3rdpartylibs/fastreports.wpf/FastReport.BaseExt/Export/Pdf/PDFExportPictures.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Drawing;
using FastReport.Utils;
using System.Drawing.Imaging;
using System.Security.Cryptography;
#if PRINT_HOUSE
using System.IO.Compression;
#endif
using System.Windows.Forms;

namespace FastReport.Export.Pdf
{
    public partial class PDFExport : ExportBase
    {
        #region AddPictureObject, AddPictureObjectRAW

        private void AddPictureObject(ReportComponentBase obj, bool drawBorder, int quality, StringBuilder sb_in)
        {
            if (obj is PictureObject)
            {
                PictureObject pict = (obj as PictureObject);
                if (pict.Transparency != 0 && pict.Transparency != 1)
                {
                    // Transparency scale for PDF
                    pict.Transparency /= 1.5f;
                }
                if (PdfCompliance == PdfStandard.PdfA_1a)
                {
                    pict.Transparency = 0;
                }
                if ((obj as PictureObject).Fill is TextureFill)
                {
                    TextureFill fill = (obj as PictureObject).Fill as TextureFill;
                    Brush textureBrush = fill.CreateBrush(new RectangleF(0, 0, obj.Width, obj.Height));
                    using (Bitmap image = new Bitmap((int)obj.Width, (int)obj.Height, PixelFormat.Format32bppArgb))
                    using (Graphics g = Graphics.FromImage(image))
                    {
                        g.FillRectangle(textureBrush, new RectangleF(0, 0, obj.Width, obj.Height));
                        PictureObject fillPic = new PictureObject();
                        fillPic.Image = image;
                        fillPic.Left = obj.AbsLeft;
                        fillPic.Top = obj.AbsTop;
                        fillPic.Width = obj.Width;
                        fillPic.Height = obj.Height;
                        AddPictureObject(fillPic, false, quality, sb_in, false);
                    }
                }
                else
                {
                    //ToDo: add other fills
                }
            }

            if (!isPdfX())
                AddAnnot(obj);

            AddPictureObject(obj, drawBorder, quality, sb_in, false);
        }

        private long AddPictureObject(ReportComponentBase obj, bool drawBorder, int quality, StringBuilder sb_in, bool keepZeroPosition)
        {
            long imageIndex = -1;
            if (ImagesOriginalResolution)
                if ((imageIndex = AddPictureObjectRAW(obj as PictureObject, drawBorder, sb_in)) >= 0)
                    return imageIndex;

            float width = obj.Width;// > paperWidth + obj.AbsLeft ? paperWidth + obj.AbsLeft : obj.Width;
            float height = obj.Height;// > paperHeight + obj.AbsTop ? paperHeight + obj.AbsTop : obj.Height;

            if (width < 0.5f || height < 0.5f)
                return -1;

            Border oldBorder = obj.Border.Clone();
            obj.Border.Lines = BorderLines.None;

            float printZoom = printOptimized ? 4 : 1;

            int bitmapWidth = (int)Math.Round(width * printZoom);
            int bitmapHeight = (int)Math.Round(height * printZoom);

            // check for max bitmap object size
            {
                // 2GB (max .net object size) / 4 (Format32bppArgb is 4 bytes)
                // see http://stackoverflow.com/a/29175905/4667434
                const ulong maxPixels = 536870912;

                if ((ulong)bitmapWidth * (ulong)bitmapHeight >= maxPixels)
                {
                    bitmapWidth = (int)width;
                    bitmapHeight = (int)height;
                }

                if ((ulong)bitmapWidth * (ulong)bitmapHeight >= maxPixels)
                {
                    return -1;
                }
            }

            using (Bitmap image = new Bitmap(bitmapWidth, bitmapHeight, PixelFormat.Format32bppArgb))
            using (Graphics g = Graphics.FromImage(image))
            {
                g.TranslateTransform(-obj.AbsLeft * printZoom, -obj.AbsTop * printZoom);
                g.Clear(transparentImages
#if !SKIA
                        && (PdfCompliance != PdfStandard.PdfA_1a)
#endif
                         ? Color.Transparent : Color.White);

