ImageGlass.ImageBox.GetSourceImageRegion C# (CSharp) Method

        public virtual RectangleF GetSourceImageRegion()
        {
            RectangleF region;

            if (!ViewSize.IsEmpty)
            {
                if (SizeMode != ImageBoxSizeMode.Stretch)
                {
                    float sourceLeft;
                    float sourceTop;
                    float sourceWidth;
                    float sourceHeight;
                    Rectangle viewPort;

                    viewPort = GetImageViewPort();
                    sourceLeft = (float)(-AutoScrollPosition.X / ZoomFactor);
                    sourceTop = (float)(-AutoScrollPosition.Y / ZoomFactor);
                    sourceWidth = (float)(viewPort.Width / ZoomFactor);
                    sourceHeight = (float)(viewPort.Height / ZoomFactor);

                    region = new RectangleF(sourceLeft, sourceTop, sourceWidth, sourceHeight);
                }
                else
                {
                    region = new RectangleF(PointF.Empty, ViewSize);
                }
            }
            else
            {
                region = RectangleF.Empty;
            }

            return region;
        }