From 4746cb8aa0ea56976150443d74d33f74eda045b5 Mon Sep 17 00:00:00 2001
From: Dustin Carlino <dabreegster@gmail.com>
Date: Thu, 6 Jun 2024 10:43:22 +0100
Subject: [PATCH] Fix pollution flickering when opacity changes

---
 src/lib/browse/layers/areas/Pollution.svelte | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/lib/browse/layers/areas/Pollution.svelte b/src/lib/browse/layers/areas/Pollution.svelte
index fa029046..0dd71055 100644
--- a/src/lib/browse/layers/areas/Pollution.svelte
+++ b/src/lib/browse/layers/areas/Pollution.svelte
@@ -40,6 +40,10 @@
     PM10Roads_viridis: ["22", "Data for 2022"],
   }[$state.pollutant];
 
+  // Changes to opacity shouldn't re-render the tile URL. Use this indirection
+  // (thanks to https://thoughtspile.github.io/2023/04/22/svelte-state/)
+  $: url = tilesUrl($state.pollutant);
+
   function wmsUrl(): string {
     return `https://ukair.maps.rcdo.co.uk/ukairserver/services/aq_amb_2022/${$state.pollutant}/MapServer/WMSServer`;
   }
@@ -122,7 +126,7 @@
   />
 {/if}
 
-<RasterTileSource tiles={[tilesUrl($state.pollutant)]} tileSize={256}>
+<RasterTileSource tiles={[url]} tileSize={256}>
   <RasterLayer
     {...layerId("pollution")}
     paint={{