/// <summary>
/// <see cref="ITextView.BringLineIntoViewAsync"/>
/// </summary>
internal override void BringLineIntoViewAsync(ITextPointer position, double suggestedX, int count, object userState)
{
// Verify that layout information is valid. Cannot continue if not valid.
if (!IsValid)
{
throw new InvalidOperationException(SR.Get(SRID.TextViewInvalidLayout));
}
if (_pendingRequest != null)
{
// Ignore new request if the previous is not completed yet.
OnBringLineIntoViewCompleted(new BringLineIntoViewCompletedEventArgs(
position, suggestedX, count, position, suggestedX, 0, false, null, false, userState));
}
else
{
_pendingRequest = new BringLineIntoViewRequest(position, suggestedX, count, userState);
BringLineIntoViewCore((BringLineIntoViewRequest)_pendingRequest);
}
}
/// <summary>
/// Bring line into view.
/// </summary>
private void BringLineIntoViewCore(BringLineIntoViewRequest request)
{
ITextPointer newPosition;
double newSuggestedX;
int linesMoved;
int pageNumber;
// Try to use existing TextViews to handle this request.
newPosition = GetPositionAtNextLineCore(request.NewPosition, request.NewSuggestedX, request.NewCount, out newSuggestedX, out linesMoved, out pageNumber);
Invariant.Assert(Math.Abs(request.NewCount) >= Math.Abs(linesMoved));
request.NewPosition = newPosition;
request.NewSuggestedX = newSuggestedX;
request.NewCount = request.NewCount - linesMoved;
request.NewPageNumber = pageNumber;
if (request.NewCount == 0)
{
OnBringLineIntoViewCompleted(request);
}
else
{
if (newPosition is DocumentSequenceTextPointer || newPosition is FixedTextPointer)
{
//Fixed generally uses a stitched viewing mechanism and the approach used for Flow does not work properly for Fixed
//NextPage() call in DocumentViewer results in DocumentGrid.ScrollToNextRow() which scrolls to firstVisibleRow + 1
//E.g. if there are two views on the screen and we need to navigate to the third, this makes it impossible to achieve
if (_viewer.CanGoToPage(pageNumber + 1))
{
_viewer.GoToPage(pageNumber + 1);
}
else
{
OnBringLineIntoViewCompleted(request);
}
}
else
{
if (request.NewCount > 0)
{
// If the viewer can navigate to the next page, request navigation and wait for
// Updated event for the TextView.
// If cannot to the next page, raise BringLineIntoViewCompleted with success = 'False'.
if (_viewer.CanGoToNextPage)
{
_viewer.NextPage();
}
else
{
OnBringLineIntoViewCompleted(request);
}
}
else
{
// If the viewer can navigate to the previous page, request navigation and wait for
// Updated event fo the TextView.
// If cannot to the previous page, raise BringLineIntoViewCompleted with success = 'False'.
if (_viewer.CanGoToPreviousPage)
{
_viewer.PreviousPage();
}
else
{
OnBringLineIntoViewCompleted(request);
}
}
}
}
}
/// <summary>
/// Fires BringLineIntoViewCompleted event.
/// </summary>
private void OnBringLineIntoViewCompleted(BringLineIntoViewRequest request)
{
_pendingRequest = null;
OnBringLineIntoViewCompleted(new BringLineIntoViewCompletedEventArgs(
request.Position, request.SuggestedX, request.Count,
request.NewPosition, request.NewSuggestedX, request.Count - request.NewCount,
request.NewCount == 0, null, false, request.UserState));
}