From c97bf3432f58261f73a260b347adf3c24aadfaa4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maximilian=20Kr=C3=B6g?= <maxi_kroeg@web.de>
Date: Sun, 4 Jul 2021 04:10:26 +0200
Subject: [PATCH] Fix transform for immediate rendering on canvas

If the canvas css transform does not match the frameState pixelRatio the drawing
is at the wrong size.
---
 src/ol/render.js | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/ol/render.js b/src/ol/render.js
index 150c8809a3..c9cd338c8d 100644
--- a/src/ol/render.js
+++ b/src/ol/render.js
@@ -88,6 +88,8 @@ export function toContext(context, opt_options) {
  * @api
  */
 export function getVectorContext(event) {
+  // canvas may be at a different pixel ratio than frameState.pixelRatio
+  const canvasPixelRatio = event.inversePixelTransform[0];
   const frameState = event.frameState;
   const transform = multiplyTransform(
     event.inversePixelTransform.slice(),
@@ -95,7 +97,7 @@ export function getVectorContext(event) {
   );
   const squaredTolerance = getSquaredTolerance(
     frameState.viewState.resolution,
-    frameState.pixelRatio
+    canvasPixelRatio
   );
   let userTransform;
   const userProjection = getUserProjection();
@@ -107,7 +109,7 @@ export function getVectorContext(event) {
   }
   return new CanvasImmediateRenderer(
     event.context,
-    frameState.pixelRatio,
+    canvasPixelRatio,
     frameState.extent,
     transform,
     frameState.viewState.rotation,