From 193a0c60f8e40f20d7c5c0035a4dcc81be8bb897 Mon Sep 17 00:00:00 2001
From: Alexander Zinchuk <alx.zinchuk@gmail.com>
Date: Wed, 5 Jul 2023 13:14:30 +0200
Subject: [PATCH] Photo: Scale down an image for a local message thumbnail
 (#3423)

---
 src/api/gramjs/apiBuilders/messages.ts                 |  2 +-
 .../middle/composer/helpers/buildAttachment.ts         | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/api/gramjs/apiBuilders/messages.ts b/src/api/gramjs/apiBuilders/messages.ts
index 4fbff39b1..cb1480b85 100644
--- a/src/api/gramjs/apiBuilders/messages.ts
+++ b/src/api/gramjs/apiBuilders/messages.ts
@@ -1439,7 +1439,7 @@ function buildUploadingMedia(
           photo: {
             id: LOCAL_MEDIA_UPLOADING_TEMP_ID,
             sizes: [],
-            thumbnail: { width, height, dataUri: blobUrl },
+            thumbnail: { width, height, dataUri: previewBlobUrl || blobUrl },
             blobUrl,
             isSpoiler: shouldSendAsSpoiler,
           },
diff --git a/src/components/middle/composer/helpers/buildAttachment.ts b/src/components/middle/composer/helpers/buildAttachment.ts
index 7b2feb10c..950d80ec1 100644
--- a/src/components/middle/composer/helpers/buildAttachment.ts
+++ b/src/components/middle/composer/helpers/buildAttachment.ts
@@ -14,6 +14,7 @@ import {
 import { scaleImage } from '../../../../util/imageResize';
 
 const MAX_QUICK_IMG_SIZE = 1280; // px
+const MAX_THUMB_IMG_SIZE = 40; // px
 const MAX_ASPECT_RATIO = 20;
 const FILE_EXT_REGEX = /\.[^/.]+$/;
 
@@ -53,7 +54,14 @@ export default async function buildAttachment(
       quick = { width, height };
     }
 
-    previewBlobUrl = blobUrl;
+    const shouldShrinkPreview = Math.max(width, height) > MAX_THUMB_IMG_SIZE;
+    if (shouldShrinkPreview) {
+      previewBlobUrl = await scaleImage(
+        blobUrl, MAX_THUMB_IMG_SIZE / Math.max(width, height), 'image/jpeg',
+      );
+    } else {
+      previewBlobUrl = blobUrl;
+    }
   } else if (SUPPORTED_VIDEO_CONTENT_TYPES.has(mimeType)) {
     const { videoWidth: width, videoHeight: height, duration } = await preloadVideo(blobUrl);
     shouldSendAsFile = !validateAspectRatio(width, height);