Add contrast effect to effect demo

Added a contrast effect and the connection needed to apply the video effects to ExoPlayer.

The effect can be applied to the video by checking the "Contrast" card, and use the slider to change the contrast value. The effects are applied when `Apply effects` button is clicked.

PiperOrigin-RevId: 707092041

demos/effect/build.gradle

@@ -76,6 +76,7 @@ dependencies {
 
     implementation project(modulePrefix + 'lib-exoplayer')
     implementation project(modulePrefix + 'lib-ui')
+    implementation project(modulePrefix + 'lib-effect')
 
     // For detecting and debugging leaks only. LeakCanary is not needed for demo app to work.
     debugImplementation 'com.squareup.leakcanary:leakcanary-android:' + leakCanaryVersion

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

@@ -23,6 +23,10 @@ import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.compose.setContent
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.annotation.OptIn
+import androidx.compose.animation.animateContentSize
+import androidx.compose.animation.core.LinearEasing
+import androidx.compose.animation.core.tween
+import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Row
@@ -30,11 +34,16 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.selection.selectable
 import androidx.compose.material3.AlertDialog
 import androidx.compose.material3.Button
+import androidx.compose.material3.Card
+import androidx.compose.material3.Checkbox
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.RadioButton
 import androidx.compose.material3.Scaffold
+import androidx.compose.material3.Slider
 import androidx.compose.material3.SnackbarHost
 import androidx.compose.material3.SnackbarHostState
 import androidx.compose.material3.Text
@@ -44,6 +53,7 @@ import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -53,9 +63,11 @@ import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.viewinterop.AndroidView
 import androidx.core.content.ContextCompat
 import androidx.lifecycle.lifecycleScope
+import androidx.media3.common.Effect
 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.exoplayer.ExoPlayer
 import androidx.media3.ui.PlayerView
 import kotlinx.coroutines.launch
@@ -72,6 +84,7 @@ class EffectActivity : ComponentActivity() {
     setContent { EffectDemo(playlistHolderList.value) }
   }
 
+  @OptIn(UnstableApi::class)
   @Composable
   private fun EffectDemo(playlistHolderList: List<PlaylistHolder>) {
     val snackbarHostState = remember { SnackbarHostState() }
@@ -80,6 +93,7 @@ class EffectActivity : ComponentActivity() {
     val exoPlayer by remember {
       mutableStateOf(ExoPlayer.Builder(context).build().apply { playWhenReady = true })
     }
+    var effectsEnabled by remember { mutableStateOf(false) }
 
     Scaffold(
       modifier = Modifier.fillMaxSize(),
@@ -96,16 +110,22 @@ class EffectActivity : ComponentActivity() {
             coroutineScope.launch { snackbarHostState.showSnackbar(message) }
           },
         ) { mediaItems ->
+          effectsEnabled = true
           exoPlayer.apply {
             setMediaItems(mediaItems)
+            setVideoEffects(emptyList())
             prepare()
           }
         }
         PlayerScreen(exoPlayer)
-        Effects(
-          onException = { message ->
-            coroutineScope.launch { snackbarHostState.showSnackbar(message) }
-          }
+        EffectControls(
+          effectsEnabled,
+          onApplyEffectsClicked = { videoEffects ->
+            exoPlayer.apply {
+              setVideoEffects(videoEffects)
+              prepare()
+            }
+          },
         )
       }
     }
@@ -120,8 +140,8 @@ class EffectActivity : ComponentActivity() {
     var showPresetInputChooser by remember { mutableStateOf(false) }
     var showLocalFileChooser by remember { mutableStateOf(false) }
     Row(
-      modifier = Modifier.padding(vertical = dimensionResource(id = R.dimen.small_padding)),
-      horizontalArrangement = Arrangement.spacedBy(dimensionResource(id = R.dimen.small_padding)),
+      Modifier.padding(vertical = dimensionResource(id = R.dimen.regular_padding)),
+      horizontalArrangement = Arrangement.spacedBy(dimensionResource(id = R.dimen.regular_padding)),
     ) {
       Button(onClick = { showPresetInputChooser = true }) {
         Text(text = stringResource(id = R.string.choose_preset_input))
@@ -245,17 +265,125 @@ class EffectActivity : ComponentActivity() {
       factory = { PlayerView(context).apply { player = exoPlayer } },
       modifier =
         Modifier.height(dimensionResource(id = R.dimen.android_view_height))
-          .padding(all = dimensionResource(id = R.dimen.small_padding)),
+          .padding(all = dimensionResource(id = R.dimen.regular_padding)),
     )
   }
 
