public class PNGFormat : ExportFormat 

//This example demonstrates how to export a layout to PNG.

//Added references
using ArcGIS.Desktop.Core;                         //Project
using ArcGIS.Desktop.Layouts;                      //Layout classes
using ArcGIS.Desktop.Framework.Threading.Tasks;    //QueuedTask
using ArcGIS.Desktop.Mapping;                      //Export formats

public class ExportLayoutToPNGExample
{
  public static Task ExportLayoutToPNGAsync(string LayoutName, string Path)
  {
    //Reference a layoutitem in a project by name
    LayoutProjectItem layoutItem = Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault(item => item.Name.Equals(LayoutName));
    if (layoutItem == null)
      return Task.FromResult<Layout>(null);

    //Create PNG format with appropriate settings
    PNGFormat PNG = new PNGFormat();
    PNG.Resolution = 300;
    PNG.OutputFileName = Path;

    return QueuedTask.Run(() =>
    {
            //Export Layout
            Layout lyt = layoutItem.GetLayout(); //Loads and returns the layout associated with a LayoutItem
            if (PNG.ValidateOutputFilePath())
      {
        lyt.Export(PNG);
      }
    });
  }
}

//This example demonstrates how to export an individual map frame on a layout to PNG.

//Added references
using ArcGIS.Desktop.Core;                         //Project
using ArcGIS.Desktop.Layouts;                      //Layout classes
using ArcGIS.Desktop.Framework.Threading.Tasks;    //QueuedTask
using ArcGIS.Desktop.Mapping;                      //Export formats

public class ExportMapFrameToPNGExample
{
  public static Task ExportMapFrameToPNGAsync(string LayoutName, string MFName, string Path)
  {
    //Reference a layoutitem in a project by name
    LayoutProjectItem layoutItem = Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault(item => item.Name.Equals(LayoutName));
    if (layoutItem == null)
      return Task.FromResult<Layout>(null);

    //Create PNG format with appropriate settings
    PNGFormat PNG = new PNGFormat();
    PNG.Resolution = 300;
    PNG.OutputFileName = Path;

    return QueuedTask.Run(() =>
    {
            //Export MapFrame
            Layout lyt = layoutItem.GetLayout(); //Loads and returns the layout associated with a LayoutItem
            MapFrame mf = lyt.FindElement(MFName) as MapFrame;
      PNG.OutputFileName = Path;
      if (PNG.ValidateOutputFilePath())
      {
        mf.Export(PNG);
      }
    });
  }
}

//This example demonstrates how to export the active mapview to PNG.

//Added references
using ArcGIS.Desktop.Framework.Threading.Tasks;    //QueuedTask
using ArcGIS.Desktop.Mapping;                      //MapView and Export formats

public class ExportActiveMapToPNGExample
{
  public static Task ExportActiveMapToPNGAsync(string Path)
  {
    return QueuedTask.Run(() =>
    {
            //Reference the active map view
            MapView mapv = MapView.Active;

            //Create PNG format with appropriate settings
            PNGFormat PNG = new PNGFormat();
      PNG.Resolution = 300;
      PNG.Height = 500;
      PNG.Width = 800;
      PNG.OutputFileName = Path;

            //Export active map view
            if (PNG.ValidateOutputFilePath())
      {
        mapv.Export(PNG);
      }
    });
  }
}

PNGFormat PNG = new PNGFormat();