Implement TrackView

app/src/main/java/de/hems/trafficsim/MainActivity.java

@@ -1,6 +1,7 @@
 package de.hems.trafficsim;
 
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.constraintlayout.widget.ConstraintLayout;
 
 import android.os.Bundle;
 import android.view.View;
@@ -12,14 +13,17 @@ import java.util.Observer;
 public class MainActivity extends AppCompatActivity implements Observer {
 
     protected Track track;
+    protected TrackView trackView;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
-        this.track = new Track(20);
+        this.track = new Track(20, 50);
+        this.trackView = new TrackView(this, this.track);
         this.track.addObserver(this);
-
+        ConstraintLayout layout = (ConstraintLayout) findViewById(R.id.constr_layout);
+        layout.addView(this.trackView);
     }
 
     @Override
@@ -35,11 +39,12 @@ public class MainActivity extends AppCompatActivity implements Observer {
         TextView view = (TextView) findViewById(R.id.debugTextView);
         view.setText(s);
         view.invalidate();
+        this.trackView.invalidate();
     }
 
     public void onStepButtonClick (View view) {
-        for (int j = 0; j < 3000; j++) {
+        //for (int j = 0; j < 3000; j++) {
             this.track.timeElapse(50);
-        }
+        //}
     }
 }

app/src/main/java/de/hems/trafficsim/Track.java

@@ -6,15 +6,19 @@ import java.util.Observable;
 
 public class Track extends Observable {
     protected List<Vehicle> vehicles;
-
+    protected float trackLength;
 
     public List<Vehicle> getVehicles() {
-
         return vehicles;
     }
 
-    public Track(int numberVehicles) {
+    public float getTrackLength() {
+        return trackLength;
+    }
+
+    public Track(int numberVehicles, float trackLength) {
         this.vehicles = createVehiclesList(numberVehicles);
+        this.trackLength = trackLength;
     }
 
     protected List<Vehicle> createVehiclesList(int numberVehicles){
@@ -37,7 +41,7 @@ public class Track extends Observable {
             Vehicle forerunner = vehicles.get(forerunnerIndex);
             float distanceForerunner = forerunner.getPosition() - v.getPosition() - 1;
             if(distanceForerunner < 0.0){
-                distanceForerunner += 50;
+                distanceForerunner += this.trackLength;
             }
             v.updateVelocity(distanceForerunner);
         }

app/src/main/java/de/hems/trafficsim/TrackView.java

@@ -0,0 +1,51 @@
+package de.hems.trafficsim;
+
+import android.content.Context;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Paint;
+import android.view.View;
+import android.view.ViewGroup;
+
+public class TrackView extends View {
+    protected Paint paint;
+    protected Track track;
+    protected int pixelPerVehicle;
+
+    public TrackView(Context context, Track track) {
+        super(context);
+        this.track = track;
+        this.paint = new Paint();
+        paint.setColor(Color.BLACK);
+        paint.setStyle(Paint.Style.FILL_AND_STROKE);
+    }
+
+    protected int getColor(float curVelocity, float maxVelocity) {
+        float perc = curVelocity / maxVelocity;
+        if (perc <= 0.5) {
+            int red = ((int) (2*perc*0xFF)) << 16;
+            int green = ((int)0xFF) << 8;
+            int blue = 0;
+            return 0xff000000 | red | green | blue;
+        } else {
+            int red = ((int)(0xFF)) << 16;
+            int green = ((int)(0xFF-0xFF*(perc-0.5)*2)) << 8;
+            int blue = 0;
+            return 0xff000000 | red | green | blue;
+        }
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        this.pixelPerVehicle = (int) (this.getWidth() / this.track.getTrackLength());
+        //super.onDraw(canvas);
+        int i = 0;
+        for (Vehicle v : this.track.getVehicles()) {
+            int left = (int) (this.pixelPerVehicle * v.getPosition());
+            this.paint.setColor(getColor(v.getCurVelocity(), v.getMaxVelocity()));
+            canvas.drawRect(left, 0, left + this.pixelPerVehicle - 1,
+                    20, this.paint);
+            i++;
+        }
+    }
+}

app/src/main/java/de/hems/trafficsim/Vehicle.java

@@ -27,6 +27,10 @@ public class Vehicle {
         return curVelocity;
     }
 
+    public float getMaxVelocity() {
+        return maxVelocity;
+    }
+
     public void updateVelocity(float distanceForerunner) {
         Random random = new Random();
 

app/src/main/res/layout/activity_main.xml

@@ -2,6 +2,7 @@
 <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/constr_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".MainActivity">