FEATURE: Add thumbnails for chat image uploads (discourse#24328)

Introduces the concept of image thumbnails in chat, prior to this we uploaded and used full size chat images within channels and direct messages.

The following changes are covered:
- Post processing of image uploads to create the thumbnail within Chat::MessageProcessor
- Extract responsive image ratios into CookedProcessorMixin (used for creating upload variations)
- Add thumbnail to upload serializer from plugin.rb
- Convert chat upload template to glimmer component using .gjs format
- Use thumbnail image within chat upload component (stores full size img in orig-src data attribute)
- Old uploads which don't have thumbnails will fallback to full size images in channels/DMs
- Update Magnific lightbox to use full size image when clicked
- Update Glimmer lightbox to use full size image (enables zooming for chat images)

app/assets/javascripts/discourse/app/lib/lightbox/process-html.js

@@ -23,7 +23,12 @@ export async function processHTML({ container, selector, clickTarget }) {
         item.parentElement?.style?.backgroundImage ||
         null;
 
-      const _fullsizeURL = item.href || item.src || innerImage.src || null;
+      const _fullsizeURL =
+        item.dataset?.largeSrc ||
+        item.href ||
+        item.src ||
+        innerImage.src ||
+        null;
 
       const _smallURL =
         innerImage.currentSrc ||

lib/cooked_post_processor.rb

@@ -222,15 +222,6 @@ def convert_to_link!(img)
     end
   end
 
-  def each_responsive_ratio
-    SiteSetting
-      .responsive_post_image_sizes
-      .split("|")
-      .map(&:to_f)
-      .sort
-      .each { |r| yield r if r > 1 }
-  end
-
   def optimize_image!(img, upload, cropped: false)
     w, h = img["width"].to_i, img["height"].to_i
     onebox = img.ancestors(".onebox, .onebox-body").first

lib/cooked_processor_mixin.rb

@@ -362,4 +362,13 @@ def create_span_node(klass, content = nil)
     span.content = content if content
     span
   end
+
+  def each_responsive_ratio
+    SiteSetting
+      .responsive_post_image_sizes
+      .split("|")
+      .map(&:to_f)
+      .sort
+      .each { |r| yield r if r > 1 }
+  end
 end

plugins/chat/assets/javascripts/discourse/components/chat-upload.gjs

@@ -7,7 +7,7 @@ import { htmlSafe } from "@ember/template";
 import { isAudio, isImage, isVideo } from "discourse/lib/uploads";
 import eq from "truth-helpers/helpers/eq";
 
-export default class extends Component {
+export default class ChatUpload extends Component {
   @service siteSettings;
 
   @tracked loaded = false;
@@ -44,6 +44,10 @@ export default class extends Component {
     return { width: width * ratio, height: height * ratio };
   }
 
+  get imageUrl() {
+    return this.args.upload.thumbnail?.url ?? this.args.upload.url;
+  }
+
   get imageStyle() {
     if (this.args.upload.dominant_color && !this.loaded) {
       return htmlSafe(`background-color: #${this.args.upload.dominant_color};`);
@@ -60,9 +64,10 @@ export default class extends Component {
       <img
         class="chat-img-upload"
         data-orig-src={{@upload.short_url}}
+        data-large-src={{@upload.url}}
         height={{this.size.height}}
         width={{this.size.width}}
-        src={{@upload.url}}
+        src={{this.imageUrl}}
         style={{this.imageStyle}}
         loading="lazy"
         tabindex="0"

plugins/chat/assets/javascripts/discourse/initializers/chat-decorators.js

@@ -161,7 +161,7 @@ export default {
         },
         callbacks: {
           elementParse: (item) => {
-            item.src = item.el[0].src;
+            item.src = item.el[0].dataset.largeSrc || item.el[0].src;
           },
         },
       });

plugins/chat/assets/javascripts/discourse/lib/chat-channel-subscription-manager.js

