Add VersatileTextWithASwitchPreference

VersatileTextWithASwitchPreference is a combination of a TextPreference
and a SwitchPreference. It mostly looks like a SwitchPreference, but the
switch and the title can be clicked separately.

The behavior is a bit special, see the javadoc for explanation.

Author: oakkitten

AnkiDroid/src/main/java/com/ichi2/preferences/VersatileTextWithASwitchPreference.kt

@@ -0,0 +1,100 @@
+/*
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by the Free Software
+ * Foundation; either version 3 of the License, or (at your option) any later
+ * version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ * PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.ichi2.preferences
+
+import android.content.Context
+import android.util.AttributeSet
+import androidx.appcompat.widget.SwitchCompat
+import androidx.core.content.edit
+import androidx.preference.EditTextPreference
+import androidx.preference.PreferenceViewHolder
+import com.ichi2.anki.R
+
+/**
+ * A combination of an EditTextPreference and a SwitchPreference.
+ * It mostly looks like a SwitchPreference, but the switch and the title can be clicked separately.
+ * If some text is set, it is possible to have the switch either of on off.
+ * However, if text is null or empty, the switch can only be in the off state.
+ *
+ * The text value is stored with the key of the preference.
+ * The key of the switch is suffixed with [SWITCH_SUFFIX].
+ *
+ * Notes on behavior:
+ *   * If text is present, tapping on the switch toggles it.
+ *   * If text is empty, tapping on the switch will open the dialog, as if the title was tapped.
+ *   * If the dialog is closed with Cancel, no changes happen.
+ *   * If the dialog is closed with Ok, and text is present, the switch will be set to on.
+ *   * If the dialog is closed with Ok, and text is empty, the switch will be set to off.
+ *
+ * The preference inherits from [VersatileTextPreference] and supports any attributes it does,
+ * including the regular [EditTextPreference] attributes.
+ */
+class VersatileTextWithASwitchPreference(context: Context, attrs: AttributeSet?) :
+    VersatileTextPreference(context, attrs), DialogFragmentProvider {
+
+    init { widgetLayoutResource = R.layout.preference_widget_switch_with_separator }
+
+    private val preferences get() = sharedPreferences!!
+
+    private val switchKey get() = key + SWITCH_SUFFIX
+
+    private val canBeSwitchedOn get() = !text.isNullOrEmpty()
+
+    // * If there is no text, we make the switch not focusable and not clickable.
+    //   This is exactly how SwitchPreference sets up its widget;
+    //   if you tap on the switch, it will behave as if you tapped on the preference itself.
+    // * If there is text, the switch can be tapped separately.
+    override fun onBindViewHolder(holder: PreferenceViewHolder) {
+        super.onBindViewHolder(holder)
+
+        val switch = holder.findViewById(R.id.switch_widget) as SwitchCompat
+
+        switch.isFocusable = canBeSwitchedOn
+        switch.isClickable = canBeSwitchedOn
+
+        switch.isChecked = preferences.getBoolean(switchKey, false)
+
+        switch.setOnCheckedChangeListener { _, checked ->
+            preferences.edit { putBoolean(switchKey, checked) }
+        }
+    }
+
+    fun onDialogClosedAndNewTextSet() {
+        preferences.edit { putBoolean(switchKey, canBeSwitchedOn) }
+    }
+
+    override fun makeDialogFragment() = VersatileTextWithASwitchPreferenceDialogFragment()
+
+    companion object {
+        const val SWITCH_SUFFIX = "_switch"
+    }
+}
+
+class VersatileTextWithASwitchPreferenceDialogFragment : VersatileTextPreferenceDialogFragment() {
+
+    // This replicates what the overridden method does, which is needed as we want to catch
+    // the event when the Ok button was pressed and the change listener approved the new value.
+    override fun onDialogClosed(positiveResult: Boolean) {
+        if (positiveResult) {
+            val preference = preference as VersatileTextWithASwitchPreference
+            val newText = editText.text.toString()
+
+            if (preference.callChangeListener(newText)) {
+                preference.text = newText
+                preference.onDialogClosedAndNewTextSet()
+            }
+        }
+    }
+}

AnkiDroid/src/main/res/layout/preference_widget_switch_with_separator.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="wrap_content"
+    android:layout_height="wrap_content"
+    android:orientation="horizontal"
+    >
+
+    <View
+        android:layout_width="1dp"
+        android:layout_height="match_parent"
+        android:background="#66888888"
+        android:layout_marginVertical="16dp"
+        />
+
+    <androidx.appcompat.widget.SwitchCompat
+        android:id="@+id/switch_widget"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:paddingStart="16dp"
+        android:background="@null"
+        />
+</LinearLayout>