Convert (most) Activities to Fragments and use AndroidX navigation component

Signed-off-by: William Brawner <me@wbrawner.com>

app/build.gradle

@@ -41,8 +41,8 @@ android {
         applicationId "com.wbrawner.simplemarkdown"
         minSdkVersion 21
         targetSdkVersion 29
-        versionCode 26
-        versionName "0.8.4"
+        versionCode 27
+        versionName "0.8.5"
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         manifestPlaceholders = [
                 sentryDsn: "https://399270639b2e4b10a028a2be9192d1d3@sentry.brawner.dev/2"
@@ -89,6 +89,8 @@ android {
 }
 
 dependencies {
+    implementation 'androidx.navigation:navigation-fragment-ktx:2.2.2'
+    implementation 'androidx.navigation:navigation-ui-ktx:2.2.2'
     testImplementation 'junit:junit:4.12'
     testImplementation 'org.robolectric:robolectric:4.2.1'
     implementation fileTree(include: ['*.jar'], dir: 'libs')
@@ -118,7 +120,6 @@ dependencies {
     def coroutines_version = "1.3.4"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:$coroutines_version"
-
     def lifecycle_version = "2.2.0"
     implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
     kapt "androidx.lifecycle:lifecycle-common-java8:$lifecycle_version"

app/src/main/AndroidManifest.xml

@@ -43,10 +43,6 @@
             </intent-filter>
         </activity>
         <activity android:name=".view.activity.MainActivity" />
-        <activity
-            android:name=".view.activity.SettingsActivity"
-            android:label="@string/title_activity_settings" />
-
         <provider
             android:name="androidx.core.content.FileProvider"
             android:authorities="${applicationId}.fileprovider"
@@ -57,14 +53,6 @@
                 android:resource="@xml/file_paths" />
         </provider>
 
-        <activity android:name=".view.activity.MarkdownInfoActivity">
-            <meta-data
-                android:name="android.support.PARENT_ACTIVITY"
-                android:value=".view.activity.MainActivity" />
-        </activity>
-
-        <activity android:name=".view.activity.SupportActivity" />
-
         <meta-data
             android:name="io.sentry.dsn"
             android:value="${sentryDsn}" />

app/src/main/java/com/wbrawner/simplemarkdown/view/activity/MainActivity.kt

@@ -1,61 +1,23 @@
 package com.wbrawner.simplemarkdown.view.activity
 
-import android.Manifest
-import android.app.Activity
-import android.content.Intent
-import android.content.pm.PackageManager
-import android.content.res.Configuration
-import android.net.Uri
-import android.os.Build
 import android.os.Bundle
-import android.view.Menu
-import android.view.MenuItem
-import android.view.View
-import android.webkit.MimeTypeMap
-import android.widget.Toast
 import androidx.activity.viewModels
-import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.app.ActivityCompat
-import androidx.core.content.ContextCompat
-import androidx.lifecycle.Observer
-import androidx.preference.PreferenceManager
-import com.wbrawner.simplemarkdown.MarkdownApplication
+import androidx.navigation.findNavController
 import com.wbrawner.simplemarkdown.R
-import com.wbrawner.simplemarkdown.utility.hideKeyboard
-import com.wbrawner.simplemarkdown.view.adapter.EditPagerAdapter
-import com.wbrawner.simplemarkdown.view.fragment.MainMenuFragment
 import com.wbrawner.simplemarkdown.viewmodel.MarkdownViewModel
-import kotlinx.android.synthetic.main.activity_main.*
 import kotlinx.coroutines.*
-import java.io.File
 import kotlin.coroutines.CoroutineContext
 
 class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsResultCallback, CoroutineScope {
 
-    private var shouldAutoSave = true
     override val coroutineContext: CoroutineContext = Dispatchers.Main
     private val viewModel: MarkdownViewModel by viewModels()
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
-        setSupportActionBar(toolbar)
-        supportActionBar?.setHomeAsUpIndicator(R.drawable.ic_menu_black_24dp)
-        supportActionBar?.setDisplayHomeAsUpEnabled(true)
-        val adapter = EditPagerAdapter(supportFragmentManager, this@MainActivity)
-        pager.adapter = adapter
-        pager.addOnPageChangeListener(adapter)
-        pager.pageMargin = 1
-        pager.setPageMarginDrawable(R.color.colorAccent)
-        tabLayout.setupWithViewPager(pager)
-        if (resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE) {
-            tabLayout!!.visibility = View.GONE
-        }
-        @Suppress("CAST_NEVER_SUCCEEDS")
-        viewModel.fileName.observe(this, Observer {
-            toolbar?.title = it
-        })
         intent?.data?.let {
             launch {
                 viewModel.load(this@MainActivity, it)
@@ -63,214 +25,8 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
         }
     }
 
