fix(wadouri): Check cache when prefetching wadouri images for volume (#…

…1765)

When using wadouri: scheme with streaming image volume loader, the first, middle and possibly last images must be cached so that the volume can be constructed from metadata. This change first checks if the required images are already in the cache before getting the loadPoolManager involved.

packages/core/src/loaders/cornerstoneStreamingImageVolumeLoader.ts

@@ -1,3 +1,4 @@
+import cache from '../cache/cache';
 import StreamingImageVolume from '../cache/classes/StreamingImageVolume';
 import { RequestType } from '../enums';
 import imageLoadPoolManager from '../requestPool/imageLoadPoolManager';
@@ -52,6 +53,10 @@ function cornerstoneStreamingImageVolumeLoader(
       const indexesToPrefetch = [0, middleImageIndex, lastImageIndex];
       await Promise.all(
         indexesToPrefetch.map((index) => {
+          // check if image is cached
+          if (cache.isLoaded(options.imageIds[index])) {
+            return Promise.resolve(true);
+          }
           return new Promise((resolve, reject) => {
             const imageId = options.imageIds[index];
             imageLoadPoolManager.addRequest(