fix preview overflow

miniprogram/components/journal-detail-panel/index.ts

@@ -96,21 +96,28 @@ Component({
 
 		/** 预览媒体 */
 		previewMedia(e: WechatMiniprogram.BaseEvent) {
-			const { mediaIndex } = e.currentTarget.dataset;
 			const journals = this.properties.journals as JournalInfo[];
-			if (!journals || journals.length === 0) return;
-
-			// 使用当前 swiper 的索引
-			const journal = journals[this.data.currentJournalIndex];
-			const sources = journal.items.map((item: any) => ({
-				url: item.sourceURL,
-				type: item.type === 0 ? "image" : "video"
-			}));
+			if (!journals || journals.length === 0) {
+				return;
+			}
+			const { itemIndex } = e.currentTarget.dataset;
+			const items = journals[this.data.currentJournalIndex].items;
+			const total = items.length;
+			
+			const startIndex = Math.max(0, itemIndex - 25);
+			const endIndex = Math.min(total, startIndex + 50);
+			const newCurrentIndex = itemIndex - startIndex;
 
+			const sources = items.slice(startIndex, endIndex).map((item) => {
+				return {
+					url: item.sourceURL,
+					type: item.type === 0 ? "image" : "video"
+				}
+			}) as any;
 			wx.previewMedia({
-				current: mediaIndex,
-				sources: sources as WechatMiniprogram.MediaSource[]
-			});
+				current: newCurrentIndex,
+				sources
+			})
 		}
 	}
 });