InputFile Component

src/Components/Web.Extensions/src/InputFile/BrowserFile.cs

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+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    internal class BrowserFile : IBrowserFile
+    {
+        internal InputFile Owner { get; set; } = default!;
+
+        public int Id { get; set; }
+
+        public string Name { get; set; } = string.Empty;
+
+        public DateTime LastModified { get; set; }
+
+        public long Size { get; set; }
+
+        public string Type { get; set; } = string.Empty;
+
+        public string? RelativePath { get; set; }
+
+        public Stream OpenReadStream(CancellationToken cancellationToken = default)
+            => Owner.OpenReadStream(this, cancellationToken);
+
+        public Task<IBrowserFile> ToImageFileAsync(string format, int maxWidth, int maxHeight)
+            => Owner.ConvertToImageFileAsync(this, format, maxWidth, maxHeight);
+    }
+}

src/Components/Web.Extensions/src/InputFile/BrowserFileStream.cs

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+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    internal abstract class BrowserFileStream : Stream
+    {
+        private long _position;
+
+        protected BrowserFile File { get; }
+
+        protected BrowserFileStream(BrowserFile file)
+        {
+            File = file;
+        }
+
+        public override bool CanRead => true;
+
+        public override bool CanSeek => false;
+
+        public override bool CanWrite => false;
+
+        public override long Length => File.Size;
+
+        public override long Position
+        {
+            get => _position;
+            set => throw new NotSupportedException();
+        }
+
+        public override void Flush()
+            => throw new NotSupportedException();
+
+        public override int Read(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException("Synchronous reads are not supported.");
+
+        public override long Seek(long offset, SeekOrigin origin)
+            => throw new NotSupportedException();
+
+        public override void SetLength(long value)
+            => throw new NotSupportedException();
+
+        public override void Write(byte[] buffer, int offset, int count)
+            => throw new NotSupportedException();
+
+        public override Task<int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken)
+            => ReadAsync(new Memory<byte>(buffer, offset, count), cancellationToken).AsTask();
+
+        public override async ValueTask<int> ReadAsync(Memory<byte> buffer, CancellationToken cancellationToken = default)
+        {
+            int maxBytesToRead = (int)(Length - Position);
+
+            if (maxBytesToRead > buffer.Length)
+            {
+                maxBytesToRead = buffer.Length;
+            }
+
+            if (maxBytesToRead <= 0)
+            {
+                return 0;
+            }
+
+            var bytesRead = await CopyFileDataIntoBuffer(_position, buffer.Slice(0, maxBytesToRead), cancellationToken);
+
+            _position += bytesRead;
+
+            return bytesRead;
+        }
+
+        protected abstract ValueTask<int> CopyFileDataIntoBuffer(long sourceOffset, Memory<byte> destination, CancellationToken cancellationToken);
+    }
+}

src/Components/Web.Extensions/src/InputFile/IBrowserFile.cs

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+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    /// <summary>
+    /// Represents the data of a file selected from an <see cref="InputFile"/> component.
+    /// </summary>
+    public interface IBrowserFile
+    {
+        /// <summary>
+        /// Gets the name of the file.
+        /// </summary>
+        string Name { get; }
+
+        /// <summary>
+        /// Gets the last modified date.
+        /// </summary>
+        DateTime LastModified { get; }
+
+        /// <summary>
+        /// Gets the size of the file in bytes.
+        /// </summary>
+        long Size { get; }
+
+        /// <summary>
+        /// Gets the MIME type of the file.
+        /// </summary>
+        string Type { get; }
+
+        /// <summary>
+        /// Opens the stream for reading the uploaded file.
+        /// </summary>
+        /// <param name="cancellationToken">A cancellation token to signal the cancellation of streaming file data.</param>
+        Stream OpenReadStream(CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// Converts the current image file to a new one of the specified file type and maximum file dimensions.
+        /// </summary>
+        /// <remarks>
+        /// The image will be scaled to fit the specified dimensions while preserving the original aspect ratio.
+        /// </remarks>
+        /// <param name="format">The new image format.</param>
+        /// <param name="maxWith">The maximum image width.</param>
+        /// <param name="maxHeight">The maximum image height</param>
+        /// <returns>A <see cref="Task"/> representing the completion of the operation.</returns>
+        Task<IBrowserFile> ToImageFileAsync(string format, int maxWith, int maxHeight);
+    }
+}

src/Components/Web.Extensions/src/InputFile/IInputFileJsCallbacks.cs

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+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    internal interface IInputFileJsCallbacks
+    {
+        Task NotifyChange(BrowserFile[] files);
+    }
+}

