Fix issues with NiaTheme gradients and backgrounds

core/designsystem/src/androidTest/java/com/google/samples/apps/nowinandroid/core/designsystem/ThemeTest.kt

@@ -21,6 +21,7 @@ import androidx.compose.material3.ColorScheme
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.dynamicDarkColorScheme
 import androidx.compose.material3.dynamicLightColorScheme
+import androidx.compose.material3.surfaceColorAtElevation
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.test.junit4.createComposeRule
@@ -28,10 +29,12 @@ import androidx.compose.ui.unit.dp
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.BackgroundTheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.DarkAndroidBackgroundTheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.DarkAndroidColorScheme
+import com.google.samples.apps.nowinandroid.core.designsystem.theme.DarkAndroidGradientColors
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.DarkDefaultColorScheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.GradientColors
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LightAndroidBackgroundTheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LightAndroidColorScheme
+import com.google.samples.apps.nowinandroid.core.designsystem.theme.LightAndroidGradientColors
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LightDefaultColorScheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalBackgroundTheme
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalGradientColors
@@ -42,7 +45,7 @@ import org.junit.Test
 
 /**
  * Tests [NiaTheme] using different combinations of the theme mode parameters:
- * darkTheme, dynamicColor, and androidTheme.
+ * darkTheme, disableDynamicTheming, and androidTheme.
  *
  * It verifies that the various composition locals — [MaterialTheme], [LocalGradientColors] and
  * [LocalBackgroundTheme] — have the expected values for a given theme mode, as specified by the
@@ -133,7 +136,7 @@ class ThemeTest {
             ) {
                 val colorScheme = LightAndroidColorScheme
                 assertColorSchemesEqual(colorScheme, MaterialTheme.colorScheme)
-                val gradientColors = emptyGradientColors
+                val gradientColors = LightAndroidGradientColors
                 assertEquals(gradientColors, LocalGradientColors.current)
                 val backgroundTheme = LightAndroidBackgroundTheme
                 assertEquals(backgroundTheme, LocalBackgroundTheme.current)
@@ -151,7 +154,7 @@ class ThemeTest {
             ) {
                 val colorScheme = DarkAndroidColorScheme
                 assertColorSchemesEqual(colorScheme, MaterialTheme.colorScheme)
-                val gradientColors = emptyGradientColors
+                val gradientColors = DarkAndroidGradientColors
                 assertEquals(gradientColors, LocalGradientColors.current)
                 val backgroundTheme = DarkAndroidBackgroundTheme
                 assertEquals(backgroundTheme, LocalBackgroundTheme.current)
@@ -166,11 +169,11 @@ class ThemeTest {
                 darkTheme = false,
                 androidTheme = true
             ) {
-                val colorScheme = dynamicLightColorSchemeWithFallback()
+                val colorScheme = LightAndroidColorScheme
                 assertColorSchemesEqual(colorScheme, MaterialTheme.colorScheme)
-                val gradientColors = dynamicGradientColorsWithFallback(colorScheme)
+                val gradientColors = LightAndroidGradientColors
                 assertEquals(gradientColors, LocalGradientColors.current)
-                val backgroundTheme = defaultBackgroundTheme(colorScheme)
+                val backgroundTheme = LightAndroidBackgroundTheme
                 assertEquals(backgroundTheme, LocalBackgroundTheme.current)
             }
         }
@@ -183,11 +186,11 @@ class ThemeTest {
                 darkTheme = true,
                 androidTheme = true
             ) {
-                val colorScheme = dynamicDarkColorSchemeWithFallback()
+                val colorScheme = DarkAndroidColorScheme
                 assertColorSchemesEqual(colorScheme, MaterialTheme.colorScheme)
-                val gradientColors = dynamicGradientColorsWithFallback(colorScheme)
+                val gradientColors = DarkAndroidGradientColors
                 assertEquals(gradientColors, LocalGradientColors.current)
-                val backgroundTheme = defaultBackgroundTheme(colorScheme)
+                val backgroundTheme = DarkAndroidBackgroundTheme
                 assertEquals(backgroundTheme, LocalBackgroundTheme.current)
             }
         }
@@ -211,7 +214,9 @@ class ThemeTest {
         }
     }
 
-    private val emptyGradientColors = GradientColors()
+    private fun emptyGradientColors(colorScheme: ColorScheme): GradientColors {
+        return GradientColors(container = colorScheme.surfaceColorAtElevation(2.dp))
+    }
 
     private fun defaultGradientColors(colorScheme: ColorScheme): GradientColors {
         return GradientColors(
@@ -223,7 +228,7 @@ class ThemeTest {
 
     private fun dynamicGradientColorsWithFallback(colorScheme: ColorScheme): GradientColors {
         return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-            emptyGradientColors
+            emptyGradientColors(colorScheme)
         } else {
             defaultGradientColors(colorScheme)
         }

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

@@ -25,6 +25,7 @@ import androidx.compose.material3.darkColorScheme
 import androidx.compose.material3.dynamicDarkColorScheme
 import androidx.compose.material3.dynamicLightColorScheme
 import androidx.compose.material3.lightColorScheme
+import androidx.compose.material3.surfaceColorAtElevation
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.ui.graphics.Color
@@ -159,6 +160,16 @@ val DarkAndroidColorScheme = darkColorScheme(
     outline = GreenGray60
 )
 
+/**
+ * Light Android gradient colors
+ */
+val LightAndroidGradientColors = GradientColors(container = DarkGreenGray95)
+
+/**
+ * Dark Android gradient colors
+ */
+val DarkAndroidGradientColors = GradientColors(container = Color.Black)
+
 /**
  * Light Android background theme
  */
@@ -207,33 +218,23 @@ internal fun NiaTheme(
 ) {
     // Color scheme
     val colorScheme = when {
-        !disableDynamicTheming -> {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-                val context = LocalContext.current
-                if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
-            } else {
-                if (darkTheme) DarkDefaultColorScheme else LightDefaultColorScheme
-            }
-        }
         androidTheme -> if (darkTheme) DarkAndroidColorScheme else LightAndroidColorScheme
+        !disableDynamicTheming && supportsDynamicTheming() -> {
+            val context = LocalContext.current
+            if (darkTheme) dynamicDarkColorScheme(context) else dynamicLightColorScheme(context)
+        }
         else -> if (darkTheme) DarkDefaultColorScheme else LightDefaultColorScheme
     }
     // Gradient colors
-    val emptyGradientColors = GradientColors()
+    val emptyGradientColors = GradientColors(container = colorScheme.surfaceColorAtElevation(2.dp))
     val defaultGradientColors = GradientColors(
         top = colorScheme.inverseOnSurface,
         bottom = colorScheme.primaryContainer,
         container = colorScheme.surface
     )
     val gradientColors = when {
-        !disableDynamicTheming -> {
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-                emptyGradientColors
-            } else {
-                defaultGradientColors
-            }
-        }
-        androidTheme -> emptyGradientColors
+        androidTheme -> if (darkTheme) DarkAndroidGradientColors else LightAndroidGradientColors
+        !disableDynamicTheming && supportsDynamicTheming() -> emptyGradientColors
         else -> defaultGradientColors
     }
     // Background theme
@@ -242,7 +243,6 @@ internal fun NiaTheme(
         tonalElevation = 2.dp
     )
     val backgroundTheme = when {
-        !disableDynamicTheming -> defaultBackgroundTheme
         androidTheme -> if (darkTheme) DarkAndroidBackgroundTheme else LightAndroidBackgroundTheme
         else -> defaultBackgroundTheme
     }