Introducing Jetpack Compose in NewPipe

This pull request integrates Jetpack Compose into NewPipe by:
- Adding the necessary dependencies and setup.
- This is part of the NewPipe rewrite and fulfils the requirement for
  the planned settings page redesign.
- Introducing a Toolbar composable with theming that aligns with
  NewPipe's design.

Note:
- Theme colors are generated using the Material Theme builder (https://m3.material.io/styles/color/overview).

app/build.gradle

@@ -92,6 +92,7 @@ android {
 
     buildFeatures {
         viewBinding true
+        compose true
     }
 
     packagingOptions {
@@ -103,6 +104,10 @@ android {
                          'META-INF/COPYRIGHT']
         }
     }
+
+    composeOptions {
+        kotlinCompilerExtensionVersion = "1.5.3"
+    }
 }
 
 ext {
@@ -284,6 +289,12 @@ dependencies {
     // Date and time formatting
     implementation "org.ocpsoft.prettytime:prettytime:5.0.7.Final"
 
+    // Jetpack Compose
+    implementation(platform('androidx.compose:compose-bom:2024.02.01'))
+    implementation 'androidx.compose.material3:material3'
+    implementation 'androidx.activity:activity-compose'
+    implementation 'androidx.compose.ui:ui-tooling-preview'
+
 /** Debugging **/
     // Memory leak detection
     debugImplementation "com.squareup.leakcanary:leakcanary-object-watcher-android:${leakCanaryVersion}"
@@ -293,6 +304,9 @@ dependencies {
     debugImplementation "com.facebook.stetho:stetho:${stethoVersion}"
     debugImplementation "com.facebook.stetho:stetho-okhttp3:${stethoVersion}"
 
+    // Jetpack Compose
+    debugImplementation 'androidx.compose.ui:ui-tooling'
+
 /** Testing **/
     testImplementation 'junit:junit:4.13.2'
     testImplementation 'org.mockito:mockito-core:5.6.0'

app/src/main/java/org/schabi/newpipe/ui/Toolbar.kt

@@ -0,0 +1,137 @@
+package org.schabi.newpipe.ui
+
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.RowScope
+import androidx.compose.foundation.layout.fillMaxHeight
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.automirrored.filled.ArrowBack
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Icon
+import androidx.compose.material3.IconButton
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.SearchBar
+import androidx.compose.material3.SearchBarDefaults
+import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBar
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import org.schabi.newpipe.R
+import org.schabi.newpipe.ui.theme.AppTheme
+
+@Composable
+fun TextAction(text: String, modifier: Modifier = Modifier) {
+    Text(text = text, color = MaterialTheme.colorScheme.onSurface, modifier = modifier)
+}
+
+@Composable
+fun NavigationIcon() {
+    Icon(
+        imageVector = Icons.AutoMirrored.Filled.ArrowBack, contentDescription = "Back",
+        modifier = Modifier.padding(horizontal = 4.dp)
+    )
+}
+
+@Composable
+fun SearchSuggestionItem(text: String) {
+    // TODO: Add more components here to display all the required details of a search suggestion item.
+    Text(text = text)
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun Toolbar(
+    title: String,
+    modifier: Modifier = Modifier,
+    hasNavigationIcon: Boolean = true,
+    hasSearch: Boolean = false,
+    onSearchQueryChange: ((String) -> List<String>)? = null,
+    actions: @Composable RowScope.() -> Unit = {}
+) {
+    var isSearchActive by remember { mutableStateOf(false) }
+    var query by remember { mutableStateOf("") }
+
+    Column {
+        TopAppBar(
+            title = { Text(text = title) },
+            modifier = modifier,
+            navigationIcon = { if (hasNavigationIcon) NavigationIcon() },
+            actions = {
+                actions()
+                if (hasSearch) {
+                    IconButton(onClick = { isSearchActive = true }) {
+                        Icon(
+                            painterResource(id = R.drawable.ic_search),
+                            contentDescription = stringResource(id = R.string.search),
+                            tint = MaterialTheme.colorScheme.onSurface
+                        )
+                    }
+                }
+            }
+        )
+        if (isSearchActive) {
+            SearchBar(
+                query = query,
+                onQueryChange = { query = it },
+                onSearch = {},
+                placeholder = {
+                    Text(text = stringResource(id = R.string.search))
+                },
+                active = true,
+                onActiveChange = {
+                    isSearchActive = it
+                },
+                colors = SearchBarDefaults.colors(
+                    containerColor = MaterialTheme.colorScheme.background,
+                    inputFieldColors = SearchBarDefaults.inputFieldColors(
+                        focusedTextColor = MaterialTheme.colorScheme.onBackground,
+                        unfocusedTextColor = MaterialTheme.colorScheme.onBackground
+                    )
+                )
+            ) {
+                onSearchQueryChange?.invoke(query)?.takeIf { it.isNotEmpty() }
+                    ?.map { suggestionText -> SearchSuggestionItem(text = suggestionText) }
+                    ?: run {
+                        Box(
+                            modifier = Modifier
+                                .fillMaxHeight()
+                                .fillMaxWidth(),
+                            contentAlignment = Alignment.Center
+                        ) {
+                            Column {
+                                Text(text = "╰(°●°╰)")
+                                Text(text = stringResource(id = R.string.search_no_results))
+                            }
+                        }
+                    }
+            }
+        }
+    }
+}
+
+@Preview
+@Composable
+fun ToolbarPreview() {
+    AppTheme {
+        Toolbar(
+            title = "Title",
+            hasSearch = true,
+            onSearchQueryChange = { emptyList() },
+            actions = {
+                TextAction(text = "Action1")
+                TextAction(text = "Action2")
+            }
+        )
+    }
+}

