Example usage for java.awt.dnd DragGestureEvent startDrag

Introduction

In this page you can find the example usage for java.awt.dnd DragGestureEvent startDrag.

Prototype

public void startDrag(Cursor dragCursor, Image dragImage, Point imageOffset, Transferable transferable,
        DragSourceListener dsl) throws InvalidDnDOperationException 

Source Link

Document

Start the drag given the initial Cursor to display, a drag Image , the offset of the Image , the Transferable object, and the DragSourceListener to use.

Usage

From source file:ColorSource.java

public void dragGestureRecognized(DragGestureEvent e) {
    // Create an image we can drag along with us.
    // Not all systems support this, but it doesn't hurt to try.
    Image colorblock = this.createImage(25, 25);
    Graphics g = colorblock.getGraphics();
    g.setColor(color);//from  w  w w  . j a  v  a 2  s.co m
    g.fillRect(0, 0, 25, 25);

    // Start dragging our transferable color object.
    e.startDrag(DragSource.DefaultMoveDrop, // The initial drag cursor
            colorblock, new Point(0, 0), // The image to drag
            tcolor, // The data being dragged
            this); // Who to notify during drag
}

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From source file:ScribbleDragAndDrop.java

/**
 * This method implements the DragGestureListener interface. It will be
 * invoked when the DragGestureRecognizer thinks that the user has initiated
 * a drag. If we're not in drawing mode, then this method will try to figure
 * out which Scribble object is being dragged, and will initiate a drag on
 * that object.//from  w ww . jav a 2  s.  c o m
 */
public void dragGestureRecognized(DragGestureEvent e) {
    // Don't drag if we're not in drag mode
    if (!dragMode)
        return;

    // Figure out where the drag started
    MouseEvent inputEvent = (MouseEvent) e.getTriggerEvent();
    int x = inputEvent.getX();
    int y = inputEvent.getY();

    // Figure out which scribble was clicked on, if any by creating a
    // small rectangle around the point and testing for intersection.
    Rectangle r = new Rectangle(x - LINEWIDTH, y - LINEWIDTH, LINEWIDTH * 2, LINEWIDTH * 2);
    int numScribbles = scribbles.size();
    for (int i = 0; i < numScribbles; i++) { // Loop through the scribbles
        Scribble s = (Scribble) scribbles.get(i);
        if (s.intersects(r)) {
            // The user started the drag on top of this scribble, so
            // start to drag it.

            // First, remember which scribble is being dragged, so we can
            // delete it later (if this is a move rather than a copy)
            beingDragged = s;

            // Next, create a copy that will be the one dragged
            Scribble dragScribble = (Scribble) s.clone();
            // Adjust the origin to the point the user clicked on.
            dragScribble.translate(-x, -y);

            // Choose a cursor based on the type of drag the user initiated
            Cursor cursor;
            switch (e.getDragAction()) {
            case DnDConstants.ACTION_COPY:
                cursor = DragSource.DefaultCopyDrop;
                break;
            case DnDConstants.ACTION_MOVE:
                cursor = DragSource.DefaultMoveDrop;
                break;
            default:
                return; // We only support move and copys
            }

            // Some systems allow us to drag an image along with the
            // cursor. If so, create an image of the scribble to drag
            if (dragSource.isDragImageSupported()) {
                Rectangle scribbleBox = dragScribble.getBounds();
                Image dragImage = this.createImage(scribbleBox.width, scribbleBox.height);
                Graphics2D g = (Graphics2D) dragImage.getGraphics();
                g.setColor(new Color(0, 0, 0, 0)); // transparent background
                g.fillRect(0, 0, scribbleBox.width, scribbleBox.height);
                g.setColor(Color.black);
                g.setStroke(linestyle);
                g.translate(-scribbleBox.x, -scribbleBox.y);
                g.draw(dragScribble);
                Point hotspot = new Point(-scribbleBox.x, -scribbleBox.y);

                // Now start dragging, using the image.
                e.startDrag(cursor, dragImage, hotspot, dragScribble, this);
            } else {
                // Or start the drag without an image
                e.startDrag(cursor, dragScribble, this);
            }
            // After we've started dragging one scribble, stop looking
            return;
        }
    }
}

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