public void mouseDragged(MouseEvent evt) {
// User has moved the mouse. Move the dragged shape by the same amount.
int x = evt.getX();
int y = evt.getY();
if (shapeBeingDragged != null) {
shapeBeingDragged.moveBy(x - prevDragX, y - prevDragY);
prevDragX = x;
prevDragY = y;
repaint(); // redraw canvas to show shape in new position
}
}
public void mouseReleased(MouseEvent evt) {
// User has released the mouse. Move the dragged shape, then set
// shapeBeingDragged to null to indicate that dragging is over.
// If the shape lies completely outside the canvas, remove it
// from the list of shapes (since there is no way to ever move
// it back onscreen).
int x = evt.getX();
int y = evt.getY();
if (shapeBeingDragged != null) {
shapeBeingDragged.moveBy(x - prevDragX, y - prevDragY);
if (shapeBeingDragged.left >= getSize().width
|| shapeBeingDragged.top >= getSize().height
|| shapeBeingDragged.left + shapeBeingDragged.width < 0
|| shapeBeingDragged.top + shapeBeingDragged.height < 0) { // shape is off-screen
shapes.remove(shapeBeingDragged); // remove shape from list of shapes
}
shapeBeingDragged = null;
repaint();
}
}