using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Pcb.Common.Utilities
{
    public class ImageUtility
    {
        public static void CompressionAndSaveImage(System.Web.HttpPostedFile file, string savePath, int width = 640, int height = 360, int Level = 80, bool CompressionAlways = false)
        {
            if (Level < 0 || Level > 100)
                throw new Exception("压缩率必须在0-100之间");
            // Get a bitmap.
            if (file.ContentLength <= 30 * 1024 && !CompressionAlways)
            {
                file.SaveAs(savePath);
                return;
            }

            Image bmpOld = Image.FromStream(file.InputStream);
            Bitmap img = new Bitmap(bmpOld);
            Bitmap bmp2 = null;
            bmpOld.Dispose();

            if (file.ContentLength > 100 * 1024 || CompressionAlways)
            {

                int srcWidth = img.Width;
                int srcHeight = img.Height;

                int thumbWidth = width;
                int thumbHeight = height;

                ImageWH iwh = GetImageNewWH(srcWidth, srcHeight, width, height);
                thumbWidth = iwh.width;
                thumbHeight = iwh.height;

                if (thumbWidth > width || thumbHeight > height)
                {
                    iwh = GetImageNewWH(thumbWidth, thumbHeight, width, height);
                    thumbWidth = iwh.width;
                    thumbHeight = iwh.height;
                }

                Bitmap bmp = new Bitmap(thumbWidth, thumbHeight);

                //从Bitmap创建一个System.Drawing.Graphics对象，用来绘制高质量的缩小图。
                System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);

                //设置 System.Drawing.Graphics对象的SmoothingMode属性为HighQuality
                gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                //gr.SmoothingMode = SmoothingMode.None;

                ////下面这个也设成高质量
                gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                //gr.CompositingQuality = CompositingQuality.HighSpeed;

                ////下面这个设成High
                gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                //gr.InterpolationMode = InterpolationMode.Low;

                gr.Clear(System.Drawing.Color.Transparent);

                img.SetResolution(72, 72);

                //把原始图像绘制成上面所设置宽高的缩小图
                System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, thumbWidth, thumbHeight);
                gr.DrawImage(img, rectDestination, 0, 0, srcWidth, srcHeight, GraphicsUnit.Pixel);
                bmp2 = new Bitmap(bmp);
                bmp.Dispose();
                gr.Dispose();
            }
            else
                bmp2 = img;

            ImageCodecInfo Encoder = null;
            Encoder = GetEncoder(ImageFormat.Jpeg);
            // Create an Encoder object based on the GUID
            // for the Quality parameter category.
            System.Drawing.Imaging.Encoder myEncoder =
                System.Drawing.Imaging.Encoder.Quality;

            // Create an EncoderParameters object.
            // An EncoderParameters object has an array of EncoderParameter
            // objects. In this case, there is only one
            // EncoderParameter object in the array.
            EncoderParameters EncoderParameters = new EncoderParameters(1);

            EncoderParameter EncoderParameter = new EncoderParameter(myEncoder, Level);
            EncoderParameters.Param[0] = EncoderParameter;
            bmp2.Save(savePath, Encoder, EncoderParameters);

            bmp2.Dispose();
            img.Dispose();
        }


        private static ImageCodecInfo GetEncoder(ImageFormat format)
        {
            ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
            foreach (ImageCodecInfo codec in codecs)
            {
                if (codec.FormatID == format.Guid)
                    return codec;
            }
            return null;
        }

        private static ImageWH GetImageNewWH(int srcWidth, int srcHeight, int width, int height)
        {
            ImageWH iwh = new ImageWH();

            if (srcWidth > width && srcHeight > height)
            {
                if (srcWidth > srcHeight)
                {
                    double heightFloat = Convert.ToDouble(srcHeight) / Convert.ToDouble(srcWidth);
                    heightFloat = heightFloat * width;
                    iwh.height = Convert.ToInt32(heightFloat);
                    iwh.width = width;
                }
                else
                {
                    double widthFloat = Convert.ToDouble(srcWidth) / Convert.ToDouble(srcHeight);
                    widthFloat = widthFloat * height;
                    iwh.width = Convert.ToInt32(widthFloat);
                    iwh.height = height;
                }
            }
            else if (srcWidth > width)
            {
                double heightFloat = Convert.ToDouble(srcHeight) / Convert.ToDouble(srcWidth);
                heightFloat = heightFloat * width;
                iwh.height = Convert.ToInt32(heightFloat);
                iwh.width = width;
            }
            else if (srcHeight > height)
            {
                double widthFloat = Convert.ToDouble(srcWidth) / Convert.ToDouble(srcHeight);
                widthFloat = widthFloat * height;
                iwh.width = Convert.ToInt32(widthFloat);
                iwh.height = height;
            }
            else
            {
                iwh.width = srcWidth;
                iwh.height = srcHeight;
            }

            return iwh;
        }

        private class ImageWH
        {
            public int width { get; set; }

            public int height { get; set; }
        }
    }
}