免费开源Blazor在线Ico转换工具

行文目录

1. 功能效果演示
1. 实现说明
- 2.1 其他图片上传
- 2.2 核心代码：其他图片转Ico
- 2.3 转换后的Ico文件下载
1. 总结

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"

            ShowSize

            OnChange="@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 streams

        var 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, 0

        iconWriter.Write((byte)0);

        iconWriter.Write((byte)0);

        // 2-3 image type, 1 = icon, 2 = cursor

        iconWriter.Write((short)1);

        // 4-5 number of images

        iconWriter.Write((short)sizes.Length);

        offset += 6 + 16 * sizes.Length;

        for (var i = 0; i < sizes.Length; i++)

        {

            // image entry 1

            // 0 image width

            iconWriter.Write((byte)sizes[i]);

            // 1 image height

            iconWriter.Write((byte)sizes[i]);

            // 2 number of colors

            iconWriter.Write((byte)0);

            // 3 reserved

            iconWriter.Write((byte)0);

            // 4-5 color planes

            iconWriter.Write((short)0);

            // 6-7 bits per pixel

            iconWriter.Write((short)32);

            // 8-11 size of image data

            iconWriter.Write((int)imageStreams[i].Length);

            // 12-15 offset of image data

            iconWriter.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 file

            iconWriter.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

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