-    override fun onStart() {
-        super.onStart()
-        launch {
-            withContext(Dispatchers.IO) {
-                val enableErrorReports = PreferenceManager.getDefaultSharedPreferences(this@MainActivity)
-                        .getBoolean(getString(R.string.error_reports_enabled), true)
-                (application as MarkdownApplication).errorHandler.enable(enableErrorReports)
-            }
-        }
-    }
-
-    override fun onUserLeaveHint() {
-        super.onUserLeaveHint()
-        launch {
-            withContext(Dispatchers.IO) {
-                val sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this@MainActivity)
-                val isAutoSaveEnabled = sharedPrefs.getBoolean(KEY_AUTOSAVE, true)
-                if (!shouldAutoSave || !isAutoSaveEnabled) {
-                    return@withContext
-                }
-
-                val uri = if (viewModel.save(this@MainActivity)) {
-                    viewModel.uri.value
-                } else {
-                    // The user has left the app, with autosave enabled, and we don't already have a
-                    // Uri for them or for some reason we were unable to save to the original Uri. In
-                    // this case, we need to just save to internal file storage so that we can recover
-                    val fileUri = Uri.fromFile(File(filesDir, viewModel.fileName.value!!))
-                    if (viewModel.save(this@MainActivity, fileUri)) {
-                        fileUri
-                    } else {
-                        null
-                    }
-                } ?: return@withContext
-                sharedPrefs.edit()
-                        .putString(getString(R.string.pref_key_autosave_uri), uri.toString())
-                        .apply()
-            }
-        }
-    }
-
-    override fun onConfigurationChanged(newConfig: Configuration) {
-        super.onConfigurationChanged(newConfig)
-        if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE)
-            tabLayout!!.visibility = View.GONE
-        else
-            tabLayout!!.visibility = View.VISIBLE
-    }
-
-    override fun onCreateOptionsMenu(menu: Menu): Boolean {
-        menuInflater.inflate(R.menu.menu_edit, menu)
-        return true
-    }
-
-    override fun onOptionsItemSelected(item: MenuItem): Boolean {
-        when (item.itemId) {
-            android.R.id.home -> {
-                MainMenuFragment().show(supportFragmentManager, null)
-                window.decorView.hideKeyboard()
-            }
-            R.id.action_save -> {
-                launch {
-                    if (!viewModel.save(this@MainActivity)) {
-                        requestFileOp(REQUEST_SAVE_FILE)
-                    } else {
-                        Toast.makeText(
-                                this@MainActivity,
-                                getString(R.string.file_saved, viewModel.fileName.value),
-                                Toast.LENGTH_SHORT
-                        ).show()
-                    }
-                }
-            }
-            R.id.action_save_as -> {
-                requestFileOp(REQUEST_SAVE_FILE)
-            }
-            R.id.action_share -> {
-                val shareIntent = Intent(Intent.ACTION_SEND)
-                shareIntent.putExtra(Intent.EXTRA_TEXT, viewModel.markdownUpdates.value)
-                shareIntent.type = "text/plain"
-                startActivity(Intent.createChooser(
-                        shareIntent,
-                        getString(R.string.share_file)
-                ))
-            }
-            R.id.action_load -> requestFileOp(REQUEST_OPEN_FILE)
-            R.id.action_new -> promptSaveOrDiscardChanges()
-            R.id.action_lock_swipe -> {
-                item.isChecked = !item.isChecked
-                pager!!.setSwipeLocked(item.isChecked)
-            }
-        }
-        return super.onOptionsItemSelected(item)
-    }
-
-    override fun onRequestPermissionsResult(
-            requestCode: Int,
-            permissions: Array<String>,
-            grantResults: IntArray
-    ) {
-        when (requestCode) {
-            REQUEST_SAVE_FILE, REQUEST_OPEN_FILE -> {
-                // If request is cancelled, the result arrays are empty.
-                if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
-                    // Permission granted, open file save dialog
-                    requestFileOp(requestCode)
-                } else {
-                    // Permission denied, do nothing
-                    Toast.makeText(this@MainActivity, R.string.no_permissions, Toast.LENGTH_SHORT)
-                            .show()
-                }
-            }
-        }
-    }
-
     override fun onBackPressed() {
-        if (pager!!.currentItem == EditPagerAdapter.FRAGMENT_EDIT)
-            super.onBackPressed()
-        else
-            pager!!.currentItem = EditPagerAdapter.FRAGMENT_EDIT
-    }
-
-    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
-        when (requestCode) {
-            REQUEST_OPEN_FILE -> {
-                if (resultCode != Activity.RESULT_OK || data?.data == null) {
-                    return
-                }
-
-                launch {
-                    val fileLoaded = viewModel.load(this@MainActivity, data.data)
-                    if (!fileLoaded) {
-                        Toast.makeText(this@MainActivity, R.string.file_load_error, Toast.LENGTH_SHORT)
-                                .show()
-                    }
-                }
-            }
-            REQUEST_SAVE_FILE -> {
-                if (resultCode != Activity.RESULT_OK || data?.data == null) {
-                    return
-                }
-
-                launch {
-                    viewModel.save(this@MainActivity, data.data)
-                }
-            }
-        }
-        super.onActivityResult(requestCode, resultCode, data)
-    }
-
-    private fun promptSaveOrDiscardChanges() {
-        if (viewModel.originalMarkdown.value == viewModel.markdownUpdates.value) {
-            viewModel.reset("Untitled.md")
-            return
-        }
-        AlertDialog.Builder(this)
-                .setTitle(R.string.save_changes)
-                .setMessage(R.string.prompt_save_changes)
-                .setNegativeButton(R.string.action_discard) { _, _ ->
-                    viewModel.reset("Untitled.md")
-                }
-                .setPositiveButton(R.string.action_save) { _, _ ->
-                    requestFileOp(REQUEST_SAVE_FILE)
-                }
-                .create()
-                .show()
-    }
-
-    private fun requestFileOp(requestType: Int) {
-        if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE)
-                != PackageManager.PERMISSION_GRANTED && Build.VERSION.SDK_INT > 22) {
-            requestPermissions(
-                    arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
-                    requestType
-            )
-            return
-        }
-        // If the user is going to save the file, we don't want to auto-save it for them
-        shouldAutoSave = false
-        val intent = when (requestType) {
-            REQUEST_SAVE_FILE -> {
-                Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
-                    type = "text/markdown"
-                    putExtra(Intent.EXTRA_TITLE, viewModel.fileName.value)
-                }
-            }
-            REQUEST_OPEN_FILE -> {
-                Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
-                    type = "*/*"
-                    if (MimeTypeMap.getSingleton().hasMimeType("md")) {
-                        // If the device doesn't recognize markdown files then we're not going to be
-                        // able to open them at all, so there's no sense in filtering them out.
-                        putExtra(Intent.EXTRA_MIME_TYPES, arrayOf("text/plain", "text/markdown"))
-                    }
-                }
-            }
-            else -> null
-        } ?: return
-        intent.addCategory(Intent.CATEGORY_OPENABLE)
-        startActivityForResult(
-                intent,
-                requestType
-        )
-    }
-
-    override fun onResume() {
-        super.onResume()
-        shouldAutoSave = true
+        findNavController(R.id.content).navigateUp()
     }
 
     override fun onDestroy() {
@@ -279,12 +35,4 @@ class MainActivity : AppCompatActivity(), ActivityCompat.OnRequestPermissionsRes
             cancel()
         }
     }
-
-    companion object {
-        // Request codes
-        const val REQUEST_OPEN_FILE = 1
-        const val REQUEST_SAVE_FILE = 2
-        const val REQUEST_DARK_MODE = 4
-        const val KEY_AUTOSAVE = "autosave"
-    }
 }

