Add confetti overlay to Effect demo

Added the first overlay effect to the Effect demo. It includes an emitter of confetti that drops from the center of the frame.

PiperOrigin-RevId: 712940163

demos/effect/lint.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright 2024 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          https://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+<lint>
+  <issue id="UnsafeOptInUsageError">
+    <option name="opt-in" value="androidx.media3.common.util.UnstableApi" />
+  </issue>
+</lint>

demos/effect/src/main/java/androidx/media3/demo/effect/ConfettiOverlay.kt

@@ -0,0 +1,140 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package androidx.media3.demo.effect
+
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.graphics.PorterDuff
+import android.os.Handler
+import androidx.media3.common.VideoFrameProcessingException
+import androidx.media3.common.util.Size
+import androidx.media3.common.util.Util
+import androidx.media3.effect.CanvasOverlay
+import kotlin.math.abs
+import kotlin.random.Random
+
+/** Mimics an emitter of confetti, dropping from the center of the frame. */
+internal class ConfettiOverlay : CanvasOverlay(/* useInputFrameSize= */ true) {
+
+  private val confettiList = mutableListOf<Confetti>()
+  private val paint = Paint()
+  private val handler = Handler(Util.getCurrentOrMainLooper())
+
+  private var addConfettiTask: (() -> Unit)? = null
+  private var width = 0f
+  private var height = 0f
+  private var started = false
+
+  override fun configure(videoSize: Size) {
+    super.configure(videoSize)
+    this.width = videoSize.width.toFloat()
+    this.height = videoSize.height.toFloat()
+  }
+
+  @Synchronized
+  override fun onDraw(canvas: Canvas, presentationTimeUs: Long) {
+    if (!started) {
+      start()
+    }
+    canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)
+
+    confettiList.removeAll { confetti ->
+      confetti.y > height / 2 || confetti.x <= 0 || confetti.x > width
+    }
+    for (confetti in confettiList) {
+      confetti.draw(canvas, paint)
+      confetti.update()
+    }
+  }
+
+  @Throws(VideoFrameProcessingException::class)
+  override fun release() {
+    super.release()
+    handler.post(this::stop)
+  }
+
+  /** Starts the confetti. */
+  fun start() {
+    addConfettiTask = this::addConfetti
+    handler.post(checkNotNull(addConfettiTask))
+    started = true
+  }
+
+  /** Stops the confetti. */
+  fun stop() {
+    handler.removeCallbacks(checkNotNull(addConfettiTask))
+    confettiList.clear()
+    started = false
+    addConfettiTask = null
+  }
+
+  @Synchronized
+  fun addConfetti() {
+    repeat(5) {
+      confettiList.add(
+        Confetti(
+          text = CONFETTI_TEXTS[abs(Random.nextInt()) % CONFETTI_TEXTS.size],
+          x = width / 2f,
+          y = EMITTER_POSITION_Y.toFloat(),
+          size = CONFETTI_BASE_SIZE + Random.nextInt(CONFETTI_SIZE_VARIATION),
+          color = Color.HSVToColor(floatArrayOf(Random.nextInt(360).toFloat(), 0.6f, 0.8f)),
+        )
+      )
+    }
+    handler.postDelayed(this::addConfetti, /* delayMillis= */ 100)
+  }
+
+  private class Confetti(
+    private val text: String,
+    private val size: Int,
+    private val color: Int,
+    var x: Float,
+    var y: Float,
+  ) {
+    private val speedX = 4 * (Random.nextFloat() * 2 - 1) // Random speed in x direction
+    private val speedY = 4 * Random.nextFloat() // Random speed in y direction
+    private val rotationSpeed = (Random.nextFloat() - 0.5f) * 4f // Random rotation speed
+
+    private var rotation = Random.nextFloat() * 360f
+
+    /** Draws the [Confetti] on the [Canvas]. */
+    fun draw(canvas: Canvas, paint: Paint) {
+      canvas.save()
+      paint.color = color
+      canvas.translate(x, y)
+      canvas.rotate(rotation)
+      paint.textSize = size.toFloat()
+      canvas.drawText(text, /* x= */ 0f, /* y= */ 0f, paint) // Only draw text
+      canvas.restore()
+    }
+
+    /** Updates the [Confetti]. */
+    fun update() {
+      x += speedX
+      y += speedY
+      rotation += rotationSpeed
+    }
+  }
+
+  private companion object {
+    val CONFETTI_TEXTS = listOf("❊", "✿", "❊", "✦︎", "♥︎", "☕︎")
+    const val EMITTER_POSITION_Y = -50
+    const val CONFETTI_BASE_SIZE = 30
+    const val CONFETTI_SIZE_VARIATION = 10
+  }
+}

demos/effect/src/main/java/androidx/media3/demo/effect/EffectActivity.kt

@@ -68,8 +68,11 @@ import androidx.media3.common.MediaItem
 import androidx.media3.common.util.UnstableApi
 import androidx.media3.common.util.Util.SDK_INT
 import androidx.media3.effect.Contrast
+import androidx.media3.effect.OverlayEffect
+import androidx.media3.effect.TextureOverlay
 import androidx.media3.exoplayer.ExoPlayer
 import androidx.media3.ui.PlayerView
+import com.google.common.collect.ImmutableList
 import kotlinx.coroutines.launch
 
 class EffectActivity : ComponentActivity() {
@@ -279,7 +282,15 @@ class EffectActivity : ComponentActivity() {
       onClick = {
         val effectsList = mutableListOf<Effect>()
 
+        if (effectControlsState.contrastValue != 0f) {
           effectsList += Contrast(effectControlsState.contrastValue)
+        }
+
+        val overlaysBuilder = ImmutableList.builder<TextureOverlay>()
+        if (effectControlsState.confettiOverlayChecked) {
+          overlaysBuilder.add(ConfettiOverlay())
+        }
+        effectsList += OverlayEffect(overlaysBuilder.build())
 
         onApplyEffectsClicked(effectsList)
         effectControlsState = effectControlsState.copy(effectsChanged = false)
@@ -333,6 +344,17 @@ class EffectActivity : ComponentActivity() {
           }
         }
       }
+      item {
+        EffectItem(
+          name = stringResource(R.string.confetti_overlay),
+          enabled = enabled,
+          onCheckedChange = { checked ->
+            onEffectControlsStateChange(
+              effectControlsState.copy(effectsChanged = true, confettiOverlayChecked = checked)
+            )
+          },
+        )
+      }
     }
   }
 
@@ -382,6 +404,7 @@ class EffectActivity : ComponentActivity() {
   data class EffectControlsState(
     val effectsChanged: Boolean = false,
     val contrastValue: Float = 0f,
+    val confettiOverlayChecked: Boolean = false,
   )
 
   companion object {

demos/effect/src/main/res/values/strings.xml

@@ -24,4 +24,5 @@
   <string name="can_not_open_file_error">"File couldn't be opened. Please try again."</string>
   <string name="permission_not_granted_error">"Permission was not granted."</string>
   <string name="contrast">Contrast</string>
+  <string name="confetti_overlay">Confetti Overlay</string>
 </resources>