The size of the graph may change due to window resizing or modifications in the DOM structure or content. For instance, the graph's size can be affected if it is displayed within a collapsed panel.
Apache ECharts has a resize method to manage that. But you can ask to the ODSChartsTheme to manage it for you calling the externalizeLegends method.
In the following collapsed div, the resize is managed by the following code:
themeManager.manageChartResize(myChart, 'barLine_chart');