C# 圖片處理，添加文字、添加圖片、圓形切割。處理後圖片不失真，不壓縮圖片 【 程序示例】

圖片處理程序示例，實現功能點有

1、遠程圖片轉換Image對象

2、在圖片上添加文字

3、在圖片上添加圖片

4、將圖片進行橢圓形（圓形）切割

5、微軟程序處理圖片失真。不少人發現圖片用微軟程序重繪之後，即時什麼也不做，圖片質量也會壓縮，微軟的Image.Save方法，不設置壓縮質量，是默認保存到圖片壓縮質量爲75，所以保存的圖片質量偏低。

代碼如下，此處是asp.net中的一般處理程序

public void ProcessRequest(HttpContext context)
{
    //產品圖片
    string ProducePicUrl = "http://img.xxx.com/group1/M00/36/B8/cnHoeV3pxMWANofjAACQFhMkSE0601_s.jpg";
    Image img = GetStreamByUrl(ProducePicUrl);
    Graphics grap = Graphics.FromImage(img);
    //設置輸出圖片質量
    grap.CompositingQuality = CompositingQuality.HighQuality;
    grap.SmoothingMode = SmoothingMode.HighQuality;
    grap.InterpolationMode = InterpolationMode.HighQualityBicubic;
    //在圖片上添加文字
    grap.DrawString("中國山東找藍翔", new Font("宋體", 20, FontStyle.Bold), Brushes.Blue, new PointF(29, 29));
    //企業logo圖片
    string ComPicUrl = "http://img.xxx.com/group1/M00/2D/62/cnHoeVsfISeAEPqhAAA5bjwdSWo698_s.jpg";
    Image Comimg = GetStreamByUrl(ComPicUrl);
    //圖片圓形切割
    Comimg = CutEllipse(Comimg, new Rectangle(0, 0, Comimg.Width, Comimg.Height), new Size(100, 100));
    //圖片上添加圖片
    grap.DrawImage(Comimg, new Rectangle(img.Width - 100, 0, 100, 100),
                        0, 0, Comimg.Width, Comimg.Height, GraphicsUnit.Pixel);
    EncoderParameters ps = new EncoderParameters(1);
    EncoderParameter p = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
    ps.Param[0] = p;
    ImageCodecInfo imgcodec = GetCodecInfo("image/jpeg");
    img.Save(context.Response.OutputStream, imgcodec, ps);
    //img.Save(context.Response.OutputStream, ImageFormat.Jpeg);常用圖片保存，質量被壓縮
    context.Response.ContentType = "image/jpeg";
}
/// <summary>
/// 圖片剪切成橢圓形
/// </summary>
/// <param name="img">原始Image對象</param>
/// <param name="rec">被切割圖片的矩形範圍</param>
/// <param name="size">橢圓的尺寸</param>
/// <returns></returns>
private Image CutEllipse(Image img, Rectangle rec, Size size)
{
    Bitmap bitmap = new Bitmap(size.Width, size.Height);
    using (Graphics g = Graphics.FromImage(bitmap))
    {
        using (TextureBrush br = new TextureBrush(img, System.Drawing.Drawing2D.WrapMode.Clamp, rec))
        {
            br.ScaleTransform(bitmap.Width / (float)rec.Width, bitmap.Height / (float)rec.Height);
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
            g.FillEllipse(br, new Rectangle(Point.Empty, size));
        }
    }
    return bitmap;
}
private ImageCodecInfo GetCodecInfo(string mimeType)
{
    ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
    foreach (ImageCodecInfo ici in CodecInfo)
    {
        if (ici.MimeType == mimeType) return ici;
    }
    return null;
}

/// <summary>
/// 獲取遠程圖片的Image對象
/// </summary>
/// <returns></returns>
public Image GetStreamByUrl(string imgurl)
{
    WebRequest myrequest = WebRequest.Create(imgurl);
    myrequest.Timeout = 3 * 1000;
    WebResponse myresponse = myrequest.GetResponse();
    Stream imgstream = myresponse.GetResponseStream();
    Image img = Image.FromStream(imgstream);
    myrequest.Abort();
    myresponse.Close();
    return img;
}

 

最終效果：右側圓形區域是企業Logo

參考資料：https://blog.csdn.net/chinacsharper/article/details/50854852