void OnTerritoryScrollScrollChanged(object sender, ScrollChangedEventArgs e)
{
if (e.ExtentHeightChange != 0 || e.ExtentWidthChange != 0)
{
Point?targetBefore = null;
Point?targetNow = null;
if (!lastMousePositionOnTarget.HasValue)
{
if (lastCenterPositionOnTarget.HasValue)
{
var centerOfViewport = new Point(TerritoryScroll.ViewportWidth / 2,
TerritoryScroll.ViewportHeight / 2);
Point centerOfTargetNow =
TerritoryScroll.TranslatePoint(centerOfViewport, TerritoryCanvas);
targetBefore = lastCenterPositionOnTarget;
targetNow = centerOfTargetNow;
}
}
else
{
targetBefore = lastMousePositionOnTarget;
targetNow = Mouse.GetPosition(TerritoryCanvas);
lastMousePositionOnTarget = null;
}
if (targetBefore.HasValue)
{
double dXInTargetPixels = targetNow.Value.X - targetBefore.Value.X;
double dYInTargetPixels = targetNow.Value.Y - targetBefore.Value.Y;
double multiplicatorX = e.ExtentWidth / TerritoryCanvas.Width;
double multiplicatorY = e.ExtentHeight / TerritoryCanvas.Height;
double newOffsetX = TerritoryScroll.HorizontalOffset -
dXInTargetPixels * multiplicatorX;
double newOffsetY = TerritoryScroll.VerticalOffset -
dYInTargetPixels * multiplicatorY;
if (double.IsNaN(newOffsetX) || double.IsNaN(newOffsetY))
{
return;
}
TerritoryScroll.ScrollToHorizontalOffset(newOffsetX);
TerritoryScroll.ScrollToVerticalOffset(newOffsetY);
}
}
}
void OnMouseMove(object sender, MouseEventArgs e)
{
Point posNow = e.GetPosition(TerritoryScroll);
MouseLocationStatus.Text = posNow.ToString();
if (lastDragPoint.HasValue)
{
if (posNow == lastDragPoint)
{
return;
}
double dX = posNow.X - lastDragPoint.Value.X;
double dY = posNow.Y - lastDragPoint.Value.Y;
TerritoryScroll.ScrollToHorizontalOffset(TerritoryScroll.HorizontalOffset - dX);
TerritoryScroll.ScrollToVerticalOffset(TerritoryScroll.VerticalOffset - dY);
lastDragPoint = posNow;
}
}