/// <summary>
/// Zoom feature implementation.
/// </summary>
private void DropZone_MouseWheel(object sender, MouseWheelEventArgs args)
{
if (!this.HasEffectiveKeyboardFocus)
{
return;
}
var scaleTransform = (ScaleTransform)((TransformGroup)VideoControl.RenderTransform).Children.First(tr => tr is ScaleTransform);
var zoom = args.Delta > 0 ? ZoomRatio : -ZoomRatio;
var relativePointCache = VideoControl.TranslatePoint(new Point(0, 0), DropZone);
var translateTransform = (TranslateTransform)((TransformGroup)VideoControl.RenderTransform).Children.First(tr => tr is TranslateTransform);
var height = VideoControl.ActualHeight * scaleTransform.ScaleY;
var width = VideoControl.ActualWidth * scaleTransform.ScaleX;
if (width + zoom < this.ActualWidth && height + zoom < this.ActualHeight && zoom < 0)
{
translateTransform.X = 0;
translateTransform.Y = 0;
return;
}
if (scaleTransform.ScaleX + zoom > ZoomMinTreshold && scaleTransform.ScaleX + zoom < ZoomMaxTreshold &&
scaleTransform.ScaleY + zoom > ZoomMinTreshold && scaleTransform.ScaleY + zoom < ZoomMaxTreshold)
{
scaleTransform.ScaleX += zoom;
scaleTransform.ScaleY += zoom;
}
if (zoom > 0)
{
return;
}
height = VideoControl.ActualHeight * scaleTransform.ScaleY;
width = VideoControl.ActualWidth * scaleTransform.ScaleX;
var relativePoint = VideoControl.TransformToVisual(DropZone).Transform(new Point(0, 0));
var mathRelativePositionY = Math.Round(relativePoint.Y - relativePointCache.Y, MidpointRounding.AwayFromZero);
var mathRelativePositionX = Math.Round(relativePoint.X - relativePointCache.X, MidpointRounding.AwayFromZero);
var mathTranslateY = Math.Round(translateTransform.Y, MidpointRounding.AwayFromZero);
var mathTranslateX = Math.Round(translateTransform.X, MidpointRounding.AwayFromZero);
if (height < DropZone.ActualHeight)
{
translateTransform.Y = 0;
}
else if (relativePoint.Y > 0)
{
translateTransform.Y = mathTranslateY - mathRelativePositionY;
}
else if (relativePoint.Y + height < DropZone.ActualHeight)
{
translateTransform.Y = mathTranslateY + mathRelativePositionY;
}
if (width < DropZone.ActualWidth)
{
translateTransform.X = 0;
}
else if (relativePoint.X > 0)
{
translateTransform.X = mathTranslateX - mathRelativePositionX;
}
else if (relativePoint.X + width < DropZone.ActualWidth)
{
translateTransform.X = mathTranslateX + mathRelativePositionX;
}
}