+  @OptIn(UnstableApi::class)
   @Composable
-  private fun Effects(onException: (String) -> Unit) {
-    Button(onClick = { onException("Button is not yet implemented.") }) {
+  private fun EffectControls(enabled: Boolean, onApplyEffectsClicked: (List<Effect>) -> Unit) {
+    var effectControlsState by remember { mutableStateOf(EffectControlsState()) }
+
+    Button(
+      enabled = enabled && effectControlsState.effectsChanged,
+      onClick = {
+        val effectsList = mutableListOf<Effect>()
+
+        effectsList += Contrast(effectControlsState.contrastValue)
+
+        onApplyEffectsClicked(effectsList)
+        effectControlsState = effectControlsState.copy(effectsChanged = false)
+      },
+    ) {
       Text(text = stringResource(id = R.string.apply_effects))
     }
+
+    EffectControlsList(enabled, effectControlsState) { newEffectControlsState ->
+      effectControlsState = newEffectControlsState
+    }
   }
 
+  @Composable
+  private fun EffectControlsList(
+    enabled: Boolean,
+    effectControlsState: EffectControlsState,
+    onEffectControlsStateChange: (EffectControlsState) -> Unit,
+  ) {
+    LazyColumn(Modifier.padding(vertical = dimensionResource(id = R.dimen.small_padding))) {
+      item {
+        EffectItem(
+          name = stringResource(id = R.string.contrast),
+          enabled = enabled,
+          onCheckedChange = {
+            onEffectControlsStateChange(
+              effectControlsState.copy(effectsChanged = true, contrastValue = 0f)
+            )
+          },
+        ) {
+          Row {
+            Text(
+              text = "%.2f".format(effectControlsState.contrastValue),
+              style = MaterialTheme.typography.bodyLarge,
+              modifier = Modifier.padding(dimensionResource(id = R.dimen.large_padding)).weight(1f),
+            )
+            Slider(
+              value = effectControlsState.contrastValue,
+              onValueChange = { newContrastValue ->
+                val newRoundedContrastValue = "%.2f".format(newContrastValue).toFloat()
+                onEffectControlsStateChange(
+                  effectControlsState.copy(
+                    effectsChanged = true,
+                    contrastValue = newRoundedContrastValue,
+                  )
+                )
+              },
+              valueRange = -1f..1f,
+              modifier = Modifier.weight(4f),
+            )
+          }
+        }
+      }
+    }
+  }
+
+  @Composable
+  fun EffectItem(
+    name: String,
+    enabled: Boolean,
+    onCheckedChange: (Boolean) -> Unit = {},
+    content: @Composable () -> Unit = {},
+  ) {
+    var checked by rememberSaveable { mutableStateOf(false) }
+    Card(
+      modifier =
+        Modifier.padding(
+            vertical = dimensionResource(id = R.dimen.small_padding),
+            horizontal = dimensionResource(id = R.dimen.regular_padding),
+          )
+          .clickable(enabled = enabled && !checked) {
+            checked = !checked
+            onCheckedChange(checked)
+          }
+    ) {
+      Column(
+        Modifier.padding(dimensionResource(id = R.dimen.large_padding))
+          .animateContentSize(animationSpec = tween(durationMillis = 200, easing = LinearEasing))
+      ) {
+        Row {
+          Column(Modifier.weight(1f).padding(dimensionResource(id = R.dimen.large_padding))) {
+            Text(text = name, style = MaterialTheme.typography.bodyLarge)
+          }
+          Checkbox(
+            enabled = enabled,
+            checked = checked,
+            onCheckedChange = {
+              checked = !checked
+              onCheckedChange(checked)
+            },
+          )
+        }
+        if (checked) {
+          content()
+        }
+      }
+    }
+  }
+
+  data class EffectControlsState(
+    val effectsChanged: Boolean = false,
+    val contrastValue: Float = 0f,
+  )
+
   companion object {
     const val JSON_FILENAME = "media.playlist.json"
   }

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

@@ -14,6 +14,8 @@
      limitations under the License.
 -->
 <resources>
-  <dimen name="small_padding">8dp</dimen>
+  <dimen name="small_padding">4dp</dimen>
+  <dimen name="regular_padding">8dp</dimen>
+  <dimen name="large_padding">12dp</dimen>
   <dimen name="android_view_height">256dp</dimen>
 </resources>

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

@@ -23,4 +23,5 @@
   <string name="no_loaded_playlists_error">There are no loaded preset inputs.</string>
   <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>
 </resources>