From d6df8d7902e469576a8fb68fc4b4243b78784f62 Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Sun, 28 Dec 2025 16:30:44 -0800
Subject: [PATCH] Update viewport dims when dpr changes

Fixes #4731
---
 addons/addon-webgl/src/WebglRenderer.ts | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/addons/addon-webgl/src/WebglRenderer.ts b/addons/addon-webgl/src/WebglRenderer.ts
index aa42af78..f78feb04 100644
--- a/addons/addon-webgl/src/WebglRenderer.ts
+++ b/addons/addon-webgl/src/WebglRenderer.ts
@@ -620,6 +620,8 @@ export class WebglRenderer extends Disposable implements IRenderer {
     // the change as it's an exact multiple of the cell sizes.
     this._canvas.width = width;
     this._canvas.height = height;
+    // Update the WebGL viewport to match the new canvas dimensions
+    this._gl.viewport(0, 0, width, height);
     // Render synchronously to avoid flicker when the canvas is cleared
     this._onRequestRedraw.fire({ start: 0, end: this._terminal.rows - 1, sync: true });
   }