Setting Font Size: Improve the choosing dialog

Now show how big the font will be in a dialog. This way the user can
make a more informed decission, instead of just choosing "Small" vs
"Normal" and not knowing how big that actually would be.

lib/screens/settings_screen.dart

@@ -128,40 +128,20 @@ class SettingsListState extends State<SettingsList> {
           }
         },
       ),
-      DropdownPreference(
+      ListTile(
-        'Font Size',
+        title: Text("Font Size"),
-        'font_size',
+        subtitle: Text(
-        defaultVal: "Normal",
+          Settings.noteViewerFontSizeToString(
-        values: [
+              Settings.instance.noteViewerFontSize),
-          "Extra Small",
+        ),
-          "Small",
+        onTap: () async {
-          "Normal",
+          String result = await showDialog<String>(
-          "Large",
+              context: context, builder: (context) => FontSizeSettingsDialog());
-          "Extra Large",
+
-        ],
+          var fontSize = Settings.noteViewerFontSizeFromString(result);
-        onChange: (newVal) {
-          NoteViewerFontSize fontSize;
-          switch (newVal) {
-            case "Extra Small":
-              fontSize = NoteViewerFontSize.ExtraSmall;
-              break;
-            case "Small":
-              fontSize = NoteViewerFontSize.Small;
-              break;
-            case "Normal":
-              fontSize = NoteViewerFontSize.Normal;
-              break;
-            case "Large":
-              fontSize = NoteViewerFontSize.Large;
-              break;
-            case "Extra Large":
-              fontSize = NoteViewerFontSize.ExtraLarge;
-              break;
-            default:
-              fontSize = NoteViewerFontSize.Normal;
-          }
           Settings.instance.noteViewerFontSize = fontSize;
           Settings.instance.save();
+          setState(() {});
         },
       ),
       SettingsHeader("Git Author Settings"),
@@ -283,3 +263,68 @@ class VersionNumberTileState extends State<VersionNumberTile> {
     );
   }
 }
+
+class FontSizeSettingsDialog extends StatelessWidget {
+  final String title = "Font Size";
+
+  @override
+  Widget build(BuildContext context) {
+    var style = Theme.of(context).textTheme.body1;
+    var sizes = <Widget>[
+      ListTile(
+        title: Text("Extra Small",
+            style: style.copyWith(
+                fontSize: Settings.noteViewerFontSizeToDouble(
+                    NoteViewerFontSize.ExtraSmall))),
+        onTap: () {
+          Navigator.of(context).pop("Extra Small");
+        },
+      ),
+      ListTile(
+        title: Text("Small",
+            style: style.copyWith(
+                fontSize: Settings.noteViewerFontSizeToDouble(
+                    NoteViewerFontSize.Small))),
+        onTap: () {
+          Navigator.of(context).pop("Small");
+        },
+      ),
+      ListTile(
+        title: Text("Normal",
+            style: style.copyWith(
+                fontSize: Settings.noteViewerFontSizeToDouble(
+                    NoteViewerFontSize.Normal))),
+        onTap: () {
+          Navigator.of(context).pop("Normal");
+        },
+      ),
+      ListTile(
+        title: Text("Large",
+            style: style.copyWith(
+                fontSize: Settings.noteViewerFontSizeToDouble(
+                    NoteViewerFontSize.Large))),
+        onTap: () {
+          Navigator.of(context).pop("Large");
+        },
+      ),
+      ListTile(
+        title: Text("Extra Large",
+            style: style.copyWith(
+                fontSize: Settings.noteViewerFontSizeToDouble(
+                    NoteViewerFontSize.ExtraLarge))),
+        onTap: () {
+          Navigator.of(context).pop("Extra Large");
+        },
+      ),
+    ];
+
+    return AlertDialog(
+      title: Text(title),
+      content: SingleChildScrollView(
+        child: ListBody(
+          children: sizes,
+        ),
+      ),
+    );
+  }
+}

lib/settings.dart

@@ -62,7 +62,11 @@ class Settings {
   }
 
   double getNoteViewerFontSize() {
-    switch (noteViewerFontSize) {
+    return noteViewerFontSizeToDouble(noteViewerFontSize);
+  }
+
+  static double noteViewerFontSizeToDouble(NoteViewerFontSize size) {
+    switch (size) {
       case NoteViewerFontSize.Normal:
         return 18.0;
       case NoteViewerFontSize.Small:
@@ -75,7 +79,42 @@ class Settings {
         return 26.0;
     }
 
-    assert(false, "getNoteViewerFontSize: We should never be here");
+    assert(false, "noteViewerFontSizeToDouble: We should never be here");
     return 50000.0;
   }
+
+  static String noteViewerFontSizeToString(NoteViewerFontSize size) {
+    switch (size) {
+      case NoteViewerFontSize.Normal:
+        return "Normal";
+      case NoteViewerFontSize.Small:
+        return "Small";
+      case NoteViewerFontSize.ExtraSmall:
+        return "Extra Small";
+      case NoteViewerFontSize.Large:
+        return "Large";
+      case NoteViewerFontSize.ExtraLarge:
+        return "Extra Large";
+    }
+
+    assert(false, "noteViewerFontSizeToString: We should never be here");
+    return "";
+  }
+
+  static NoteViewerFontSize noteViewerFontSizeFromString(String val) {
+    switch (val) {
+      case "Extra Small":
+        return NoteViewerFontSize.ExtraSmall;
+      case "Small":
+        return NoteViewerFontSize.Small;
+      case "Normal":
+        return NoteViewerFontSize.Normal;
+      case "Large":
+        return NoteViewerFontSize.Large;
+      case "Extra Large":
+        return NoteViewerFontSize.ExtraLarge;
+      default:
+        return NoteViewerFontSize.Normal;
+    }
+  }
 }