public Canvas(System.Windows.Media.DrawingContext drawingContext, IRenderTarget target, ImageLoader imageLoader)
{
_drawingContext = drawingContext;
_target = target;
_imageLoader = imageLoader;
_transform = new Transform();
_strokeColor = new System.Windows.Media.SolidColorBrush();
_stroke = new System.Windows.Media.Pen(_strokeColor, 1);
_fillColor = new System.Windows.Media.SolidColorBrush();
_fontStyle = FontStyles.Normal;
_fontWeight = FontWeights.Normal;
_fontStretch = FontStretches.Normal;
_groups = new Dictionary <string, Group>();
_activeGroup = new Group(Rect.Empty, new Transform());
}