From 361998bd346a0114b182899e1b35ca53aaa18d73 Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Fri, 16 Jul 2021 10:08:36 -0700
Subject: [PATCH] Fix cursor ghosting in canvas/webgl renderers

Fixes #3391
---
 .../xterm-addon-webgl/src/renderLayer/CursorRenderLayer.ts | 7 ++++++-
 src/browser/renderer/CursorRenderLayer.ts                  | 7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/addons/xterm-addon-webgl/src/renderLayer/CursorRenderLayer.ts b/addons/xterm-addon-webgl/src/renderLayer/CursorRenderLayer.ts
index b2e834d3..6aa33828 100644
--- a/addons/xterm-addon-webgl/src/renderLayer/CursorRenderLayer.ts
+++ b/addons/xterm-addon-webgl/src/renderLayer/CursorRenderLayer.ts
@@ -193,7 +193,12 @@ export class CursorRenderLayer extends BaseRenderLayer {
 
   private _clearCursor(): void {
     if (this._state) {
-      this._clearCells(this._state.x, this._state.y, this._state.width, 1);
+      // Avoid potential rounding errors when device pixel ratio is an odd number
+      if (window.devicePixelRatio % 1 !== 0) {
+        this._clearAll();
+      } else {
+        this._clearCells(this._state.x, this._state.y, this._state.width, 1);
+      }
       this._state = {
         x: 0,
         y: 0,
diff --git a/src/browser/renderer/CursorRenderLayer.ts b/src/browser/renderer/CursorRenderLayer.ts
index a78b2048..8fda0b35 100644
--- a/src/browser/renderer/CursorRenderLayer.ts
+++ b/src/browser/renderer/CursorRenderLayer.ts
@@ -197,7 +197,12 @@ export class CursorRenderLayer extends BaseRenderLayer {
 
   private _clearCursor(): void {
     if (this._state) {
-      this._clearCells(this._state.x, this._state.y, this._state.width, 1);
+      // Avoid potential rounding errors when device pixel ratio is less than 1
+      if (window.devicePixelRatio < 1) {
+        this._clearAll();
+      } else {
+        this._clearCells(this._state.x, this._state.y, this._state.width, 1);
+      }
       this._state = {
         x: 0,
         y: 0,