                // if PDF/X-3 or PDF/A-1a then render image with page
                // because they don't support transparency
                if (PdfCompliance == PdfStandard.PdfX_3 &&
                    obj.Page != null &&
                    obj.Page is ReportPage)
                {
                    ReportPage page = obj.Page as ReportPage;
                    float leftMargin = (int)Math.Round(page.LeftMargin * Units.Millimeters * printZoom);
                    float topMargin = (int)Math.Round(page.TopMargin * Units.Millimeters * printZoom);
                    g.TranslateTransform(-leftMargin, -topMargin);

                    obj.Page.Draw(new FRPaintEventArgs(g, printZoom, printZoom, Report.GraphicCache));
                }
                else
                {
                    obj.Draw(new FRPaintEventArgs(g, printZoom, printZoom, Report.GraphicCache));
                }

                imageIndex = AppendPDFImage(image, quality);
            }

            if (imageIndex == -1)
                return imageIndex;

            AddImageToList(imageIndex);

            StringBuilder sb = new StringBuilder(256);
            sb.AppendLine("q");

            if (obj is PictureObject)
                GetPDFFillTransparent(Color.FromArgb((byte)((1 - (obj as PictureObject).Transparency) * 255f), Color.Black), sb);

            float bWidth = width == 0 ? 1 : width * PDF_DIVIDER;
            float bHeight = height == 0 ? 1 : height * PDF_DIVIDER;

            sb.Append(FloatToString(bWidth)).Append(" 0 0 ");
            sb.Append(FloatToString(bHeight)).Append(" ");
            if (keepZeroPosition)
            {
                sb.Append("0 0");
            }
            else
            {
                sb.Append(FloatToString(GetLeft(obj.AbsLeft))).Append(" ");
                sb.Append(FloatToString(GetTop(obj.AbsTop + height)));
            }

            sb.AppendLine(" cm");
            sb.Append("/Im").Append(imageIndex).AppendLine(" Do");
            sb.AppendLine("Q");
            sb_in.Append(sb);
            obj.Border = oldBorder;

            if (drawBorder)
                DrawPDFBorder(obj.Border, obj.AbsLeft, obj.AbsTop, width, height, sb_in);
            return imageIndex;
        }

        private long AppendPDFImage(Bitmap image, int quality)
        {
            int[] rawBitmap = GetRawBitmap(image);
            string hash = CalculateHash(rawBitmap);
            long imageIndex = GetImageIndexByHash(hash);

            if (imageIndex == -1)
            {
                using (MemoryStream imageStream = new MemoryStream())
                using (MemoryStream maskStream = GetMask(rawBitmap))
                {
                    if (JpegCompression)
                    {
                        ExportUtils.SaveJpeg(image, imageStream, quality);
                        imageStream.Position = 0;
                        imageIndex = WriteImage_Jpeg(imageStream, maskStream, image.Width, image.Height);
                    }
                    else
                    {
                        // grayscale is set to false
                        // because it's already grayscaled
                        // if "Grayscale" option is set to true
                        WritePixelColors(rawBitmap, imageStream, false);
                        imageStream.Position = 0;
                        using (MemoryStream imageDeflateStream = new MemoryStream())
                        {
                            ExportUtils.ZLibDeflate(imageStream, imageDeflateStream);
                            imageDeflateStream.Position = 0;
                            imageIndex = WriteImage_Deflate(imageDeflateStream, maskStream, image.Width, image.Height);
                        }
                    }
                }

                SetImageIndexByHash(hash, imageIndex);
            }
            return imageIndex;
        }

        private long AddPictureObjectRAW(PictureObject obj, bool drawBorder, StringBuilder sb_in)
        {
            if (obj == null)
                return -1;

            if (obj.Width < 0.5f || obj.Height < 0.5f)
                return -1;

            obj.ForceLoadImage();

            if (obj.Image == null)
                return -1;

            int rawWidth = obj.Image.Width;
            int rawHeight = obj.Image.Height;

            long imageIndex = -1;

            // convert to PixelFormat.Format32bppArgb
            using (Bitmap image = new Bitmap(obj.Image.Width, obj.Image.Height, PixelFormat.Format32bppArgb))
            using (Graphics g = Graphics.FromImage(image))
            {
                g.DrawImage(obj.Image, new Rectangle(0, 0, obj.Image.Width, obj.Image.Height));

                int[] rawBitmap = GetRawBitmap(image);

                // for hash we also use Width, Height and SizeMode
                // because there are different masks for them
                string hash = CalculateHash(rawBitmap) +
                    "|" + obj.SizeMode.ToString() +
                    "|" + obj.Width.ToString() +
                    "|" + obj.Height.ToString();

                imageIndex = GetImageIndexByHash(hash);

                if (imageIndex == -1)
                {
                    using (MemoryStream colorsRawStream = new MemoryStream())
                    {
                        bool hasMask = false;
                        byte[] mask = null;

