JavaFX：根据左窗格中的用户输入在中心窗格上绘制

Question

Here is my summary code

public class KlArgon extends Application {

    BorderPane border ;
    Scene scene ;
    Stage stage;

    @Override
    public void start(Stage stage) {
       :
       border = new BorderPane();
       : 
       HBox infoBox = addInfoHBox();
       border.setTop(infoBox);
       :
       VBox menuBox = addMenuVBox();
       border.setLeft(menuBox);
       :
       border.setCenter(addAnchorPane(addGridPane()));
       // setRight and setBottom is not used

       :
        scene = new Scene (border);
        stage.setScene(scene);
        stage.show();
    }

    private Node addAnchorPane(GridPane grid) {
         AnchorPane anchorpane = new AnchorPane();
         anchorpane.getChildren().add(grid);
         AnchorPane.setTopAnchor(grid, 10.0);
         return anchorpane;   
    }

    private GridPane addGridPane() {
         GridPane grid = new GridPane();
         grid.setHgap(10);
         grid.setVgap(10);
         grid.setPadding(new Insets(0, 10, 0, 10));
         grid.add(addWhiteboard(), 1, 0); 
         return grid;
    }

    private Node addWhiteboard() {
         Canvas canvas = new Canvas (wboardWd, wdboardHt);
         GraphicsContext gc = canvas.getGraphicsContext2D();
         drawShapes(gc);
         drawfromClipboard(gc);
         return canvas;
    }

}

I refer to the Center pane as the "Whiteboard". Among other things, I have two buttons in menuBox - btnCopyFromClipboard and btnClearWhiteboard .

When user presses btnCopyFromClipboard - the user should be able to draw an rectangle in the "Whiteboard" only (ie Center pane only) and then the clipboard image will be copied (scaled) into that rectangle.

So I made border , scene , stage as global and I am trying to get this to work - not only it is buggy/ugly- to me it looks like a hack. Is there a cleaner way to do this ie manage Center Pane when button in left pane is pressed? Basically I want the Center Pane to be the Canvas and the GraphicsContext operations are performed whe the Buttons in Left Pane is pressed.

What I have working is pressing the btnCopyFromClipboard lets me draw the rectangle anywhere/everywhere (instead of limiting it to the Center Pane / the whiteboard). I want to restrict the rectangle to be drawn inside the Center Pane / the whiteboard only.

Some inputs/pointers from someone who has been through this will be very much appreciated.

http://docs.oracle.com/javafx/2/layout/builtin_layouts.htm was helpful to get me started.

Answer 1

I was in a fix as well and here is a question which I asked in Oracle Forums, to which, James gave me a vivid reply. Please go through this, it has your answer

https://community.oracle.com/thread/2598756