免費開源Blazor線上Ico轉換工具

Dotnet9個人部落格發表於2022-02-25
Blazor

行文目錄

    1. 功能效果演示
    1. 實現說明
    • 2.1 其他圖片上傳
    • 2.2 核心程式碼：其他圖片轉Ico
    • 2.3 轉換後的Ico檔案下載
    1. 總結

1. 功能效果演示

倉庫地址：IcoTool

線上演示地址：https://tool.dotnet9.com/ico

演示下檔案上傳、轉換結果：

image

通過該工具及程式碼，能瞭解到：

  1. 使用Blazor怎麼上傳檔案到伺服器(Blazor Server)。
  2. 怎麼從伺服器下載檔案。
  3. 如何將png等圖片轉換為Ico圖片。

下面對該工具的實現程式碼做個簡單說明，不太清楚的可以留言交流。

2. 實現說明

通過該工具，能瞭解到：

  1. 使用Blazor怎麼上傳檔案到伺服器(Blazor Server)。
  2. 怎麼從伺服器下載檔案。
  3. 如何將png等圖片轉換為Ico圖片。

下面對該工具的實現程式碼做個簡單說明，不太清楚的可以留言交流。

2.1 其他圖片上傳

使用的MASA Blazor上傳元件MFileInput，看下面的程式碼，就一個上傳元件加上傳時檔案儲存操作，程式碼檔案：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 核心程式碼：其他圖片轉Ico

參考程式碼：https://gist.github.com/darkfall/1656050

因為使用到Bitmap，vs會提示只支援Windows平臺，目前工具程式也部署在Windows Server 2019伺服器上，如果有其他轉換程式碼，支援跨平臺歡迎技術討論，下面給出我使用的其他圖片轉Ico的程式碼，程式碼路徑在：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
}

簡單的單元測試還是要有的，程式碼見：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);
    }
}

頁面呼叫Ico轉換功能程式碼如下，提供一個觸發轉換的按鈕和執行轉換的方法，程式碼檔案：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 轉換後的Ico檔案下載

檔案轉換成功後，怎麼提供下載呢？

起初想使用一個<a href="/files/xxx.ico" target="_blank">xxx.ico</a>標籤提供瀏覽下載的，但動態生成的圖片無法訪問，不知道什麼原因，只能暫時採用一個折衷的方式，有朋友有好的想法歡迎留言。

目前採用的是提供按鈕下載，下面是封裝的js下載方法，來自微軟的文件：ASP.NET Core Blazor file downloads

我把JS程式碼放_Layout.cshtml：

<script>
    // 省略部分程式碼

    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>

頁面下載時使用以下程式碼，使用到JS互操作(什麼是JS互操作？可以參考我轉載的這篇文章瞭解首頁.NETBlazorBlazor Server
(14/30)大家一起學Blazor：JavaScript interop(互操作))，程式碼放：IcoTool.razor


@inject IJSRuntime JS

// 省略n多程式碼

@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. 總結

  1. Blazor元件庫使用的MASA Blazor，很美觀大方的Material Design設計風格。
  2. Ico轉換，使用到了System.Drawing.Common包的Bitmap，.NET 6開始不支援跨平臺，提示只支援Windows平臺。
  3. 本工具使用7.0.100-preview.1開發、編譯、上線，使用.NET 6的同學，請放心使用，可以無縫升級。

Dotnet9工具箱會不斷新增新的免費、開源、線上工具，歡迎star支援，有什麼需求我會考慮加上，倉庫地址：Dotnet9.Tools，可提交issue、網站留言、微信公眾號(dotnet9)聯絡等等。

本工具原始碼：IcoTool

介紹文章：Blazor線上Ico轉換工具

線上演示地址：https://tool.dotnet9.com/ico

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