added in-app changelog

app/src/main/java/de/salomax/currencies/view/preference/ChangelogDialog.kt

@@ -0,0 +1,22 @@
+package de.salomax.currencies.view.preference
+
+import android.app.Dialog
+import android.os.Bundle
+import android.view.View
+import androidx.appcompat.app.AlertDialog
+import androidx.appcompat.app.AppCompatDialogFragment
+import de.salomax.currencies.R
+
+class ChangelogDialog : AppCompatDialogFragment() {
+
+    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+        val view = View.inflate(context, R.layout.fragment_changelog, null)
+
+        return AlertDialog.Builder(requireContext())
+            .setPositiveButton(android.R.string.ok, null)
+            .setTitle(R.string.title_changelog)
+            .setView(view)
+            .create()
+    }
+
+}

app/src/main/java/de/salomax/currencies/view/preference/PreferenceFragment.kt

@@ -31,6 +31,10 @@ class PreferenceFragment: PreferenceFragmentCompat() {
         val aboutPreference = findPreference<Preference>(getString(R.string.prefKey_about))!!
         aboutPreference.title = getString(R.string.prefTitle_about, BuildConfig.VERSION_NAME)
         aboutPreference.summary = getString(R.string.prefSummary_about, Calendar.getInstance().get(Calendar.YEAR))
+        aboutPreference.setOnPreferenceClickListener {
+            ChangelogDialog().show(childFragmentManager, null)
+            true
+        }
     }
 
 }

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

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:paddingStart="@dimen/margin3x"
+    android:paddingTop="@dimen/margin2x"
+    android:paddingEnd="@dimen/margin3x"
+    android:scrollbars="none">
+
+    <TextView
+        style="@style/TextAppearance.AppCompat.Body1"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/changelog" />
+</ScrollView>

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

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string name="title_changelog">Changelog</string>
+
+    <string name="changelog">
+        <b><big>0.1.0</big></b>
+        \n
+        \n• More fail-proof updating of the currency rates
+        \n• Added a disclaimer
+        \n• Added this changelog
+        \n
+        \n<b><big>0.0.1</big></b>
+        \n
+        \n• Initial pre-release
+    </string>
+
+</resources>