public override void EnsureNoOpenRenderer()
{
// dispose any open renderer
if (_renderer != null)
{
_renderer.Dispose();
_renderer = null;
}
}
protected override Image DoRenderPage(int pageNumber, float dpiX, float dpiY, double scaleFactor, int rotate, Action <Image> progressiveUpdate, Func <bool> cancellationCallback)
{
// try to render the page
var image = (Bitmap)null;
var newRenderer = false;
Retry:
try
{
// ensure there is a renderer
if (_renderer == null)
{
newRenderer = true;
_renderer = new GhostscriptRenderer();
DoRunInitialize(_renderer);
}
// clear the output buffers
_renderer.StdOut.Clear();
_renderer.StdErr.Clear();
// hook up the poll event
var poll = new EventHandler <CancelEventArgs>((o, e) => e.Cancel = cancellationCallback());
if (cancellationCallback != null)
{
_renderer.Poll += poll;
}
try
{
// hook up the progressive update event
var update = new EventHandler <GhostscriptRendererEventArgs>((o, e) => { if (image == null)
{
progressiveUpdate(e.Image);
}
});
if (progressiveUpdate != null)
{
_renderer.Update += update;
}
try
{
// hook up the page event
var page = new EventHandler <GhostscriptRendererEventArgs>((o, e) => image = e.Image);
_renderer.Page += page;
try
{
// set the page settings and run the page
_renderer.Run(string.Format(CultureInfo.InvariantCulture, "<<\n/HWResolution [{0} {1}]\n/Orientation {2}\n>> setpagedevice\n", dpiX * scaleFactor, dpiY * scaleFactor, (rotate / 90) % 4));
DoRunPage(_renderer, pageNumber);
}
finally
{
// remove the page event
_renderer.Page -= page;
}
}
finally
{
// remove the progressive update event
if (progressiveUpdate != null)
{
_renderer.Update -= update;
}
}
}
finally
{
// remove the poll event
if (cancellationCallback != null)
{
_renderer.Poll -= poll;
}
}
}
catch (Exception)
{
// dispose the renderer and image
EnsureNoOpenRenderer();
if (image != null)
{
image.Dispose();
image = null;
}
// try again if we used an old renderer (sometimes it fails)
if (!newRenderer)
{
goto Retry;
}
// re-throw the error
throw;
}
// ensure there is an image
if (image == null)
{
throw new InvalidOperationException(string.Format(Resources.Document_PageNotRendered, pageNumber));
}
// set the resolution and return the image
image.SetResolution(dpiX, dpiY);
return(image);
}
