Add arbitrary crop module

src/Modules.js

@@ -3,6 +3,7 @@
 */
 module.exports = {
   'add-qr': require('./modules/AddQR'),
+  'arbitrary-crop': require('./modules/ArbitraryCrop'),
   'average': require('./modules/Average'),
   'blend': require('./modules/Blend'),
   'blob-analysis': require('./modules/BlobAnalysis'),

src/modules/ArbitraryCrop/Module.js

@@ -0,0 +1,104 @@
+module.exports = function ArbitraryCrop(options, UI, util) {
+  var defaults = require('../../util/getDefaults.js')(require('./info.json'));
+
+  options.x1 = options.x1 || defaults.x1;
+  options.y1 = options.y1 || defaults.y1;
+  options.x2 = options.x2 || defaults.x2;
+  options.y2 = options.y2 || defaults.y2;
+  options.x3 = options.x3 || defaults.x3;
+  options.y3 = options.y3 || defaults.y3;
+  options.x4 = options.x4 || defaults.x4;
+  options.y4 = options.y4 || defaults.y4;
+
+  var output;
+
+  // This function is called on every draw.
+  function draw(input, callback, progressObj) {
+    progressObj.stop(true);
+    progressObj.overrideFlag = true;
+
+    var step = this;
+
+    var x1 = options.x1,
+      y1 = options.y1,
+      x2 = options.x2,
+      y2 = options.y2,
+      x3 = options.x3,
+      y3 = options.y3,
+      x4 = options.x4,
+      y4 = options.y4;
+
+    // Equation of line l1.
+    function l1(x, y) {
+      var d = (x - x1) * (y2 - y1) - (y - y1) * (x2 - x1);
+      return d;
+    }
+
+    // Equation of line l2.
+    function l2(x, y) {
+      var d = (x - x2) * (y4 - y2) - (y - y2) * (x4 - x2);
+      return d;
+    }
+
+    // Equation of line l3.
+    function l3(x, y) {
+      var d = (x - x3) * (y4 - y3) - (y - y3) * (x4 - x3);
+      return d;
+    }
+
+    // Equation of line l4.
+    function l4(x, y) {
+      var d = (x - x1) * (y3 - y1) - (y - y1) * (x3 - x1);
+      return d;
+    }
+
+    function changePixel(r, g, b, a, x, y) {
+
+      if(l1(x, y) * l3(x, y) <= 0 && l2(x, y) * l4(x, y) <= 0)  return [r, g, b, a];
+
+      else return [r, g, b, 0];
+    }
+
+    function extraManipulation(pixels) {
+
+      x = Math.min(x1, x2, x3, x4);
+      y = Math.min(y1, y2, y3, y4);
+
+      w = Math.max(x1, x2, x3, x4);
+      h = Math.max(y1, y2, y3, y4);
+
+      newPixels = require('../Crop/Crop')(pixels, {x, y, w, h});
+
+      return newPixels;
+
+    }
+
+    function output(image, datauri, mimetype, wasmSuccess) {
+      step.output = {
+        src: datauri,
+        format: mimetype,
+        wasmSuccess,
+        useWasm: options.useWasm
+      };
+    }
+
+    return require('../_nomodule/PixelManipulation.js')(input, {
+      output: output,
+      ui: options.step.ui, //don't pass this in if you don't want your module to support progress bars
+      changePixel: changePixel,
+      format: input.format,
+      image: options.image,
+      inBrowser: options.inBrowser,
+      callback: callback,
+      useWasm: options.useWasm,
+      extraManipulation
+    });
+  }
+
+  return {
+    options: options,
+    draw: draw,
+    output: output,
+    UI: UI
+  };
+};

src/modules/ArbitraryCrop/index.js

@@ -0,0 +1,4 @@
+module.exports = [
+  require('./Module'),
+  require('./info.json')
+];

src/modules/ArbitraryCrop/info.json

@@ -0,0 +1,48 @@
+{
+  "name": "arbitrary-crop",
+  "description": "Crops image for any arbitrary quadilateral according to given values, where (x1, y1) are top-left cordinates, (x2, y2) are top-right cordinates, (x3, y3) are bottom-right cordinates, (x4, y4) are bottom-left cordinates",
+  "url": "https://github.com/publiclab/image-sequencer/tree/master/MODULES.md",
+  "inputs": {
+    "x1": {
+      "type": "integer",
+      "desc": "Cordinate x1 of quadilateral",
+      "default": 100
+    },
+    "y1": {
+      "type": "integer",
+      "desc": "Cordinate y1 of quadilateral",
+      "default": 100
+    },
+    "x2": {
+      "type": "integer",
+      "desc": "Cordinate x2 of quadilateral",
+      "default": 200
+    },
+    "y2": {
+      "type": "integer",
+      "desc": "Cordinate y2 of quadilateral",
+      "default": 100
+    },
+    "x3": {
+      "type": "integer",
+      "desc": "Cordinate x3 of quadilateral",
+      "default": 100
+    },
+    "y3": {
+      "type": "integer",
+      "desc": "Cordinate y3 of quadilateral",
+      "default": 200
+    },
+    "x4": {
+      "type": "integer",
+      "desc": "Cordinate x4 of quadilateral",
+      "default": 200
+    },
+    "y4": {
+      "type": "integer",
+      "desc": "Cordinate y4 of quadilateral",
+      "default": 200
+    }
+  },
+  "docs-link": "https://github.com/publiclab/image-sequencer/blob/main/docs/MODULES.md"
+}