title: Javafx 2 chart and freehand zoom
body: <p>This code plots an XYChart and using combination of right mouse button click and drag perform free hand draw, while with left mouse button click and drag perform Zoom In on selected area.</p>
  
  <p>My problem is about zoom on freehand draw it always get translated. For example try to draw somewhere around a corner.</p>
  
  <p><strong>How can I solve this?</strong></p>
  
  <pre><code>public class Zoom extends Application {
  
  Path path;//Add path for freehand
  BorderPane pane;
  Rectangle rect;
  SimpleDoubleProperty rectinitX = new SimpleDoubleProperty();
  SimpleDoubleProperty rectinitY = new SimpleDoubleProperty();
  SimpleDoubleProperty rectX = new SimpleDoubleProperty();
  SimpleDoubleProperty rectY = new SimpleDoubleProperty();
  
  double initXLowerBound = 0, initXUpperBound = 0, initYLowerBound = 0, initYUpperBound = 0;
  @Override
  public void start(Stage stage) {    
  stage.setTitle("Lines plot");
  final NumberAxis xAxis = new NumberAxis(1, 12, 1);
  final NumberAxis yAxis = new NumberAxis(0.53000, 0.53910, 0.0005);
  
  yAxis.setTickLabelFormatter(new NumberAxis.DefaultFormatter(yAxis) {
  
      @Override
      public String toString(Number object) {
          return String.format("%7.5f", object);
      }
  });
  
   final LineChart&lt;Number, Number&gt; lineChart = new LineChart&lt;Number, Number&gt;(xAxis, yAxis);
  
  lineChart.setCreateSymbols(false);
  lineChart.setAlternativeRowFillVisible(false);
  lineChart.setAnimated(true);
  
  XYChart.Series series1 = new XYChart.Series();
  series1.getData().add(new XYChart.Data(1, 0.53185));
  series1.getData().add(new XYChart.Data(2, 0.532235));
  series1.getData().add(new XYChart.Data(3, 0.53234));
  series1.getData().add(new XYChart.Data(4, 0.538765));
  series1.getData().add(new XYChart.Data(5, 0.53442));
  series1.getData().add(new XYChart.Data(6, 0.534658));
  series1.getData().add(new XYChart.Data(7, 0.53023));
  series1.getData().add(new XYChart.Data(8, 0.53001));
  series1.getData().add(new XYChart.Data(9, 0.53589));
  series1.getData().add(new XYChart.Data(10, 0.53476));
  series1.getData().add(new XYChart.Data(11, 0.530123));
  series1.getData().add(new XYChart.Data(12, 0.53035));
  
  
  pane = new BorderPane();
  pane.setCenter(lineChart);
  Scene scene = new Scene(pane, 800, 600);
  lineChart.getData().addAll(series1);
  
  initXLowerBound = ((NumberAxis) lineChart.getXAxis()).getLowerBound();
  initXUpperBound = ((NumberAxis) lineChart.getXAxis()).getUpperBound();
  initYLowerBound = ((NumberAxis) lineChart.getYAxis()).getLowerBound();
  initYUpperBound = ((NumberAxis) lineChart.getYAxis()).getUpperBound();
  
  stage.setScene(scene);        
  
  path = new Path();
  path.setStrokeWidth(1);
  path.setStroke(Color.BLACK);
  
  scene.setOnMouseClicked(mouseHandler);
  scene.setOnMouseDragged(mouseHandler);
  scene.setOnMouseEntered(mouseHandler);
  scene.setOnMouseExited(mouseHandler);
  scene.setOnMouseMoved(mouseHandler);
  scene.setOnMousePressed(mouseHandler);
  scene.setOnMouseReleased(mouseHandler);
  
  pane.getChildren().add(path);
  
  rect = new Rectangle();
  rect.setFill(Color.web("blue", 0.1));
  rect.setStroke(Color.BLUE);
  rect.setStrokeDashOffset(50);
  
  rect.widthProperty().bind(rectX.subtract(rectinitX));
  rect.heightProperty().bind(rectY.subtract(rectinitY));
  pane.getChildren().add(rect);
  
  stage.show();
  }
  EventHandler&lt;MouseEvent&gt; mouseHandler = new EventHandler&lt;MouseEvent&gt;() {
  
  @Override
  public void handle(MouseEvent mouseEvent) {
      if (mouseEvent.getButton() == MouseButton.PRIMARY)
      {
              if (mouseEvent.getEventType() == MouseEvent.MOUSE_PRESSED) {
                  rect.setX(mouseEvent.getX());
                  rect.setY(mouseEvent.getY());
                  rectinitX.set(mouseEvent.getX());
                  rectinitY.set(mouseEvent.getY());
              } else if (mouseEvent.getEventType() == MouseEvent.MOUSE_DRAGGED) {
                  rectX.set(mouseEvent.getX());
                  rectY.set(mouseEvent.getY());
              } else if (mouseEvent.getEventType() == MouseEvent.MOUSE_RELEASED) {
  
                  if ((rectinitX.get() &gt;= rectX.get())&amp;&amp;(rectinitY.get() &gt;= rectY.get()))
                  {
                      LineChart&lt;Number, Number&gt; lineChart = (LineChart&lt;Number, Number&gt;) pane.getCenter();
  
