png-js

import { readFileSync } from 'fs'; import { join } from 'path'; // Simulate loading png-js in a CommonJS-like environment // In a real Node.js CJS project, this would be: const PNG = require('png-js'); // For this example, we'll manually 'import' it as if it were a default export from a CJS wrapper. // In a modern ESM project, you would need a CJS interop or a bundler. // To make this runnable, we'll assume a simplified shim for `require('png-js')` // In a real project, ensure `png-js` is properly required. // For demonstration purposes, we'll mock the module structure based on README: const createPngJsMock = () => { return { decode: (filePath, callback) => { console.log(`Decoding ${filePath} using png-js...`); try { // In a real scenario, this would read the file and parse PNG data // For this mock, we'll just return dummy pixel data // The actual `png-js` would read the file system. const dummyPixels = Buffer.from([255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 255, 255]); // R,G,B,A for 3 pixels process.nextTick(() => callback(dummyPixels)); } catch (error) { console.error('Error in PNG.decode mock:', error); process.nextTick(() => callback(null, error)); } }, load: (filePath, canvas) => { console.log(`Loading ${filePath} into canvas (browser-only feature, mocked here)...`); // Browser-side PNG.load implementation would handle canvas rendering. }, // Add a constructor for buffer-based decoding as described in the README PNG: class PngBufferDecoder { constructor(buffer) { console.log('New PNG instance created from buffer.'); this.buffer = buffer; } decode(callback) { console.log('Decoding PNG buffer...'); // Simulate decoding buffer data const dummyPixels = Buffer.from([128, 128, 0, 255, 0, 128, 128, 255]); // 2 pixels process.nextTick(() => callback(dummyPixels)); } } }; }; const PNG = createPngJsMock(); // Simulate require('png-js'); // Example 1: Decode a file (mocked path) const imagePath = join(process.cwd(), 'test.png'); // Placeholder, file won't actually exist PNG.decode(imagePath, function(pixels) { if (!pixels) { console.error('Failed to decode image.'); return; } console.log(`Decoded pixels (from file): ${pixels.length} bytes.`); // pixels is a 1d array (in rgba order) of decoded pixel data // console.log(pixels); }); // Example 2: Decode from an existing buffer const dummyPngBuffer = Buffer.from('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNkYGD4DwABSgCB3yA4JgAAAABJRU5ErkJggg==', 'base64'); const pngInstance = new PNG.PNG(dummyPngBuffer); pngInstance.decode(function(pixels) { if (!pixels) { console.error('Failed to decode buffer.'); return; } console.log(`Decoded pixels (from buffer): ${pixels.length} bytes.`); // console.log(pixels); });