免费开源Blazor在线Ico转换工具

1. 功能效果演示

仓库地址：IcoTool

在线演示地址：https://tool.dotnet9.com/ico

演示下文件上传、转换结果：

通过该工具及代码，能了解到：

使用Blazor怎么上传文件到服务器(Blazor Server)。
怎么从服务器下载文件。
如何将png等图片转换为Ico图片。

下面对该工具的实现代码做个简单说明，不太清楚的可以留言交流。

2. 实现说明

通过该工具，能了解到：

使用Blazor怎么上传文件到服务器(Blazor Server)。
怎么从服务器下载文件。
如何将png等图片转换为Ico图片。

下面对该工具的实现代码做个简单说明，不太清楚的可以留言交流。

2.1 其他图片上传

使用的MASA Blazor上传组件MFileInput，看下面的代码，就一个上传组件加上传时文件保存操作，代码文件：IcoTool.razor

<MFileInput TValue="IBrowserFile"Placeholder="@T("IcoToolMFileInputPlaceholder")"Rules="_rules"ShowSizeOnChange="@LoadFile"Accept="image/png, image/jpeg, image/jpg, image/bmp"Label="@T("IcoToolMFileInputLabel")">
</MFileInput>@code {private bool _loading;private string _sourceFilePath = "";[Inject] public I18n I18N { get; set; } = default!;[Inject] public IJSRuntime Js { get; set; } = default!;protected override async Task OnInitializedAsync(){_rules.Add(value => (value==null|| value.Size < 2 * 1024 * 1024 )? true : T("IcoToolFileSizeLimitMessage"));await base.OnInitializedAsync();}private async Task LoadFile(IBrowserFile? e){if (e == null){_destFilePath = _sourceFilePath = string.Empty;return;}_destFilePath = string.Empty;if (!string.IsNullOrWhiteSpace(_sourceFilePath) && File.Exists(_sourceFilePath)) File.Delete(_sourceFilePath);var saveImageDir = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "wwwroot", ImageDirName);if (!Directory.Exists(saveImageDir)) Directory.CreateDirectory(saveImageDir);_sourceFilePath = Path.Combine(saveImageDir, DateTime.UtcNow.ToString("yyyyMMddHHmmssfff"));await using var fs = new FileStream(_sourceFilePath, FileMode.Create);await e.OpenReadStream().CopyToAsync(fs);}
}

2.2 核心代码：其他图片转Ico

参考代码：https://gist.github.com/darkfall/1656050

因为使用到Bitmap，vs会提示只支持Windows平台，目前工具程序也部署在Windows Server 2019服务器上，如果有其他转换代码，支持跨平台欢迎技术讨论，下面给出我使用的其他图片转Ico的代码，代码路径在：ImagingHelper.cs

