private void ApplyZoomToChildren(ZoomEventArgs e)
{
foreach (UIElement cur in this.Children)
{
cur.RenderTransform = e.NewScale;
Canvas.SetLeft(cur, e.ContentOffset.X);
Canvas.SetTop(cur, e.ContentOffset.Y);
}
}
protected override void OnMouseWheel(MouseWheelEventArgs e)
{
e.Handled = true;
//Calculate new scaling factor
if ((_wheelOffset == MinWheelOffset && e.Delta < 0) || (_wheelOffset == MaxWheelOffset && e.Delta > 0))
{
return;
}
_wheelOffset += e.Delta / 120;
if (_wheelOffset < MinWheelOffset)
{
_wheelOffset = MinWheelOffset;
}
else if (_wheelOffset > MaxWheelOffset)
{
_wheelOffset = MaxWheelOffset;
}
double oldScale = _curScaleTransform.ScaleX;
double newScale = Math.Log(1 + ((_wheelOffset) / 10d)) * 2d;
//Calculate current viewing window onto the content
Point topLeftContentSpace = TranslatePoint(new Point(0, 0), Children[0]);
Point bottomRightContentSpace = TranslatePoint(new Point(ActualWidth, ActualHeight), Children[0]);
Rect curView = new Rect
{
Location = topLeftContentSpace,
Size = new Size(bottomRightContentSpace.X - topLeftContentSpace.X, bottomRightContentSpace.Y - topLeftContentSpace.Y)
};
//Mouse position as a fraction of the view size
Point viewSpaceMousePos = e.GetPosition(this);
Point relZoomPoint = new Point
{
X = viewSpaceMousePos.X / this.ActualWidth,
Y = viewSpaceMousePos.Y / this.ActualHeight
};
//Calculate new viewing window
Rect newView = ZoomView(curView, oldScale, newScale, relZoomPoint);
//Calculate new content offset based on the new view
Point newOffset = new Point(-newView.X * newScale, -newView.Y * newScale);
//Calculate new viewing window scale
ScaleTransform newScaleTransform = new ScaleTransform
{
ScaleX = newScale,
ScaleY = newScale
};
var zoomEvent = new ZoomEventArgs(e, _curScaleTransform, newScaleTransform, newOffset);
Zoom?.Invoke(this, zoomEvent);
ApplyZoomToChildren(zoomEvent);
_curScaleTransform = newScaleTransform;
}