More cryptic: Enigma machine, version 2 in Java

Paint Quick Response Code in Java More cryptic: Enigma machine, version 2

Version 1 of the project has a couple of issues that need addressing. First, the user needs to be able to view and change the state of the rotors. Second, we need to introduce some way to capture the encoded output. To fix the first problem we re going to turn the Rotor class into a node that can be used not only to encode a message but also to set the encryption parameters. To fix the second we ll develop a simple printout display, which looks like a teletype page, that records our output along with the lamps. You can see what it looks like at the top of figure 9.8. As a glance at figure 9.8 reveals, each rotor will show its letter in a gradient-filled display, with arrow buttons constructed from scene graph polygons. The paper node we ll develop will be shaded at the top, giving the impression its text is vanishing over a curved surface. Changes to the Enigma class will tie the features into the application s interface, giving a more polished look.

Figure 9.8 Quite an improvement: the Enigma emulator acquires a printout display and rotors, as well as an attractive shaded backdrop.

The Rotor class needs a makeover to turn it into a fully fledged custom node, allowing users to interact with it. Because this code is being integrated into the existing class, I ve taken the liberty of snipping (omitting for the sake of brevity) the bulk of the code from the previous version, as you ll see from listing 9.8. (It may not save many trees, but it could help save a few branches.) The snipped parts have been marked with bold comments to show what has been dropped and where. Refer to listing 9.1 for a reminder of what s missing.

Listing 9.8 Rotor.fx (version 2 changes only)

package jfxia.chapter9; import import import import import import import import import import javafx.scene.Node; javafx.scene.CustomNode; javafx.scene.Group; javafx.scene.input.MouseEvent; javafx.scene.paint.Color; javafx.scene.paint.LinearGradient; javafx.scene.paint.Stop; javafx.scene.shape.Polygon; javafx.scene.shape.Rectangle; javafx.scene.text.Font;

import javafx.scene.text.FontWeight; import javafx.scene.text.Text; import javafx.scene.text.TextOrigin; package class Rotor extends CustomNode { // [Snipped variables: see previous version] def def def def def ); // [Snipped init block: see previous version] override function create() : Node { var r:Node; var t:Node; Group { Up arrow content: [ polygon Polygon { points: [ width/2 , 0.0 , 0.0 , buttonHeight , width , buttonHeight ]; fill: Color.BEIGE; onMouseClicked: function(ev:MouseEvent) { rotorPosition = if(rotorPosition==0) 25 else rotorPosition-1; } } , r = Rectangle { Rotor layoutY: buttonHeight; display rim width: width; height: height; fill: LinearGradient { proportional: false; endX:0; endY:height; stops: [ Stop { offset: 0.0; color: Color.DARKSLATEGRAY; } , Stop { offset: 0.25; color: Color.DARKGRAY; } , Stop { offset: 1.0; color: Color.BLACK; } ] } } , Rectangle { Rotor layoutX: 4; display body layoutY: buttonHeight; width: width-8; height: height; fill: LinearGradient { fontSize:Integer = 40; width:Number = 60; height:Number = 60; buttonHeight:Number = 20.0; letterFont:Font = Font.font( "Helvetic" , FontWeight.BOLD, fontSize

proportional: false; endX:0; endY:height; stops: [ Stop { offset: 0.0; color: Color.DARKGRAY; } , Stop { offset: 0.25; color: Color.WHITE; } , Stop { offset: 0.75; color: Color.DARKGRAY; } , Stop { offset: 1.0; color: Color.BLACK; } ] } Rotor current } , letter t = Text { layoutX: bind Util.center(r,t,true); layoutY: bind buttonHeight + Util.center(r,t,false); content: bind posToChr(rotorPosition); font: letterFont; textOrigin: TextOrigin.TOP; } , Polygon { Down arrow layoutY: buttonHeight+height; polygon points: [ 0.0 , 0.0 , width/2 , buttonHeight , width , 0.0 Move rotor ]; forward one fill: Color.BEIGE; onMouseClicked: function(ev:MouseEvent) { rotorPosition = if(rotorPosition==25) 0 else rotorPosition+1; } } ]; } } // [Snipped encode(), nextPosition(): see previous version] } // [Snipped posToChr(), chrToPos(): see previous version]

The new Rotor class contains a hefty set of additions. The scene graph, as assembled by create(), brings together several layered elements to form the final image. The graph is structured around a Group, at the top and tail of which are Polygon shapes. As its name suggests, the Polygon is a node that allows its silhouette to be custom defined from a sequence of coordinate pairs. The values in the points sequence are alternate x and y positions. They form the outline of a shape, with the last coordinate connecting back to the first to seal the perimeter. Both of our polygons are simple triangles, with points at the extreme left, extreme right, and in the middle, forming up and down arrows.