; }; } } }; return(image); } Array names[30]; for (n = 0; n < names@length; n++) { names[n] = "SCREW_" + toString(n); addCursor(names[n], PaintScrew(n*180/names@length)); } JFrame frame1 = { String title = "Frame 1"; Object transferhandler = NULL; // just in case Color background = Color.lightGray; int next = 1; int incr = 1; Dimension size = { double width = VM.screen.width/3; double height = VM.screen.height/3; }; Point location = { double x = 72/2; double y = (VM.screen.height - size.height)/2; }; dragGestureRecognized(DragGestureEvent e) { // // We have to return something that's not NULL, even though // this example doesn't transfer anything, otherwise dragging // won't start. // e.cursor = names[next++ % names@length]; return(""); // bogus return } dragEnter(DropTargetEvent e) { return(TRUE); } dragOver(DragSourceEvent e) { e.cursor = names[next]; if ((next += incr) < 0) next = names@length - 1; else if (next >= names@length) next = 0; } }; JFrame frame2 = { String title = "Frame 2"; Object transferhandler = NULL; // just in case Color background = Color.darkGray; int next = 1; int incr = -1; Dimension size = { double width = VM.screen.width/3; double height = VM.screen.height/3; }; Point location = { double x = VM.screen.width - size.width - 72/2; double y = (VM.screen.height - size.height)/2; }; dragGestureRecognized(DragGestureEvent e) { // // We have to return something that's not NULL, even though // this example doesn't transfer anything, otherwise dragging // won't start. // e.cursor = names[next++ % names@length]; return(""); // bogus return } dragOver(Object e) { // // The argument will be a DropTargetEvent or DragSourceEvent. // We accept by always returning TRUE (the return value is // ignored when e is a DragSourceEvent) and we change the // when e is a DragSourceEvent. // if (e instanceof DragSourceEvent) { e.cursor = names[next]; if ((next += incr) < 0) next = names@length - 1; else if (next >= names@length) next = 0; } return(TRUE); } }; frame1.visible = TRUE; frame2.visible = TRUE; and start dragging in either frame and you should see cursors that rotate as they move, and the direction of the rotation depends on the frame that started the drag. See what happens if you let dragMouseMoved handle the animation.
See Also:	ActionEvent, AdjustmentEvent, CaretEvent, ChangeEvent, ComponentEvent, DragGestureEvent, DropTargetEvent, Event, FocusEvent, HyperlinkEvent, InvocationEvent, invokeLater, isDispatchThread, ItemEvent, KeyEvent, ListSelectionEvent, MouseEvent, MouseWheelEvent, PaintEvent, postEvent, TextEvent, TreeSelectionEvent, WindowEvent