auto scroll to selected item

src/components/mobile/TreeViewSelectionSheet.vue

@@ -84,8 +84,9 @@ export default {
         }
     },
     methods: {
-        onSheetOpen() {
+        onSheetOpen(event) {
             this.currentValue = this.value;
+            this.scrollToSelectedItem(event.$el);
         },
         onSheetClosed() {
             this.$emit('update:show', false);
@@ -119,6 +120,27 @@ export default {
             } else {
                 return this.currentValue === subItem;
             }
+        },
+        scrollToSelectedItem(parent) {
+            if (!parent || !parent.length) {
+                return;
+            }
+
+            const container = parent.find('.page-content');
+            const selectedItem = parent.find('.treeview-item .treeview-item-selected');
+
+            if (!container.length || !selectedItem.length) {
+                return;
+            }
+
+            let targetPos = selectedItem.offset().top - container.offset().top - parseInt(container.css('padding-top'), 10)
+                - (container.outerHeight() - selectedItem.outerHeight()) / 2;
+
+            if (targetPos <= 0) {
+                return;
+            }
+
+            container.scrollTop(targetPos);
         }
     }
 }