geotiff
Version:
GeoTIFF image decoding in JavaScript
90 lines • 2.36 kB
JavaScript
import fs from 'fs';
import { BaseSource } from './basesource.js';
/**
* @param {number} fd
* @returns {Promise<void>}
*/
function closeAsync(fd) {
return new Promise((resolve, reject) => {
fs.close(fd, (err) => {
if (err) {
reject(err);
}
else {
resolve();
}
});
});
}
/**
* @param {string} path
* @param {string} flags
* @param {number|undefined} mode
* @returns {Promise<number>}
*/
function openAsync(path, flags, mode = undefined) {
return new Promise((resolve, reject) => {
fs.open(path, flags, mode, (err, fd) => {
if (err) {
reject(err);
}
else {
resolve(fd);
}
});
});
}
/**
* @param {number} fd
* @param {Uint8Array} buffer
* @param {number} offset
* @param {number} length
* @param {number} position
* @returns {Promise<{bytesRead: number, buffer: Uint8Array}>}
*/
function readAsync(fd, buffer, offset, length, position) {
return new Promise((resolve, reject) => {
fs.read(fd, buffer, offset, length, position, (err, bytesRead, outBuffer) => {
if (err) {
reject(err);
}
else {
resolve({ bytesRead, buffer: outBuffer });
}
});
});
}
class FileSource extends BaseSource {
/**
* @param {string} path
*/
constructor(path) {
super();
this.path = path;
this.openRequest = openAsync(path, 'r');
}
/**
* @param {import('./basesource.js').Slice} slice
* @param {AbortSignal} [_signal] not implemented
* @returns {Promise<import('./basesource.js').SliceWithData>}
*/
async fetchSlice(slice, _signal) {
// TODO: use `signal`
const fd = await this.openRequest;
const { buffer } = await readAsync(fd, new Uint8Array(slice.length), 0, slice.length, slice.offset);
return {
data: buffer.buffer,
offset: slice.offset,
length: slice.length,
};
}
async close() {
const fd = await this.openRequest;
await closeAsync(fd);
}
}
/** @param {string} path */
export function makeFileSource(path) {
return new FileSource(path);
}
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