app/src/main/java/org/schabi/newpipe/ui/theme/Color.kt

@@ -0,0 +1,63 @@
+package org.schabi.newpipe.ui.theme
+
+import androidx.compose.ui.graphics.Color
+
+val md_theme_light_primary = Color(0xFFBB171C)
+val md_theme_light_onPrimary = Color(0xFFFFFFFF)
+val md_theme_light_primaryContainer = Color(0xFFFFDAD6)
+val md_theme_light_onPrimaryContainer = Color(0xFF410002)
+val md_theme_light_secondary = Color(0xFF984061)
+val md_theme_light_onSecondary = Color(0xFFFFFFFF)
+val md_theme_light_secondaryContainer = Color(0xFFFFD9E2)
+val md_theme_light_onSecondaryContainer = Color(0xFF3E001D)
+val md_theme_light_tertiary = Color(0xFF006874)
+val md_theme_light_onTertiary = Color(0xFFFFFFFF)
+val md_theme_light_tertiaryContainer = Color(0xFF97F0FF)
+val md_theme_light_onTertiaryContainer = Color(0xFF001F24)
+val md_theme_light_error = Color(0xFFBA1A1A)
+val md_theme_light_errorContainer = Color(0xFFFFDAD6)
+val md_theme_light_onError = Color(0xFFFFFFFF)
+val md_theme_light_onErrorContainer = Color(0xFF410002)
+val md_theme_light_background = Color(0xFFEEEEEE)
+val md_theme_light_onBackground = Color(0xFF1B1B1B)
+val md_theme_light_surface = Color(0xFFE53835)
+val md_theme_light_onSurface = Color(0xFFFFFFFF)
+val md_theme_light_surfaceVariant = Color(0xFFF5DDDB)
+val md_theme_light_onSurfaceVariant = Color(0xFF534341)
+val md_theme_light_outline = Color(0xFF857371)
+val md_theme_light_inverseOnSurface = Color(0xFFD6F6FF)
+val md_theme_light_inverseSurface = Color(0xFF00363F)
+val md_theme_light_inversePrimary = Color(0xFFFFB4AC)
+val md_theme_light_surfaceTint = Color(0xFFBB171C)
+val md_theme_light_outlineVariant = Color(0xFFD8C2BF)
+val md_theme_light_scrim = Color(0xFF000000)
+
+val md_theme_dark_primary = Color(0xFFFFB4AC)
+val md_theme_dark_onPrimary = Color(0xFF690006)
+val md_theme_dark_primaryContainer = Color(0xFF93000D)
+val md_theme_dark_onPrimaryContainer = Color(0xFFFFDAD6)
+val md_theme_dark_secondary = Color(0xFFFFB1C8)
+val md_theme_dark_onSecondary = Color(0xFF5E1133)
+val md_theme_dark_secondaryContainer = Color(0xFF7B2949)
+val md_theme_dark_onSecondaryContainer = Color(0xFFFFD9E2)
+val md_theme_dark_tertiary = Color(0xFF4FD8EB)
+val md_theme_dark_onTertiary = Color(0xFF00363D)
+val md_theme_dark_tertiaryContainer = Color(0xFF004F58)
+val md_theme_dark_onTertiaryContainer = Color(0xFF97F0FF)
+val md_theme_dark_error = Color(0xFFFFB4AB)
+val md_theme_dark_errorContainer = Color(0xFF93000A)
+val md_theme_dark_onError = Color(0xFF690005)
+val md_theme_dark_onErrorContainer = Color(0xFFFFDAD6)
+val md_theme_dark_background = Color(0xFF212121)
+val md_theme_dark_onBackground = Color(0xFFFFFFFF)
+val md_theme_dark_surface = Color(0xFF992521)
+val md_theme_dark_onSurface = Color(0xFFFFFFFF)
+val md_theme_dark_surfaceVariant = Color(0xFF534341)
+val md_theme_dark_onSurfaceVariant = Color(0xFFD8C2BF)
+val md_theme_dark_outline = Color(0xFFA08C8A)
+val md_theme_dark_inverseOnSurface = Color(0xFF001F25)
+val md_theme_dark_inverseSurface = Color(0xFFA6EEFF)
+val md_theme_dark_inversePrimary = Color(0xFFBB171C)
+val md_theme_dark_surfaceTint = Color(0xFFFFB4AC)
+val md_theme_dark_outlineVariant = Color(0xFF534341)
+val md_theme_dark_scrim = Color(0xFF000000)

