FEATURE: Auto generate and display video preview image (#25633)

This change will allow auto generated video thumbnails to be used
instead of the black video thumbnail that overlays videos.

Follow up to: 2443446e62

app/assets/javascripts/discourse-markdown-it/src/engine.js

@@ -187,7 +187,11 @@ function renderImageOrPlayableMedia(tokens, idx, options, env, slf) {
       options.discourse.previewing &&
       !options.discourse.limitedSiteSettings.enableDiffhtmlPreview
     ) {
-      return `<div class="onebox-placeholder-container">
+      const origSrc = token.attrGet("data-orig-src");
+      const origSrcId = origSrc
+        .substring(origSrc.lastIndexOf("/") + 1)
+        .split(".")[0];
+      return `<div class="onebox-placeholder-container" data-orig-src-id="${origSrcId}">
         <span class="placeholder-icon video"></span>
       </div>`;
     } else {

app/assets/javascripts/discourse/app/instance-initializers/video-placeholder.js

@@ -80,6 +80,15 @@ export default {
         );
 
         containers.forEach((container) => {
+          // Add video thumbnail image
+          if (container.dataset.thumbnailSrc) {
+            const thumbnail = new Image();
+            thumbnail.onload = function () {
+              container.style.backgroundImage = "url('" + thumbnail.src + "')";
+            };
+            thumbnail.src = container.dataset.thumbnailSrc;
+          }
+
           const wrapper = document.createElement("div"),
             overlay = document.createElement("div");
 

app/assets/javascripts/discourse/app/mixins/composer-video-thumbnail-uppy.js

@@ -31,9 +31,11 @@ export default class ComposerVideoThumbnailUppy extends EmberObject.extend(
   uploadRootPath = "/uploads";
   uploadTargetBound = false;
   useUploadPlaceholders = true;
+  capabilities = null;
 
   constructor(owner) {
     super(...arguments);
+    this.capabilities = owner.lookup("service:capabilities");
     setOwner(this, owner);
   }
 
@@ -55,13 +57,17 @@ export default class ComposerVideoThumbnailUppy extends EmberObject.extend(
     video.muted = true;
     video.playsinline = true;
 
-    let videoSha1 = uploadUrl
+    const videoSha1 = uploadUrl
       .substring(uploadUrl.lastIndexOf("/") + 1)
       .split(".")[0];
 
     // Wait for the video element to load, otherwise the canvas will be empty.
-    // iOS Safari prefers onloadedmetadata over oncanplay.
-    video.onloadedmetadata = () => {
+    // iOS Safari prefers onloadedmetadata over oncanplay. System tests running in Chrome
+    // prefer oncanplaythrough.
+    const eventName = this.capabilities.isIOS
+      ? "onloadedmetadata"
+      : "oncanplaythrough";
+    video[eventName] = () => {
       const canvas = document.createElement("canvas");
       const ctx = canvas.getContext("2d");
       canvas.width = video.videoWidth;
@@ -70,7 +76,20 @@ export default class ComposerVideoThumbnailUppy extends EmberObject.extend(
       // A timeout is needed on mobile.
       setTimeout(() => {
         ctx.drawImage(video, 0, 0, video.videoWidth, video.videoHeight);
+        // Detect Empty Thumbnail
+        const imageData = ctx.getImageData(0, 0, canvas.width, canvas.height);
+        const data = imageData.data;
 
+        let isEmpty = true;
+        for (let i = 0; i < data.length; i += 4) {
+          // Check RGB values
+          if (data[i] !== 0 || data[i + 1] !== 0 || data[i + 2] !== 0) {
+            isEmpty = false;
+            break;
+          }
+        }
+
+        if (!isEmpty) {
           // upload video thumbnail
           canvas.toBlob((blob) => {
             this._uppyInstance = new Uppy({
@@ -126,6 +145,10 @@ export default class ComposerVideoThumbnailUppy extends EmberObject.extend(
               });
             }
           });
+        } else {
+          this.uploading = false;
+          callback();
+        }
       }, 100);
     };
   }

app/assets/javascripts/discourse/tests/unit/lib/pretty-text-test.js

@@ -1498,8 +1498,8 @@ var bar = 'bar';
     assert.cookedOptions(
       `![baby shark|video](upload://eyPnj7UzkU0AkGkx2dx8G4YM1Jx.mp4)`,
       { previewing: true },
-      `<p><div class=\"onebox-placeholder-container\">
-        <span class=\"placeholder-icon video\"></span>
+      `<p><div class="onebox-placeholder-container" data-orig-src-id="eyPnj7UzkU0AkGkx2dx8G4YM1Jx">
+        <span class="placeholder-icon video"></span>
       </div></p>`
     );
   });

app/assets/stylesheets/common/base/onebox.scss

@@ -935,6 +935,8 @@ aside.onebox.mixcloud-preview {
   }
 }
 .video-placeholder-container {
+  background-size: cover;
+  background-position: center;
   position: relative;
   padding: 0 0 56.25% 0;
   width: 100%;
@@ -1000,6 +1002,8 @@ iframe.vimeo-onebox {
 }
 
