private void ThumbPreviewMouseMove(object sender, MouseEventArgs e)
{
var thumb = sender as Thumb;
if (thumb is null)
{
return;
}
var gridViewColumn = FindParentColumn(thumb);
if (gridViewColumn is null)
{
return;
}
// suppress column resizing for proportional, fixed and range fill columns
if (ProportionalColumn.IsProportionalColumn(gridViewColumn) || FixedColumn.IsFixedColumn(gridViewColumn) || IsFillColumn(gridViewColumn))
{
thumb.SetCurrentValue(FrameworkElement.CursorProperty, null);
return;
}
// check range column bounds
if (thumb.IsMouseCaptured && RangeColumn.IsRangeColumn(gridViewColumn))
{
var minWidth = RangeColumn.GetRangeMinWidth(gridViewColumn);
var maxWidth = RangeColumn.GetRangeMaxWidth(gridViewColumn);
if (minWidth.HasValue && maxWidth.HasValue && (minWidth > maxWidth))
{
return; // invalid case
}
if (_resizeCursor is null)
{
_resizeCursor = thumb.Cursor; // save the resize cursor
}
if (minWidth.HasValue && gridViewColumn.Width <= minWidth.Value)
{
thumb.SetCurrentValue(FrameworkElement.CursorProperty, Cursors.No);
}
else if (maxWidth.HasValue && gridViewColumn.Width >= maxWidth.Value)
{
thumb.SetCurrentValue(FrameworkElement.CursorProperty, Cursors.No);
}
else
{
thumb.SetCurrentValue(FrameworkElement.CursorProperty, _resizeCursor); // between valid min/max
}
}
}
private void ThumbPreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
if (!(sender is Thumb thumb))
{
return;
}
var gridViewColumn = FindParentColumn(thumb);
// suppress column resizing for proportional, fixed and range fill columns
if (ProportionalColumn.IsProportionalColumn(gridViewColumn) || FixedColumn.IsFixedColumn(gridViewColumn) || IsFillColumn(gridViewColumn))
{
e.Handled = true;
}
}
private void RegisterEvents(DependencyObject?start)
{
if (start is null)
{
return;
}
for (var i = 0; i < VisualTreeHelper.GetChildrenCount(start); i++)
{
var childVisual = VisualTreeHelper.GetChild(start, i) as Visual;
if (childVisual is Thumb)
{
var gridViewColumn = FindParentColumn(childVisual);
if (gridViewColumn != null)
{
if (childVisual is Thumb thumb)
{
if (ProportionalColumn.IsProportionalColumn(gridViewColumn) || FixedColumn.IsFixedColumn(gridViewColumn) || IsFillColumn(gridViewColumn))
{
thumb.SetCurrentValue(UIElement.IsHitTestVisibleProperty, false);
}
else
{
thumb.PreviewMouseMove += new MouseEventHandler(ThumbPreviewMouseMove);
thumb.PreviewMouseLeftButtonDown += new MouseButtonEventHandler(ThumbPreviewMouseLeftButtonDown);
DependencyPropertyDescriptor.FromProperty(
GridViewColumn.WidthProperty,
typeof(GridViewColumn)).AddValueChanged(gridViewColumn, GridColumnWidthChanged);
}
}
}
}
else if (childVisual is GridViewColumnHeader columnHeader)
{
columnHeader.SizeChanged += new SizeChangedEventHandler(GridColumnHeaderSizeChanged);
}
else if (_scrollViewer is null && childVisual is ScrollViewer scrollViewer)
{
_scrollViewer = scrollViewer;
_scrollViewer.ScrollChanged += new ScrollChangedEventHandler(ScrollViewerScrollChanged);
// assume we do the regulation of the horizontal scrollbar
_scrollViewer.SetCurrentValue(ScrollViewer.HorizontalScrollBarVisibilityProperty, ScrollBarVisibility.Hidden);
_scrollViewer.SetCurrentValue(ScrollViewer.VerticalScrollBarVisibilityProperty, VerticalScrollBarVisibility);
}
RegisterEvents(childVisual);
}
}
private void UnregisterEvents(DependencyObject?start)
{
if (start is null)
{
return;
}
for (var i = 0; i < VisualTreeHelper.GetChildrenCount(start); i++)
{
var childVisual = VisualTreeHelper.GetChild(start, i) as Visual;
if (childVisual is Thumb)
{
var gridViewColumn = FindParentColumn(childVisual);
if (gridViewColumn != null)
{
if (childVisual is Thumb thumb)
{
if (ProportionalColumn.IsProportionalColumn(gridViewColumn) || FixedColumn.IsFixedColumn(gridViewColumn) || IsFillColumn(gridViewColumn))
{
thumb.SetCurrentValue(UIElement.IsHitTestVisibleProperty, true);
}
else
{
thumb.PreviewMouseMove -= new MouseEventHandler(ThumbPreviewMouseMove);
thumb.PreviewMouseLeftButtonDown -= new MouseButtonEventHandler(ThumbPreviewMouseLeftButtonDown);
DependencyPropertyDescriptor.FromProperty(
GridViewColumn.WidthProperty,
typeof(GridViewColumn)).RemoveValueChanged(gridViewColumn, GridColumnWidthChanged);
}
}
}
}
else if (childVisual is GridViewColumnHeader columnHeader)
{
columnHeader.SizeChanged -= new SizeChangedEventHandler(GridColumnHeaderSizeChanged);
}
else if (_scrollViewer is null && childVisual is ScrollViewer scrollViewer)
{
_scrollViewer = scrollViewer;
_scrollViewer.ScrollChanged -= new ScrollChangedEventHandler(ScrollViewerScrollChanged);
}
UnregisterEvents(childVisual);
}
}