app/src/main/java/com/wbrawner/simplemarkdown/view/activity/SettingsActivity.kt

@@ -1,29 +0,0 @@
-package com.wbrawner.simplemarkdown.view.activity
-
-import android.os.Bundle
-import android.view.MenuItem
-import androidx.appcompat.app.AppCompatActivity
-import com.wbrawner.simplemarkdown.R
-import com.wbrawner.simplemarkdown.view.fragment.SettingsFragment
-
-class SettingsActivity : AppCompatActivity() {
-
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_settings)
-        setSupportActionBar(findViewById(R.id.toolbar))
-        supportActionBar?.setDisplayHomeAsUpEnabled(true)
-        if (supportFragmentManager.fragments.isEmpty()) {
-            supportFragmentManager.beginTransaction()
-                    .add(R.id.fragment_settings, SettingsFragment())
-                    .commit()
-        }
-    }
-
-    override fun onOptionsItemSelected(item: MenuItem): Boolean {
-        // The only menu item is the back button
-        setResult(RESULT_OK)
-        finish()
-        return true
-    }
-}

app/src/main/java/com/wbrawner/simplemarkdown/view/activity/SupportActivity.kt

@@ -1,58 +0,0 @@
-package com.wbrawner.simplemarkdown.view.activity
-
-import android.content.ActivityNotFoundException
-import android.content.Intent
-import android.net.Uri
-import android.os.Bundle
-import android.view.MenuItem
-import androidx.appcompat.app.AppCompatActivity
-import androidx.browser.customtabs.CustomTabsIntent
-import androidx.lifecycle.Observer
-import com.wbrawner.simplemarkdown.R
-import com.wbrawner.simplemarkdown.utility.SupportLinkProvider
-import kotlinx.android.synthetic.main.activity_support.*
-
-
-class SupportActivity : AppCompatActivity() {
-    override fun onCreate(savedInstanceState: Bundle?) {
-        super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_support)
-        setSupportActionBar(toolbar)
-        setTitle(R.string.support_title)
-        supportActionBar?.setDisplayHomeAsUpEnabled(true)
-        githubButton.setOnClickListener {
-            CustomTabsIntent.Builder()
-                    .addDefaultShareMenuItem()
-                    .build()
-                    .launchUrl(this@SupportActivity, Uri.parse("https://github.com/wbrawner/SimpleMarkdown"))
-        }
-        rateButton.setOnClickListener {
-            val playStoreIntent = Intent(Intent.ACTION_VIEW)
-                    .apply {
-                        data = Uri.parse("market://details?id=${packageName}")
-                        addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY or
-                                Intent.FLAG_ACTIVITY_NEW_DOCUMENT or
-                                Intent.FLAG_ACTIVITY_MULTIPLE_TASK)
-                    }
-            try {
-                startActivity(playStoreIntent)
-            } catch (ignored: ActivityNotFoundException) {
-                playStoreIntent.data = Uri.parse("https://play.google.com/store/apps/details?id=${packageName}")
-                startActivity(playStoreIntent)
-            }
-        }
-        SupportLinkProvider(this).supportLinks.observe(this, Observer { links ->
-            links.forEach {
-                supportButtons.addView(it)
-            }
-        })
-    }
-
-    override fun onOptionsItemSelected(item: MenuItem): Boolean {
-        if (item.itemId == android.R.id.home) {
-            finish()
-            return true
-        }
-        return super.onOptionsItemSelected(item)
-    }
-}

