Refactor NiaGradientBackground to accept GradientColors

Change-Id: I55840b22e123490097710570bf11554554df90f9

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -66,6 +66,7 @@ import com.google.samples.apps.nowinandroid.core.designsystem.component.NiaTopAp
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.DrawableResourceIcon
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.ImageVectorIcon
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
+import com.google.samples.apps.nowinandroid.core.designsystem.theme.GradientColors
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalGradientColors
 import com.google.samples.apps.nowinandroid.feature.settings.R as settingsR
 import com.google.samples.apps.nowinandroid.feature.settings.SettingsDialog
@@ -92,20 +93,10 @@ fun NiaApp(
 
     NiaBackground {
         NiaGradientBackground(
-            topColor = if (shouldShowGradientBackground) {
-                LocalGradientColors.current.top
+            gradientColors = if (shouldShowGradientBackground) {
+                LocalGradientColors.current
             } else {
-                Color.Unspecified
-            },
-            bottomColor = if (shouldShowGradientBackground) {
-                LocalGradientColors.current.bottom
-            } else {
-                Color.Unspecified
-            },
-            containerColor = if (shouldShowGradientBackground) {
-                LocalGradientColors.current.container
-            } else {
-                Color.Unspecified
+                GradientColors()
             },
         ) {
             val snackbarHostState = remember { SnackbarHostState() }

core/designsystem/src/main/java/com/google/samples/apps/nowinandroid/core/designsystem/component/Background.kt

@@ -34,6 +34,7 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
+import com.google.samples.apps.nowinandroid.core.designsystem.theme.GradientColors
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalBackgroundTheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalGradientColors
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.NiaTheme
@@ -69,23 +70,23 @@ fun NiaBackground(
  * of a [Box] within a [Surface].
  *
  * @param modifier Modifier to be applied to the background.
- * @param topColor The top gradient color to be rendered.
- * @param bottomColor The bottom gradient color to be rendered.
- * @param containerColor The container color over which the gradient will be rendered.
+ * @param gradientColors The gradient colors to be rendered.
  * @param content The background content.
  */
 @Composable
 fun NiaGradientBackground(
     modifier: Modifier = Modifier,
-    topColor: Color = LocalGradientColors.current.top,
-    bottomColor: Color = LocalGradientColors.current.bottom,
-    containerColor: Color = LocalGradientColors.current.container,
+    gradientColors: GradientColors = LocalGradientColors.current,
     content: @Composable () -> Unit
 ) {
-    val currentTopColor by rememberUpdatedState(topColor)
-    val currentBottomColor by rememberUpdatedState(bottomColor)
+    val currentTopColor by rememberUpdatedState(gradientColors.top)
+    val currentBottomColor by rememberUpdatedState(gradientColors.bottom)
     Surface(
-        color = if (containerColor == Color.Unspecified) Color.Transparent else containerColor,
+        color = if (gradientColors.container == Color.Unspecified) {
+            Color.Transparent
+        } else {
+            gradientColors.container
+        },
         modifier = modifier.fillMaxSize()
     ) {
         Box(

core/designsystem/src/main/java/com/google/samples/apps/nowinandroid/core/designsystem/theme/Gradient.kt

@@ -22,6 +22,10 @@ import androidx.compose.ui.graphics.Color
 
 /**
  * A class to model gradient color values for Now in Android.
+ *
+ * @param top The top gradient color to be rendered.
+ * @param bottom The bottom gradient color to be rendered.
+ * @param container The container gradient color over which the gradient will be rendered.
  */
 @Immutable
 data class GradientColors(