HagiCode.Libs.Imaging 0.4.1-dev.137.1

HagiCode.Libs.Imaging

In-process image work for .NET hosts, using native libvips libraries bundled in the package:

• AVIF conversion (IAvifConverter): PNG, JPEG, WebP and GIF (first frame) sources to still AVIF images.

• Model image preparation (IModelImagePreparer): turns an uploaded image into one a model accepts (PNG, JPEG, GIF or WEBP within 5 MiB and 8000 pixels per side), in memory. See Model image preparation.

• No ffmpeg, avifenc or other command-line tool is needed, or looked up on PATH.

• The package never starts a child process.

• The native libraries load from the package. No environment variable or library path setting is needed.

Install

dotnet add package HagiCode.Libs.Imaging

Usage

using HagiCode.Libs.Imaging;

// Dependency injection (singleton converter, limits applied from the configure delegate)
services.AddHagiCodeImaging(options =>
{
    options.MaxInputBytes = 64 * 1024 * 1024;
    options.MaxConcurrentConversions = 4;
});

// Buffer to buffer: AVIF bytes are in result.Data
var result = await converter.ConvertAsync(uploadBytes, new AvifConversionOptions
{
    Resize = new AvifResize(AvifResizeMode.Fit, 200, 200),
    Alpha = AvifAlphaMode.Flatten,
    FlattenColor = "#64748b",
});

// Stream to stream: nothing is written to the destination unless the conversion succeeds
await converter.ConvertAsync(sourceStream, destinationStream, options, cancellationToken);

// File to file: written to a temporary file, then moved into place
await converter.ConvertFileAsync("in.png", "out.avif", options, overwrite: true, cancellationToken);

Check the runtime at start-up if you need a health signal:

var status = AvifRuntime.Probe(); // cached; never throws
if (!status.IsAvailable) { /* log status.UnavailableReason and fall back */ }

Model image preparation

IModelImagePreparer prepares an image for a model that accepts only PNG, JPEG, GIF or WEBP within a size and pixel limit. The stored file is never changed, and nothing is written to disk.

services.AddHagiCodeImaging(); // registers IAvifConverter and IModelImagePreparer as singletons

var prepared = await preparer.PrepareAsync(path, ModelImageLimits.Default, cancellationToken);
if (prepared.IsUsable)
{
    // prepared.MediaType and prepared.Bytes (ReadOnlyMemory<byte>) go to the model.
}
else
{
    // prepared.Reason says why; the image is skipped. Image bytes are never in Reason or ToString.
}

Format is decided from the content, never from the file name. Each image gets one outcome:

ModelImageLimits (per call, defaults are the Claude limits):

Reduction makes at most 6 encode attempts. If none fits, the result is NotPreparable. The preparer never throws for bad input: a corrupt, truncated, unsupported or malformed image is a NotPreparable result. Only cancellation is thrown, as OperationCanceledException.

SVG handling is bounded. The document is loaded from its buffer with no base path, so relative references cannot resolve. Entity declarations (<!ENTITY) are refused before rendering. A declared size is never rendered at full size: the render scale keeps the longest edge within 2048 pixels.

SVG and untrusted-operation blocking

Probe result (task 1.4a, libvips bundled in NetVips.Native 8.18.7, Linux x64):

• With NetVips.BlockUntrusted = true, libvips refuses the SVG loader for every input (unable to call svgload_buffer). AvifConverter sets that flag for the process by default (ConfigureProcessWideEngineSettings). While the flag is on, the preparer reports an SVG as NotPreparable with reason "could not be rasterized".
• With the flag off, SVG rasterization works. A file:// reference, an absolute-path reference and an http:// reference are not fetched. A local canary image was not drawn, and no HTTP request reached a local listener.

The blocking flag is process-wide and the converter does not use generic or untrusted loaders, so the flag adds no protection to AVIF conversion. Choosing between the two is an open decision; see the change design notes.

Options

AvifConversionOptions (per call):

AvifConverterOptions (per converter):

Result

AvifConversionResult reports SourceFormat, SourceWidth and SourceHeight (after orientation, before resize), OutputWidth, OutputHeight, OutputByteLength, HasAlpha, Elapsed and Data (filled only by the buffer overload).

Errors

Every failure is an AvifConversionException with a stable ErrorCode. Branch on the code, not the message.

Cancellation ends as OperationCanceledException, not as an AvifConversionException, and leaves no output behind.

Supported platforms

The Linux build needs the standard C++ runtime (libstdc++) that glibc distributions provide. Other platforms, including linux-musl-x64, linux-arm64 and win-arm64, report NativeRuntimeUnavailable. Signature detection (AvifFormat.IsAvif) keeps working on every platform.

Model image preparation on an unsupported platform, or when AvifRuntime.Probe() is unavailable: an image within the limits still passes through unchanged (its size and pixels are read from the header in managed code, and no decode is run). Anything that needs conversion (over a limit, SVG, or a dimension above the limit) is NotPreparable with a reason that names the runtime.

Limits and behavior

• Input and pixel limits protect memory. The pixel check reads the header and does not decode the pixels.
• Loaders are explicit and use failOn: Error, so a truncated file is rejected instead of decoded partially.
• Concurrent encodes are bounded by MaxConcurrentConversions.
• Animated GIF input yields a single still image built from the first frame. Animated AVIF output is not supported.
• A running native encode cannot be interrupted. Cancellation takes effect when the encode returns, and the output is discarded.

Package contents and size

The package carries the four native libraries (about 18 to 20 MB each). A publish for one runtime identifier copies only that platform's library. The nupkg is about 34 MB. It contains README.md, icon.png and THIRD-PARTY-NOTICES.md.

Third-party notices

The bundled native components (libvips, libheif, aom and others) are listed with versions and licenses in THIRD-PARTY-NOTICES.md, packed at the root of this package.

Integration

The backend integration guide, with option mappings from the current ffmpeg-based AVIF path and the thumbnail mapping, is in the monorepo at docs/avif-backend-integration-guide.md.