[Expressive design] Add NormalPaddingMixin

A base interface to indicate that a Preference should have normal
paddings.

Bug: 366336385
Flag: com.android.settingslib.widget.theme.flags.is_expressive_design_enabled
Test: manual
Change-Id: I00212b46ca66b5e12b1e85d8672a0851bb5af418

2 files changed, 45 insertions, 2 deletions

diff --git a/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/NormalPaddingMixin.kt b/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/NormalPaddingMixin.kt
new file mode 100644
index 000000000000..5035542b9783
--- /dev/null
+++ b/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/NormalPaddingMixin.kt
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 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 com.android.settingslib.widget
+
+/**
+ * A base interface to indicate that a Preference should have normal paddings.
+ *
+ * Preferences implementing this interface will be treated as has normal paddings both inside and
+ * outside.
+ */
+interface NormalPaddingMixin
\ No newline at end of file
diff --git a/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/SettingsPreferenceGroupAdapter.kt b/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/SettingsPreferenceGroupAdapter.kt
index a04fce7eeb86..2672787a0519 100644
--- a/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/SettingsPreferenceGroupAdapter.kt
+++ b/packages/SettingsLib/SettingsTheme/src/com/android/settingslib/widget/SettingsPreferenceGroupAdapter.kt
@@ -177,14 +177,32 @@ open class SettingsPreferenceGroupAdapter(preferenceGroup: PreferenceGroup) :
         val v = holder.itemView
         // Update padding
         if (SettingsThemeHelper.isExpressiveTheme(context)) {
-            val paddingStart = if (backgroundRes == 0) mNormalPaddingStart else mGroupPaddingStart
-            val paddingEnd = if (backgroundRes == 0) mNormalPaddingEnd else mGroupPaddingEnd
+            val (paddingStart, paddingEnd) = getStartEndPadding(position, backgroundRes)
             v.setPaddingRelative(paddingStart, v.paddingTop, paddingEnd, v.paddingBottom)
+            v.clipToOutline = backgroundRes != 0
         }
         // Update background
         v.setBackgroundResource(backgroundRes)
     }
 
+    private fun getStartEndPadding(position: Int, backgroundRes: Int): Pair<Int, Int> {
+        val item = getItem(position)
+        return when {
+            // This item handles edge to edge itself
+            item is NormalPaddingMixin && item is GroupSectionDividerMixin -> 0 to 0
+
+            // According to mappingPreferenceGroup(), backgroundRes == 0 means this item is
+            // GroupSectionDividerMixin or PreferenceCategory, which is design to have normal
+            // padding.
+            // NormalPaddingMixin items are also designed to have normal padding.
+            backgroundRes == 0 || item is NormalPaddingMixin ->
+                mNormalPaddingStart to mNormalPaddingEnd
+
+            // Other items are suppose to have group padding.
+            else -> mGroupPaddingStart to mGroupPaddingEnd
+        }
+    }
+
     @DrawableRes
     protected fun getRoundCornerDrawableRes(position: Int, isSelected: Boolean): Int {
         return getRoundCornerDrawableRes(position, isSelected, false)