                      ((NumberAxis) lineChart.getXAxis()).setLowerBound(initXLowerBound);
                      ((NumberAxis) lineChart.getXAxis()).setUpperBound(initXUpperBound);
  
                      ((NumberAxis) lineChart.getYAxis()).setLowerBound(initYLowerBound);
                      ((NumberAxis) lineChart.getYAxis()).setUpperBound(initYUpperBound);
  
                      ZoomFreeHand(path, 1.0, 1.0, 0, 0);
  
                  }
                  else
                  {
                      //Zoom In
  
                      double Tgap = 0;
                      double newLowerBound, newUpperBound, axisShift;
                      double xScaleFactor, yScaleFactor;
                      double xaxisShift, yaxisShift;
  
                      LineChart&lt;Number, Number&gt; lineChart = (LineChart&lt;Number, Number&gt;) pane.getCenter();
  
                      // Zoom in Y-axis by changing bound range.            
                      NumberAxis yAxis = (NumberAxis) lineChart.getYAxis();
                      Tgap = yAxis.getHeight()/(yAxis.getUpperBound() - yAxis.getLowerBound());
                      axisShift = getSceneShiftY(yAxis);
                      yaxisShift = axisShift;
  
                      newUpperBound = yAxis.getUpperBound() - ((rectinitY.get() - axisShift) / Tgap);
                      newLowerBound = yAxis.getUpperBound() - (( rectY.get() - axisShift) / Tgap);
  
  
                      if (newUpperBound &gt; yAxis.getUpperBound())
                          newUpperBound = yAxis.getUpperBound();
  
                      yScaleFactor = (yAxis.getUpperBound() - yAxis.getLowerBound())/(newUpperBound - newLowerBound);
                      yAxis.setLowerBound(newLowerBound);
                      yAxis.setUpperBound(newUpperBound);
  
  
                      NumberAxis xAxis = (NumberAxis) lineChart.getXAxis();
  
                      Tgap = xAxis.getWidth()/(xAxis.getUpperBound() - xAxis.getLowerBound());            
                      axisShift = getSceneShiftX(xAxis);                        
                      xaxisShift = axisShift;                                                                                
                      newLowerBound = ((rectinitX.get() - axisShift) / Tgap) + xAxis.getLowerBound();
                      newUpperBound = ((rectX.get() - axisShift) / Tgap) + xAxis.getLowerBound();                
  
                      if (newUpperBound &gt; xAxis.getUpperBound())
                          newUpperBound = xAxis.getUpperBound();
  
                      xScaleFactor = (xAxis.getUpperBound() - xAxis.getLowerBound())/(newUpperBound - newLowerBound);
                      xAxis.setLowerBound( newLowerBound );
                      xAxis.setUpperBound( newUpperBound );                      
  
                      ZoomFreeHand(path, xScaleFactor, yScaleFactor, xaxisShift, yaxisShift);
                  }
                  // Hide the rectangle
                  rectX.set(0);
                  rectY.set(0);
              }
      }
      else if (mouseEvent.getButton() == MouseButton.SECONDARY) //free hand graphics
      {
          if(mouseEvent.getEventType() == MouseEvent.MOUSE_PRESSED){
              path.getElements().clear();
              path.getElements().add(new MoveTo(mouseEvent.getX(), mouseEvent.getY()));
          }
          else if(mouseEvent.getEventType()==MouseEvent.MOUSE_DRAGGED){
              path.getElements().add(new LineTo(mouseEvent.getX(), mouseEvent.getY()));
          }
      } 
    }
    };
  private static double getSceneShiftX(Node node) {
  double shift = 0;
  do { 
      shift += node.getLayoutX(); 
      node = node.getParent();
  } while (node != null);
  return shift;
  }
  private static double getSceneShiftY(Node node) {
  double shift = 0;
  do { 
      shift += node.getLayoutY(); 
      node = node.getParent();
  } while (node != null);
  return shift;
  }
  private static void ZoomFreeHand(Path path, double xScaleFactor, double yScaleFactor, double xaxisShift, double yaxisShift) {
  
  double layX, layY;
  
  layX = path.getLayoutX();
  layY = path.getLayoutY();
  path.setScaleX(xScaleFactor);
  path.setScaleY(yScaleFactor);
  path.setTranslateX(xaxisShift);
  path.setTranslateY(yaxisShift);
    }
    public static void main(String[] args) {
      launch(args);
     }        
    }
  </code></pre>
  
  <p>I think it worth using something like this:</p>
  
  <pre><code> ObservableList&lt;PathElement&gt; mypathElements = path.getElements();
   for (int i = 0; i &lt; mypathElements.size(); i++) {
     final PathElement element = mypathElements.get(i);
     if (element instanceof MoveTo) {
       final MoveTo move = (MoveTo)element;
       //change move coordinates     
     } else if (element instanceof LineTo) {
     final LineTo line = (LineTo)element;                                    
     //change line coordinates
     }
   }
  </code></pre>