asp.net生成高清晰缩略图-CSDN博客

本文链接：https://blog.csdn.net/chenxueyong7345/article/details/83481225

#region 图像处理
    /// <summary>
    /// 生成缩略图
    /// </summary>
    /// <param name="M_OriginalImagePath">源图路径（物理路径）</param>
    /// <param name="M_ThumbnailPath">缩略图路径（物理路径）</param>
    /// <param name="M_Width">缩略图宽度</param>
    /// <param name="M_Height">缩略图高度</param>
    public static void MakeThumbnail(string M_OriginalImagePath, string M_ThumbnailPath, int M_Width, int M_Height)
    {
        System.Drawing.Image originalImage = System.Drawing.Image.FromFile(M_OriginalImagePath);
        int towidth = 0;
        int toheight = 0;
        if (originalImage.Width >= M_Width && originalImage.Height <= M_Height)
        {
            towidth = M_Width;
            toheight = originalImage.Height;
        }
        if (originalImage.Width <= M_Width && originalImage.Height >= M_Height)
        {
            towidth = originalImage.Width;
            toheight = M_Height;
        }
        if (originalImage.Width >= M_Width && originalImage.Height >= M_Height)
        {
            towidth = M_Width;
            toheight = M_Height;
        }
        if (originalImage.Width <= M_Width && originalImage.Height <= M_Height)
        {
            towidth = originalImage.Width;
            toheight = originalImage.Height;
        }
        int x = 0;//左上角的x坐标
        int y = 0;//左上角的y坐标
         //新建一个bmp图片
        System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
        //新建一个画板
        Graphics g = System.Drawing.Graphics.FromImage(bitmap);
        //设置高质量插值法
        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
        //设置高质量,低速度呈现平滑程度
        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
        //清空画布并以透明背景色填充
        g.Clear(Color.Transparent);
        //在指定位置并且按指定大小绘制原图片的指定部分
        g.DrawImage(originalImage, x, y, towidth, toheight);
        try
        {
            //以jpg格式保存缩略图
            bitmap.Save(M_ThumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
        }
        catch (System.Exception e)
        {
            throw e;
        }
        finally
        {
            originalImage.Dispose();
            bitmap.Dispose();
            g.Dispose();
        }
    }
    #endregion