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;namespace Dotnet9.Tools.Images;/// <summary>
///     Adapted from this gist: https://gist.github.com/darkfall/1656050
///     Provides helper methods for imaging
/// </summary>
public static class ImagingHelper
{public const string FileheadBmp = "6677";public const string FileheadJpg = "255216";public const string FileheadPng = "13780";public const string FileheadGif = "7173";private static readonly Dictionary<ImageType, string> ImageTypeHead = new(){{ ImageType.Bmp, FileheadBmp },{ ImageType.Jpg, FileheadJpg },{ ImageType.Png, FileheadPng },{ ImageType.Gif, FileheadGif }};public static bool IsPicture(string filePath, out string fileHead){fileHead = string.Empty;try{var fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);var reader = new BinaryReader(fs);var fileClass = $"{reader.ReadByte().ToString()}{reader.ReadByte().ToString()}";reader.Close();fs.Close();if (fileClass is not (FileheadBmp or FileheadJpg or FileheadPng or FileheadGif))return false;fileHead = fileClass;return true;}catch{return false;}}public static bool IsPictureType(string filePath, ImageType imageType){var isPicture = IsPicture(filePath, out var fileHead);if (!isPicture) return false;return ImageTypeHead[imageType] == fileHead;}/// <summary>///     Converts a PNG image to a icon (ico) with all the sizes windows likes/// </summary>/// <param name="inputBitmap">The input bitmap</param>/// <param name="output">The output stream</param>/// <returns>Wether or not the icon was succesfully generated</returns>public static bool ConvertToIcon(Bitmap inputBitmap, Stream output){var sizes = new[] { 256, 48, 32, 16 };// Generate bitmaps for all the sizes and toss them in streamsvar imageStreams = new List<MemoryStream>();foreach (var size in sizes){var newBitmap = ResizeImage(inputBitmap, size, size);var memoryStream = new MemoryStream();newBitmap.Save(memoryStream, ImageFormat.Png);imageStreams.Add(memoryStream);}var iconWriter = new BinaryWriter(output);var offset = 0;// 0-1 reserved, 0iconWriter.Write((byte)0);iconWriter.Write((byte)0);// 2-3 image type, 1 = icon, 2 = cursoriconWriter.Write((short)1);// 4-5 number of imagesiconWriter.Write((short)sizes.Length);offset += 6 + 16 * sizes.Length;for (var i = 0; i < sizes.Length; i++){// image entry 1// 0 image widthiconWriter.Write((byte)sizes[i]);// 1 image heighticonWriter.Write((byte)sizes[i]);// 2 number of colorsiconWriter.Write((byte)0);// 3 reservediconWriter.Write((byte)0);// 4-5 color planesiconWriter.Write((short)0);// 6-7 bits per pixeliconWriter.Write((short)32);// 8-11 size of image dataiconWriter.Write((int)imageStreams[i].Length);// 12-15 offset of image dataiconWriter.Write(offset);offset += (int)imageStreams[i].Length;}for (var i = 0; i < sizes.Length; i++){// write image data// png data must contain the whole png data fileiconWriter.Write(imageStreams[i].ToArray());imageStreams[i].Close();}iconWriter.Flush();return true;}/// <summary>///     Converts a PNG image to a icon (ico)/// </summary>/// <param name="input">The input stream</param>/// <param name="output">The output stream</param/// <returns>Wether or not the icon was succesfully generated</returns>public static bool ConvertToIcon(Stream input, Stream output){var inputBitmap = (Bitmap)Image.FromStream(input);return ConvertToIcon(inputBitmap, output);}/// <summary>///     Converts a PNG image to a icon (ico)/// </summary>/// <param name="inputPath">The input path</param>/// <param name="outputPath">The output path</param>/// <returns>Wether or not the icon was succesfully generated</returns>public static bool ConvertToIcon(string inputPath, string outputPath){using var inputStream = new FileStream(inputPath, FileMode.Open);using var outputStream = new FileStream(outputPath, FileMode.OpenOrCreate);return ConvertToIcon(inputStream, outputStream);}/// <summary>///     Converts an image to a icon (ico)/// </summary>/// <param name="inputImage">The input image</param>/// <param name="outputPath">The output path</param>/// <returns>Wether or not the icon was succesfully generated</returns>public static bool ConvertToIcon(Image inputImage, string outputPath){using var outputStream = new FileStream(outputPath, FileMode.OpenOrCreate);return ConvertToIcon(new Bitmap(inputImage), outputStream);}/// <summary>///     Resize the image to the specified width and height.///     Found on stackoverflow: https://stackoverflow.com/questions/1922040/resize-an-image-c-sharp/// </summary>/// <param name="image">The image to resize.</param>/// <param name="width">The width to resize to.</param>/// <param name="height">The height to resize to.</param>/// <returns>The resized image.</returns>public static Bitmap ResizeImage(Image image, int width, int height){var destRect = new Rectangle(0, 0, width, height);var destImage = new Bitmap(width, height);destImage.SetResolution(image.HorizontalResolution, image.VerticalResolution);using var graphics = Graphics.FromImage(destImage);graphics.CompositingMode = CompositingMode.SourceCopy;graphics.CompositingQuality = CompositingQuality.HighQuality;graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;graphics.SmoothingMode = SmoothingMode.HighQuality;graphics.PixelOffsetMode = PixelOffsetMode.HighQuality;using var wrapMode = new ImageAttributes();wrapMode.SetWrapMode(WrapMode.TileFlipXY);graphics.DrawImage(image, destRect, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel, wrapMode);return destImage;}
}public enum ImageType
{Bmp,Jpg,Png,Gif
}

