From a490c658fb37eab79359000925f3fa379cb24814 Mon Sep 17 00:00:00 2001
From: Tim Schaub <tim.schaub@gmail.com>
Date: Fri, 16 Nov 2018 13:34:13 +0100
Subject: [PATCH] Overscale canvas if sources have non-zero min zoom

---
 src/ol/renderer/canvas/TileLayer.js | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/ol/renderer/canvas/TileLayer.js b/src/ol/renderer/canvas/TileLayer.js
index ca151222d3..3c8c56a8a2 100644
--- a/src/ol/renderer/canvas/TileLayer.js
+++ b/src/ol/renderer/canvas/TileLayer.js
@@ -153,9 +153,15 @@ class CanvasTileLayerRenderer extends CanvasLayerRenderer {
     let width = Math.round(frameState.size[0] * tilePixelRatio);
     let height = Math.round(frameState.size[1] * tilePixelRatio);
     if (tileResolution < viewResolution) {
-      // scale canvas so it covers the viewport until new tiles come it
-      width *= 1.5;
-      height *= 1.5;
+      // scale canvas so it covers the viewport until new tiles come in
+      let scale;
+      if (z <= tileGrid.minZoom) {
+        scale = Math.round(viewResolution / tileResolution);
+      } else {
+        scale = 1.5; // rely on lower z tiles
+      }
+      width *= scale;
+      height *= scale;
     }
 
     if (rotation) {