fix(timeline): significantly reduce unexpected vertical jumping when moving the timeline (#1677)

* Significantly reduce unexpected vertical jumping when moving the timeline

* style(timeline): remove unnecessary indent change

---------

Co-authored-by: Joshua Walsh <[email protected]>
Co-authored-by: Tomina <[email protected]>

Author: 3 people

lib/timeline/component/Group.js

@@ -32,6 +32,7 @@ class Group {
     this.subgroupOrderer = data && data.subgroupOrder;
     this.itemSet = itemSet;
     this.isVisible = null;
+    this.height = 0;
     this.stackDirty = true; // if true, items will be restacked on next redraw
 
     // This is a stack of functions (`() => void`) that will be executed before
@@ -537,7 +538,7 @@ class Group {
       this._updateSubgroupsSizes.bind(this),
 
       () => {
-        height = this._calculateHeight.bind(this)(margin);
+        height = this.height = this._calculateHeight.bind(this)(margin);
       },
 
       // calculate actual size and position again
@@ -627,7 +628,9 @@ class Group {
       items = this.visibleItems;
     }
 
-    if (items.length > 0) {
+    if(!this.isVisible && this.height) {
+      height = Math.max(this.height, this.props.label.height);
+    } else if (items.length > 0) {
       let min = items[0].top;
       let max = items[0].top + items[0].height;
       util.forEach(items, item => {