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/MainFragment.kt

@@ -0,0 +1,301 @@
+package com.wbrawner.simplemarkdown.view.fragment
+
+import android.Manifest
+import android.app.Activity
+import android.content.Intent
+import android.content.pm.PackageManager
+import android.content.res.Configuration
+import android.net.Uri
+import android.os.Build
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.webkit.MimeTypeMap
+import android.widget.Toast
+import androidx.appcompat.app.AlertDialog
+import androidx.core.app.ActivityCompat
+import androidx.core.content.ContextCompat
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.activityViewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.ui.AppBarConfiguration
+import androidx.navigation.ui.onNavDestinationSelected
+import androidx.navigation.ui.setupWithNavController
+import androidx.preference.PreferenceManager
+import com.wbrawner.simplemarkdown.MarkdownApplication
+import com.wbrawner.simplemarkdown.R
+import com.wbrawner.simplemarkdown.view.adapter.EditPagerAdapter
+import com.wbrawner.simplemarkdown.viewmodel.MarkdownViewModel
+import kotlinx.android.synthetic.main.fragment_main.*
+import kotlinx.coroutines.*
+import java.io.File
+import kotlin.coroutines.CoroutineContext
+
+class MainFragment : Fragment(), ActivityCompat.OnRequestPermissionsResultCallback, CoroutineScope {
+
+    private var shouldAutoSave = true
+    override val coroutineContext: CoroutineContext = Dispatchers.Main
+    private val viewModel: MarkdownViewModel by activityViewModels()
+    private var appBarConfiguration: AppBarConfiguration? = null
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setHasOptionsMenu(true)
+    }
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
+            inflater.inflate(R.layout.fragment_main, container, false)
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        with(findNavController()) {
+            appBarConfiguration = AppBarConfiguration(graph, drawerLayout)
+            toolbar.setupWithNavController(this, appBarConfiguration!!)
+            toolbar.inflateMenu(R.menu.menu_edit)
+            toolbar.setOnMenuItemClickListener { item ->
+                return@setOnMenuItemClickListener when (item.itemId) {
+                    R.id.action_save -> {
+                        launch {
+                            if (!viewModel.save(requireContext())) {
+                                requestFileOp(REQUEST_SAVE_FILE)
+                            } else {
+                                Toast.makeText(
+                                        requireContext(),
+                                        getString(R.string.file_saved, viewModel.fileName.value),
+                                        Toast.LENGTH_SHORT
+                                ).show()
+                            }
+                        }
+                        true
+                    }
+                    R.id.action_save_as -> {
+                        requestFileOp(REQUEST_SAVE_FILE)
+                        true
+                    }
+                    R.id.action_share -> {
+                        val shareIntent = Intent(Intent.ACTION_SEND)
+                        shareIntent.putExtra(Intent.EXTRA_TEXT, viewModel.markdownUpdates.value)
+                        shareIntent.type = "text/plain"
+                        startActivity(Intent.createChooser(
+                                shareIntent,
+                                getString(R.string.share_file)
+                        ))
+                        true
+                    }
+                    R.id.action_load -> {
+                        requestFileOp(REQUEST_OPEN_FILE)
+                        true
+                    }
+                    R.id.action_new -> {
+                        promptSaveOrDiscardChanges()
+                        true
+                    }
+                    R.id.action_lock_swipe -> {
+                        item.isChecked = !item.isChecked
+                        pager!!.setSwipeLocked(item.isChecked)
+                        true
+                    }
+                    else -> item.onNavDestinationSelected(findNavController())
+                }
+            }
+            navigationView.setupWithNavController(this)
+        }
+        val adapter = EditPagerAdapter(childFragmentManager, view.context)
+        pager.adapter = adapter
+        pager.addOnPageChangeListener(adapter)
+        pager.pageMargin = 1
+        pager.setPageMarginDrawable(R.color.colorAccent)
+        tabLayout.setupWithViewPager(pager)
+        if (resources.configuration.orientation == Configuration.ORIENTATION_LANDSCAPE) {
+            tabLayout!!.visibility = View.GONE
+        }
+        @Suppress("CAST_NEVER_SUCCEEDS")
+        viewModel.fileName.observe(viewLifecycleOwner, Observer {
+            toolbar?.title = it
+        })
+    }
+
+    override fun onStart() {
+        super.onStart()
+        launch {
+            withContext(Dispatchers.IO) {
+                val enableErrorReports = PreferenceManager.getDefaultSharedPreferences(requireContext())
+                        .getBoolean(getString(R.string.error_reports_enabled), true)
+                (requireActivity().application as MarkdownApplication).errorHandler.enable(enableErrorReports)
+            }
+        }
+    }
+
+    override fun onPause() {
+        super.onPause()
+        launch {
+            val context = context?.applicationContext ?: return@launch
+            withContext(Dispatchers.IO) {
+                val sharedPrefs = PreferenceManager.getDefaultSharedPreferences(context)
+                val isAutoSaveEnabled = sharedPrefs.getBoolean(KEY_AUTOSAVE, true)
+                if (!shouldAutoSave || !isAutoSaveEnabled) {
+                    return@withContext
+                }
+
+                val uri = if (viewModel.save(context)) {
+                    viewModel.uri.value
+                } else {
+                    // The user has left the app, with autosave enabled, and we don't already have a
+                    // Uri for them or for some reason we were unable to save to the original Uri. In
+                    // this case, we need to just save to internal file storage so that we can recover
+                    val fileUri = Uri.fromFile(File(context.filesDir, viewModel.fileName.value!!))
+                    if (viewModel.save(context, fileUri)) {
+                        fileUri
+                    } else {
+                        null
+                    }
+                } ?: return@withContext
+                sharedPrefs.edit()
+                        .putString(getString(R.string.pref_key_autosave_uri), uri.toString())
+                        .apply()
+            }
+        }
+    }
+
+    override fun onConfigurationChanged(newConfig: Configuration) {
+        super.onConfigurationChanged(newConfig)
+        if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE)
+            tabLayout!!.visibility = View.GONE
+        else
+            tabLayout!!.visibility = View.VISIBLE
+    }
+
+    override fun onRequestPermissionsResult(
+            requestCode: Int,
+            permissions: Array<String>,
+            grantResults: IntArray
+    ) {
+        when (requestCode) {
+            REQUEST_SAVE_FILE, REQUEST_OPEN_FILE -> {
+                // If request is cancelled, the result arrays are empty.
+                if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
+                    // Permission granted, open file save dialog
+                    requestFileOp(requestCode)
+                } else {
+                    // Permission denied, do nothing
+                    context?.let {
+                        Toast.makeText(it, R.string.no_permissions, Toast.LENGTH_SHORT)
+                                .show()
+                    }
+                }
+            }
+        }
+    }
+
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        when (requestCode) {
+            REQUEST_OPEN_FILE -> {
+                if (resultCode != Activity.RESULT_OK || data?.data == null) {
+                    return
+                }
+
+                launch {
+                    val fileLoaded = context?.let {
+                        viewModel.load(it, data.data)
+                    }
+                    if (fileLoaded == false) {
+                        context?.let {
+                            Toast.makeText(it, R.string.file_load_error, Toast.LENGTH_SHORT)
+                                    .show()
+                        }
+                    }
+                }
+            }
+            REQUEST_SAVE_FILE -> {
+                if (resultCode != Activity.RESULT_OK || data?.data == null) {
+                    return
+                }
+
+                launch {
+                    context?.let {
+                        viewModel.save(it, data.data)
+                    }
+                }
+            }
+        }
+        super.onActivityResult(requestCode, resultCode, data)
+    }
+
+    private fun promptSaveOrDiscardChanges() {
+        if (viewModel.originalMarkdown.value == viewModel.markdownUpdates.value) {
+            viewModel.reset("Untitled.md")
+            return
+        }
+        val context = context ?: return
+        AlertDialog.Builder(context)
+                .setTitle(R.string.save_changes)
+                .setMessage(R.string.prompt_save_changes)
+                .setNegativeButton(R.string.action_discard) { _, _ ->
+                    viewModel.reset("Untitled.md")
+                }
+                .setPositiveButton(R.string.action_save) { _, _ ->
+                    requestFileOp(REQUEST_SAVE_FILE)
+                }
+                .create()
+                .show()
+    }
+
+    private fun requestFileOp(requestType: Int) {
+        val context = context ?: return
+        if (ContextCompat.checkSelfPermission(context, Manifest.permission.WRITE_EXTERNAL_STORAGE)
+                != PackageManager.PERMISSION_GRANTED && Build.VERSION.SDK_INT > 22) {
+            requestPermissions(
+                    arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
+                    requestType
+            )
+            return
+        }
+        // If the user is going to save the file, we don't want to auto-save it for them
+        shouldAutoSave = false
+        val intent = when (requestType) {
+            REQUEST_SAVE_FILE -> {
+                Intent(Intent.ACTION_CREATE_DOCUMENT).apply {
+                    type = "text/markdown"
+                    putExtra(Intent.EXTRA_TITLE, viewModel.fileName.value)
+                }
+            }
+            REQUEST_OPEN_FILE -> {
+                Intent(Intent.ACTION_OPEN_DOCUMENT).apply {
+                    type = "*/*"
+                    if (MimeTypeMap.getSingleton().hasMimeType("md")) {
+                        // If the device doesn't recognize markdown files then we're not going to be
+                        // able to open them at all, so there's no sense in filtering them out.
+                        putExtra(Intent.EXTRA_MIME_TYPES, arrayOf("text/plain", "text/markdown"))
+                    }
+                }
+            }
+            else -> null
+        } ?: return
+        intent.addCategory(Intent.CATEGORY_OPENABLE)
+        startActivityForResult(
+                intent,
+                requestType
+        )
+    }
+
+    override fun onResume() {
+        super.onResume()
+        shouldAutoSave = true
+    }
+
+    override fun onDestroy() {
+        super.onDestroy()
+        coroutineContext[Job]?.let {
+            cancel()
+        }
+    }
+
+    companion object {
+        // Request codes
+        const val REQUEST_OPEN_FILE = 1
+        const val REQUEST_SAVE_FILE = 2
+        const val REQUEST_DARK_MODE = 4
+        const val KEY_AUTOSAVE = "autosave"
+    }
+}

