How to resize component with mouse drag in JavaFX

Question

I'm interested how I can resize this component with mouse drag:

VBox stackedTitledPanes = createStackedTitledPanes();

    ScrollPane scroll = makeScrollable(stackedTitledPanes);

    TabPane tabPane = new TabPane();
    BorderPane mainPane = new BorderPane();

    tabPane.setStyle("-fx-font-size: 12pt;"); // Set global size for the font
    // Create Tabs
    Tab tabA = new Tab();
    tabA.setText("Main Component");
    tabA.setStyle("-fx-font-size: 12pt;"); // Set size of the tab name
    // Add something in Tab
    StackPane tabA_stack = new StackPane();
    tabA_stack.setAlignment(Pos.CENTER);
    tabA_stack.getChildren().add(scroll); 
    tabA.setContent(tabA_stack);
    tabPane.getTabs().add(tabA);

    Tab tabB = new Tab();
    tabB.setText("Second Component");
    tabB.setStyle("-fx-font-size: 12pt;"); // Set size of the tab name
    // Add something in Tab
    StackPane tabB_stack = new StackPane();
    tabB_stack.setAlignment(Pos.CENTER);
    tabB_stack.getChildren().add(new Label("Label@Tab B"));
    tabB.setContent(tabB_stack);
    tabPane.getTabs().add(tabB);

    Tab tabC = new Tab();
    tabC.setText("Last Component");
    tabC.setStyle("-fx-font-size: 12pt;"); // Set size of the tab name
    // Add something in Tab
    StackPane tabC_vBox = new StackPane();
    tabC_vBox.setAlignment(Pos.CENTER);
    tabC_vBox.getChildren().add(new Label("Label@Tab C"));
    tabC.setContent(tabC_vBox);
    tabPane.getTabs().add(tabC);

    mainPane.setCenter(tabPane);

    mainPane.setPrefSize(395, 580);
    mainPane.setLayoutX(850);
    mainPane.setLayoutY(32);

    scroll.setPrefSize(395, 580);
    scroll.setLayoutX(850);
    scroll.setLayoutY(32);

    root.getChildren().add(mainPane);

The problem is that I have several components placed on the main stage. When I resize one component for example increase the height of the component I have to reduce the size of the next component without stepping over the component. How I can do this?

Answer 1

Here is a modified version for the case of an upper and lower Region. If one Region grows the other one gets smaller.

public class DragResizer {

    /**
     * The margin around the control that a user can click in to start resizing
     * the region.
     */
    private static final int RESIZE_MARGIN = 5;

    private final Region top, bottom;

    private double y;

    private boolean initMinHeight;

    private boolean dragging;

    private double ySum;

    private DragResizer(Region top, Region bottom) {
        this.top = top;
        this.bottom = bottom;
        ySum = top.getPrefHeight() + bottom.getPrefHeight();
    }

    public static void makeResizable(Region top, Region bottom) {
        final DragResizer resizer = new DragResizer(top, bottom);

        top.setOnMousePressed(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mousePressed(event);
            }});
        top.setOnMouseDragged(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseDragged(event);
            }});
        top.setOnMouseMoved(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseOver(event);
            }});
        top.setOnMouseReleased(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseReleased(event);
            }});
    }

    protected void mouseReleased(MouseEvent event) {
        dragging = false;
        top.setCursor(Cursor.DEFAULT);
    }

    protected void mouseOver(MouseEvent event) {
        if(isInDraggableZone(event) || dragging) {
            top.setCursor(Cursor.S_RESIZE);
        }
        else {
            top.setCursor(Cursor.DEFAULT);
        }
    }

    protected boolean isInDraggableZone(MouseEvent event) {
        return event.getY() > (top.getHeight() - RESIZE_MARGIN);
    }

    protected void mouseDragged(MouseEvent event) {
        if(!dragging) {
            return;
        }

        double mousey = event.getY();

        double dy = (mousey - y);