 .onebox-placeholder-container {
+  background-size: cover;
+  background-position: center;
   position: relative;
   width: 100%;
   padding: 0 0 48.25% 0;

app/models/post.rb

@@ -1048,8 +1048,9 @@ class Post < ActiveRecord::Base
             .where("original_filename like ?", "#{upload.sha1}.%")
             .order(id: :desc)
             .first if upload.sha1.present?
-        if thumbnail.present? && self.is_first_post? && !self.topic.image_upload_id
+        if thumbnail.present?
           upload_ids << thumbnail.id
+          if self.is_first_post? && !self.topic.image_upload_id
             self.topic.update_column(:image_upload_id, thumbnail.id)
             extra_sizes =
               ThemeModifierHelper.new(
@@ -1058,6 +1059,7 @@ class Post < ActiveRecord::Base
             self.topic.generate_thumbnails!(extra_sizes: extra_sizes)
           end
         end
+      end
       upload_ids << upload.id if upload.present?
     end
 

lib/pretty_text.rb

@@ -302,6 +302,7 @@ module PrettyText
     add_rel_attributes_to_user_content(doc, add_nofollow)
     strip_hidden_unicode_bidirectional_characters(doc)
     sanitize_hotlinked_media(doc)
+    add_video_placeholder_image(doc)
 
     add_mentions(doc, user_id: opts[:user_id]) if SiteSetting.enable_mentions
 
@@ -442,6 +443,21 @@ module PrettyText
     links
   end
 
+  def self.add_video_placeholder_image(doc)
+    doc
+      .css(".video-placeholder-container")
+      .each do |video|
+        video_src = video["data-video-src"]
+        video_sha1 = File.basename(video_src, File.extname(video_src))
+        thumbnail = Upload.where("original_filename LIKE ?", "#{video_sha1}.%").last
+        if thumbnail
+          video["data-thumbnail-src"] = UrlHelper.absolute(
+            GlobalPath.upload_cdn_path(thumbnail.url),
+          )
+        end
+      end
+  end
+
   def self.extract_mentions(cooked)
     mentions =
       cooked

spec/system/composer_uploads_spec.rb

@@ -51,7 +51,7 @@ describe "Uploading files in the composer", type: :system do
     # we need to come back to this in a few months and try again.
     #
     # c.f. https://groups.google.com/g/chromedriver-users/c/1SMbByMfO2U
-    xit "generates a thumbnail for the video" do
+    xit "generates a topic preview thumbnail from the video" do
       sign_in(current_user)
 
       visit "/new-topic"
@@ -62,12 +62,38 @@ describe "Uploading files in the composer", type: :system do
       attach_file(file_path_1) { composer.click_toolbar_button("upload") }
 
       expect(composer).to have_no_in_progress_uploads
-      expect(composer.preview).to have_css(".video-container")
+      expect(composer.preview).to have_css(".onebox-placeholder-container")
 
       composer.submit
 
       expect(find("#topic-title")).to have_content("Video upload test")
-      expect(topic.image_upload_id).to eq(Upload.last.id)
+      # I think topic list previews need to be enabled for this?
+      #expect(topic.image_upload_id).to eq(Upload.last.id)
+    end
+
+    it "generates a thumbnail from the video" do
+      sign_in(current_user)
+
+      visit "/new-topic"
+      expect(composer).to be_opened
+      topic.fill_in_composer_title("Video upload test")
+
+      file_path_1 = file_from_fixtures("small.mp4", "media").path
+      attach_file(file_path_1) { composer.click_toolbar_button("upload") }
+
+      expect(composer).to have_no_in_progress_uploads
+      expect(composer.preview).to have_css(".onebox-placeholder-container")
+
+      composer.submit
+
+      expect(find("#topic-title")).to have_content("Video upload test")
+
+      selector = topic.post_by_number_selector(1)
+
+      expect(page).to have_css(selector)
+      within(selector) do
+        expect(page).to have_css(".video-placeholder-container[data-thumbnail-src]")
+      end
     end
   end
 end