[Glitch] Resize images by area instead of fixed dimensions

Port WebUI part of 91aadec929 to glitch-soc

app/javascript/flavours/glitch/util/resize_image.js

@@ -1,6 +1,6 @@
 import EXIF from 'exif-js';
 
-const MAX_IMAGE_DIMENSION = 1280;
+const MAX_IMAGE_PIXELS = 1638400; // 1280x1280px
 
 const getImageUrl = inputFile => new Promise((resolve, reject) => {
   if (window.URL && URL.createObjectURL) {
@@ -73,18 +73,8 @@ const processImage = (img, { width, height, orientation, type = 'image/png' }) =
 const resizeImage = (img, type = 'image/png') => new Promise((resolve, reject) => {
   const { width, height } = img;
 
-  let newWidth, newHeight;
-
-  if (width > height) {
-    newHeight = height * MAX_IMAGE_DIMENSION / width;
-    newWidth  = MAX_IMAGE_DIMENSION;
-  } else if (height > width) {
-    newWidth  = width * MAX_IMAGE_DIMENSION / height;
-    newHeight = MAX_IMAGE_DIMENSION;
-  } else {
-    newWidth  = MAX_IMAGE_DIMENSION;
-    newHeight = MAX_IMAGE_DIMENSION;
-  }
+  const newWidth  = Math.round(Math.sqrt(MAX_IMAGE_PIXELS * (width / height)));
+  const newHeight = Math.round(Math.sqrt(MAX_IMAGE_PIXELS * (height / width)));
 
   getOrientation(img, type)
     .then(orientation => processImage(img, {
@@ -104,7 +94,7 @@ export default inputFile => new Promise((resolve, reject) => {
   }
 
   loadImage(inputFile).then(img => {
-    if (img.width < MAX_IMAGE_DIMENSION && img.height < MAX_IMAGE_DIMENSION) {
+    if (img.width * img.height < MAX_IMAGE_PIXELS) {
       resolve(inputFile);
       return;
     }