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/MainMenuFragment.kt

@@ -1,81 +0,0 @@
-package com.wbrawner.simplemarkdown.view.fragment
-
-import android.content.Intent
-import android.os.Bundle
-import android.view.LayoutInflater
-import android.view.View
-import android.view.ViewGroup
-import com.google.android.material.bottomsheet.BottomSheetDialogFragment
-import com.wbrawner.simplemarkdown.R
-import com.wbrawner.simplemarkdown.view.activity.MainActivity
-import com.wbrawner.simplemarkdown.view.activity.MarkdownInfoActivity
-import com.wbrawner.simplemarkdown.view.activity.MarkdownInfoActivity.Companion.EXTRA_FILE
-import com.wbrawner.simplemarkdown.view.activity.MarkdownInfoActivity.Companion.EXTRA_TITLE
-import com.wbrawner.simplemarkdown.view.activity.SettingsActivity
-import com.wbrawner.simplemarkdown.view.activity.SupportActivity
-import kotlinx.android.synthetic.main.fragment_menu_main.*
-
-class MainMenuFragment : BottomSheetDialogFragment() {
-    override fun onCreateView(
-            inflater: LayoutInflater,
-            container: ViewGroup?,
-            savedInstanceState: Bundle?
-    ): View? = inflater.inflate(R.layout.fragment_menu_main, container, false)
-
-    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
-        super.onViewCreated(view, savedInstanceState)
-        mainMenuNavigationView.setNavigationItemSelectedListener { menuItem ->
-            val (intentClass, fileName, title) = when (menuItem.itemId) {
-                R.id.action_help -> Triple(
-                        MarkdownInfoActivity::class.java,
-                        "Cheatsheet.md",
-                        R.string.action_help
-                )
-                R.id.action_settings -> Triple(
-                        SettingsActivity::class.java,
-                        null,
-                        null
-                )
-                R.id.action_libraries -> Triple(
-                        MarkdownInfoActivity::class.java,
-                        "Libraries.md",
-                        R.string.action_libraries
-                )
-                R.id.action_privacy -> Triple(
-                        MarkdownInfoActivity::class.java,
-                        "Privacy Policy.md",
-                        R.string.action_privacy
-                )
-                R.id.action_support -> Triple(
-                        SupportActivity::class.java,
-                        null,
-                        null
-                )
-                else -> throw IllegalStateException("This shouldn't happen")
-            }
-            val intent = Intent(context, intentClass)
-            fileName?.let {
-                intent.putExtra(EXTRA_FILE, it)
-            }
-            title?.let {
-                intent.putExtra(EXTRA_TITLE, getString(it))
-            }
-            if (intentClass == SettingsActivity::class.java) {
-                startActivityForResult(intent, MainActivity.REQUEST_DARK_MODE)
-            } else {
-                startActivity(intent)
-                dialog?.dismiss()
-            }
-            true
-        }
-    }
-
-    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
-        if (requestCode == MainActivity.REQUEST_DARK_MODE) {
-            activity?.recreate()
-        } else {
-            super.onActivityResult(requestCode, resultCode, data)
-        }
-        dialog?.dismiss()
-    }
-}

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/MarkdownInfoFragment.kt

@@ -1,38 +1,46 @@
-package com.wbrawner.simplemarkdown.view.activity
+package com.wbrawner.simplemarkdown.view.fragment
 
 import android.content.res.Configuration
 import android.os.Bundle
+import android.view.LayoutInflater
 import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
 import android.widget.Toast
-import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.app.AppCompatDelegate
+import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.ui.setupWithNavController
 import com.wbrawner.simplemarkdown.MarkdownApplication
 import com.wbrawner.simplemarkdown.R
 import com.wbrawner.simplemarkdown.utility.readAssetToString
 import com.wbrawner.simplemarkdown.utility.toHtml
-import kotlinx.android.synthetic.main.activity_markdown_info.*
+import kotlinx.android.synthetic.main.fragment_markdown_info.*
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.Job
 import kotlinx.coroutines.launch
 import kotlin.coroutines.CoroutineContext
 
-class MarkdownInfoActivity : AppCompatActivity(), CoroutineScope {
+class MarkdownInfoFragment : Fragment(), CoroutineScope {
     override val coroutineContext: CoroutineContext = Dispatchers.Main
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_markdown_info)
-        setSupportActionBar(toolbar)
-        supportActionBar?.setDisplayHomeAsUpEnabled(true)
-        val title = intent?.getStringExtra(EXTRA_TITLE)
-        val fileName = intent?.getStringExtra(EXTRA_FILE)
-        if (title.isNullOrBlank() || fileName.isNullOrBlank()) {
-            finish()
-            return
+        setHasOptionsMenu(true)
     }
 