app/src/main/java/org/schabi/newpipe/ui/theme/Theme.kt

@@ -0,0 +1,79 @@
+package org.schabi.newpipe.ui.theme
+
+import androidx.compose.foundation.isSystemInDarkTheme
+import androidx.compose.material3.MaterialTheme
+import androidx.compose.material3.darkColorScheme
+import androidx.compose.material3.lightColorScheme
+import androidx.compose.runtime.Composable
+
+private val LightColors = lightColorScheme(
+    primary = md_theme_light_primary,
+    onPrimary = md_theme_light_onPrimary,
+    primaryContainer = md_theme_light_primaryContainer,
+    onPrimaryContainer = md_theme_light_onPrimaryContainer,
+    secondary = md_theme_light_secondary,
+    onSecondary = md_theme_light_onSecondary,
+    secondaryContainer = md_theme_light_secondaryContainer,
+    onSecondaryContainer = md_theme_light_onSecondaryContainer,
+    tertiary = md_theme_light_tertiary,
+    onTertiary = md_theme_light_onTertiary,
+    tertiaryContainer = md_theme_light_tertiaryContainer,
+    onTertiaryContainer = md_theme_light_onTertiaryContainer,
+    error = md_theme_light_error,
+    errorContainer = md_theme_light_errorContainer,
+    onError = md_theme_light_onError,
+    onErrorContainer = md_theme_light_onErrorContainer,
+    background = md_theme_light_background,
+    onBackground = md_theme_light_onBackground,
+    surface = md_theme_light_surface,
+    onSurface = md_theme_light_onSurface,
+    surfaceVariant = md_theme_light_surfaceVariant,
+    onSurfaceVariant = md_theme_light_onSurfaceVariant,
+    outline = md_theme_light_outline,
+    inverseOnSurface = md_theme_light_inverseOnSurface,
+    inverseSurface = md_theme_light_inverseSurface,
+    inversePrimary = md_theme_light_inversePrimary,
+    surfaceTint = md_theme_light_surfaceTint,
+    outlineVariant = md_theme_light_outlineVariant,
+    scrim = md_theme_light_scrim,
+)
+
+private val DarkColors = darkColorScheme(
+    primary = md_theme_dark_primary,
+    onPrimary = md_theme_dark_onPrimary,
+    primaryContainer = md_theme_dark_primaryContainer,
+    onPrimaryContainer = md_theme_dark_onPrimaryContainer,
+    secondary = md_theme_dark_secondary,
+    onSecondary = md_theme_dark_onSecondary,
+    secondaryContainer = md_theme_dark_secondaryContainer,
+    onSecondaryContainer = md_theme_dark_onSecondaryContainer,
+    tertiary = md_theme_dark_tertiary,
+    onTertiary = md_theme_dark_onTertiary,
+    tertiaryContainer = md_theme_dark_tertiaryContainer,
+    onTertiaryContainer = md_theme_dark_onTertiaryContainer,
+    error = md_theme_dark_error,
+    errorContainer = md_theme_dark_errorContainer,
+    onError = md_theme_dark_onError,
+    onErrorContainer = md_theme_dark_onErrorContainer,
+    background = md_theme_dark_background,
+    onBackground = md_theme_dark_onBackground,
+    surface = md_theme_dark_surface,
+    onSurface = md_theme_dark_onSurface,
+    surfaceVariant = md_theme_dark_surfaceVariant,
+    onSurfaceVariant = md_theme_dark_onSurfaceVariant,
+    outline = md_theme_dark_outline,
+    inverseOnSurface = md_theme_dark_inverseOnSurface,
+    inverseSurface = md_theme_dark_inverseSurface,
+    inversePrimary = md_theme_dark_inversePrimary,
+    surfaceTint = md_theme_dark_surfaceTint,
+    outlineVariant = md_theme_dark_outlineVariant,
+    scrim = md_theme_dark_scrim,
+)
+
+@Composable
+fun AppTheme(useDarkTheme: Boolean = isSystemInDarkTheme(), content: @Composable () -> Unit) {
+    MaterialTheme(
+        colorScheme = if (useDarkTheme) DarkColors else LightColors,
+        content = content
+    )
+}