vCloud/Common/Vinno.vCloud.Common.Vid2Codec.Standard/VinnoImageEncoder.cs

using SkiaSharp;
using System;
using System.IO;
using Vinno.IUS.Common.Log;


namespace Vinno.vCloud.Common.Vid2.Codec
{
    public class VinnoImageEncoder
    {
        private readonly float _xScale;
        private readonly float _yScale;

        private int _currentIndex;

        public VinnoImageEncoder(float xScale = 1.0f, float yScale = 1.0f)
        {
            _currentIndex = -1;
            _xScale = xScale;
            _yScale = yScale;
        }


        /// <summary>
        /// Convert bitmap to jpeg image bytes.
        /// </summary>
        /// <param name="image"></param>
        /// <param name="compressLevel">The compress level for image, default is 75</param>
        /// <returns></returns>
        private byte[] ImageToBytes(SKBitmap image, long compressLevel = 80)
        {
            try
            {
                var newWidth = (int)(image.Width * _xScale);
                var newHeight = (int)(image.Height * _yScale);
                SKBitmap tempImage = image;
                if (image.Width != newWidth || image.Height != newHeight)
                {
                    tempImage = image.Resize(new SKImageInfo(newWidth, newHeight), SKFilterQuality.None);
                }
                try
                {
                    using (var map = new SKPixmap(new SKImageInfo(tempImage.Width, tempImage.Height, tempImage.ColorType), tempImage.GetPixels()))
                    {
                        using (var stream = new SKDynamicMemoryWStream())
                        {
                            SKPixmap.Encode(stream, map, SKEncodedImageFormat.Jpeg, (int)compressLevel);
                            return stream.CopyToData().ToArray();
                        }
                    }
                }
                catch (Exception exception)
                {
                    throw new Exception($"ImageToBytes error:{exception}");
                }
                finally
                {
                    tempImage.Dispose();
                }
            }
            catch (Exception e)
            {
                Logger.WriteLineError(
                    $"Vinno image encode error image width :{image.Width}, image height :{image.Height}, stack is {e}");
            }

            return new byte[0];
        }


        /// <summary>
        /// Encode a bitmap to VinnoImage.
        /// </summary>
        /// <param name="image">The bitmap to be encoded.</param>
        /// <returns>The VinnoImage</returns>
        public VinnoImage Encode(SKBitmap image)
        {
            _currentIndex++;
            return new VinnoImage(_currentIndex, image.Width, image.Height, ImageToBytes(image));
        }


        /// <summary>
        /// Compress a VinnoImage to a 480p image with 50 quality.
        /// </summary>
        /// <param name="vinnoImage"></param>
        /// <returns></returns>
        public VinnoImage Compress(VinnoImage vinnoImage)
        {
            byte[] compressedData = vinnoImage.ImageData;
            using (var ms = new MemoryStream(compressedData))
            {
                using (var image = SKBitmap.Decode(ms))
                {
                    //Get 480p ratio
                    var ratio = (double)480 / image.Height;
                    if (ratio < 1)
                    {
                        var width = (int)(image.Width * ratio);
                        var height = (int)(image.Height * ratio);
                        SKBitmap tempImage = image;
                        if (image.Width != width || image.Height != height)
                        {
                            tempImage = image.Resize(new SKImageInfo(width, height), SKFilterQuality.High);
                        }
                        try
                        {
                            using (var map = new SKPixmap(new SKImageInfo(tempImage.Width, tempImage.Height, tempImage.ColorType), tempImage.GetPixels()))
                            {
                                using (var stream = new SKDynamicMemoryWStream())
                                {
                                    SKPixmap.Encode(stream, map, SKEncodedImageFormat.Jpeg, 50);
                                    compressedData = stream.CopyToData().ToArray();
                                }
                            }
                        }
                        catch (Exception exception)
                        {
                            throw new Exception($"Compress error:{exception}");
                        }
                        finally
                        {
                            tempImage.Dispose();
                        }
                    }
                }
            }
            var updater = new VinnoImageUpdater(vinnoImage);
            updater.Update(compressedData);
            return vinnoImage;
        }
    }
}