-        setTitle(title)
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
+            inflater.inflate(R.layout.fragment_markdown_info, container, false)
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        val fileName = arguments?.getString(EXTRA_FILE)
+        if (fileName.isNullOrBlank()) {
+            findNavController().navigateUp()
+            return
+        }
+        toolbar.setupWithNavController(findNavController())
+
         val isNightMode = AppCompatDelegate.getDefaultNightMode() ==
                 AppCompatDelegate.MODE_NIGHT_YES
                 || resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK == Configuration.UI_MODE_NIGHT_YES
@@ -44,7 +52,7 @@ class MarkdownInfoActivity : AppCompatActivity(), CoroutineScope {
         val css: String? = getString(defaultCssId)
         launch {
             try {
-                val html = assets?.readAssetToString(fileName)
+                val html = view.context.assets?.readAssetToString(fileName)
                         ?.toHtml()
                         ?: throw RuntimeException("Unable to open stream to $fileName")
                 infoWebview.loadDataWithBaseURL(null,
@@ -53,9 +61,9 @@ class MarkdownInfoActivity : AppCompatActivity(), CoroutineScope {
                         "UTF-8", null
                 )
             } catch (e: Exception) {
-                (application as MarkdownApplication).errorHandler.reportException(e)
-                Toast.makeText(this@MarkdownInfoActivity, R.string.file_load_error, Toast.LENGTH_SHORT).show()
-                finish()
+                (requireActivity().application as MarkdownApplication).errorHandler.reportException(e)
+                Toast.makeText(view.context, R.string.file_load_error, Toast.LENGTH_SHORT).show()
+                findNavController().navigateUp()
             }
         }
     }
@@ -68,7 +76,7 @@ class MarkdownInfoActivity : AppCompatActivity(), CoroutineScope {
 
     override fun onOptionsItemSelected(item: MenuItem): Boolean {
         if (item.itemId == android.R.id.home) {
-            onBackPressed()
+            findNavController().navigateUp()
             return true
         }
         return super.onOptionsItemSelected(item)

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/PreviewFragment.kt

@@ -64,7 +64,7 @@ class PreviewFragment : Fragment(), CoroutineScope {
     override fun onAttach(context: Context) {
         super.onAttach(context)
         updateWebContent(viewModel.markdownUpdates.value ?: "")
-        viewModel.markdownUpdates.observe(viewLifecycleOwner, Observer {
+        viewModel.markdownUpdates.observe(this, Observer {
             updateWebContent(it)
         })
     }

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/SettingsContainerFragment.kt

@@ -0,0 +1,28 @@
+package com.wbrawner.simplemarkdown.view.fragment
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.MenuItem
+import android.view.View
+import android.view.ViewGroup
+import androidx.fragment.app.Fragment
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.ui.setupWithNavController
+import com.wbrawner.simplemarkdown.R
+import kotlinx.android.synthetic.main.fragment_settings.*
+
+class SettingsContainerFragment : Fragment() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setHasOptionsMenu(true)
+    }
+
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
+            inflater.inflate(R.layout.fragment_settings, container, false)
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        toolbar.setupWithNavController(findNavController())
+    }
+
+    override fun onOptionsItemSelected(item: MenuItem): Boolean = findNavController().navigateUp()
+}

app/src/main/java/com/wbrawner/simplemarkdown/view/fragment/SupportFragment.kt

@@ -0,0 +1,61 @@
+package com.wbrawner.simplemarkdown.view.fragment
+
+import android.content.ActivityNotFoundException
+import android.content.Intent
+import android.net.Uri
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import androidx.browser.customtabs.CustomTabsIntent
+import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import androidx.navigation.ui.setupWithNavController
+import com.wbrawner.simplemarkdown.R
+import com.wbrawner.simplemarkdown.utility.SupportLinkProvider
+import kotlinx.android.synthetic.main.fragment_support.*
+
+class SupportFragment : Fragment() {
+    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
+            inflater.inflate(R.layout.fragment_support, container, false)
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        toolbar.setupWithNavController(findNavController())
+        githubButton.setOnClickListener {
+            CustomTabsIntent.Builder()
+                    .addDefaultShareMenuItem()
+                    .build()
+                    .launchUrl(view.context, Uri.parse("https://github" +
+                            ".com/wbrawner/SimpleMarkdown"))
+        }
+        rateButton.setOnClickListener {
+            val playStoreIntent = Intent(Intent.ACTION_VIEW)
+                    .apply {
+                        data = Uri.parse("market://details?id=${view.context.packageName}")
+                        addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY or
+                                Intent.FLAG_ACTIVITY_NEW_DOCUMENT or
+                                Intent.FLAG_ACTIVITY_MULTIPLE_TASK)
+                    }
+            try {
+                startActivity(playStoreIntent)
+            } catch (ignored: ActivityNotFoundException) {
+                playStoreIntent.data = Uri.parse("https://play.google.com/store/apps/details?id=${view.context.packageName}")
+                startActivity(playStoreIntent)
+            }
+        }
+        SupportLinkProvider(requireActivity()).supportLinks.observe(viewLifecycleOwner, Observer { links ->
+            links.forEach {
+                supportButtons.addView(it)
+            }
+        })
+    }
+
+//    override fun onOptionsItemSelected(item: MenuItem): Boolean {
+//        if (item.itemId == android.R.id.home) {
+//            findNavController().navigateUp()
+//            return true
+//        }
+//        return super.onOptionsItemSelected(item)
+//    }
+}