#if PRINT_HOUSE
                        if (ColorSpace == PdfColorSpace.CMYK)
                            using (Stream rawCMYKA = FindRawCMYKA(obj))
                                if (rawCMYKA != null && rawCMYKA.Length > 0)
                                {
                                    if (rawCMYKA.Length != rawWidth * rawHeight * 5)
                                        throw new Exception(ExportUtils.StringFormat("Incorrect CMYKA data length (length={0}, width={1}, height={2})", rawCMYKA.Length, rawWidth, rawHeight));

                                    mask = new byte[rawWidth * rawHeight];

                                    const int cmykaSamples = 5;
                                    for (int i = 0, mask_i = 0; i < rawCMYKA.Length; i += cmykaSamples, mask_i++)
                                    {
                                        colorsRawStream.WriteByte((byte)rawCMYKA.ReadByte()); // C
                                        colorsRawStream.WriteByte((byte)rawCMYKA.ReadByte()); // M
                                        colorsRawStream.WriteByte((byte)rawCMYKA.ReadByte()); // Y
                                        colorsRawStream.WriteByte((byte)rawCMYKA.ReadByte()); // K
                                        mask[mask_i] = (byte)rawCMYKA.ReadByte(); // A
                                        if (!hasMask && mask[mask_i] != 0xff)
                                            hasMask = true;
                                    }
                                }
#endif


                        if (mask == null)
                        {
                            mask = new byte[rawWidth * rawHeight];

                            for (int i = 0, mask_i = 0; i < rawBitmap.Length; i++, mask_i++)
                            {
                                mask[mask_i] = (byte)(((UInt32)rawBitmap[i]) >> 24);
                                if (!hasMask && mask[mask_i] != 0xff)
                                    hasMask = true;
                            }

                            WritePixelColors(rawBitmap, colorsRawStream, obj.Grayscale);
                        }

                        // emulate PictureBoxSizeMode.Normal behavior
                        if (obj.SizeMode == PictureBoxSizeMode.Normal)
                        {
                            for (int x = 0; x < rawWidth; x++)
                                for (int y = 0; y < rawHeight; y++)
                                    if (x >= obj.Width || y >= obj.Height)
                                    {
                                        mask[y * rawWidth + x] = 0;
                                        if (!hasMask)
                                            hasMask = true;
                                    }
                        }
                        // emulate PictureBoxSizeMode.CenterImage behavior
                        else if (obj.SizeMode == PictureBoxSizeMode.CenterImage)
                        {
                            if (obj.Width < rawWidth || obj.Height < rawHeight)
                            {
                                float imgWidth = rawWidth;
                                float imgHeight = rawHeight;
                                float imgLeft = obj.AbsLeft + obj.Width / 2 - imgWidth / 2;
                                float imgTop = obj.AbsTop + obj.Height / 2 - imgHeight / 2;

                                float borderWidth = obj.Width;
                                float borderHeight = obj.Height;
                                float borderLeft = obj.AbsLeft;
                                float borderTop = obj.AbsTop;

                                RectangleF imgRect = new RectangleF
                                (
                                    imgLeft,
                                    imgTop,
                                    imgWidth,
                                    imgHeight
                                );

                                RectangleF borderRect = new RectangleF
                                (
                                    borderLeft,
                                    borderTop,
                                    borderWidth,
                                    borderHeight
                                );

                                if (imgRect.IntersectsWith(borderRect))
                                {
                                    // todo: need better check
                                    // on high zoom borders don't match image area

                                    RectangleF intersect = RectangleF.Intersect(imgRect, borderRect);
                                    intersect.Width = (int)intersect.Width;
                                    intersect.Height = (int)intersect.Height;

                                    for (int x = 0; x < rawWidth; x++)
                                        for (int y = 0; y < rawHeight; y++)
                                        {
                                            int _x = (x + (int)imgRect.X);
                                            int _y = (y + (int)imgRect.Y);

                                            if (!intersect.Contains(_x, _y))
                                            {
                                                mask[y * rawWidth + x] = 0;
                                                if (!hasMask)
                                                    hasMask = true;
                                            }
                                        }
                                }
                            }
                        }

