(PR) fix. Stylus button press changes tool to Eraser but do not erase.

saber-notes#1428

Signed-off-by: AnErrupTion <anerruption@disroot.org>

Author: AnErrupTion

lib/data/prefs.dart

@@ -199,6 +199,11 @@ class Stows {
     false,
     volatile: !_isOnMainIsolate,
   );
+  final eraserOnStylusButtonPressAndRelease = PlainStow(
+    'eraserOnStylusButtonPressAndRelease',
+    false,
+    volatile: !_isOnMainIsolate,
+  );
   final hideFingerDrawingToggle = PlainStow(
     'hideFingerDrawingToggle',
     false,

lib/i18n/strings_en.g.dart

@@ -623,6 +623,9 @@ class TranslationsSettingsPrefLabelsEn {
 	/// en: 'Auto-disable the eraser'
 	String get disableEraserAfterUse => 'Auto-disable the eraser';
 
+	/// en: 'Eraser on stylus button press and release'
+	String get eraserOnStylusButtonPressAndRelease => 'Eraser on stylus button press and release';
+
 	/// en: 'Hide the finger drawing toggle'
 	String get hideFingerDrawingToggle => 'Hide the finger drawing toggle';
 

lib/pages/editor/editor.dart

@@ -744,19 +744,46 @@ class EditorState extends State<Editor> {
     // whether the stylus button is or was pressed
     stylusButtonPressed = stylusButtonPressed || buttonPressed;
 
-    if (isHovering) {
-      if (buttonPressed) {
-        if (currentTool is Eraser) return;
-        tmpTool = currentTool;
-        currentTool = Eraser();
-        setState(() {});
-      } else {
-        if (tmpTool != null && currentTool is Eraser) {
-          currentTool = tmpTool!;
-          tmpTool = null;
-          setState(() {});
-        }
-      }
+    if (!Prefs.eraserOnStylusButtonPressAndRelease.value) {
+    	// standard behavior of stylus button, while holding is erasing
+    	if (isHovering) {
+       if (buttonPressed) {
+         if (currentTool is Eraser) return;
+         tmpTool = currentTool;
+         currentTool = Eraser();
+         setState(() {});
+       } else {
+         if (tmpTool != null && currentTool is Eraser) {
+           currentTool = tmpTool!;
+           tmpTool = null;
+           setState(() {});
+         }
+       }
+     }
+    } else {
+	   	// some pens do not send moving events when stylus button is pressed
+	    // so switch to eraser when button is pressed and back on next press
+	    if (isHovering) {
+	      if (buttonPressed) {
+	        // switch to Eraser
+	        if (currentTool is Eraser) {
+	          if (tmpTool != null) {
+	            // change back original tool
+	            currentTool = tmpTool!;
+	            tmpTool = null;
+	            setState(() {});
+	          }
+	          else {
+	            return; // when I am on eraser and previous tool is not set, it means that Eraser is main tool
+	          }
+	        }
+	        else {
+	          tmpTool = currentTool;
+	          currentTool = Eraser();
+	          setState(() {});
+	        }
+	      }
+	    }
     }
   }
 

lib/pages/home/settings.dart

@@ -368,6 +368,12 @@ class _SettingsPageState extends State<SettingsPage> {
                   icon: FontAwesomeIcons.eraser,
                   pref: stows.disableEraserAfterUse,
                 ),
+                SettingsSwitch(
+                  title: t.settings.prefLabels.eraserOnStylusButtonPressAndRelease,
+                  subtitle: t.settings.prefDescriptions.eraserOnStylusButtonPressAndRelease,
+                  icon: FontAwesomeIcons.eraser,
+                  pref: stows.eraserOnStylusButtonPressAndRelease,
+                ),
                 ValueListenableBuilder(
                   valueListenable: stows.hideFingerDrawingToggle,
                   builder: (context, _, _) {