如何使用C#grapics类绘制图像

我想使用C#图形类，使用提供的X、Y坐标和缩放值来绘制图像。我试过这样做，但没有给我正确的结果。

Stream originalStream = ImageHelper.UrlToImageStream(list1.FirstOrDefault().OriginalImageUrl);
var bmp = new Bitmap(bmp.Width, bmp.Height);
int width = 0;
int height = 0;
var img = new Bitmap(bmp,
                    (int)(bmp.Size.Width / zoomLevel),
                    (int)(bmp.Size.Height / zoomLevel));
var g = Graphics.FromImage(bmp);
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.DrawString(Text, SystemFonts.DefaultFont, Brushes.White, new Rectangle((int)CurrentTextX, (int)CurrentTextY, bmp.Width, bmp.Height));
g.DrawImage(img, new Rectangle((int)CurrentX, (int)CurrentY, bmp.Width, bmp.Height));
var stream = new System.IO.MemoryStream();
img.Save(stream, ImageFormat.Jpeg);

private void mapPaint(object sender, PaintEventArgs e)
{
    Graphics g = e.Graphics;
    Image img = Image.FromFile(@"C:'img.png");
    g.DrawImage(img, new Rectangle(10,10,img.Width/zoomLevel, img.Height/zoomLevel);
}