private void _zoomStart(UIPinchGestureRecognizer recognizer)
{
if (embeddingView == null || previewLayer == null)
{
return;
}
var allTouchesOnPreviewLayer = true;
var numTouch = recognizer.NumberOfTouches;
for (int i = 0; i < numTouch; i++)
{
var location = recognizer.LocationOfTouch(i, embeddingView);
var convertedTouch = previewLayer.ConvertPointFromLayer(location, previewLayer.SuperLayer);
if (!previewLayer.Contains(convertedTouch))
{
allTouchesOnPreviewLayer = false;
break;
}
}
if (allTouchesOnPreviewLayer)
{
_zoom(recognizer.Scale);
}
}