feat: Add Eraser 🎉 (#4887)

* feat: Add Eraser 🎉

* Eraser working

* remove unused state

* fix

* toggle eraser

* Support deselect with Alt/Option

* rename actionDelete -> actionErase

* Add util isEraserActive

* show eraser in mobile

* render eraser conditionally in mobile

* use selection if eraser in local storage state

* Add sampling to erase accurately

* use pointerDownState

* set eraser to false in AllowedExcalidrawElementTypes

* rename/reword fixes

* don't use updateScene

* handle bound text when erasing

* fix hover state in mobile

* consider all hitElements instead of a single

* code improvements

* revert to select if eraser active and elements selected

* show eraser in zenmode

* erase element when clicked on element while eraser active

* set groupIds to empty when eraser active

* fix test

* remove dragged distance

src/components/MobileMenu.tsx

@@ -8,7 +8,7 @@ import { NonDeletedExcalidrawElement } from "../element/types";
 import { FixedSideContainer } from "./FixedSideContainer";
 import { Island } from "./Island";
 import { HintViewer } from "./HintViewer";
-import { calculateScrollCenter } from "../scene";
+import { calculateScrollCenter, getSelectedElements } from "../scene";
 import { SelectedShapeActions, ShapesSwitcher } from "./Actions";
 import { Section } from "./Section";
 import CollabButton from "./CollabButton";
@@ -113,6 +113,12 @@ export const MobileMenu = ({
   };
 
   const renderAppToolbar = () => {
+    // Render eraser conditionally in mobile
+    const showEraser =
+      !appState.viewModeEnabled &&
+      !appState.editingElement &&
+      getSelectedElements(elements, appState).length === 0;
+
     if (viewModeEnabled) {
       return (
         <div className="App-toolbar-content">
@@ -120,12 +126,16 @@ export const MobileMenu = ({
         </div>
       );
     }
+
     return (
       <div className="App-toolbar-content">
         {actionManager.renderAction("toggleCanvasMenu")}
         {actionManager.renderAction("toggleEditMenu")}
+
         {actionManager.renderAction("undo")}
         {actionManager.renderAction("redo")}
+        {showEraser && actionManager.renderAction("eraser")}
+
         {actionManager.renderAction(
           appState.multiElement ? "finalize" : "duplicateSelection",
         )}