C# FrameworkElement.BringIntoView方法代码示例

    private bool BringIntoViewScrollingCell( Cell cell, FrameworkElement container, RequestBringIntoViewEventArgs e )
    {
      Debug.Assert( cell != null );
      Debug.Assert( container != null );

      // The cell must be measured/arranged for the BringIntoView to correctly reacts
      if( this.ForceScrollingCellToLayout( cell ) )
      {
        container.UpdateLayout();
      }

      var fixedWidth = this.GetFixedWidth();
      var scrollingPanel = this.ScrollingCellsDecorator;
      var scrollingArea = new Rect( scrollingPanel.TranslatePoint( FixedCellPanel.EmptyPoint, this ),
                                    new Size( this.ParentScrollViewer.ViewportWidth - fixedWidth, scrollingPanel.ActualHeight ) );
      var cellArea = new Rect( cell.TranslatePoint( FixedCellPanel.EmptyPoint, this ),
                               new Size( cell.ParentColumn.ActualWidth, cell.ActualHeight ) );

      // The cell is larger than the scrolling area.
      if( cellArea.Width > scrollingArea.Width )
      {
        var targetObject = e.TargetObject as UIElement;
        var targetRect = e.TargetRect;

        // Try to narrow the area within the cell that we clearly want to bring into view.
        if( ( targetObject != null ) && ( targetObject != cell || !targetRect.IsEmpty ) )
        {
          Debug.Assert( targetObject.IsDescendantOf( cell ) );

          if( targetRect.IsEmpty )
          {
            targetRect = new Rect( new Point( 0d, 0d ), targetObject.RenderSize );
          }

          if( targetRect.Width <= scrollingArea.Width )
          {
            var offset = targetObject.TranslatePoint( FixedCellPanel.EmptyPoint, cell );
            var location = cellArea.Location;
            location.Offset( offset.X, offset.Y );

            cellArea.Location = location;
            cellArea.Size = targetRect.Size;
          }
        }
      }

      if( ( cellArea.Left <= scrollingArea.Left ) && ( cellArea.Right >= scrollingArea.Right ) )
      {
        // Ensure to bring the container into view vertically.
        container.BringIntoView();
      }
      else if( cellArea.Left < scrollingArea.Left )
      {
        // The ScrollViewer's extent width includes the fixed section.  We must offset the target area or the cell
        // will come into view under the fixed panel.
        cellArea.X -= fixedWidth;

        this.BringIntoView( cellArea );
      }
      else if( cellArea.Right > scrollingArea.Right )
      {
        this.BringIntoView( cellArea );
      }
      // The cell is fully visible.
      else
      {
        // Ensure to bring the container into view vertically.
        container.BringIntoView();
      }

      return true;
    }

        //
        // Shifts the viewport to make the given index visible.
        //
        internal void MakeVisible(FrameworkElement container, FocusNavigationDirection direction, bool alwaysAtTopOfViewport)
        {
            if (ScrollHost != null && ItemsHost != null)
            {
                double oldHorizontalOffset;
                double oldVerticalOffset;

                FrameworkElement viewportElement = GetViewportElement();

                while (container != null && !IsOnCurrentPage(viewportElement, container, direction, false /*fullyVisible*/))
                {
                    oldHorizontalOffset = ScrollHost.HorizontalOffset;
                    oldVerticalOffset = ScrollHost.VerticalOffset;

                    container.BringIntoView();

                    // Wait for layout
                    ItemsHost.UpdateLayout();

                    // If offset does not change - exit the loop
                    if (DoubleUtil.AreClose(oldHorizontalOffset, ScrollHost.HorizontalOffset) &&
                        DoubleUtil.AreClose(oldVerticalOffset, ScrollHost.VerticalOffset))
                        break;
                }

                if (container != null && alwaysAtTopOfViewport)
                {
                    bool isHorizontal = (ItemsHost.HasLogicalOrientation && ItemsHost.LogicalOrientation == Orientation.Horizontal);

                    FrameworkElement firstElement;
                    GetFirstItemOnCurrentPage(container, FocusNavigationDirection.Up, out firstElement);
                    while (firstElement != container)
                    {
                        oldHorizontalOffset = ScrollHost.HorizontalOffset;
                        oldVerticalOffset = ScrollHost.VerticalOffset;

                        if (isHorizontal)
                        {
                            ScrollHost.LineRight();
                        }
                        else
                        {
                            ScrollHost.LineDown();
                        }

                        ScrollHost.UpdateLayout();

                        // If offset does not change - exit the loop
                        if (DoubleUtil.AreClose(oldHorizontalOffset, ScrollHost.HorizontalOffset) &&
                            DoubleUtil.AreClose(oldVerticalOffset, ScrollHost.VerticalOffset))
                            break;

                        GetFirstItemOnCurrentPage(container, FocusNavigationDirection.Up, out firstElement);
                    }
                }
            }
        }

    private bool BringIntoViewFixedCell( FrameworkElement container )
    {
      Debug.Assert( container != null );

      // We always want the horizontal offset to change if Tab, Home, Left or Right is pressed.
      if( Keyboard.IsKeyDown( Key.Tab ) || Keyboard.IsKeyDown( Key.Home ) || Keyboard.IsKeyDown( Key.Left ) || Keyboard.IsKeyDown( Key.Right ) )
      {
        container.BringIntoView( new Rect( 0d, 0d, 0d, 0d ) );
      }
      else
      {
        // Ensure to bring the container into view vertically.
        container.BringIntoView();
      }

      return true;
    }