Add alt text support for attachments

README.md

@@ -30,7 +30,7 @@ It is still in early development, this README will be updated when I get to depl
     - Strict access control for your outbox enforced via HTTP signature
  - **No** Javascript
     - The UI is pure HTML/CSS
-    - Except a tiny bit of hand-written JS in the note composer to insert emoji
+    - Except tiny bits of hand-written JS in the note composer to insert emoji and add alt text to images
  - IndieWeb citizen
     - [IndieAuth](https://www.w3.org/TR/indieauth/) support (OAuth2 extension)
     - [Microformats](http://microformats.org/wiki/Main_Page) everywhere

alembic/versions/c9f204f5611d_alt_text_for_attachments.py

@@ -0,0 +1,32 @@
+"""Alt text for attachments
+
+Revision ID: c9f204f5611d
+Revises: 8ae9fc9ac88c
+Create Date: 2022-07-21 22:33:41.569754
+
+"""
+import sqlalchemy as sa
+
+from alembic import op
+
+# revision identifiers, used by Alembic.
+revision = 'c9f204f5611d'
+down_revision = '8ae9fc9ac88c'
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('outbox_object_attachment', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('alt', sa.String(), nullable=True))
+
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('outbox_object_attachment', schema=None) as batch_op:
+        batch_op.drop_column('alt')
+
+    # ### end Alembic commands ###

app/admin.py

@@ -662,10 +662,12 @@ async def admin_actions_new(
 ) -> RedirectResponse:
     # XXX: for some reason, no files restuls in an empty single file
     uploads = []
+    raw_form_data = await request.form()
     if len(files) >= 1 and files[0].filename:
         for f in files:
             upload = await save_upload(db_session, f)
-            uploads.append((upload, f.filename))
+            uploads.append((upload, f.filename, raw_form_data.get("alt_" + f.filename)))
+
     public_id = await boxes.send_create(
         db_session,
         source=content,

app/boxes.py

@@ -286,7 +286,7 @@ async def send_undo(db_session: AsyncSession, ap_object_id: str) -> None:
 async def send_create(
     db_session: AsyncSession,
     source: str,
-    uploads: list[tuple[models.Upload, str]],
+    uploads: list[tuple[models.Upload, str, str | None]],
     in_reply_to: str | None,
     visibility: ap.VisibilityEnum,
     content_warning: str | None = None,
@@ -315,8 +315,8 @@ async def send_create(
                 .values(replies_count=models.OutboxObject.replies_count + 1)
             )
 
-    for (upload, filename) in uploads:
-        attachments.append(upload_to_attachment(upload, filename))
+    for (upload, filename, alt_text) in uploads:
+        attachments.append(upload_to_attachment(upload, filename, alt_text))
 
     to = []
     cc = []
@@ -366,9 +366,12 @@ async def send_create(
             )
             db_session.add(tagged_object)
 
-    for (upload, filename) in uploads:
+    for (upload, filename, alt) in uploads:
         outbox_object_attachment = models.OutboxObjectAttachment(
-            filename=filename, outbox_object_id=outbox_object.id, upload_id=upload.id
+            filename=filename,
+            alt=alt,
+            outbox_object_id=outbox_object.id,
+            upload_id=upload.id,
         )
         db_session.add(outbox_object_attachment)
 

app/main.py

@@ -77,7 +77,6 @@ _RESIZED_CACHE: MutableMapping[tuple[str, int], tuple[bytes, str, Any]] = LFUCac
 #
 # Next:
 # - show pending follow request (and prevent double follow?)
-# - a way to add alt text on image (maybe via special markup in content?)
 # - UI support for updating posts
 # - Support for processing update
 # - Article support

app/models.py

@@ -234,7 +234,7 @@ class OutboxObject(Base, BaseObject):
                     {
                         "type": "Document",
                         "mediaType": attachment.upload.content_type,
-                        "name": attachment.filename,
+                        "name": attachment.alt or attachment.filename,
                         "url": url,
                         "proxiedUrl": url,
                         "resizedUrl": BASE_URL
@@ -403,6 +403,7 @@ class OutboxObjectAttachment(Base):
     id = Column(Integer, primary_key=True, index=True)
     created_at = Column(DateTime(timezone=True), nullable=False, default=now)
     filename = Column(String, nullable=False)
+    alt = Column(String, nullable=True)
 
     outbox_object_id = Column(Integer, ForeignKey("outbox.id"), nullable=False)
 

app/static/new.js

@@ -30,3 +30,23 @@ var items = document.getElementsByClassName("ji")
 for (var i = 0; i < items.length; i++) {
     items[i].addEventListener('click', ji);
 }
+
+// Add new input text dynamically to allow setting an alt text on attachments
+var files = document.getElementById("files");
+var alts = document.getElementById("alts");
+files.addEventListener("change", function(e) {
+    // Reset the div content
+    alts.innerHTML = "";
+
+    // Add an input for each files
+    for (var i = 0; i < e.target.files.length; i++) {
+        var p = document.createElement("p");
+        var altInput = document.createElement("input");
+        altInput.setAttribute("type", "text");
+        altInput.setAttribute("name", "alt_" + e.target.files[i].name);
+        altInput.setAttribute("placeholder", "Alt text for " + e.target.files[i].name);
+        altInput.setAttribute("style", "width:95%;")
+        p.appendChild(altInput);
+        alts.appendChild(p);
+    }
+});

app/templates/admin_new.html

@@ -39,8 +39,9 @@
     </p>
     <input type="hidden" name="in_reply_to" value="{{ request.query_params.in_reply_to }}">
     <p>
-        <input name="files" type="file" multiple>
+        <input id="files" name="files" type="file" multiple style="width:95%;">
     </p>
+    <div id="alts"></div>
     <p>
         <input type="submit" value="Publish">
     </p>

app/uploads.py

@@ -96,7 +96,11 @@ async def save_upload(db_session: AsyncSession, f: UploadFile) -> models.Upload:
     return new_upload
 
 
-def upload_to_attachment(upload: models.Upload, filename: str) -> ap.RawObject:
+def upload_to_attachment(
+    upload: models.Upload,
+    filename: str,
+    alt_text: str | None,
+) -> ap.RawObject:
     extra_attachment_fields = {}
     if upload.blurhash:
         extra_attachment_fields.update(
@@ -109,7 +113,7 @@ def upload_to_attachment(upload: models.Upload, filename: str) -> ap.RawObject:
     return {
         "type": "Document",
         "mediaType": upload.content_type,
-        "name": filename,
+        "name": alt_text or filename,
         "url": BASE_URL + f"/attachments/{upload.content_hash}/{filename}",
         **extra_attachment_fields,
     }