JavaFX ScrollPane programmatically moving the viewport - centering content

Question

I can use the setVvalue(double) and setHvalue(double) methods to move a viewport in a JavaFX ScrollPane. What I\'m struggling to do is center a particular node in the conte

Answer 1

Here is an example on how to center a pic that has been rotated. The code is in Scala and therefore applicable to ScalaFX, but JavaFX and Java developers will be able to read/use it :

  def turnPic(angle:Int) {
    val virtualSurfaceMultiplier = 8.0;
    currentAngle = ( floor((currentAngle % 360) / 90) * 90 + angle + 360 ) % 360;
    imageView.rotate = currentAngle;
    val orientationSwitched = (currentAngle / 90) % 2 > 0;
    val width= scrollPane.getViewportBounds().getWidth();
    val height= scrollPane.getViewportBounds().getHeight();
    val viewPort = new Rectangle2D(0, 0, image.width.value, image.height.value);
    imageView.setViewport(viewPort);
    imageView.fitHeight.value = virtualSurfaceMultiplier * height;
    imageView.fitWidth.value = 0 //virtualSurfaceMultiplier * width;
    def centerV(picHeight:Double) {
      val node  = scrollPane.getContent();
      val totalHeight = scrollPane.getContent().getBoundsInLocal().getHeight();
      val offsetToCenter = (node.getBoundsInParent().getMaxY() + node.getBoundsInParent().getMinY()) / 2.0;
      val viewportWidth = scrollPane.getViewportBounds().getHeight();
      val res = (scrollPane.getVmax() * ((offsetToCenter - 0.5 * picHeight * zoomFactor) / (totalHeight - picHeight * zoomFactor)));
      scrollPane.setVvalue(res);
    }
    def centerH(picWidth:Double) {
      val node  = scrollPane.getContent();
      val totalWidth = scrollPane.getContent().getBoundsInLocal().getWidth();
      val offsetToCenter = (node.getBoundsInParent().getMaxX() + node.getBoundsInParent().getMinX()) / 2.0;
      val viewportWidth = scrollPane.getViewportBounds().getWidth();
      val res = (scrollPane.getHmax() * ((offsetToCenter - 0.5 * picWidth * zoomFactor) / (totalWidth - picWidth * zoomFactor)));
      scrollPane.setHvalue(res);
      System.err.println(s"trace centerH> $FILE:$LINE:" + " totalWidth:" + totalWidth + " offsetToCenter=" + offsetToCenter + " vWidth=" + viewportWidth + "res=" + res);
    }
    if (orientationSwitched) {
      zoomFactor = 1.0 / (virtualSurfaceMultiplier * image.width.value / image.height.value);
      centerH(height);
      centerV(width);
    }
    else
    {
      zoomFactor = 1.0 / virtualSurfaceMultiplier;
      centerH(width);
      centerV(height);
    }
    imageView.setScaleX(zoomFactor);
    imageView.setScaleY(zoomFactor);
  }