//// This code is part of Document Solutions for Imaging demos.// Copyright (c) MESCIUS inc. All rights reserved.//using System;using System.IO;using System.Drawing;using GrapeCity.Documents.Imaging;
namespace DsImagingWeb.Demos{    // This sample loads an existing GIF and modifies its frames.    // Specifically, it applies a color matrix to change the colors,    // and flips the images horizontally.    // The GIF loaded in this sample is the one produced by IndexedGif.    public class UpdateGif    {        public string DefaultMime { get => Common.Util.MimeTypes.GIF; }
        public Stream GenerateImageStream(string targetMime, Size pixelSize, float dpi, bool opaque, string[] sampleParams = null)        {            if (targetMime != Common.Util.MimeTypes.GIF)                throw new Exception("This sample only supports GIF output format.");
            // Matrix to change colors to greenish blues:            var colorMatrix = new ColorMatrix5x4()            {                M11 = 0.2f,                M12 = 0.3f,                M22 = 0.5f            };
            var ms = new MemoryStream();            // Read source GIF, write modified one (change palette and flip and rotate frames):            using (var gr = new GcGifReader(Path.Combine("Resources", "Gifs", "goldfish-indexed.gif")))            using (var gw = new GcGifWriter(ms))            {                var pal = gr.GetGlobalPalette();                // This sample will only work with GIFs that have a global palette:                if (pal == null)                    throw new Exception("Source GIF does not have a global palette.");                // Use color matrix to update the palette:                using (var palBmp = new GcBitmap(pal, pal.Length, 1, true))                    palBmp.ApplyColorMatrix(colorMatrix);
                // Set target palette and other properties:                gw.GlobalPalette = pal;                gw.LogicalScreenWidth = gr.LogicalScreenWidth;                gw.LogicalScreenHeight = gr.LogicalScreenHeight;                gw.PixelAspectRatio = gr.PixelAspectRatio;                gw.AllowAddingTransparentColor = false;                using (var tbmp = new GcBitmap())                    for (int i = 0; i < gr.Frames.Count; i++)                    {                        var frame = gr.Frames[i];                        frame.ToGcBitmap(tbmp, i - 1);
                        // Flip the image horizontally (this will reverse the 'rotation' of the fish):                        using (var bmp = tbmp.FlipRotate(FlipRotateAction.FlipHorizontal))                        {                            // Apply the color matrix and append the frame to the target GIF:                            bmp.ApplyColorMatrix(colorMatrix);                            gw.AppendFrame(bmp, pal, DitheringMethod.NoDithering, 0, 0, GifDisposalMethod.DoNotDispose, frame.DelayTime, false);                        }                    }            }            ms.Seek(0, SeekOrigin.Begin);            return ms;        }    }}