Convert scroll to EventEmitter2

src/AccessibilityManager.ts

@@ -74,7 +74,7 @@ export class AccessibilityManager extends Disposable {
     this.register(this._renderRowsDebouncer);
     this.register(this._terminal.addDisposableListener('resize', data => this._onResize(data.rows)));
     this.register(this._terminal.addDisposableListener('refresh', data => this._refreshRows(data.start, data.end)));
-    this.register(this._terminal.addDisposableListener('scroll', data => this._refreshRows()));
+    this.register(this._terminal.onScroll(() => this._refreshRows()));
     // Line feed is an issue as the prompt won't be read out after a command is run
     this.register(this._terminal.addDisposableListener('a11y.char', (char) => this._onChar(char)));
     this.register(this._terminal.onLineFeed(() => this._onChar('\n')));

src/InputHandler.ts

@@ -111,6 +111,8 @@ export class InputHandler extends Disposable implements IInputHandler {
   public get onCursorMove(): IEvent<void> { return this._onCursorMove.event; }
   private _onLineFeed = new EventEmitter2<void>();
   public get onLineFeed(): IEvent<void> { return this._onLineFeed.event; }
+  private _onScroll = new EventEmitter2<number>();
+  public get onScroll(): IEvent<number> { return this._onScroll.event; }
 
   constructor(
       protected _terminal: IInputHandlingTerminal,
@@ -764,7 +766,7 @@ export class InputHandler extends Disposable implements IInputHandler {
           this._terminal.buffer.ybase = Math.max(this._terminal.buffer.ybase - scrollBackSize, 0);
           this._terminal.buffer.ydisp = Math.max(this._terminal.buffer.ydisp - scrollBackSize, 0);
           // Force a scroll event to refresh viewport
-          this._terminal.emit('scroll', 0);
+          this._onScroll.fire(0);
         }
         break;
     }

src/Terminal.test.ts

@@ -90,7 +90,6 @@ describe('xterm.js', () => {
         term.on('cursormove', () => {
           done();
         });
-
         term.write('foo');
       });
     });
@@ -100,11 +99,26 @@ describe('xterm.js', () => {
         term.on('linefeed', () => {
           done();
         });
-
         term.write('\n');
       });
     });
 
+    describe('scroll', () => {
+      it('should emit a scroll event when scrollback is created', (done) => {
+        term.on('scroll', () => {
+          done();
+        });
+        term.write('\n'.repeat(INIT_ROWS));
+      });
+      it('should emit a scroll event when scrollback is cleared', (done) => {
+        term.write('\n'.repeat(INIT_ROWS));
+        term.on('scroll', () => {
+          done();
+        });
+        term.clear();
+      });
+    });
+
     describe(`keypress (including 'key' event)`, () => {
       it('should receive a string and event object', (done) => {
         let steps = 0;

src/Terminal.ts

@@ -263,7 +263,6 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
     // TODO: Replace EventEmitter with EventEmitter2 internally
     this.on('selection', () => this._onSelectionChange.fire());
     this.on('data', e => this._onInput.fire(e));
-    this.on('scroll', e => this._onScroll.fire(e));
     this.on('refresh', e => this._onRender.fire(e));
 
     // TODO: Remove these in v4
@@ -272,6 +271,7 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
     this.onKey(e => this.emit('key', e.key, e.domEvent));
     this.onLineFeed(() => this.emit('linefeed'));
     this.onResize(e => this.emit('resize', e));
+    this.onScroll(e => this.emit('scroll', e));
     this.onTitleChange(e => this.emit('title', e));
   }
 
@@ -740,7 +740,7 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
 
     this._mouseZoneManager = new MouseZoneManager(this);
     this.register(this._mouseZoneManager);
-    this.register(this.addDisposableListener('scroll', () => this._mouseZoneManager.clearAll()));
+    this.register(this.onScroll(() => this._mouseZoneManager.clearAll()));
     this.linkifier.attachToDom(this._mouseZoneManager);
 
     this.textarea = document.createElement('textarea');
@@ -795,7 +795,7 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
       this.textarea.focus();
       this.textarea.select();
     }));
-    this.register(this.addDisposableListener('scroll', () => {
+    this.register(this.onScroll(() => {
       this.viewport.syncScrollArea();
       this.selectionManager.refresh();
     }));
@@ -1302,13 +1302,7 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
     this.updateRange(this.buffer.scrollTop);
     this.updateRange(this.buffer.scrollBottom);
 
-    /**
-     * This event is emitted whenever the terminal is scrolled.
-     * The one parameter passed is the new y display position.
-     *
-     * @event scroll
-     */
-    this.emit('scroll', this.buffer.ydisp);
+    this._onScroll.fire(this.buffer.ydisp);
   }
 
   /**
@@ -1337,7 +1331,7 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
     }
 
     if (!suppressScrollEvent) {
-      this.emit('scroll', this.buffer.ydisp);
+      this._onScroll.fire(this.buffer.ydisp);
     }
 
     this.refresh(0, this.rows - 1);
@@ -1825,7 +1819,7 @@ export class Terminal extends EventEmitter implements ITerminal, IDisposable, II
       this.buffer.lines.push(this.buffer.getBlankLine(DEFAULT_ATTR_DATA));
     }
     this.refresh(0, this.rows - 1);
-    this.emit('scroll', this.buffer.ydisp);
+    this._onScroll.fire(this.buffer.ydisp);
   }
 
   /**