/// <summary>
/// <see cref="ITextView.BringLineIntoViewAsync"/>
/// </summary>
internal override void BringPageIntoViewAsync(ITextPointer position, Point suggestedOffset, 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.
OnBringPageIntoViewCompleted(new BringPageIntoViewCompletedEventArgs(
position, suggestedOffset, count, position, suggestedOffset, 0, false, null, false, userState));
}
else
{
_pendingRequest = new BringPageIntoViewRequest(position, suggestedOffset, count, userState);
BringPageIntoViewCore((BringPageIntoViewRequest)_pendingRequest);
}
}
/// <summary>
/// Bring page into view.
/// </summary>
private void BringPageIntoViewCore(BringPageIntoViewRequest request)
{
ITextPointer newPosition;
Point newSuggestedOffset;
int pagesMoved;
int newPageNumber;
// Try to use existing TextViews to handle this request.
newPosition = GetPositionAtNextPageCore(request.NewPosition, request.NewSuggestedOffset, request.NewCount, out newSuggestedOffset, out pagesMoved, out newPageNumber);
Invariant.Assert(Math.Abs(request.NewCount) >= Math.Abs(pagesMoved));
request.NewPosition = newPosition;
request.NewSuggestedOffset = newSuggestedOffset;
request.NewCount = request.NewCount - pagesMoved;
if (request.NewCount == 0 || newPageNumber == -1)
{
OnBringPageIntoViewCompleted(request);
}
else
{
// 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'.
newPageNumber += (request.NewCount > 0) ? 1 : -1;
if (_viewer.CanGoToPage(newPageNumber + 1))
{
request.NewPageNumber = newPageNumber;
_viewer.GoToPage(newPageNumber + 1);
}
else
{
OnBringPageIntoViewCompleted(request);
}
}
}
/// <summary>
/// Fires BringPageIntoViewCompleted event.
/// </summary>
private void OnBringPageIntoViewCompleted(BringPageIntoViewRequest request)
{
_pendingRequest = null;
OnBringPageIntoViewCompleted(new BringPageIntoViewCompletedEventArgs(
request.Position, request.SuggestedOffset, request.Count,
request.NewPosition, request.NewSuggestedOffset, request.Count - request.NewCount,
request.NewCount == 0, null, false, request.UserState));
}
