Last Time Our triangles didn't draw at the end of class because we forgot to insert a minus sign. It's shown here so you can fix yours.

    public void draw(GraphicsContext pen)
    {
        //draw myself
        pen.setFill(color);
        pen.beginPath();
        pen.moveTo(xCenter,  yCenter - size/Math.sqrt(3));
        //note - sign below.
        pen.lineTo(xCenter - size/2, yCenter + size/(2*Math.sqrt(3)));
        pen.lineTo(xCenter + size/2, yCenter + size/(2*Math.sqrt(3)));
        pen.closePath();
        pen.fill();
    }

Yesterday's program is available in the zip archive linked in the navigation area. It also includes a .jar file, which you can run with this command.

unix> javafx -jar Coordinated.jar

You will want it because we will do some frankencoding from it.

A Draw Program

Get your starter code on the left. Compile and run it right away. Right at the beginning of class, download, compile, and run this. We have a canvas and menus inserted into the scene in this window. Also some basic state has been inserted and it has been initialized in the constructor.

Easy Assignment Create a size menu and allow the user to change the size of the shapes displayed on the screen.

/**************************************************
*   Author: Morrison
*   Date:  03 Nov 202020
**************************************************/

import javafx.application.Application;
import javafx.application.Platform;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.paint.Color;
import javafx.scene.layout.BorderPane;
import javafx.scene.control.Menu;
import javafx.scene.control.MenuBar;
import javafx.scene.control.MenuItem;

public class Draw extends Application
{
    private final Canvas canvas;
    private final GraphicsContext pen;
    private Color bgColor;
    private Color currentColor;
    public Draw()
    {
        canvas = new Canvas(800, 600);
        pen = canvas.getGraphicsContext2D();
        bgColor = Color.WHITE;
        currentColor = Color.BLACK;
    }
    
    @Override
    public void init()
    {
    }

    @Override
    public void start(Stage primary)
    {
        primary.setTitle("Draw Application");
        BorderPane bp = new BorderPane();
        bp.setCenter(canvas);
        bp.setTop(buildMenus());
        primary.setScene(new Scene(bp));
        primary.show();
    }

    private MenuBar buildMenus()
    {
        MenuBar mbar = new MenuBar();
        Menu fileMenu = new Menu("File");
        MenuItem quitItem = new MenuItem("Quit");
        fileMenu.setOnAction(e -> Platform.exit());
        fileMenu.getItems().addAll(quitItem);
        Menu colorMenu = new Menu("Color");
        Menu bgMenu = new Menu("Background");
        Menu widthMenu = new Menu("Width");
        mbar.getMenus().addAll(fileMenu, colorMenu, bgMenu,
            widthMenu);

        return mbar;
    }
    @Override
    public void stop()
    {
    }
}