Resize images by area instead of fixed dimensions (#8083)

To improve the way super tall or super ride images are treated, the
numbers remain the same, 1280x1280 and 400x400, but if an image
is less in one dimension than the other, the other can become larger

Thanks to @WAHa_06x36@mastodon.social for the tip

1 files changed, 4 insertions, 14 deletions

diff --git a/app/javascript/mastodon/utils/resize_image.js b/app/javascript/mastodon/utils/resize_image.js
index 279a858ca..d1608094f 100644
--- a/app/javascript/mastodon/utils/resize_image.js
+++ b/app/javascript/mastodon/utils/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;
     }