@@ -126,6 +126,7 @@ export default class ChatChannelSubscriptionManager {
     const message = this.messagesManager.findMessage(data.chat_message.id);
     if (message) {
       message.cooked = data.chat_message.cooked;
+      message.uploads = cloneJSON(data.chat_message.uploads || []);
       message.processed = true;
       message.incrementVersion();
     }

plugins/chat/assets/javascripts/discourse/lib/chat-channel-thread-subscription-manager.js

@@ -116,6 +116,7 @@ export default class ChatChannelThreadSubscriptionManager {
     const message = this.messagesManager.findMessage(data.chat_message.id);
     if (message) {
       message.cooked = data.chat_message.cooked;
+      message.uploads = cloneJSON(data.chat_message.uploads || []);
       message.processed = true;
       message.incrementVersion();
     }

plugins/chat/lib/chat/message_processor.rb

@@ -17,9 +17,39 @@ def initialize(chat_message, opts = {})
 
     def run!
       post_process_oneboxes
+      process_thumbnails
       DiscourseEvent.trigger(:chat_message_processed, @doc, @model)
     end
 
+    def process_thumbnails
+      @model.uploads.each do |upload|
+        if upload.width <= SiteSetting.max_image_width &&
+             upload.height <= SiteSetting.max_image_height
+          return false
+        end
+
+        crop =
+          SiteSetting.min_ratio_to_crop > 0 &&
+            upload.width.to_f / upload.height.to_f < SiteSetting.min_ratio_to_crop
+
+        width = upload.thumbnail_width
+        height = upload.thumbnail_height
+
+        # create the main thumbnail
+        upload.create_thumbnail!(width, height, crop: crop)
+
+        # create additional responsive thumbnails
+        each_responsive_ratio do |ratio|
+          resized_w = (width * ratio).to_i
+          resized_h = (height * ratio).to_i
+
+          if upload.width && resized_w <= upload.width
+            upload.create_thumbnail!(resized_w, resized_h, crop: crop)
+          end
+        end
+      end
+    end
+
     def large_images
       []
     end

plugins/chat/plugin.rb

@@ -253,6 +253,12 @@ module ::Chat
     object.chat_separate_sidebar_mode
   end
 
+  add_to_serializer(
+    :upload,
+    :thumbnail,
+    include_condition: -> { SiteSetting.chat_enabled && SiteSetting.create_thumbnails },
+  ) { object.thumbnail }
+
   RETENTION_SETTINGS_TO_USER_OPTION_FIELDS = {
     chat_channel_retention_days: :dismissed_channel_retention_reminder,
     chat_dm_retention_days: :dismissed_dm_retention_reminder,

plugins/chat/spec/system/uploads_spec.rb

@@ -12,6 +12,7 @@
 
   context "when uploading to a new message" do
     before do
+      Jobs.run_immediately!
       channel_1.add(current_user)
       sign_in(current_user)
     end
@@ -39,6 +40,34 @@
       expect(Chat::Message.last.uploads.count).to eq(1)
     end
 
+    it "adds a thumbnail for large images" do
+      SiteSetting.create_thumbnails = true
+
+      chat.visit_channel(channel_1)
+      file_path = file_from_fixtures("huge.jpg", "images").path
+
+      attach_file(file_path) do
+        channel_page.open_action_menu
+        channel_page.click_action_button("chat-upload-btn")
+      end
+
+      expect { channel_page.send_message }.to change { Chat::Message.count }.by(1)
+
+      expect(channel_page).to have_no_css(".chat-composer-upload")
+
+      message = Chat::Message.last
+
+      try_until_success(timeout: 5) { expect(message.uploads.first.thumbnail).to be_present }
+
+      upload = message.uploads.first
+
+      # image has src attribute with thumbnail url
+      expect(channel_page).to have_css(".chat-uploads img[src$='#{upload.thumbnail.url}']")
+
+      # image has data-large-src with original image src
+      expect(channel_page).to have_css(".chat-uploads img[data-large-src$='#{upload.url}']")
+    end
+
     it "adds dominant color attribute to images" do
       chat.visit_channel(channel_1)
       file_path = file_from_fixtures("logo.png", "images").path