                        using (MemoryStream colorsDeflateStream = new MemoryStream())
                        {
                            colorsRawStream.Position = 0;
                            ExportUtils.ZLibDeflate(colorsRawStream, colorsDeflateStream);
                            colorsDeflateStream.Position = 0;

                            using (MemoryStream maskStream = hasMask ? new MemoryStream(mask) : null)
                            {
                                imageIndex = WriteImage_Deflate(colorsDeflateStream, maskStream, rawWidth, rawHeight);
                            }
                        }
                    }

                    SetImageIndexByHash(hash, imageIndex);
                }
            }

            if (imageIndex == -1)
                return -1;

            AddImageToList(imageIndex);

            StringBuilder sb = new StringBuilder(256);
            sb.AppendLine("q");

            GetPDFFillTransparent(Color.FromArgb((byte)((1 - obj.Transparency) * 255f), Color.Black), sb);

            RectangleF area = CalculateArea(obj, rawWidth, rawHeight);
            //double angle = (Math.PI / 180) * -obj.Angle; // get angle in radians

            // PLEASE NOTE
            // to avoid distortion, matrices should be in this order:
            // 1. translate
            // 2. rotate
            // 3. scale.

            // translate matrix
            sb.AppendLine(ExportUtils.StringFormat("1 0 0 1 {0} {1} cm",
                FloatToString(area.Left),
                FloatToString(area.Top)
            ));

            // we don't yet support rotation
            // rotate matrix
            /*sb.AppendLine(ExportUtils.StringFormat("{0} {1} {2} {3} 0 0 cm",
                FloatToString(Math.Cos(angle)),
                FloatToString(Math.Sin(angle)),
                FloatToString(-Math.Sin(angle)),
                FloatToString(Math.Cos(angle))
            ));*/

            // scale matrix
            sb.AppendLine(ExportUtils.StringFormat("{0} 0 0 {1} 0 0 cm",
                FloatToString(area.Width),
                FloatToString(area.Height)
            ));

            // draw image
            sb.AppendLine(ExportUtils.StringFormat("/Im{0} Do",
                imageIndex.ToString()
            ));

            sb.AppendLine("Q");
            sb_in.Append(sb);

            if (drawBorder)
                DrawPDFBorder(obj.Border, obj.AbsLeft, obj.AbsTop, /*width*/obj.Width, /*height*/obj.Height, sb_in);

            return imageIndex;
        }

        #endregion

        #region WriteMask, WriteImage_Deflate, WriteImage_Jpeg

        private long WriteMask(MemoryStream mask, int width, int height)
        {
            long maskIndex = -1;

            if (mask == null || mask.Length == 0)
                return maskIndex;

            maskIndex = UpdateXRef();

            WriteLn(pdf, ObjNumber(maskIndex));
            WriteLn(pdf, "<<");
            WriteLn(pdf, "/Type /XObject");
            WriteLn(pdf, "/Subtype /Image");
            WriteLn(pdf, "/Width " + width.ToString());
            WriteLn(pdf, "/Height " + height.ToString());
            WriteLn(pdf, "/ColorSpace /DeviceGray/Matte[ 0 0 0]");
            WriteLn(pdf, "/BitsPerComponent 8");
            WriteLn(pdf, "/Interpolate false");

            WritePDFStream(pdf, mask, maskIndex, compressed, encrypted, false, true);

            return maskIndex;
        }

        private long WriteImage_Deflate(MemoryStream image, MemoryStream mask, int width, int height)
        {
            long imageIndex = -1;

            if (image == null || image.Length == 0)
                return imageIndex;

            long maskIndex = WriteMask(mask, width, height);
            imageIndex = UpdateXRef();

            WriteLn(pdf, ObjNumber(imageIndex));
            WriteLn(pdf, "<<");
            WriteLn(pdf, "/Type /XObject");
            WriteLn(pdf, "/Subtype /Image");
            WriteLn(pdf, "/Width " + width.ToString());
            WriteLn(pdf, "/Height " + height.ToString());
            WriteLn(pdf, "/Predictor 10");

            if (ColorSpace == PdfColorSpace.RGB)
                WriteLn(pdf, "/ColorSpace /DeviceRGB");
            else if (ColorSpace == PdfColorSpace.CMYK)
                WriteLn(pdf, "/ColorSpace /DeviceCMYK");

            WriteLn(pdf, "/BitsPerComponent 8");
            WriteLn(pdf, "/Filter /FlateDecode");
            WriteLn(pdf, "/Interpolate false");

            if (maskIndex != -1)
                WriteLn(pdf, "/SMask " + ObjNumberRef(maskIndex));

