Hi,
You can use the above macro or, you can take inspiration from the web part itself - \CMS\CMSWebParts\Text\editableimage.ascx.cs and check the code of the LoadContent method:
public override void LoadContent(string content, bool forceReload)
{
if (!StopProcessing)
{
ucEditableImage.LoadContent(content, forceReload);
if (!string.IsNullOrEmpty(ucEditableImage.DefaultImage))
{
// Default image defined => content is not empty
EmptyContent = false;
}
}
}
Which is also calling the LoadContent method (CMS.Controls.CMSEditableImage.LoadContent(System.String, [System.Boolean])).