Utility class for loading images from a URI. More...

#include "donner/svg/resources/ImageLoader.h"

Public Types
using	Result = std::variant<ImageResource, SvgImageContent, UrlLoaderError>
	Result type returned by fromUri. Contains either decoded raster pixels, raw SVG content, or an error.
using	DecodedImageAdmission = std::function<bool(size_t)>
	Callback that reserves exact decoded RGBA bytes after dimensions are known but before decode. Returning false fails the load with UrlLoaderError::ResourceTooLarge without exhausting the shared byte budget; decodedImageAdmissionRefused then returns true.

Public Member Functions
	ImageLoader (ResourceLoaderInterface &resourceLoader, size_t maximumResourceSize=UrlLoader::kDefaultMaximumResourceSize, size_t *remainingResourceBytes=nullptr, size_t maximumDecodedImageSize=kDefaultMaximumDecodedImageSize, DecodedImageAdmission decodedImageAdmission={})
	Create a new image loader that uses the given resource loader to fetch external resources.
	~ImageLoader ()=default
	Destructor.
	ImageLoader (const ImageLoader &)=delete
	ImageLoader (ImageLoader &&)=delete
ImageLoader &	operator= (const ImageLoader &)=delete
ImageLoader &	operator= (ImageLoader &&)=delete
Result	fromUri (std::string_view uri)
	Read an image from a URI, which can be a file path, a URL, or a data URL (e.g.
bool	decodedImageAdmissionRefused () const
	Whether the last load was refused specifically by the decoded-byte admission callback.

Static Public Attributes
static constexpr size_t	kDefaultMaximumDecodedImageSize = 64 * 1024 * 1024
	Default maximum number of decoded RGBA bytes for one raster image.
static constexpr size_t	kMaximumDecodedBytesPerInputByte = 4096
	Decode-amplification budget: output RGBA bytes may not exceed 4096 times the encoded input size, with a 1 MiB floor for small ordinary images.
static constexpr size_t	kMinimumDecodedImageAllowance = 1 * 1024 * 1024
	Minimum decoded-byte allowance for small encoded image inputs.

Detailed Description

Utility class for loading images from a URI.

Supports both raster images (PNG, JPEG, GIF) and SVG images. Raster images are decoded into pixel data (ImageResource), while SVG images are returned as raw bytes (SvgImageContent) for parsing by the caller.

Constructor & Destructor Documentation

◆ ImageLoader()

donner::svg::ImageLoader::ImageLoader	(	ResourceLoaderInterface &	resourceLoader,
		size_t	maximumResourceSize = UrlLoader::kDefaultMaximumResourceSize,
		size_t *	remainingResourceBytes = nullptr,
		size_t	maximumDecodedImageSize = kDefaultMaximumDecodedImageSize,
		DecodedImageAdmission	decodedImageAdmission = {} )

inlineexplicit

Create a new image loader that uses the given resource loader to fetch external resources.

Parameters

resourceLoader	Resource loader to use for fetching external resources.
maximumResourceSize	Maximum encoded bytes accepted from one resource.
remainingResourceBytes	Optional shared byte budget charged for encoded input and decoded raster output.
maximumDecodedImageSize	Maximum decoded RGBA bytes accepted for one image.
decodedImageAdmission	Optional exact decoded-byte admission callback.

Member Function Documentation

◆ fromUri()

Result donner::svg::ImageLoader::fromUri ( std::string_view uri )

Read an image from a URI, which can be a file path, a URL, or a data URL (e.g.

"data:image/png;base64,...").

If the resource is an SVG image (image/svg+xml), returns SvgImageContent with raw bytes. Otherwise, decodes the image into RGBA pixel data and returns ImageResource.

Parameters

uri	URI of the image, or data URL containing a base64 embedded image.

Returns: A variant containing the loaded ImageResource, SvgImageContent, or a UrlLoaderError.

Member Data Documentation

◆ kMaximumDecodedBytesPerInputByte

size_t donner::svg::ImageLoader::kMaximumDecodedBytesPerInputByte = 4096

staticconstexpr

Decode-amplification budget: output RGBA bytes may not exceed 4096 times the encoded input size, with a 1 MiB floor for small ordinary images.

The configured per-image limit and shared document budget remain additional caps. This bounds synchronous work from tiny inputs.

The documentation for this class was generated from the following file:

donner/svg/resources/ImageLoader.h

Public Types

Public Member Functions