Implement first prototype with rects

app/src/main/java/com/google/mlkit/vision/demo/CameraXLivePreviewActivity.java

@@ -117,6 +117,7 @@ public final class CameraXLivePreviewActivity extends AppCompatActivity
     private CameraSelector cameraSelector;
 
     private TextView emotionTextView;
+    private GameView gameView;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -199,6 +200,7 @@ protected void onCreate(Bundle savedInstanceState) {
         findViewById(R.id.control).setVisibility(View.GONE);
 
         emotionTextView = findViewById(R.id.emotionTextView);
+        gameView = findViewById(R.id.gameView);
     }
 
     @Override
@@ -494,6 +496,7 @@ private static boolean isPermissionGranted(Context context, String permission) {
         public void onEmotion(FaceDetectorProcessor.Emotion emotion) {
             EmotionFlags flags = estimator.estimate(emotion);
             showFlagsSmiles(flags);
+            gameView.setEmotionFlags(flags);
         }
     };
 

app/src/main/java/com/google/mlkit/vision/demo/GameView.kt

@@ -0,0 +1,163 @@
+package com.google.mlkit.vision.demo
+
+import android.content.Context
+import android.graphics.*
+import android.util.AttributeSet
+import android.view.View
+import java.util.concurrent.TimeUnit
+import kotlin.random.Random
+
+class GameView @JvmOverloads constructor(
+        context: Context,
+        attributeSet: AttributeSet? = null,
+        defStyleAttr: Int = 0
+) : View(context, attributeSet, defStyleAttr) {
+
+    private var isGameInitialized = false
+    private val playerPaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.FILL
+        color = Color.BLUE
+    }
+    private val cakePaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        style = Paint.Style.FILL
+        color = Color.RED
+    }
+    private val scorePaint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        color = Color.GREEN
+        textSize = context.resources.getDimension(R.dimen.score_size)
+    }
+    private var score: Int = 0
+    private var scorePoint = PointF()
+    private var playerSize = 0
+    private var playerRect = RectF()
+    private var cakeSize = 0
+    private var cakeRect = RectF()
+    private val cakeSpeed = 1f / TimeUnit.SECONDS.toMillis(5) // Full screen width per millis
+    private var flags: EmotionFlags = EmotionFlags(false, false, false)
+    private var previousTimestamp = 0L
+
+    fun setEmotionFlags(flags: EmotionFlags) {
+        this.flags = flags
+    }
+
+    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
+        super.onSizeChanged(w, h, oldw, oldh)
+        isGameInitialized = false
+    }
+
+    private fun isSizeZeros() = width == 0 && height == 0
+
+    override fun onDraw(canvas: Canvas) {
+        super.onDraw(canvas)
+        if (isSizeZeros()) {
+            return
+        }
+
+        if (!isGameInitialized) {
+            initializePlayer()
+            initializeCake()
+            initializeScore()
+            initializeTimestamp()
+            isGameInitialized = true
+        }
+
+        movePlayer()
+        moveCake()
+
+        checkPlayerCaughtCake()
+        checkCakeIsOutOfScreenStart()
+
+        drawPlayer(canvas)
+        drawCake(canvas)
+        drawScore(canvas)
+
+        invalidate()
+    }
+
+    private fun initializePlayer() {
+        playerSize = height / 4
+
+        playerRect.left = playerSize / 2f
+        playerRect.right = playerRect.left + playerSize
+    }
+
+    private fun initializeCake() {
+        cakeSize = height / 8
+        moveCakeToStartPoint()
+    }
+
+    private fun moveCakeToStartPoint() {
+        // Random position outside of screen
+        cakeRect.left = width + width * Random.nextFloat()
+        cakeRect.right = cakeRect.left + cakeSize
+
+        // Random top or bottom line
+        val isTopLine = Random.nextBoolean()
+        cakeRect.top = getObjectYTopForLine(cakeSize, isTopLine).toFloat()
+        cakeRect.bottom = cakeRect.top + cakeSize
+    }
+
+    // Get top position of object with size,
+    // that places object in the middle of top or bottom line
+    private fun getObjectYTopForLine(size: Int, isTopLine: Boolean): Int {
+        return if (isTopLine) {
+            width / 2 - width / 4 - size / 2
+        } else {
+            width / 2 + width / 4 - size / 2
+        }
+    }
+
+    private fun initializeScore() {
+        val bounds = Rect()
+        scorePaint.getTextBounds("0", 0, 1, bounds)
+        val scoreMargin = resources.getDimension(R.dimen.score_margin)
+        scorePoint = PointF(width / 2f, scoreMargin + bounds.height())
+        score = 0
+    }
+
+    private fun initializeTimestamp() {
+        previousTimestamp = System.currentTimeMillis()
+    }
+
+    private fun movePlayer() {
+        playerRect.top = getObjectYTopForLine(playerSize, isTopLine = flags.isSmile).toFloat()
+        playerRect.bottom = playerRect.top + playerSize
+    }
+
+    private fun moveCake() {
+        val currentTime = System.currentTimeMillis()
+        val deltaTime = currentTime - previousTimestamp
+        val deltaX = cakeSpeed * width * deltaTime
+
+        cakeRect.left -= deltaX
+        cakeRect.right = cakeRect.left + cakeSize
+
+        previousTimestamp = currentTime
+    }
+
+    private fun checkPlayerCaughtCake() {
+        if (RectF.intersects(playerRect, cakeRect)) {
+            score += if (flags.isLeftEyeOpen && flags.isRightEyeOpen) 1 else 2 // Double bonus for closed eye
+            moveCakeToStartPoint()
+        }
+    }
+
+    private fun checkCakeIsOutOfScreenStart() {
+        if (cakeRect.right < 0) {
+            moveCakeToStartPoint()
+        }
+    }
+
+    private fun drawPlayer(canvas: Canvas) {
+        canvas.drawRect(playerRect, playerPaint)
+    }
+
+    private fun drawCake(canvas: Canvas) {
+        canvas.drawRect(cakeRect, cakePaint)
+    }
+
+    private fun drawScore(canvas: Canvas) {
+        canvas.drawText(score.toString(), scorePoint.x, scorePoint.y, scorePaint)
+    }
+
+}

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

@@ -10,8 +10,8 @@
       android:id="@+id/preview_view"
       android:layout_width="match_parent"
       android:layout_height="0dp"
-      app:layout_constraintTop_toTopOf="parent"
-      app:layout_constraintBottom_toTopOf="@+id/control"/>
+      app:layout_constraintHeight_percent="0.5"
+      app:layout_constraintTop_toTopOf="parent"/>
 
   <com.google.mlkit.vision.demo.GraphicOverlay
       android:id="@+id/graphic_overlay"
@@ -69,4 +69,13 @@
       android:layout_width="wrap_content"
       android:layout_height="wrap_content" />
 
+  <com.google.mlkit.vision.demo.GameView
+      android:id="@+id/gameView"
+      app:layout_constraintStart_toStartOf="parent"
+      app:layout_constraintEnd_toEndOf="parent"
+      app:layout_constraintHeight_percent="0.5"
+      app:layout_constraintBottom_toBottomOf="parent"
+      android:layout_width="0dp"
+      android:layout_height="0dp" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/values/dimens.xml

@@ -3,4 +3,6 @@
     <dimen name="activity_horizontal_margin">16dp</dimen>
     <dimen name="activity_vertical_margin">16dp</dimen>
     <dimen name="padding_standard">10dp</dimen>
+    <dimen name="score_size">30sp</dimen>
+    <dimen name="score_margin">16dp</dimen>
 </resources>