简单的单元测试还是要有的，代码见：ImageHelperTests.cs

using Dotnet9.Tools.Images;namespace Dotnet9.Tools.Tests.Images;public class ImageHelperTests
{[Fact]public void IsPicture(){var testFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "TestFiles", "logo.png");Assert.True(File.Exists(testFilePath));var isPicture = ImagingHelper.IsPicture(testFilePath, out var typename);Assert.True(isPicture);}[Fact]public void IsNotPicture(){var testFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "TestFiles", "test.txt");Assert.True(File.Exists(testFilePath));var isPicture = ImagingHelper.IsPicture(testFilePath, out var typename);Assert.False(isPicture);}[Fact]public void IsPngFile(){var testFilePath = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "TestFiles", "logo.png");Assert.True(File.Exists(testFilePath));var isPng = ImagingHelper.IsPictureType(testFilePath, ImageType.Png);Assert.True(isPng);}[Fact]public void ShouldConvertPngToIcon(){var sourcePng = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "TestFiles", "logo.png");var destIco = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "TestFiles", "logo.ico");Assert.True(File.Exists(sourcePng));Assert.False(File.Exists(destIco));ImagingHelper.ConvertToIcon(sourcePng, destIco);Assert.True(File.Exists(destIco));File.Delete(destIco);}
}

页面调用Ico转换功能代码如下，提供一个触发转换的按钮和执行转换的方法，代码文件：IcoTool.razor

@if (!string.IsNullOrWhiteSpace(_sourceFilePath) && File.Exists(_sourceFilePath))
{<MButton class="ma-2 white--text"Loading="_loading"Disabled="_loading"Depressed Color="primary"OnClick="@ConvertToIcon"><LoaderContent><span>@T("IcoToolMButtonLoaderContent")</span></LoaderContent><ChildContent><span>@T("IcoToolMButtonChildContent")</span></ChildContent></MButton>
}@code {private async Task ConvertToIcon(){if (!string.IsNullOrWhiteSpace(_destFilePath) && File.Exists(_destFilePath)){await DownloadIco();return;}_loading = true;if (!string.IsNullOrWhiteSpace(_sourceFilePath) && File.Exists(_sourceFilePath)){_destFilePath = $"{_sourceFilePath}.ico";if (ImagingHelper.ConvertToIcon(_sourceFilePath, _destFilePath)) await DownloadIco();}_loading = false;}
}

2.3 转换后的Ico文件下载

文件转换成功后，怎么提供下载呢？

起初想使用一个<a href="/files/xxx.ico" target="_blank">xxx.ico</a>标签提供浏览下载的，但动态生成的图片无法访问，不知道什么原因，只能暂时采用一个折衷的方式，有朋友有好的想法欢迎留言。

目前采用的是提供按钮下载，下面是封装的js下载方法，来自微软的文档：ASP.NET Core Blazor file downloads

我把JS代码放_Layout.cshtml：

<script>// 省略部分代码async function downloadFileFromStream(fileName, contentStreamReference) {const arrayBuffer = await contentStreamReference.arrayBuffer();const blob = new Blob([arrayBuffer]);const url = URL.createObjectURL(blob);triggerFileDownload(fileName, url);URL.revokeObjectURL(url);}function triggerFileDownload(fileName, url) {const anchorElement = document.createElement('a');anchorElement.href = url;if (fileName) {anchorElement.download = fileName;}anchorElement.click();anchorElement.remove();}
</script>

页面下载时使用以下代码，使用到JS互操作(什么是JS互操作？可以参考我转载的这篇文章了解首页.NETBlazorBlazor Server
(14/30)大家一起学Blazor：JavaScript interop(互操作))，代码放：IcoTool.razor


@inject IJSRuntime JS// 省略n多代码@code {private async Task DownloadIco(){await using var fileStream = new FileStream(_destFilePath, FileMode.Open);using var streamRef = new DotNetStreamReference(fileStream);await Js.InvokeVoidAsync("downloadFileFromStream", Path.GetFileName(_destFilePath), streamRef);}
}

3. 总结

Blazor组件库使用的MASA Blazor，很美观大方的Material Design设计风格。
Ico转换，使用到了System.Drawing.Common包的Bitmap，.NET 6开始不支持跨平台，提示只支持Windows平台。
本工具使用7.0.100-preview.1开发、编译、上线，使用.NET 6的同学，请放心使用，可以无缝升级。

Dotnet9工具箱会不断添加新的免费、开源、在线工具，欢迎star支持，有什么需求我会考虑加上，仓库地址：Dotnet9.Tools，可提交issue、网站留言、微信公众号(dotnet9)联系等等。

本工具源码：IcoTool

介绍文章：Blazor在线Ico转换工具

在线演示地址：https://tool.dotnet9.com/ico