From d7aeb4b764d6bbaa98b03d9e8abf1a5d673189ff Mon Sep 17 00:00:00 2001
From: Stepan Kuzmin <stepan.kuzmin@mapbox.com>
Date: Mon, 4 Dec 2023 12:11:18 +0200
Subject: [PATCH] Duplicate tile reloading logic from RasterSource in
 CustomSource (#12993)

---
 src/source/custom_source.js      | 27 +++++++++++++++++----------
 src/source/raster_tile_source.js | 11 -----------
 2 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/src/source/custom_source.js b/src/source/custom_source.js
index 03bab71e927..6fbdbfd7a87 100644
--- a/src/source/custom_source.js
+++ b/src/source/custom_source.js
@@ -2,8 +2,8 @@
 
 import Tile from './tile.js';
 import window from '../util/window.js';
+import Texture from '../render/texture.js';
 import TileBounds from './tile_bounds.js';
-import RasterTileSource from './raster_tile_source.js';
 import {extend, pick} from '../util/util.js';
 import {Event, ErrorEvent, Evented} from '../util/evented.js';
 import {makeFQID} from '../util/fqid.js';
@@ -314,24 +314,31 @@ class CustomSource<T> extends Evented implements Source {
 
     loadTileData(tile: Tile, data: T): void {
         // Only raster data supported at the moment
-        RasterTileSource.loadTileData(tile, (data: any), this._map.painter);
-    }
-
-    unloadTileData(tile: Tile): void {
-        // Only raster data supported at the moment
-        RasterTileSource.unloadTileData(tile, this._map.painter);
+        tile.setTexture((data: any), this._map.painter);
     }
 
     // $FlowFixMe[method-unbinding]
     unloadTile(tile: Tile, callback: Callback<void>): void {
-        this.unloadTileData(tile);
+        // Only raster data supported at the moment
+        // Cache the tile texture to avoid re-allocating Textures if they'll just be reloaded
+        if (tile.texture && tile.texture instanceof Texture) {
+            // Clean everything else up owned by the tile, but preserve the texture.
+            // Destroy first to prevent racing with the texture cache being popped.
+            tile.destroy(true);
+
+            // Save the texture to the cache
+            if (tile.texture && tile.texture instanceof Texture) {
+                this._map.painter.saveTileTexture(tile.texture);
+            }
+        } else {
+            tile.destroy();
+        }
+
         if (this._implementation.unloadTile) {
             const {x, y, z} = tile.tileID.canonical;
             this._implementation.unloadTile({x, y, z});
         }
 
-        tile.destroy();
-
         callback();
     }
 
diff --git a/src/source/raster_tile_source.js b/src/source/raster_tile_source.js
index db3b6b20533..a0262d01ea8 100644
--- a/src/source/raster_tile_source.js
+++ b/src/source/raster_tile_source.js
@@ -14,12 +14,10 @@ import {makeFQID} from '../util/fqid.js';
 import type {Source} from './source.js';
 import type {OverscaledTileID} from './tile_id.js';
 import type Map from '../ui/map.js';
-import type Painter from '../render/painter.js';
 import type Dispatcher from '../util/dispatcher.js';
 import type Tile from './tile.js';
 import type {Callback} from '../types/callback.js';
 import type {Cancelable} from '../types/cancelable.js';
-import type {TextureImage} from "../render/texture.js";
 import type {
     RasterSourceSpecification,
     RasterDEMSourceSpecification
@@ -219,15 +217,6 @@ class RasterTileSource extends Evented implements Source {
         });
     }
 
-    static loadTileData(tile: Tile, data: TextureImage, painter: Painter) {
-        tile.setTexture(data, painter);
-    }
-
-    // eslint-disable-next-line no-unused-vars
-    static unloadTileData(tile: Tile, painter: Painter) {
-        // Texture caching on unload occurs in unloadTile
-    }
-
     // $FlowFixMe[method-unbinding]
     abortTile(tile: Tile, callback: Callback<void>) {
         if (tile.request) {