            WritePDFStream(pdf, image, imageIndex, false, encrypted, false, true);

            return imageIndex;
        }

        private long WriteImage_Jpeg(MemoryStream image, MemoryStream mask, int width, int height)
        {
            long imageIndex = -1;

            if (image == null || image.Length == 0)
                return imageIndex;

            long maskIndex = WriteMask(mask, width, height);
            imageIndex = UpdateXRef();

            WriteLn(pdf, ObjNumber(imageIndex));
            WriteLn(pdf, "<<");
            WriteLn(pdf, "/Type /XObject");
            WriteLn(pdf, "/Subtype /Image");
            WriteLn(pdf, "/Width " + width.ToString());
            WriteLn(pdf, "/Height " + height.ToString());
            WriteLn(pdf, "/ColorSpace /DeviceRGB");
            WriteLn(pdf, "/BitsPerComponent 8");
            WriteLn(pdf, "/Filter /DCTDecode");
            WriteLn(pdf, "/Interpolate false");

            if (maskIndex != -1)
                WriteLn(pdf, "/SMask " + ObjNumberRef(maskIndex));

            WritePDFStream(pdf, image, imageIndex, false, encrypted, false, true);

            return imageIndex;
        }

        #endregion

        #region Other methods

        private int[] GetRawBitmap(Bitmap image)
        {
            int raw_size = image.Width * image.Height;
            int[] raw_picture = new int[raw_size];
            BitmapData bmpdata = image.LockBits(new Rectangle(0, 0, image.Width, image.Height), ImageLockMode.ReadOnly, image.PixelFormat);
            IntPtr ptr = bmpdata.Scan0;
            System.Runtime.InteropServices.Marshal.Copy(ptr, raw_picture, 0, raw_size);
            image.UnlockBits(bmpdata);
            return raw_picture;
        }

        private string CalculateHash(int[] raw_picture)
        {
            byte[] raw_picture_byte = new byte[raw_picture.Length * sizeof(int)];
            Buffer.BlockCopy(raw_picture, 0, raw_picture_byte, 0, raw_picture_byte.Length);
            byte[] hash = new Murmur3().ComputeHash(raw_picture_byte);
            return Convert.ToBase64String(hash);
        }

        /// <summary>
        /// Calculates mask for <see cref="PixelFormat.Format32bppArgb"/> image.
        /// </summary>
        private MemoryStream GetMask(int[] raw_pixels)
        {
            if (!transparentImages)
                return null;

            if (PdfCompliance == PdfStandard.PdfX_3)
                return null;

            MemoryStream mask_stream = new MemoryStream(raw_pixels.Length);

            bool alpha = false;
            byte pixel;

            for (int i = 0; i < raw_pixels.Length; i++) unchecked
                {
                    pixel = (byte)(((UInt32)raw_pixels[i]) >> 24);
                    if (!alpha && pixel != 0xff)
                        alpha = true;
                    mask_stream.WriteByte(pixel);
                }

            if (alpha)
            {
                mask_stream.Position = 0;
                return mask_stream;
            }

            return null;
        }

        /// <summary>
        /// Calculates image bounds according to <see cref="PictureBoxSizeMode"/>.
        /// </summary>
        RectangleF CalculateArea(PictureObject obj, int raw_width, int raw_height)
        {
            float width = obj.Width;
            float height = obj.Height;

            float pdfLeft = GetLeft(obj.AbsLeft);
            float pdfTop = GetTop(obj.AbsTop + height);

            switch (obj.SizeMode)
            {
                case PictureBoxSizeMode.Normal:
                    {
                        width = raw_width;
                        height = raw_height;

                        pdfTop = GetTop(obj.AbsTop + height);
                    }
                    break;
                case PictureBoxSizeMode.Zoom:
                    {
                        float w = obj.Width / raw_width;
                        float h = obj.Height / raw_height;

                        if (w > h)
                        {
                            width = raw_width * h;
                            height = raw_height * h;
                            pdfLeft = GetLeft(obj.AbsLeft + obj.Width / 2 - width / 2);
                        }
                        else
                        {
                            width = raw_width * w;
                            height = raw_height * w;
                            pdfTop = GetTop(obj.AbsTop + height + obj.Height / 2 - height / 2);
                        }
                    }
                    break;
                case PictureBoxSizeMode.CenterImage:
                    {
                        width = raw_width;
                        height = raw_height;

