Question

我有一个可拖动的窗格，位于另一个窗格中。我想让子窗格只能在父窗格的边界内拖动，但默认情况下，子窗格可以拖动到任何位置。如何解决这个问题。

Answer 1

看看这个demo。该应用程序生成可拖动的标签，可以在场景周围移动。要设置边界限制，需要使用以下技术：在onMouseDragged处理程序中，我们计算节点的当前位置，如果它不满足某些条件，我们不会修改它。特别：

label.setOnMouseDragged(new EventHandler<MouseEvent>() {
    @Override public void handle(MouseEvent mouseEvent) {

      //Sets the drag boundaries limit
      double newX = mouseEvent.getSceneX() + dragDelta.x;
      if (newX > 200 || newX < 10) {
        return;
      }

      label.setLayoutX(mouseEvent.getSceneX() + dragDelta.x);
      label.setLayoutY(mouseEvent.getSceneY() + dragDelta.y);
    }
  });

Answer 2

添加到xuesheng answer，而不是

 if (newX > 200 || newX < 10) { return; }

使用

if( outSideParentBounds(label.getLayoutBounds(), newX, newY) ) {    return; }

outSideParentBounds定义于：

private boolean outSideParentBounds( Bounds childBounds, double newX, double newY) {

        Bounds parentBounds = getLayoutBounds();

        //check if too left
        if( parentBounds.getMaxX() <= (newX + childBounds.getMaxX()) ) {
            return true ;
        }

        //check if too right
        if( parentBounds.getMinX() >= (newX + childBounds.getMinX()) ) {
            return true ;
        }

        //check if too down
        if( parentBounds.getMaxY() <= (newY + childBounds.getMaxY()) ) {
            return true ;
        }

        //check if too up
        if( parentBounds.getMinY() >= (newY + childBounds.getMinY()) ) {
            return true ;
        }

        return false;

        /* Alternative implementation 
        Point2D topLeft = new Point2D(newX + childBounds.getMinX(), newY + childBounds.getMinY());
        Point2D topRight = new Point2D(newX + childBounds.getMaxX(), newY + childBounds.getMinY());
        Point2D bottomLeft = new Point2D(newX + childBounds.getMinX(), newY + childBounds.getMaxY());
        Point2D bottomRight = new Point2D(newX + childBounds.getMaxX(), newY + childBounds.getMaxY());
        Bounds newBounds = BoundsUtils.createBoundingBox(topLeft, topRight, bottomLeft, bottomRight);

        return ! parentBounds.contains(newBounds);
         */
    }

在其父窗格内设置可拖动窗格的边界限制

2 个答案: