void OnImageHandlerScroolViewerScrollChanged(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(ImageHandlerScroolViewer.ViewportWidth / 2,
ImageHandlerScroolViewer.ViewportHeight / 2);
Point centerOfTargetNow =
ImageHandlerScroolViewer.TranslatePoint(centerOfViewport, ImageHandler);
targetBefore = lastCenterPositionOnTarget;
targetNow = centerOfTargetNow;
}
}
else
{
targetBefore = lastMousePositionOnTarget;
targetNow = Mouse.GetPosition(ImageHandler);
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 / ImageHandler.Width;
double multiplicatorY = e.ExtentHeight / ImageHandler.Height;
double newOffsetX = ImageHandlerScroolViewer.HorizontalOffset -
dXInTargetPixels * multiplicatorX;
double newOffsetY = ImageHandlerScroolViewer.VerticalOffset -
dYInTargetPixels * multiplicatorY;
if (double.IsNaN(newOffsetX) || double.IsNaN(newOffsetY))
{
return;
}
ImageHandlerScroolViewer.ScrollToHorizontalOffset(newOffsetX);
ImageHandlerScroolViewer.ScrollToVerticalOffset(newOffsetY);
}
}
}
} //skończone
#endregion
#region Image Handler Events
/// <summary>
/// When user interact with image
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void OnMouseMove(object sender, MouseEventArgs e)
{
if (lastDragPoint.HasValue)
{
Point posNow = e.GetPosition(ImageHandlerScroolViewer);
double dX = posNow.X - lastDragPoint.Value.X;
double dY = posNow.Y - lastDragPoint.Value.Y;
lastDragPoint = posNow;
ImageHandlerScroolViewer.ScrollToHorizontalOffset(ImageHandlerScroolViewer.HorizontalOffset - dX);
ImageHandlerScroolViewer.ScrollToVerticalOffset(ImageHandlerScroolViewer.VerticalOffset - dY);
}
}