        if(top.getMinHeight() + dy >= ySum || bottom.getPrefHeight() - dy >= ySum)
            return;

        top.setMinHeight(top.getMinHeight() + dy);
        top.setPrefHeight(top.getPrefHeight() + dy);

        bottom.setMinHeight(bottom.getMinHeight() - dy);
        bottom.setPrefHeight(bottom.getPrefHeight() - dy);

        y = mousey;
    }

    protected void mousePressed(MouseEvent event) {

        // ignore clicks outside of the draggable margin
        if(!isInDraggableZone(event)) {
            return;
        }

        dragging = true;

        // make sure that the minimum height is set to the current height once,
        // setting a min height that is smaller than the current height will
        // have no effect
        if (!initMinHeight) {
            top.setMinHeight(top.getHeight());
            initMinHeight = true;
        }

        y = event.getY();
    }
}

Answer 2

I think it is stack pane that is causing the problem, it does not support resize behaviour like VBox or HBox does. I am dragging in my own program to resize TextArea or List components to make them larger if necessary. Check out the code here:

https://bitbucket.org/atill/estimate/src/22390a2ca034b55f1916e46435b714e5c489b90e/src/main/java/projmon/ui/DragResizer.java?at=master

and usage:

https://bitbucket.org/atill/estimate/src/22390a2ca034b55f1916e46435b714e5c489b90e/src/main/java/projmon/control/TaskFormController.java?at=master

EDIT I have pulled EstiMate but the drag resizer is still open source in this gist.

https://gist.github.com/andytill/4369729

Or the full code.

import javafx.event.EventHandler;
import javafx.scene.Cursor;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Region;

/**
 * {@link DragResizer} can be used to add mouse listeners to a {@link Region}
 * and make it resizable by the user by clicking and dragging the border in the
 * same way as a window.
 * <p>
 * Only height resizing is currently implemented. Usage: <pre>DragResizer.makeResizable(myAnchorPane);</pre>
 * 
 * @author atill
 * 
 */
public class DragResizer {

    /**
     * The margin around the control that a user can click in to start resizing
     * the region.
     */
    private static final int RESIZE_MARGIN = 5;

    private final Region region;

    private double y;

    private boolean initMinHeight;

    private boolean dragging;

    private DragResizer(Region aRegion) {
        region = aRegion;
    }

    public static void makeResizable(Region region) {
        final DragResizer resizer = new DragResizer(region);

        region.setOnMousePressed(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mousePressed(event);
            }});
        region.setOnMouseDragged(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseDragged(event);
            }});
        region.setOnMouseMoved(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseOver(event);
            }});
        region.setOnMouseReleased(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                resizer.mouseReleased(event);
            }});
    }

    protected void mouseReleased(MouseEvent event) {
        dragging = false;
        region.setCursor(Cursor.DEFAULT);
    }

    protected void mouseOver(MouseEvent event) {
        if(isInDraggableZone(event) || dragging) {
            region.setCursor(Cursor.S_RESIZE);
        }
        else {
            region.setCursor(Cursor.DEFAULT);
        }
    }

    protected boolean isInDraggableZone(MouseEvent event) {
        return event.getY() > (region.getHeight() - RESIZE_MARGIN);
    }

    protected void mouseDragged(MouseEvent event) {
        if(!dragging) {
            return;
        }

        double mousey = event.getY();

        double newHeight = region.getMinHeight() + (mousey - y);

        region.setMinHeight(newHeight);

        y = mousey;
    }

    protected void mousePressed(MouseEvent event) {

        // ignore clicks outside of the draggable margin
        if(!isInDraggableZone(event)) {
            return;
        }

        dragging = true;

        // make sure that the minimum height is set to the current height once,
        // setting a min height that is smaller than the current height will
        // have no effect
        if (!initMinHeight) {
            region.setMinHeight(region.getHeight());
            initMinHeight = true;
        }

        y = event.getY();
    }
}