message: chore(ImagePreview): improve watcher
diff: @@ -112,6 +112,8 @@ export default createComponent({
  },
  watch: {
  + startPosition: 'setActive',
  +
  value(val) {
  if (val) {
  this.setActive(+this.startPosition);
  @@ -126,10 +128,6 @@ export default createComponent({
  }
  },
  - startPosition(val) {
  - this.setActive(val);
  - },
  -
  shouldRender: {
  handler(val) {
  if (val) {
  