Add Reverse Tap to Turn Page. Close #186

lib/foundation/appdata.dart

@@ -135,6 +135,7 @@ class _Settings with ChangeNotifier {
     'readerMode': 'galleryLeftToRight', // values of [ReaderMode]
     'readerScreenPicNumber': 1, // 1 - 5
     'enableTapToTurnPages': true,
+    'reverseTapToTurnPages': false,
     'enablePageAnimation': true,
     'language': 'system', // system, zh-CN, zh-TW, en-US
     'cacheSize': 2048, // in MB

lib/pages/reader/gesture.dart

@@ -191,31 +191,37 @@ class _ReaderGestureDetectorState extends State<_ReaderGestureDetector> {
           isBottom = true;
         }
         bool isCenter = false;
+        var prev = context.reader.toPrevPage;
+        var next = context.reader.toNextPage;
+        if (appdata.settings['reverseTapToTurnPages']) {
+          prev = context.reader.toNextPage;
+          next = context.reader.toPrevPage;
+        }
         switch (context.reader.mode) {
           case ReaderMode.galleryLeftToRight:
           case ReaderMode.continuousLeftToRight:
             if (isLeft) {
-              context.reader.toPrevPage();
+              prev();
             } else if (isRight) {
-              context.reader.toNextPage();
+              next();
             } else {
               isCenter = true;
             }
           case ReaderMode.galleryRightToLeft:
           case ReaderMode.continuousRightToLeft:
             if (isLeft) {
-              context.reader.toNextPage();
+              next();
             } else if (isRight) {
-              context.reader.toPrevPage();
+              prev();
             } else {
               isCenter = true;
             }
           case ReaderMode.galleryTopToBottom:
           case ReaderMode.continuousTopToBottom:
             if (isTop) {
-              context.reader.toPrevPage();
+              prev();
             } else if (isBottom) {
-              context.reader.toNextPage();
+              next();
             } else {
               isCenter = true;
             }

lib/pages/reader/images.dart

@@ -700,10 +700,8 @@ class _ContinuousModeState extends State<_ContinuousMode>
   @override
   bool handleOnTap(Offset location) {
     if (delayedIsScrolling) {
-      print('isScrolling');
       return true;
     }
-    print('isNotScrolling');
     return false;
   }
 }

lib/pages/settings/reader.dart

@@ -22,6 +22,13 @@ class _ReaderSettingsState extends State<ReaderSettings> {
             widget.onChanged?.call("enableTapToTurnPages");
           },
         ).toSliver(),
+        _SwitchSetting(
+          title: "Reverse tap to turn Pages".tl,
+          settingKey: "reverseTapToTurnPages",
+          onChanged: () {
+            widget.onChanged?.call("reverseTapToTurnPages");
+          },
+        ).toSliver(),
         _SwitchSetting(
           title: "Page animation".tl,
           settingKey: "enablePageAnimation",