src/Components/Web.Extensions/src/InputFile/InputFile.cs

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+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Components.Rendering;
+using Microsoft.Extensions.Options;
+using Microsoft.JSInterop;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    /// <summary>
+    /// A component that wraps the HTML file input element and exposes a <see cref="Stream"/> for each file's contents.
+    /// </summary>
+    public class InputFile : ComponentBase, IInputFileJsCallbacks, IDisposable
+    {
+        private ElementReference _inputFileElement;
+
+        private IJSUnmarshalledRuntime? _jsUnmarshalledRuntime;
+
+        private InputFileJsCallbacksRelay? _jsCallbacksRelay;
+
+        [Inject]
+        private IJSRuntime JSRuntime { get; set; } = default!;
+
+        [Inject]
+        private IOptions<RemoteBrowserFileStreamOptions> Options { get; set; } = default!;
+
+        /// <summary>
+        /// Gets or sets the event callback that will be invoked when the collection of selected files changes.
+        /// </summary>
+        [Parameter]
+        public EventCallback<InputFileChangeEventArgs> OnChange { get; set; }
+
+        /// <summary>
+        /// Gets or sets a collection of additional attributes that will be applied to the input element.
+        /// </summary>
+        [Parameter(CaptureUnmatchedValues = true)]
+        public IDictionary<string, object>? AdditionalAttributes { get; set; }
+
+        protected override void OnInitialized()
+        {
+            _jsUnmarshalledRuntime = JSRuntime as IJSUnmarshalledRuntime;
+        }
+
+        protected override async Task OnAfterRenderAsync(bool firstRender)
+        {
+            if (firstRender)
+            {
+                _jsCallbacksRelay = new InputFileJsCallbacksRelay(this);
+                await JSRuntime.InvokeVoidAsync(InputFileInterop.Init, _jsCallbacksRelay.DotNetReference, _inputFileElement);
+            }
+        }
+
+        protected override void BuildRenderTree(RenderTreeBuilder builder)
+        {
+            builder.OpenElement(0, "input");
+            builder.AddMultipleAttributes(1, AdditionalAttributes);
+            builder.AddAttribute(2, "type", "file");
+            builder.AddElementReferenceCapture(3, elementReference => _inputFileElement = elementReference);
+            builder.CloseElement();
+        }
+
+        internal Stream OpenReadStream(BrowserFile file, CancellationToken cancellationToken)
+            => _jsUnmarshalledRuntime != null ?
+                (Stream)new SharedBrowserFileStream(JSRuntime, _jsUnmarshalledRuntime, _inputFileElement, file) :
+                new RemoteBrowserFileStream(JSRuntime, _inputFileElement, file, Options.Value, cancellationToken);
+
+        internal async Task<IBrowserFile> ConvertToImageFileAsync(BrowserFile file, string format, int maxWidth, int maxHeight)
+        {
+            var imageFile = await JSRuntime.InvokeAsync<BrowserFile>(InputFileInterop.ToImageFile, _inputFileElement, file.Id, format, maxWidth, maxHeight);
+
+            imageFile.Owner = this;
+
+            return imageFile;
+        }
+
+        Task IInputFileJsCallbacks.NotifyChange(BrowserFile[] files)
+        {
+            foreach (var file in files)
+            {
+                file.Owner = this;
+            }
+
+            return OnChange.InvokeAsync(new InputFileChangeEventArgs(files));
+        }
+
+        void IDisposable.Dispose()
+        {
+            _jsCallbacksRelay?.Dispose();
+        }
+    }
+}

src/Components/Web.Extensions/src/InputFile/InputFileChangeEventArgs.cs

@@ -0,0 +1,28 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    /// <summary>
+    /// Supplies information about an <see cref="InputFile.OnChange"/> event being raised.
+    /// </summary>
+    public class InputFileChangeEventArgs : EventArgs
+    {
+        /// <summary>
+        /// The updated file entries list.
+        /// </summary>
+        public IReadOnlyList<IBrowserFile> Files { get; }
+
+        /// <summary>
+        /// Constructs a new <see cref="InputFileChangeEventArgs"/> instance.
+        /// </summary>
+        /// <param name="files">The updated file entries list.</param>
+        public InputFileChangeEventArgs(IReadOnlyList<IBrowserFile> files)
+        {
+            Files = files;
+        }
+    }
+}

src/Components/Web.Extensions/src/InputFile/InputFileInterop.cs

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+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    internal static class InputFileInterop
+    {
+        private const string JsFunctionsPrefix = "_blazorInputFile.";
+
+        public const string Init = JsFunctionsPrefix + "init";
+
+        public const string EnsureArrayBufferReadyForSharedMemoryInterop = JsFunctionsPrefix + "ensureArrayBufferReadyForSharedMemoryInterop";
+
+        public const string ReadFileData = JsFunctionsPrefix + "readFileData";
+
+        public const string ReadFileDataSharedMemory = JsFunctionsPrefix + "readFileDataSharedMemory";
+
+        public const string ToImageFile = JsFunctionsPrefix + "toImageFile";
+    }
+}

src/Components/Web.Extensions/src/InputFile/InputFileJsCallbacksRelay.cs

@@ -0,0 +1,32 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Threading.Tasks;
+using Microsoft.JSInterop;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    internal class InputFileJsCallbacksRelay : IDisposable
+    {
+        private readonly IInputFileJsCallbacks _callbacks;
+
+        public IDisposable DotNetReference { get; }
+
+        public InputFileJsCallbacksRelay(IInputFileJsCallbacks callbacks)
+        {
+            _callbacks = callbacks;
+
+            DotNetReference = DotNetObjectReference.Create(this);
+        }
+
+        [JSInvokable]
+        public Task NotifyChange(BrowserFile[] files)
+            => _callbacks.NotifyChange(files);
+
+        public void Dispose()
+        {
+            DotNetReference.Dispose();
+        }
+    }
+}

src/Components/Web.Extensions/src/InputFile/ReadRequest.cs

@@ -0,0 +1,29 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Runtime.InteropServices;
+
+namespace Microsoft.AspNetCore.Components.Web.Extensions
+{
+    [StructLayout(LayoutKind.Explicit)]
+    internal struct ReadRequest
+    {
+        [FieldOffset(0)]
+        public string InputFileElementReferenceId;
+
+        [FieldOffset(4)]
+        public int FileId;
+
+        [FieldOffset(8)]
+        public long SourceOffset;
+
+        [FieldOffset(16)]
+        public byte[] Destination;
+
+        [FieldOffset(20)]
+        public int DestinationOffset;
+
+        [FieldOffset(24)]
+        public int MaxBytes;
+    }
+}