How to center the content of a javafx 8 scrollpane

Question

I have a ScrollPane, which contains a GridPane, which contains an ImageView, which contains an Image. What I want is for the Image to be centered in the GridPane.

W

Answer 1

What's happening is that while the grid pane is centering the scroll pane, the image view is sitting at the top left of the scroll pane.

One fix is to wrap the image view in a stack pane (which centers by default), and make sure the stack pane is at least as wide as the scroll pane's viewport:

SSCCE:

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.geometry.HPos;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.ScrollPane;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Priority;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class ImageDB extends Application
{
  @Override
  public void start(Stage root)
  {
//    Image image = new Image("0.jpg");
    Image image = createImage();
    ImageView view = new ImageView();
    view.setImage(image);
    StackPane imageHolder = new StackPane(view);

    ScrollPane scroll = new ScrollPane();
    scroll.setContent(imageHolder);

    GridPane grid = new GridPane();

    imageHolder.minWidthProperty().bind(Bindings.createDoubleBinding(() -> 
        scroll.getViewportBounds().getWidth(), scroll.viewportBoundsProperty()));
    grid.getChildren().add(imageHolder);

//    grid.setAlignment(Pos.TOP_CENTER);

    BorderPane border = new BorderPane();
    border.setCenter(scroll);

    root.setScene(new Scene(border));
    root.setMaximized(true);
    root.show();
  }

  private Image createImage() {
      return new Rectangle(400, 200, Color.CORNFLOWERBLUE).snapshot(null, null);
  }

  public static void main(String[] args) {
      launch(args);
  }
}