Add a drag indicator element at the top of LicenceDialog

A new `DragIndicatorView` had been introduced, which draws a drag indicator drawable. Users of this view should add the callback member as a behavior callback for proper hiding of the indicator when the dialog is fully expanded.

app/src/main/java/emu/skyline/preference/LicenseDialog.kt

@@ -8,6 +8,7 @@ package emu.skyline.preference
 import android.graphics.Rect
 import android.os.Bundle
 import android.view.*
+import com.google.android.material.bottomsheet.BottomSheetBehavior
 import com.google.android.material.bottomsheet.BottomSheetDialogFragment
 import emu.skyline.databinding.LicenseDialogBinding
 
@@ -32,6 +33,13 @@ class LicenseDialog : BottomSheetDialogFragment() {
         }.root
     }
 
+    override fun onStart() {
+        super.onStart()
+
+        val behavior = BottomSheetBehavior.from(requireView().parent as View)
+        behavior.addBottomSheetCallback(binding.dragIndicator.callback)
+    }
+
     override fun onViewCreated(view : View, savedInstanceState : Bundle?) {
         super.onViewCreated(view, savedInstanceState)
 

app/src/main/java/emu/skyline/views/DragIndicatorView.kt

@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: MPL-2.0
+ * Copyright © 2022 Skyline Team and Contributors (https://github.com/skyline-emu/)
+ */
+
+package emu.skyline.views
+
+import android.content.Context
+import android.util.AttributeSet
+import android.view.View
+import android.view.ViewGroup
+import androidx.transition.TransitionManager
+import com.google.android.material.bottomsheet.BottomSheetBehavior
+import emu.skyline.R
+
+class DragIndicatorView : androidx.appcompat.widget.AppCompatImageView {
+    val callback = DragIndicatorCallback()
+
+    init {
+        setImageResource(R.drawable.drag_indicator)
+    }
+
+    constructor(context : Context) : super(context)
+    constructor(context : Context, attrs : AttributeSet?) : super(context, attrs)
+    constructor(context : Context, attrs : AttributeSet?, defStyleAttr : Int) : super(context, attrs, defStyleAttr)
+
+    inner class DragIndicatorCallback : BottomSheetBehavior.BottomSheetCallback() {
+        override fun onStateChanged(bottomSheet : View, newState : Int) {
+            // Enables animation between visibility states
+            TransitionManager.beginDelayedTransition(parent as ViewGroup)
+
+            visibility = if (newState == BottomSheetBehavior.STATE_EXPANDED && bottomSheet.top == 0)
+                View.INVISIBLE
+            else
+                View.VISIBLE
+        }
+
+        override fun onSlide(bottomSheet : View, slideOffset : Float) {}
+    }
+}

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

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android"
+    android:shape="rectangle">
+    <size
+        android:width="48dp"
+        android:height="4dp" />
+    <solid android:color="@color/onBackgroundLight" />
+    <corners android:radius="4dp" />
+</shape>

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

@@ -8,8 +8,13 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:orientation="vertical"
-        android:paddingHorizontal="2.5dp"
+        android:paddingHorizontal="2.5dp">
-        android:paddingTop="20dp">
+
+        <emu.skyline.views.DragIndicatorView
+            android:id="@+id/drag_indicator"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:paddingVertical="10dp" />
 
         <TextView
             android:id="@+id/library_title"
@@ -29,6 +34,7 @@
             android:textAlignment="center"
             android:textAppearance="@style/TextAppearance.MaterialComponents.Headline5"
             android:textSize="15sp"
+            tools:ignore="TouchTargetSizeCheck"
             tools:text="https://github.com/skyline-emu/skyline" />
 
         <TextView
@@ -46,10 +52,10 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:autoLink="web"
+            android:justificationMode="inter_word"
+            android:paddingHorizontal="15dp"
             android:paddingTop="15dp"
             android:paddingBottom="15dp"
-            android:paddingHorizontal="15dp"
-            android:justificationMode="inter_word"
             android:textAppearance="@style/TextAppearance.MaterialComponents.Body1"
             tools:text="@string/mpl2_license" />
 

app/src/main/res/values-night/colors.xml

@@ -4,4 +4,5 @@
     <color name="backgroundColor">#FF121212</color>
     <color name="backgroundColorVariant">#323232</color>
     <color name="dividerColor">@android:color/white</color>
+    <color name="onBackgroundLight">#1AFFFFFF</color>
 </resources>

app/src/main/res/values/colors.xml

@@ -5,4 +5,5 @@
     <color name="backgroundColor">@android:color/white</color>
     <color name="backgroundColorVariant">#F8F8F8</color>
     <color name="dividerColor">@android:color/black</color>
+    <color name="onBackgroundLight">#1E000000</color>
 </resources>