[C#] 取得picture box在zoom模式時的正確圖片座標

private Point unScale(Point scaledP)
{
 if (picturebox1.SizeMode != PictureBoxSizeMode.Zoom) //only zoom mode need to scale
  return scaledP;
 Point unscaled_p = new Point();
 // image and container dimensions
 int w_i = picturebox1.Image.Width;
 int h_i = picturebox1.Image.Height;
 int w_c = picturebox1.Width;
 int h_c = picturebox1.Height;
 float imageRatio = w_i / (float)h_i; // image W:H ratio
 float containerRatio = w_c / (float)h_c; // container W:H ratio

 if (imageRatio >= containerRatio)
 {
  // horizontal image
  float scaleFactor = w_c / (float)w_i;
  float scaledHeight = h_i * scaleFactor;
  // calculate gap between top of container and top of image
  float filler = Math.Abs(h_c - scaledHeight) / 2;
  unscaled_p.X = (int)(scaledP.X / scaleFactor);
  unscaled_p.Y = (int)((scaledP.Y - filler) / scaleFactor);
 }
 else
 {
  // vertical image
  float scaleFactor = h_c / (float)h_i;
  float scaledWidth = w_i * scaleFactor;
  float filler = Math.Abs(w_c - scaledWidth) / 2;
  unscaled_p.X = (int)((scaledP.X - filler) / scaleFactor);
  unscaled_p.Y = (int)(scaledP.Y / scaleFactor);
 }
 return unscaled_p;
}