feat: ability to mask images before processing #79

api/src/util/mask.image.util.js

@@ -0,0 +1,43 @@
+const { promisify } = require('util');
+const { createCanvas, loadImage } = require('canvas');
+const sizeOf = promisify(require('image-size'));
+
+const { MASKS } = require('../constants');
+
+module.exports = async (event, tmp) => {
+  const masks = MASKS
+    ? MASKS.filter(({ CAMERA }) => CAMERA === event.camera).map(({ MASK }) => MASK)
+    : [];
+  const coordinates = [];
+  masks.forEach((mask) => {
+    coordinates.push([]);
+    mask.split(',').forEach((value, i) => {
+      if (i % 2 === 0) {
+        coordinates[coordinates.length - 1].push({ x: value });
+      } else {
+        const objectLength = coordinates[coordinates.length - 1].length - 1;
+        coordinates[coordinates.length - 1][objectLength].y = value;
+      }
+    });
+  });
+
+  if (!coordinates.length) return false;
+
+  const { width, height } = await sizeOf(tmp);
+  const canvas = createCanvas(width, height);
+  const ctx = canvas.getContext('2d');
+  const image = await loadImage(tmp);
+  ctx.fillStyle = '#000';
+  ctx.drawImage(image, 0, 0);
+  coordinates.forEach((coordinate) => {
+    ctx.beginPath();
+    coordinate.forEach(({ x, y }, i) => {
+      if (i === 0) ctx.moveTo(x, y);
+      else ctx.lineTo(x, y);
+    });
+    ctx.closePath();
+    ctx.fill();
+  });
+
+  return canvas.toBuffer('image/jpeg');
+};

api/src/util/process.util.js

@@ -4,6 +4,7 @@ const perf = require('execution-time')();
 const { v4: uuidv4 } = require('uuid');
 const filesystem = require('./fs.util');
 const database = require('./db.util');
+const mask = require('./mask.image.util');
 const { recognize, normalize } = require('./detectors/actions');
 const { STORAGE, SAVE } = require('../constants');
 const DETECTORS = require('../constants/config').detectors();
@@ -30,6 +31,9 @@ module.exports.polling = async (event, { retries, id, type, url, breakMatch, MAT
         const promises = [];
         filesystem.writer(tmp, stream);
 
+        const maskBuffer = await mask(event, tmp);
+        if (maskBuffer) filesystem.writer(tmp, maskBuffer);
+
         for (const detector of DETECTORS) {
           promises.push(this.process({ attempt: attempts, detector, tmp }));
         }