/// <summary>
/// Fires the <see cref="Graphic.Drawing"/> event. Should be called by an <see cref="IRenderer"/>
/// for each object just before it is drawn/rendered, hence the reason it is public.
/// </summary>
/// <remarks>
/// When this graphic is drawn, the <see cref="PresentationState"/> is deserialized. Any exceptions are caught
/// and drawn to an exception text graphic placed at the <see cref="IApplicationGraphicsProvider">application-level</see>,
/// if available. If no such in-grahic exception reporting mechanism is available, then the exception is thrown and
/// the renderer will handle it according to its specific implementation.
/// </remarks>
public override void OnDrawing()
{
if (!_applied && base.ParentPresentationImage != null)
{
// set flag up here, in case deserializing the presentation state causes another draw
_applied = true;
if (_presentationState != null)
{
Exception exception = null;
try
{
_presentationState.Deserialize(base.ParentPresentationImage);
}
catch (Exception ex)
{
Platform.Log(LogLevel.Warn, ex, "An error has occurred while deserializing the image presentation state.");
exception = ex;
}
if (base.ParentPresentationImage is IApplicationGraphicsProvider)
{
ExceptionGraphic exGraphic = (ExceptionGraphic)((IApplicationGraphicsProvider)base.ParentPresentationImage).ApplicationGraphics.FirstOrDefault(IsType <ExceptionGraphic>);
if (exGraphic == null)
{
((IApplicationGraphicsProvider)base.ParentPresentationImage).ApplicationGraphics.Add(exGraphic = new ExceptionGraphic());
}
exGraphic.Set(exception);
}
else if (exception != null)
{
// fallback mechanism when no other exception reporting mechanism is available
throw exception;
}
}
}
base.OnDrawing();
}
/// <summary>
/// Cloning constructor.
/// </summary>
private ExceptionGraphic(ExceptionGraphic source, ICloningContext context) : base()
{
context.CloneFields(source, this);
}