Scale at pivot point in an already scaled node

Question

I\'m trying to create an application with a zoomable/pannable canvas.

Features:

• zoom in/out with mouse wheel at pivot points

Answer 1

I change your SceneGestures class so now working.

class SceneGestures {
    private double oldx;
    private double oldy;
    double ttx=0;
    double tty=0;
    private static final double MAX_SCALE = 10.0d;
    private static final double MIN_SCALE = .1d;

    private DragContext sceneDragContext = new DragContext();

    PannableCanvas canvas;

    public SceneGestures( PannableCanvas canvas) {
        this.canvas = canvas;
    }

    public EventHandler getOnMousePressedEventHandler() {
        return onMousePressedEventHandler;
    }

    public EventHandler getOnMouseDraggedEventHandler() {
        return onMouseDraggedEventHandler;
    }

    public EventHandler getOnScrollEventHandler() {
        return onScrollEventHandler;
    }

    private EventHandler onMousePressedEventHandler = new EventHandler() {

        public void handle(MouseEvent event) {

            // right mouse button => panning
            if( !event.isSecondaryButtonDown())
                return;

            sceneDragContext.mouseAnchorX = event.getSceneX();
            sceneDragContext.mouseAnchorY = event.getSceneY();

            sceneDragContext.translateAnchorX = canvas.getTranslateX();
            sceneDragContext.translateAnchorY = canvas.getTranslateY();

        }

    };

    private EventHandler onMouseDraggedEventHandler = new EventHandler() {
        public void handle(MouseEvent event) {

            // right mouse button => panning
            if( !event.isSecondaryButtonDown())
                return;

            canvas.setTranslateX(sceneDragContext.translateAnchorX + event.getSceneX() - sceneDragContext.mouseAnchorX);
            canvas.setTranslateY(sceneDragContext.translateAnchorY + event.getSceneY() - sceneDragContext.mouseAnchorY);

            event.consume();
        }
    };

    /**
     * Mouse wheel handler: zoom to pivot point
     */
    private EventHandler onScrollEventHandler = new EventHandler() {

        @Override
        public void handle(ScrollEvent event) {

            double delta = 1;

            double scale = canvas.getScale(); // currently we only use Y, same value is used for X
            double oldScale = scale;

            if (event.getDeltaY() < 0)
                scale -= delta;
            else
                scale += delta;

            if (scale <= MIN_SCALE) {
                scale = MIN_SCALE;
            } else if (scale >= MAX_SCALE) {
                scale = MAX_SCALE;
            }



            if (oldx==0){
             ttx=event.getSceneX() ;  
             tty=event.getSceneY() ;
            }else{
            if (oldx!=event.getSceneX()){
            ttx=((event.getSceneX()+oldx)/2) ;    
            }
            if (oldy!=event.getSceneY()){
            tty=((event.getSceneY()+oldy)/2);    
            }
            }
            // pivot value must be untransformed, i. e. without scaling
            canvas.setPivot( 
                    ((ttx- canvas.getBoundsInParent().getMinX()) / oldScale),
                    ((tty- canvas.getBoundsInParent().getMinY()) / oldScale)
                    );
         //    if (oldx==0){
            oldx=event.getSceneX();
            oldy=event.getSceneY();
         //   }
            //try {
             //   Robot rbt=new Robot();
             //   rbt.mouseMove(512, 384);
            //} catch (AWTException ex) {
            //    System.out.println(ex.getMessage());
           // }

             canvas.setScale( scale);


            System.out.println( "new pivot x: " + canvas.scaleTransform.getPivotX() + "/" + canvas.scaleTransform.getPivotY() + ", new scale: " + scale);
            System.out.println( "bounds: " + canvas.getBoundsInParent());       
            System.out.println( "old: " + oldx+"  "+oldy);  
            System.out.println( "tt: " + ttx+"  "+tty);  
            event.consume();

        }

    };


}