public void MyOnPreviewMouseLeftButtonDown(MouseButtonEventArgs e)
{
//Console.WriteLine(string.Format("Left click on {0}, handled {1}.", this.Name, e.Handled));
// super call
base.OnPreviewMouseLeftButtonDown(e);
// check if we clicked inside the color circle
var clickPosition = e.GetPosition(colorCircle);
var circleCenter = new Point(colorCircle.Width / 2, colorCircle.Height / 2);
var circleRadius = colorCircle.Width / 2;
var clickDistanceFromCenter = (clickPosition - circleCenter).Length;
var nearEnough = clickDistanceFromCenter < circleRadius;
if (!nearEnough)
return;
// save current values of rotation and scale
var arrow = (Arrow)DataContext;
var position = e.GetPosition(this);
arrowDraggingData = new ArrowDraggingData(
arrow.Angle, arrow.NormalizedLength,
position,
new Point(ActualWidth / 2, ActualHeight / 2));
IsDragging = true;
// tell the event has been handled
e.Handled = true;
}
private void stopDrag()
{
arrowDraggingData = null;
IsDragging = false;
}
public void MyOnPreviewMouseMove(MouseEventArgs e)
{
// super call
base.OnPreviewMouseMove(e);
// check if the mouse button is still down
if (e.LeftButton == MouseButtonState.Released)
stopDrag();
// check if we are in a dragging operation
if (arrowDraggingData == null)
return;
// compute data for the new position
var newArrowDraggingData = new ArrowDraggingData(
0, 0, // actually not used
e.GetPosition(this), new Point(ActualWidth / 2, ActualHeight / 2));
// compute the new angle
var deltaAngle = newArrowDraggingData.ClickAngle - arrowDraggingData.ClickAngle;
var newAngle = arrowDraggingData.StartingAngle + deltaAngle;
// compute the new normalized length
var deltaMouseNormalizedLength = newArrowDraggingData.ClickNormalizedLength - arrowDraggingData.ClickNormalizedLength;
var newNormalizedLength = arrowDraggingData.StartingNormalizedLength + deltaMouseNormalizedLength;
// apply changes to model
var arrow = (Arrow)DataContext;
arrow.Angle = newAngle;
arrow.NormalizedLength = newNormalizedLength;
// we handled the event
e.Handled = true;
}