                        pdfLeft = GetLeft(obj.AbsLeft + obj.Width / 2 - width / 2);
                        pdfTop = GetTop(obj.AbsTop + height + obj.Height / 2 - height / 2);
                    }
                    break;
            }

            float pdfWidth = width * PDF_DIVIDER;
            float pdfHeight = height * PDF_DIVIDER;

            return new RectangleF(pdfLeft, pdfTop, pdfWidth, pdfHeight);
        }

        /// <summary>
        /// Writes pixels' colors without alpha to stream according to CMYK or RGB color space.
        /// Pixels should be in the <see cref="PixelFormat.Format32bppArgb"/> format.
        /// </summary>
        void WritePixelColors(int[] pixels, Stream stream, bool grayscale)
        {
            for (int i = 0; i < pixels.Length; i++)
            {
                byte blue = (byte)(pixels[i] & 0xFF);
                byte green = (byte)((pixels[i] >> 8) & 0xFF);
                byte red = (byte)((pixels[i] >> 16) & 0xFF);

                if (ColorSpace == PdfColorSpace.RGB)
                {
                    if (grayscale)
                    {
                        byte gray = (byte)(red * 0.299 + green * 0.587 + blue * 0.114);
                        stream.WriteByte(gray);
                        stream.WriteByte(gray);
                        stream.WriteByte(gray);
                    }
                    else
                    {
                        stream.WriteByte(red);
                        stream.WriteByte(green);
                        stream.WriteByte(blue);
                    }
                }
                else if (ColorSpace == PdfColorSpace.CMYK)
                {
                    if (grayscale)
                    {
                        byte gray = (byte)(255 - (red * 0.299 + green * 0.587 + blue * 0.114));
                        stream.WriteByte(0);
                        stream.WriteByte(0);
                        stream.WriteByte(0);
                        stream.WriteByte(gray);
                    }
                    else
                    {
                        float fred = ((float)red) / 255f;
                        float fgreen = ((float)green) / 255f;
                        float fblue = ((float)blue) / 255f;

                        float fblack = 1 - Math.Max(fred, Math.Max(fgreen, fblue));
                        float fcyan = (1 - fred - fblack) / (1 - fblack);
                        float fmagenta = (1 - fgreen - fblack) / (1 - fblack);
                        float fyellow = (1 - fblue - fblack) / (1 - fblack);

                        byte black = (byte)(fblack * 255);
                        byte cyan = (byte)(fcyan * 255);
                        byte magenta = (byte)(fmagenta * 255);
                        byte yellow = (byte)(fyellow * 255);

                        stream.WriteByte(cyan);
                        stream.WriteByte(magenta);
                        stream.WriteByte(yellow);
                        stream.WriteByte(black);
                    }
                }
            }
        }

#if PRINT_HOUSE
        /// <summary>
        /// This method attempts to find a raw CMYKA data
        /// which should be stored in a separate file
        /// alongside of the image location.
        /// </summary>
        Stream FindRawCMYKA(PictureObject picObj)
        {
            Stream stream = null;

            if (picObj != null && picObj.ImageLocation != null && picObj.ImageLocation.Trim() != "")
            {
                string file = picObj.ImageLocation + ".cmyka";
                string file_gz = picObj.ImageLocation + ".cmyka.gz";

                if (File.Exists(file))
                {
                    stream = File.OpenRead(file);
                }
                else if (File.Exists(file_gz))
                {
                    //stream = new GZipStream(File.OpenRead(file_gz), CompressionMode.Decompress);

                    using (FileStream reader = File.OpenRead(file_gz))
                    using (GZipStream zip = new GZipStream(reader, CompressionMode.Decompress, true))
                    {
                        stream = new MemoryStream();
                        zip.CopyTo(stream);
                        stream.Position = 0;
                    }
                }
            }

            return stream;
        }
#endif

        #endregion

        #region Picture list and hashes

        private List<long> picResList;
        private Dictionary<string, long> hashList;

        private long GetImageIndexByHash(string hash)
        {
            long result = -1;
            if (hashList.TryGetValue(hash, out result))
                return result;
            else
                return -1;
        }

        private void SetImageIndexByHash(string hash, long index)
        {
            hashList.Add(hash, index);
        }

        private void AddImageToList(long imageIndex)
        {
            if (picResList.IndexOf(imageIndex) == -1)
                picResList.Add(imageIndex);
        }

        #endregion
    }
}