Do not send non animated png images to mod detail banner animatedsource

Knossos.NET/Classes/APNGHelper.cs

@@ -0,0 +1,84 @@
+using System;
+using System.IO;
+using System.Text;
+
+namespace Knossos.NET.Classes
+{
+    /// <summary>
+    /// Helper class to read APNG files.
+    /// </summary>
+    public static class APNGHelper
+    {
+        // PNG signature
+        private static readonly byte[] PngSignature = { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
+
+        /// <summary>
+        ///  Reads a stream to verify if it is a valid APNG file
+        ///  Checks for acTL chuck presence.
+        ///  Doesn't close or disposes the stream.
+        ///  Throws a exception if the stream doesn't contains a png file data
+        /// </summary>
+        /// <param name="pngStream"></param>
+        /// <returns>true if file is apng</returns>
+        /// <exception cref="Exception"></exception>
+        public static bool IsApng(Stream pngStream)
+        {
+            if (pngStream == null || !pngStream.CanRead)
+                throw new ArgumentException("Stream inválido.");
+
+            long originalPos = pngStream.Position;
+
+            try
+            {
+                using (var br = new BinaryReader(pngStream, Encoding.ASCII, leaveOpen: true))
+                {
+                    var sig = br.ReadBytes(8);
+                    if (!BytesEqual(sig, PngSignature))
+                        throw new Exception("Incorrect PNG Signature");
+
+                    // Look for acTL o IEND
+                    while (pngStream.Position < pngStream.Length)
+                    {
+                        var lengthBytes = br.ReadBytes(4);
+                        if (lengthBytes.Length < 4) break;
+                        int length = ReadBigEndianInt(lengthBytes);
+
+                        var chunkType = Encoding.ASCII.GetString(br.ReadBytes(4));
+
+                        if (chunkType == "acTL")
+                        {
+                            return true;
+                        }
+
+                        pngStream.Seek(length + 4, SeekOrigin.Current);
+
+                        if (chunkType == "IEND")
+                            break; 
+                    }
+                }
+                return false;
+            }
+            finally
+            {
+                pngStream.Seek(originalPos, SeekOrigin.Begin);
+            }
+        }
+
+
+        // Helpers
+
+        private static bool BytesEqual(byte[] a, byte[] b)
+        {
+            if (a.Length != b.Length) return false;
+            for (int i = 0; i < a.Length; i++)
+                if (a[i] != b[i]) return false;
+            return true;
+        }
+
+        private static int ReadBigEndianInt(byte[] bytes)
+        {
+            if (BitConverter.IsLittleEndian) Array.Reverse(bytes);
+            return BitConverter.ToInt32(bytes, 0);
+        }
+    }
+}

Knossos.NET/ViewModels/Windows/ModDetailsViewModel.cs

@@ -4,14 +4,14 @@
 using Avalonia.Threading;
 using BBcodes;
 using CommunityToolkit.Mvvm.ComponentModel;
+using Knossos.NET.Classes;
 using Knossos.NET.Models;
 using Knossos.NET.Views;
 using System;
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
-using System.Net.Http;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 using System.Web;
@@ -86,6 +86,8 @@ public partial class ModDetailsViewModel : ViewModelBase
         [ObservableProperty]
         internal string? banner = null;
         [ObservableProperty]
+        internal string? apngBanner = null;
+        [ObservableProperty]
         internal bool forumAvailable = false;
         [ObservableProperty]
         internal bool isInstalled = false;
@@ -281,9 +283,30 @@ private void LoadBanner(int selectedIndex)
                 if (!string.IsNullOrEmpty(modVersions[selectedIndex].banner))
                 {
                     HasBanner = true;
-                    if (System.IO.File.Exists(modVersions[selectedIndex].fullPath + Path.DirectorySeparatorChar + modVersions[selectedIndex].banner))
+                    var bannerLocalPath = modVersions[selectedIndex].fullPath + Path.DirectorySeparatorChar + modVersions[selectedIndex].banner;
+                    if (System.IO.File.Exists(bannerLocalPath))
                     {
-                        Banner = modVersions[selectedIndex].fullPath + Path.DirectorySeparatorChar + modVersions[selectedIndex].banner;
+                        var isApng = false;
+                        using (var stream = new FileStream(bannerLocalPath, FileMode.Open, FileAccess.Read))
+                        {
+                            try
+                            {
+                                isApng = APNGHelper.IsApng(stream);
+
+                            }
+                            catch { /* Not a valid png*/ }
+                        }
+                        Dispatcher.UIThread.Invoke(() =>
+                        {
+                            if (isApng)
+                            {
+                                ApngBanner = bannerLocalPath;
+                            }
+                            else
+                            {
+                                Banner = bannerLocalPath;
+                            }
+                        });
                     }
                     else
                     {
@@ -293,9 +316,30 @@ private void LoadBanner(int selectedIndex)
                             Task.Run(async () =>
                             {
                                 var fs = await KnUtils.GetRemoteResource(url).ConfigureAwait(false);
-                                Dispatcher.UIThread.Invoke(() => { 
-                                        Banner = fs;
-                                });
+                                if (fs != null)
+                                {
+                                    var isApng = false;
+                                    using (var stream = new FileStream(fs, FileMode.Open, FileAccess.Read))
+                                    {
+                                        try
+                                        {
+                                            isApng = APNGHelper.IsApng(stream);
+
+                                        }
+                                        catch { /* Not a valid png*/ }
+                                    }
+                                    Dispatcher.UIThread.Invoke(() =>
+                                    {
+                                        if (isApng)
+                                        {
+                                            ApngBanner = fs;
+                                        }
+                                        else
+                                        {
+                                            Banner = fs;
+                                        }
+                                    });
+                                }
                             }).ConfigureAwait(false);
                         }
                     }

Knossos.NET/Views/Windows/ModDetailsView.axaml

@@ -27,7 +27,7 @@
 	<ScrollViewer Background="{StaticResource BackgroundColorPrimary}">
 	<Grid RowDefinitions="Auto,Auto,*,Auto">
 		<StackPanel Grid.Row="0" Margin="25">
-			<Image Source="{Binding Banner, Converter={StaticResource imageConverter}}" anim:ImageBehavior.AnimatedSource="{Binding Banner}" HorizontalAlignment="Stretch" Height="300" IsVisible="{Binding HasBanner}"></Image>
+			<Image Source="{Binding Banner, Converter={StaticResource imageConverter}}" anim:ImageBehavior.AnimatedSource="{Binding ApngBanner}" HorizontalAlignment="Stretch" Height="300" IsVisible="{Binding HasBanner}"></Image>
 			<Label Content="{Binding Name, Converter={StaticResource escapeUnderscoresConverter}}" FontWeight="Bold" FontSize="24" VerticalContentAlignment="Top" HorizontalContentAlignment="Center" Foreground="White"/>
 
 			<!--Buttons and Mod info-->