/// <summary>
/// get page async.
/// </summary>
/// <param name="pageNumber">The page number.</param>
/// <param name="userState">The user state.</param>
public override void GetPageAsync(int pageNumber, object userState)
{
flowDocPaginator.GetPageAsync(pageNumber, userState);
}
/// <summary>
/// Content measurement.
/// </summary>
/// <param name="availableSize">Available size that parent can give to the child. This is soft constraint.</param>
/// <returns>The DocumentPageView's desired size.</returns>
protected override sealed Size MeasureOverride(Size availableSize)
{
Size newPageSize, pageZoom;
Size pageSize;
Size desiredSize = new Size(); // If no page is available, return (0,0) as size.
CheckDisposed();
if (_suspendLayout)
{
desiredSize = this.DesiredSize;
}
else if (_documentPaginator != null)
{
// Reflow content if needed.
if (ShouldReflowContent())
{
// Reflow is disabled when dealing with infinite size in both directions.
// If only one dimention is infinte, calculate value based on PageSize of the
// document and Stretching properties.
if (!Double.IsInfinity(availableSize.Width) || !Double.IsInfinity(availableSize.Height))
{
pageSize = _documentPaginator.PageSize;
if (Double.IsInfinity(availableSize.Width))
{
newPageSize = new Size();
newPageSize.Height = availableSize.Height / _pageZoom;
newPageSize.Width = newPageSize.Height * (pageSize.Width / pageSize.Height); // Keep aspect ratio.
}
else if (Double.IsInfinity(availableSize.Height))
{
newPageSize = new Size();
newPageSize.Width = availableSize.Width / _pageZoom;
newPageSize.Height = newPageSize.Width * (pageSize.Height / pageSize.Width); // Keep aspect ratio.
}
else
{
newPageSize = new Size(availableSize.Width / _pageZoom, availableSize.Height / _pageZoom);
}
if (!DoubleUtil.AreClose(pageSize, newPageSize))
{
_documentPaginator.PageSize = newPageSize;
}
}
}
// If the main page or pending async page are not available yet,
// asynchronously request new page from Paginator.
if (_documentPage == null && _documentPageAsync == null)
{
if (PageNumber >= 0)
{
if (_useAsynchronous)
{
_documentPaginator.GetPageAsync(PageNumber, this);
}
else
{
_documentPageAsync = _documentPaginator.GetPage(PageNumber);
if (_documentPageAsync == null)
{
_documentPageAsync = DocumentPage.Missing;
}
}
}
else
{
_documentPage = DocumentPage.Missing;
}
}
// If pending async page is available, discard the main page and
// set _documentPage to _documentPageAsync.
if (_documentPageAsync != null)
{
// Do cleanup for currently used page, because it gets replaced.
DisposeCurrentPage();
// DisposeCurrentPage raises PageDisposed and DocumentPage.PageDestroyed events.
// Handlers for those events may dispose _documentPageAsync. Treat this situation
// as missing page.
if (_documentPageAsync == null)
{
_documentPageAsync = DocumentPage.Missing;
}
if (_pageVisualClone != null)
{
RemoveDuplicateVisual();
}
// Replace the main page with cached async page.
_documentPage = _documentPageAsync;
if (_documentPage != DocumentPage.Missing)
{
_documentPage.PageDestroyed += new EventHandler(HandlePageDestroyed);
_documentPageAsync.PageDestroyed -= new EventHandler(HandleAsyncPageDestroyed);
}
_documentPageAsync = null;
// Set a flag that will indicate that a PageConnected must be fired in
// ArrangeOverride
_newPageConnected = true;
}
// If page is available, return its size as desired size.
if (_documentPage != null && _documentPage != DocumentPage.Missing)
{
pageSize = new Size(_documentPage.Size.Width * _pageZoom, _documentPage.Size.Height * _pageZoom);
pageZoom = Viewbox.ComputeScaleFactor(availableSize, pageSize, this.Stretch, this.StretchDirection);
desiredSize = new Size(pageSize.Width * pageZoom.Width, pageSize.Height * pageZoom.Height);
}
if (_pageVisualClone != null)
{
desiredSize = _visualCloneSize;
}
}
return desiredSize;
}
