Added aspect ratio module (#1454)

* Base file

* Added aspect ratio module

* Compatiable with Experimental GIF Manipulation

* some refactoring

* Changed the name from aspect-ratio to Constrained Crop

* cleanup

* Changes requested

* Added test module

Co-authored-by: Harsh Khandeparkar <34770591+HarshKhandeparkar@users.noreply.github.com>
Co-authored-by: Jeffrey Warren <jeff@unterbahn.com>

src/modules/ConstrainedCrop/Module.js

@@ -0,0 +1,56 @@
+/*
+* Crops an Image on the basis of the ratio provided
+*/
+module.exports = function ConstrainedCrop(options, UI) {
+
+  var defaults = require('./../../util/getDefaults.js')(require('./info.json'));
+  var output;
+
+  function draw(input, callback) {
+
+    var step = this,
+      startingX = Number(options.startingX || defaults.startingX),
+      startingY = Number(options.startingY || defaults.startingY),
+      aspectRatio = (options.aspectRatio || defaults.aspectRatio).split(':'),
+      widthRatio = Number(aspectRatio[0]),
+      heightRatio = Number(aspectRatio[1]);
+
+    function extraManipulation(pixels) {
+      var width = pixels.shape[0],
+        height = pixels.shape[1];
+      var endX, endY;
+      if(((width - startingX) / widthRatio) * heightRatio <= (height - startingY)) {
+        endX = width;
+        endY = (((width - startingX) / widthRatio) * heightRatio) + startingY;
+      }
+      else {
+        endX = (((height - startingY) / heightRatio) * widthRatio) + startingX;
+        endY = height;
+      }
+      const newPixels = require('../Crop/Crop')(pixels, {'x': startingX, 'y': startingY, 'w': endX - startingX, 'h': endY - startingY}, function() {
+      });
+      return newPixels;
+    }
+
+
+    function output(image, datauri, mimetype, wasmSuccess) {
+      step.output = { src: datauri, format: mimetype, wasmSuccess, useWasm: options.useWasm };
+    }
+    return require('../_nomodule/PixelManipulation')(input, {
+      output: output,
+      ui: options.step.ui,
+      extraManipulation: extraManipulation,
+      format: input.format,
+      image: options.image,
+      inBrowser: options.inBrowser,
+      callback: callback,
+      useWasm:options.useWasm
+    });
+  }
+  return {
+    options: options,
+    draw: draw,
+    output: output,
+    UI: UI
+  };
+};