The code requires dependencies on fs, path, os, and child_process to interact with the file system, work with file paths, and execute system commands. The systemBuffer function generates a graph usage PNG image from a given data parameter, writing and converting an SVG to a PNG before returning the PNG image as a buffer.

Run example

npm run import -- "system usage png buffer"

system usage png buffer

const fs = require('fs')
const path = require('path')
const TEMP_DIR = os.tmpdir();
const {spawnSync} = require('child_process')

let count = 0

async function systemBuffer(data) {
  const graphUsage = await importer.import("system usage graph")
  let svg = await graphUsage(data)
  let svgTempFile = path.join(TEMP_DIR, 'tmp' + (count % 4) + '.svg')
  fs.writeFileSync(svgTempFile, svg)
  await spawnSync('convert', ['-density', '1200', '-resize', '300x200', svgTempFile, svgTempFile.replace('.svg', '.png')], {
    cwd: TEMP_DIR,
    timeout: 3000,
  })

  count++
  return fs.readFileSync(svgTempFile.replace('.svg', '.png'))
}


module.exports = systemBuffer

// Import required modules
const fs = require('fs');
const path = require('path');
const os = require('os'); // Add os module for accessing system properties
const { spawnSync } = require('child_process');
const importer = require('./importer'); // Replace 'importer' with actual module path

// Define constants
const TEMP_DIR = os.tmpdir(); // Use constant for path
const MAX_TEMP_FILES = 4; // Define maximum temp files limit
const TEMP_FILE_EXTENSION = '.svg'; // Extract file extension to a constant
const OUTPUT_FILE_EXTENSION = '.png'; // Extract file extension to a constant
const MAX_RESIZE_TIME = 3000; // Define timeout in milliseconds

// Initialize counter for temp file names
let count = 0;

/**
 * Generates a system usage graph and returns it as a PNG file.
 * 
 * @param {Object} data - Input data for the graph
 * @returns {Buffer} PNG file buffer representation
 */
async function systemBuffer(data) {
  try {
    // Import system usage graph module
    const graphUsage = await importer.import('system usage graph');
    
    // Generate SVG graph
    let svg = await graphUsage(data);
    
    // Create a temp file name using the counter
    let svgTempFile = path.join(TEMP_DIR, `tmp${count % MAX_TEMP_FILES}${TEMP_FILE_EXTENSION}`);
    
    // Write SVG to temp file
    fs.writeFileSync(svgTempFile, svg);
    
    // Resize SVG to PNG using ImageMagick
    await spawnSync('convert', [
      '-density', '1200', 
      '-resize', '300x200', 
      svgTempFile, 
      svgTempFile.replace(TEMP_FILE_EXTENSION, OUTPUT_FILE_EXTENSION)
    ], {
      cwd: TEMP_DIR,
      timeout: MAX_RESIZE_TIME,
    });
    
    // Increment counter for next temp file
    count++;
    
    // Return PNG file buffer
    return fs.readFileSync(svgTempFile.replace(TEMP_FILE_EXTENSION, OUTPUT_FILE_EXTENSION));
  } catch (error) {
    // Log any errors that occur during the process
    console.error('Error generating system usage graph:', error);
    throw error;
  }
}

// Export the systemBuffer function
module.exports = systemBuffer;

Code Breakdown

Dependencies and Variables

• The code requires the following dependencies:
  • fs (File System) for interacting with the file system
  • path for working with file paths
  • os (Operating System) for accessing temporary directories
  • child_process for executing system commands
• The following variables are defined:
  • TEMP_DIR: the temporary directory on the system
  • count: a counter used to generate unique file names (starts at 0)

systemBuffer Function

• systemBuffer is an asynchronous function that takes a data parameter
• The function:
  1. Imports a graph usage graph module using importer.import('system usage graph')
  2. Generates a graph usage SVG image using the imported module and data
  3. Writes the SVG image to a temporary file in the TEMP_DIR
  4. Uses the convert command from the child_process to convert the SVG image to a PNG image
  5. Returns the contents of the resulting PNG image file as a buffer

Function Exports

• The systemBuffer function is exported as a module using module.exports = systemBuffer

Notes

• The function uses a counter to generate unique file names, which may not be necessary if the file names are not critical
• The timeout option in the spawnSync function is set to 3000 (3 seconds), which means the function will timeout if the convert command takes longer than 3 seconds to complete.