protected virtual void OnBeginDrag(ChessmanPreviewDragEventArgs e)
{
var parent = Parent as Checkerboard;
var canvas = parent.Canvas;
parent.Children.Remove(this);
Width = parent.CellSize;
Height = parent.CellSize;
canvas.Children.Add(this);
}
public Chessman()
{
bool isMove = false;
bool leftClick = false;
bool enabled = false;
bool captureMouse = false;
Point start = new Point();
Checkerboard parent = null;
Canvas canvas = null;
MouseLeftButtonDown += (sender, e) => {
if (!(captureMouse = Freedom))
{
return;
}
parent = VisualTreeHelper.GetParent(this) as Checkerboard;
if (parent == null)
{
return;
}
canvas = parent.Canvas;
if (canvas == null)
{
return;
}
PreviewMouseDown += HookMouseLeftButton;
PreviewMouseUp += HookMouseLeftButton;
if (captureMouse)
{
CaptureMouse();
}
start = e.GetPosition(canvas);
enabled = true;
leftClick = true;
e.Handled = true;
};
MouseMove += (sender, e) => {
if (!enabled)
{
return;
}
var curr = e.GetPosition(canvas);
if (Freedom && (isMove || Math.Abs(curr.X - start.X) > 4 || Math.Abs(curr.Y - start.Y) > 4))
{
var oldColumn = (int)GetValue(Checkerboard.ColumnProperty);
var oldRow = (int)GetValue(Checkerboard.RowProperty);
ChessmanPreviewDragEventArgs eventArgs;
if (!isMove)
{
// begin drag
isMove = true;
eventArgs = new ChessmanPreviewDragEventArgs(BeginDragEvent, this, parent, oldColumn, oldRow)
{
StartPointRelativeToCanvas = start,
PointRelativeToCanvas = curr
};
RaiseEvent(eventArgs);
if (eventArgs.Cancel)
{
enabled = false;
return;
}
OnBeginDrag(eventArgs);
}
// drag
eventArgs = new ChessmanPreviewDragEventArgs(DragEvent, this, parent, oldColumn, oldRow)
{
StartPointRelativeToCanvas = start,
PointRelativeToCanvas = curr
};
RaiseEvent(eventArgs);
OnDrag(eventArgs);
e.Handled = true;
}
};
MouseLeftButtonUp += (sender, e) => {
if (!enabled)
{
return;
}
enabled = false;
if (isMove)
{
// end drag
isMove = false;
bool hitSuccess = false;
ChessmanDragEventArgs eventArgs = null;
var oldColumn = (int)GetValue(Checkerboard.ColumnProperty);
var oldRow = (int)GetValue(Checkerboard.RowProperty);
VisualTreeHelper.HitTest(canvas,
d => d is Checkerboard ? HitTestFilterBehavior.ContinueSkipChildren : HitTestFilterBehavior.ContinueSkipSelf,
r => {
if (r.VisualHit is Checkerboard checkerboard)
{
var curr = e.GetPosition(checkerboard);
var columns = checkerboard.Columns;
var rows = checkerboard.Rows;
var cellSize = checkerboard.CellSize;
var newColumn = (int)(curr.X / cellSize);
var newRow = (int)(curr.Y / cellSize);
if (newColumn >= 0 && newColumn < columns && newRow >= 0 && newRow < rows)
{
eventArgs = new ChessmanDragEventArgs(PreviewEndDragEvent, this, parent, oldColumn, oldRow, checkerboard, newColumn, newRow);
RaiseEvent(eventArgs);
if (!eventArgs.Cancel)
{
hitSuccess = true;
eventArgs = new ChessmanDragEventArgs(EndDragEvent, this, parent, oldColumn, oldRow, eventArgs.NewCheckerboard, eventArgs.NewColumn, eventArgs.NewRow);
OnEndDrag(eventArgs);
RaiseEvent(eventArgs);
}
else
{
System.Diagnostics.Debug.Print("cancel");
}
}
}
return(HitTestResultBehavior.Stop);
}, new PointHitTestParameters(e.GetPosition(canvas)));
if (!hitSuccess)
{
if (eventArgs != null)
{
eventArgs = new ChessmanDragEventArgs(CancelDragEvent, this, parent, oldColumn, oldRow, eventArgs.NewCheckerboard, eventArgs.NewColumn, eventArgs.NewRow);
}
else
{
eventArgs = new ChessmanDragEventArgs(CancelDragEvent, this, parent, oldColumn, oldRow, null, 0, 0);
}
OnCancelDrag(eventArgs);
RaiseEvent(eventArgs);
}
}
else
{
if (leftClick)
{
// click
leftClick = false;
RaiseEvent(new RoutedEventArgs(LeftClickEvent, this));
}
}
if (captureMouse)
{
ReleaseMouseCapture();
}
PreviewMouseDown -= HookMouseLeftButton;
PreviewMouseUp -= HookMouseLeftButton;
e.Handled = true;
};
bool rightClick = false;
MouseRightButtonDown += delegate {
rightClick = true;
};
MouseLeave += delegate {
rightClick = false;
leftClick = false;
};
MouseRightButtonUp += delegate {
if (rightClick)
{
rightClick = false;
RaiseEvent(new RoutedEventArgs(RightClickEvent, this));
}
};
Loaded += delegate {
if (VisualTreeHelper.GetParent(this) is Checkerboard checkerboard)
{
CellSize = checkerboard.CellSize;
}
};
}
protected virtual void OnDrag(ChessmanPreviewDragEventArgs e)
{
Canvas.SetLeft(this, e.PointRelativeToCanvas.X - Width / 2);
Canvas.SetTop(this, e.PointRelativeToCanvas.Y - Height / 2);
}