vjrj
2b419e6516
Replace the Blossom media-server approach with a fully decentralized one: generate a small (~320px) JPEG thumbnail from the lot's cover photo and embed it in the offer event as a data: URI, so photos ride the relays with no server and no IP leak. The full photo stays in the encrypted inventory. - offer_thumbnail.dart: downscale-until-it-fits data-URI builder + decoder - market_widgets: render data: URIs from memory, http(s) URLs from network - offers_cubit: publish a thumbnail (best-effort) in place of an upload - drop MediaTransport/Blossom from commons_core (http/crypto deps) and the media-server setting; parked on branch parked/offer-photos-blossom Relay event-size limits cap the image to a thumbnail; higher-res sharing would need the parked Blossom path.
56 lines
2.1 KiB
Dart
56 lines
2.1 KiB
Dart
import 'dart:convert';
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import 'dart:typed_data';
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import 'package:image/image.dart' as img;
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/// Builds a tiny `data:image/jpeg;base64,…` thumbnail from a full photo, small
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/// enough to ride *inside* a Nostr offer event — no media server, fully
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/// decentralized. The full-resolution photo stays in the encrypted local
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/// inventory; only this shrunken preview is published so peers can see the seed.
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///
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/// Relays cap event size, so we downscale (longest edge) and re-encode until the
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/// base64 fits under [maxBytes]. Returns null when the bytes aren't a decodable
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/// image or no size small enough is reachable — the offer then publishes without
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/// a photo (graceful, never a hard failure).
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String? offerThumbnailDataUri(
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Uint8List bytes, {
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int maxBytes = 40000,
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List<int> edges = const [320, 256, 192, 128],
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int quality = 68,
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}) {
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try {
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final decoded = img.decodeImage(bytes);
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if (decoded == null) return null;
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for (final edge in edges) {
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final resized = _fitWithin(decoded, edge);
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final jpeg = img.encodeJpg(resized, quality: quality);
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final b64 = base64.encode(jpeg);
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if (b64.length <= maxBytes) return 'data:image/jpeg;base64,$b64';
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}
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return null; // even the smallest edge didn't fit — skip the image
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} catch (_) {
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return null; // undecodable/corrupt bytes — publish without a photo
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}
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}
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/// Extracts the raw bytes from a `data:...;base64,…` URI, or null when [uri] is
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/// not a base64 data URI. Used by the UI to render an inline thumbnail with
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/// `Image.memory` instead of a network fetch.
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Uint8List? decodeDataUri(String uri) {
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if (!uri.startsWith('data:')) return null;
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try {
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return Uri.parse(uri).data?.contentAsBytes();
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} on FormatException {
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return null;
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}
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}
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/// Resizes [image] so its longest edge is at most [edge], preserving aspect
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/// ratio. Never upscales a photo that's already smaller.
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img.Image _fitWithin(img.Image image, int edge) {
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if (image.width <= edge && image.height <= edge) return image;
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return image.width >= image.height
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? img.copyResize(image, width: edge)
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: img.copyResize(image, height: edge);
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}
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