app/src/main/res/layout-land/activity_main.xml

@@ -1,47 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent">
-
-    <com.wbrawner.simplemarkdown.view.DisableableViewPager
-        android:id="@+id/pager"
-        android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        app:layout_behavior="@string/appbar_scrolling_view_behavior" />
-
-    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/bottomSheet"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content">
-
-        <com.google.android.material.appbar.MaterialToolbar
-            android:id="@+id/toolbar"
-            android:layout_width="match_parent"
-            android:layout_height="?attr/actionBarSize"
-            android:background="@color/colorBackground"
-            app:layout_scrollFlags="scroll|enterAlways" />
-
-        <com.google.android.material.tabs.TabLayout
-            android:id="@+id/tabLayout"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:background="@color/colorBackground"
-            android:visibility="gone">
-
-            <com.google.android.material.tabs.TabItem
-                android:id="@+id/editTab"
-                android:layout_width="0dp"
-                android:layout_height="wrap_content"
-                android:text="@string/action_edit" />
-
-            <com.google.android.material.tabs.TabItem
-                android:id="@+id/previewTab"
-                android:layout_width="0dp"
-                android:layout_height="wrap_content"
-                android:text="@string/action_preview" />
-        </com.google.android.material.tabs.TabLayout>
-
-    </com.google.android.material.appbar.AppBarLayout>
-
-</androidx.coordinatorlayout.widget.CoordinatorLayout>

app/src/main/res/layout-land/fragment_main.xml

@@ -0,0 +1,61 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:id="@+id/drawerLayout">
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <com.wbrawner.simplemarkdown.view.DisableableViewPager
+            android:id="@+id/pager"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
+
+        <com.google.android.material.appbar.AppBarLayout
+            android:id="@+id/bottomSheet"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content">
+
+            <com.google.android.material.appbar.MaterialToolbar
+                android:id="@+id/toolbar"
+                android:layout_width="match_parent"
+                android:layout_height="?attr/actionBarSize"
+                android:background="@color/colorBackground"
+                app:layout_scrollFlags="scroll|enterAlways" />
+
+            <com.google.android.material.tabs.TabLayout
+                android:id="@+id/tabLayout"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:background="@color/colorBackground"
+                android:visibility="gone">
+
+                <com.google.android.material.tabs.TabItem
+                    android:id="@+id/editTab"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:text="@string/action_edit" />
+
+                <com.google.android.material.tabs.TabItem
+                    android:id="@+id/previewTab"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:text="@string/action_preview" />
+            </com.google.android.material.tabs.TabLayout>
+
+        </com.google.android.material.appbar.AppBarLayout>
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+
+    <com.google.android.material.navigation.NavigationView
+        android:id="@+id/navigationView"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_gravity="start"
+        android:fitsSystemWindows="true"
+        app:menu="@menu/menu_main" />
+
+</androidx.drawerlayout.widget.DrawerLayout>

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

@@ -1,48 +1,9 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<androidx.fragment.app.FragmentContainerView xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent">
-
-    <com.wbrawner.simplemarkdown.view.DisableableViewPager
-        android:id="@+id/pager"
+    android:id="@+id/content"
+    android:name="androidx.navigation.fragment.NavHostFragment"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-        app:layout_behavior="@string/appbar_scrolling_view_behavior" />
-
-    <com.google.android.material.appbar.AppBarLayout
-        android:id="@+id/bottomSheet"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        app:liftOnScroll="true">
-
-        <com.google.android.material.appbar.MaterialToolbar
-            android:id="@+id/toolbar"
-            android:layout_width="match_parent"
-            android:layout_height="?attr/actionBarSize"
-            app:layout_scrollFlags="scroll|enterAlways|snap"
-            android:background="@color/colorBackground" />
-
-        <com.google.android.material.tabs.TabLayout
-            android:id="@+id/tabLayout"
-            android:layout_width="match_parent"
-            android:layout_height="wrap_content"
-            android:layout_gravity="bottom"
-            android:background="@color/colorBackground">
-
-            <com.google.android.material.tabs.TabItem
-                android:id="@+id/editTab"
-                android:layout_width="0dp"
-                android:layout_height="wrap_content"
-                android:text="@string/action_edit" />
-
-            <com.google.android.material.tabs.TabItem
-                android:id="@+id/previewTab"
-                android:layout_width="0dp"
-                android:layout_height="wrap_content"
-                android:text="@string/action_preview" />
-        </com.google.android.material.tabs.TabLayout>
-
-    </com.google.android.material.appbar.AppBarLayout>
-
-</androidx.coordinatorlayout.widget.CoordinatorLayout>
+    app:defaultNavHost="true"
+    app:navGraph="@navigation/nav_graph" />

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

@@ -0,0 +1,63 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@color/colorBackground"
+    android:id="@+id/drawerLayout">
+
+    <androidx.coordinatorlayout.widget.CoordinatorLayout
+        android:layout_width="match_parent"
+        android:layout_height="match_parent">
+
+        <com.wbrawner.simplemarkdown.view.DisableableViewPager
+            android:id="@+id/pager"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            app:layout_behavior="@string/appbar_scrolling_view_behavior" />
+
+        <com.google.android.material.appbar.AppBarLayout
+            android:id="@+id/bottomSheet"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            app:liftOnScroll="true">
+
+            <com.google.android.material.appbar.MaterialToolbar
+                android:id="@+id/toolbar"
+                android:layout_width="match_parent"
+                android:layout_height="?attr/actionBarSize"
+                android:background="@color/colorBackground"
+                app:layout_scrollFlags="scroll|enterAlways|snap" />
+
+            <com.google.android.material.tabs.TabLayout
+                android:id="@+id/tabLayout"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_gravity="bottom"
+                android:background="@color/colorBackground">
+
+                <com.google.android.material.tabs.TabItem
+                    android:id="@+id/editTab"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:text="@string/action_edit" />
+
+                <com.google.android.material.tabs.TabItem
+                    android:id="@+id/previewTab"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:text="@string/action_preview" />
+            </com.google.android.material.tabs.TabLayout>
+
+        </com.google.android.material.appbar.AppBarLayout>
+    </androidx.coordinatorlayout.widget.CoordinatorLayout>
+
+    <com.google.android.material.navigation.NavigationView
+        android:id="@+id/navigationView"
+        android:layout_width="wrap_content"
+        android:layout_height="match_parent"
+        android:layout_gravity="start"
+        android:fitsSystemWindows="true"
+        app:menu="@menu/menu_main" />
+
+</androidx.drawerlayout.widget.DrawerLayout>

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

@@ -4,7 +4,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    tools:context="com.wbrawner.simplemarkdown.view.activity.MarkdownInfoActivity">
+    tools:context="com.wbrawner.simplemarkdown.view.fragment.MarkdownInfoFragment">
 
     <com.google.android.material.appbar.AppBarLayout
         android:id="@+id/appBarLayout"

