void RenderShownPage()
{
CancelRenderingShownPage();
var pageInfo = document.GetPageInfo(indexOfShownPage);
if (pageInfo == null)
{
PdfImageView.Image = null;
return;
}
var pageRect = pageInfo.Rect;
var pageImageViewSize = PdfImageView.Bounds.Size;
var pageImageWidth = pageImageViewSize.Width;
var pageImageHeight = (nfloat)Math.Ceiling(pageImageWidth * (pageRect.Height / pageRect.Width));
// Rendering a page requires you to first set up a rendering request and
// specify what and how exactly we want to render.
var renderRequest = new PSPDFMutableRenderRequest(document)
{
PageIndex = indexOfShownPage,
ImageSize = new CGSize(pageImageWidth, pageImageHeight),
ImageScale = PdfImageView?.Window?.BackingScaleFactor ?? 1,
CachePolicy = PSPDFRenderRequestCachePolicy.ReloadIgnoringCacheData
};
// Having the rendering request, we can then create a rendering task.
// Think of the rendering request being a configuration object for the
// render task (once the render task is created, the render request is
// no longer needed).
var renderTask = new PSPDFRenderTask(renderRequest);
if (renderTask == null)
{
Console.WriteLine($"[EXAMPLE] Couldn't create a render task from render request: {renderRequest}.");
PdfImageView.Image = null;
return;
}
// We also assign a high priority for our render task because most of
// the time it is initiated by the user and we therefore need the result
// as fast as possible.
renderTask.Priority = PSPDFRenderQueuePriority.UserInteractive;
// As soon as the task finishes, it notifies its delegate, see
// implemetation of the delegate protocol below.
renderTask.Delegate = this;
// Becuase we display only one page at a time, we can cancel a
// previously issue rendering request if the rendering hasn't finished
// in time. For that, we need to keep a reference to the render task.
shownPageRenderTask = renderTask;
// Finally, we can schedule a render task on the default render queue.
PSPDFKitGlobal.SharedInstance.RenderManager.RenderQueue.Schedule(renderTask);
Console.WriteLine("[EXAMPLE] Scheduled rendering shown page.");
}
void CancelRenderingShownPage()
{
if (shownPageRenderTask == null)
{
return;
}
shownPageRenderTask.Cancel();
shownPageRenderTask = null;
Console.WriteLine("[EXAMPLE] Cancelled rendering shown page.");
}
public void RenderTaskDidFinish(PSPDFRenderTask task)
{
if (task.IsEqual(shownPageRenderTask))
{
// A rendering request might finish but not have an image. This
// happens for example for password protected but not yet unlocked
// documents. In that case, we clear the old image and don't show
// anything.
var image = task.Image;
if (image == null)
{
Console.WriteLine("[EXAMPLE] Finished rendering shown page, but image was 'null'.");
PdfImageView.Image = null;
return;
}
Console.WriteLine("[EXAMPLE] Finished rendering shown page, image is valid.");
// The page is rendered properly, so we can show the result.
PdfImageView.Image = image;
}
}