Normalize file naming conventions

app/src/main/res/drawable/line.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+
+    <solid android:color="?attr/colorSurfaceContainerHighest" />
+
+    <padding
+        android:bottom="10dp"
+        android:left="10dp"
+        android:right="10dp"
+        android:top="10dp" />
+</shape>

app/src/main/res/drawable/line_drawable.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@drawable/line" android:state_pressed="true" />
+
+    <item android:drawable="@drawable/line" />
+</selector>

app/src/main/res/drawable/thumb.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+
+    <corners
+        android:bottomLeftRadius="44dp"
+        android:bottomRightRadius="44dp"
+        android:topLeftRadius="44dp"
+        android:topRightRadius="44dp" />
+
+    <padding
+        android:paddingLeft="22dp"
+        android:paddingRight="22dp" />
+
+    <solid android:color="?attr/colorSecondary" />
+</shape>

app/src/main/res/drawable/thumb_drawable.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:drawable="@drawable/thumb" android:state_pressed="true" />
+
+    <item android:drawable="@drawable/thumb" />
+</selector>

app/src/main/res/layout/activity_about.xml

@@ -16,7 +16,7 @@
             android:id="@+id/toolbar"
             android:layout_width="match_parent"
             android:layout_height="?attr/actionBarSize"
-            app:navigationIcon="@drawable/arrow_back_24"
+            app:navigationIcon="@drawable/ic_arrow_back"
             app:title="@string/about_label" />
 
     </com.google.android.material.appbar.AppBarLayout>
@@ -94,7 +94,7 @@
                             android:layout_width="wrap_content"
                             android:layout_height="wrap_content"
                             android:layout_marginStart="15dp"
-                            app:srcCompat="@drawable/update_24" />
+                            app:srcCompat="@drawable/ic_update" />
 
                         <TextView
                             android:id="@+id/check_update_text"
@@ -121,7 +121,7 @@
                             android:layout_width="wrap_content"
                             android:layout_height="wrap_content"
                             android:layout_marginStart="15dp"
-                            app:srcCompat="@drawable/github_24" />
+                            app:srcCompat="@drawable/ic_github" />
 
                         <TextView
                             android:id="@+id/open_source_text"
@@ -148,7 +148,7 @@
                             android:layout_width="wrap_content"
                             android:layout_height="wrap_content"
                             android:layout_marginStart="15dp"
-                            app:srcCompat="@drawable/person_24" />
+                            app:srcCompat="@drawable/ic_person" />
 
                         <TextView
                             android:id="@+id/developer_name"

app/src/main/res/layout/activity_crash.xml

@@ -55,6 +55,6 @@
         android:layout_gravity="bottom|end"
         android:layout_margin="16dp"
         android:text="@string/exit_app"
-        app:icon="@drawable/exit_to_app_24" />
+        app:icon="@drawable/ic_exit" />
 
 </androidx.coordinatorlayout.widget.CoordinatorLayout>

app/src/main/res/layout/activity_settings.xml

@@ -16,7 +16,7 @@
             android:id="@+id/toolbar"
             android:layout_width="match_parent"
             android:layout_height="?attr/actionBarSize"
-            app:navigationIcon="@drawable/arrow_back_24"
+            app:navigationIcon="@drawable/ic_arrow_back"
             app:title="@string/settings_label" />
 
     </com.google.android.material.appbar.AppBarLayout>

app/src/main/res/layout/item_todo.xml

@@ -49,7 +49,7 @@
             android:layout_height="wrap_content"
             android:layout_marginEnd="15dp"
             android:tooltipText="@string/delete_one"
-            app:icon="@drawable/delete_24" />
+            app:icon="@drawable/ic_delete" />
 
         <Button
             android:id="@+id/check_item_btn"
@@ -58,6 +58,6 @@
             android:layout_height="wrap_content"
             android:layout_marginEnd="15dp"
             android:tooltipText="@string/check_one"
-            app:icon="@drawable/check_24" />
+            app:icon="@drawable/ic_check" />
     </LinearLayout>
 </com.google.android.material.card.MaterialCardView>

app/src/main/res/menu/main.xml

@@ -3,7 +3,7 @@
     xmlns:app="http://schemas.android.com/apk/res-auto">
     <item
         android:id="@+id/item_settings"
-        android:icon="@drawable/settings_24"
+        android:icon="@drawable/ic_settings"
         android:title="@string/settings_label"
         android:tooltipText="@string/settings_label"
         app:showAsAction="always" />

app/src/main/res/xml/preferences.xml

@@ -5,7 +5,7 @@
             android:defaultValue="0"
             android:entries="@array/appearance"
             android:entryValues="@array/appearance_value"
-            android:icon="@drawable/dark_mode_24"
+            android:icon="@drawable/ic_dark_mode"
             android:key="dark_mode"
             android:title="@string/dark_mode"
             app:summary="@string/dark_mode_summary" />
@@ -21,26 +21,26 @@
             app:dialogMessage="多个项目请使用英文逗号隔开"
             app:summary="自定义创建待办时文本框的预测项" />-->
         <SwitchPreferenceCompat
-            android:icon="@drawable/screenshot_24"
+            android:icon="@drawable/ic_screenshot"
             app:defaultValue="false"
             app:key="secure_mode"
             app:summary="@string/secure_mode_summary"
             app:title="@string/secure_mode" />
         <Preference
-            android:icon="@drawable/backup_24"
+            android:icon="@drawable/ic_backup"
             app:key="backupDB"
             app:summary="@string/backup_summary"
             app:title="@string/backup" />
         <Preference
-            android:icon="@drawable/restore_24"
+            android:icon="@drawable/ic_restore"
             app:key="restoreDB"
             app:summary="@string/restore_summary"
             app:title="@string/restore" />
     </PreferenceCategory>
 
     <PreferenceCategory android:title="@string/others">
         <Preference
-            android:icon="@drawable/about_24"
+            android:icon="@drawable/ic_about"
             app:title="@string/about_label">
             <intent
                 android:targetClass="cn.super12138.todo.views.about.AboutActivity"