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

@@ -1,7 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<com.google.android.material.navigation.NavigationView xmlns:android="http://schemas.android.com/apk/res/android"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:id="@+id/mainMenuNavigationView"
-    app:menu="@menu/menu_main" />

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

@@ -1,15 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
-<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:fitsSystemWindows="true">
+    android:orientation="vertical">
 
     <com.google.android.material.appbar.AppBarLayout
         android:id="@+id/appBarLayout"
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        app:layout_constraintTop_toTopOf="parent">
+        android:layout_height="wrap_content">
 
         <com.google.android.material.appbar.MaterialToolbar
             android:id="@+id/toolbar"
@@ -20,11 +18,9 @@
 
     <androidx.fragment.app.FragmentContainerView
         android:id="@+id/fragment_settings"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.SettingsFragment"
         android:layout_width="match_parent"
         android:layout_height="0dp"
-        app:layout_constraintBottom_toBottomOf="parent"
-        app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/appBarLayout" />
+        android:layout_weight="1" />
 
-</androidx.constraintlayout.widget.ConstraintLayout>
+</LinearLayout>

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

@@ -3,29 +3,29 @@
     xmlns:app="http://schemas.android.com/apk/res-auto">
     <group android:id="@+id/mainGroup">
         <item
-            android:id="@+id/action_settings"
+            android:id="@+id/action_mainFragment_to_settingsContainerFragment"
             android:title="@string/action_settings"
             android:icon="@drawable/ic_settings_black_24dp"
             app:showAsAction="never" />
         <item
-            android:id="@+id/action_support"
+            android:id="@+id/action_mainFragment_to_supportFragment"
             android:title="@string/support_title"
             android:icon="@drawable/ic_favorite_black_24dp"
             app:showAsAction="never" />
     </group>
     <group android:id="@+id/addtionalInfoGroup">
         <item
-            android:id="@+id/action_help"
+            android:id="@+id/action_mainFragment_to_helpFragment"
             android:title="@string/action_help"
             android:icon="@drawable/ic_help_black_24dp"
             app:showAsAction="never" />
         <item
-            android:id="@+id/action_libraries"
+            android:id="@+id/action_mainFragment_to_librariesFragment"
             android:title="@string/action_libraries"
             android:icon="@drawable/ic_info_black_24dp"
             app:showAsAction="never" />
         <item
-            android:id="@+id/action_privacy"
+            android:id="@+id/action_mainFragment_to_privacyFragment"
             android:title="@string/action_privacy"
             android:icon="@drawable/ic_eye_black_24dp"
             app:showAsAction="never" />

app/src/main/res/navigation/nav_graph.xml

@@ -0,0 +1,87 @@
+<?xml version="1.0" encoding="utf-8"?>
+<navigation xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/nav_graph"
+    app:startDestination="@+id/mainFragment">
+
+    <fragment
+        android:id="@+id/settingsContainerFragment"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.SettingsContainerFragment"
+        android:label="@string/title_activity_settings" />
+    <fragment
+        android:id="@+id/mainFragment"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.MainFragment"
+        android:label="">
+        <action
+            android:id="@+id/action_mainFragment_to_helpFragment"
+            app:destination="@id/helpFragment"
+            app:enterAnim="@android:anim/slide_in_left"
+            app:exitAnim="@android:anim/slide_out_right"
+            app:popExitAnim="@android:anim/slide_out_right"
+            app:popUpTo="@id/mainFragment" />
+        <action
+            android:id="@+id/action_mainFragment_to_privacyFragment"
+            app:destination="@id/privacyFragment"
+            app:enterAnim="@android:anim/slide_in_left"
+            app:exitAnim="@android:anim/slide_out_right"
+            app:popExitAnim="@android:anim/slide_out_right"
+            app:popUpTo="@id/mainFragment" />
+        <action
+            android:id="@+id/action_mainFragment_to_librariesFragment"
+            app:destination="@id/librariesFragment"
+            app:enterAnim="@android:anim/slide_in_left"
+            app:exitAnim="@android:anim/slide_out_right"
+            app:popExitAnim="@android:anim/slide_out_right"
+            app:popUpTo="@id/mainFragment" />
+        <action
+            android:id="@+id/action_mainFragment_to_settingsContainerFragment"
+            app:destination="@id/settingsContainerFragment"
+            app:enterAnim="@android:anim/slide_in_left"
+            app:exitAnim="@android:anim/slide_out_right"
+            app:popExitAnim="@android:anim/slide_out_right"
+            app:popUpTo="@id/mainFragment" />
+        <action
+            android:id="@+id/action_mainFragment_to_supportFragment"
+            app:destination="@id/supportFragment"
+            app:enterAnim="@anim/nav_default_enter_anim"
+            app:exitAnim="@anim/nav_default_exit_anim"
+            app:popEnterAnim="@anim/nav_default_pop_enter_anim"
+            app:popExitAnim="@anim/nav_default_pop_exit_anim"
+            app:popUpTo="@id/mainFragment" />
+    </fragment>
+    <fragment
+        android:id="@+id/supportFragment"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.SupportFragment"
+        android:label="@string/support_title" />
+    <fragment
+        android:id="@+id/helpFragment"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.MarkdownInfoFragment"
+        android:label="@string/action_help"
+        tools:layout="@layout/fragment_markdown_info">
+        <argument
+            android:name="file"
+            app:argType="string"
+            android:defaultValue="Cheatsheet.md" />
+    </fragment>
+    <fragment
+        android:id="@+id/privacyFragment"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.MarkdownInfoFragment"
+        android:label="@string/action_privacy"
+        tools:layout="@layout/fragment_markdown_info">
+        <argument
+            android:name="file"
+            android:defaultValue="Privacy Policy.md"
+            app:argType="string" />
+    </fragment>
+    <fragment
+        android:id="@+id/librariesFragment"
+        android:name="com.wbrawner.simplemarkdown.view.fragment.MarkdownInfoFragment"
+        android:label="@string/action_libraries"
+        tools:layout="@layout/fragment_markdown_info">
+        <argument
+            android:name="file"
+            android:defaultValue="Libraries.md"
+            app:argType="string" />
+    </fragment>
+</navigation>