feat(v3): simplify the project to contain only required tools

backend/processing/services.py

@@ -1,13 +1,15 @@
 import time
 
+import cv2
 import numpy as np
 from django.conf import settings
+from django.db.models import Max
 from django.utils import timezone
 
 from .algorithms import ProcessingError, average_images, decode_image, histogram, histogram_payload, normalize_to_uint8, process_image, verify_registration
 from .models import ImageSession, ImageState, ProcessingJob
 from .registry import apply_registered_operation
-from .storage import load_image_array, payload_for_image, save_image_array
+from .storage import delete_relative_file, load_image_array, payload_for_image, save_image_array
 from .tasks import run_batch_job
 
 
@@ -15,7 +17,7 @@ def image_session_create(*, uploaded_file=None, image_base64=None):
     if uploaded_file and uploaded_file.size > settings.MAX_UPLOAD_MB * 1024 * 1024:
         raise ProcessingError(f"Upload exceeds {settings.MAX_UPLOAD_MB} MB.")
 
-    image = decode_image(uploaded_file=uploaded_file, base64_image=image_base64)
+    image = compact_workspace_image(decode_image(uploaded_file=uploaded_file, base64_image=image_base64))
     relative_path = save_image_array(image, "original")
     hist = histogram(image)
     session = ImageSession.objects.create(
@@ -52,9 +54,23 @@ def image_session_create(*, uploaded_file=None, image_base64=None):
     return payload
 
 
+def compact_workspace_image(image):
+    max_dimension = int(getattr(settings, "IMAGE_WORKSPACE_MAX_DIMENSION", 1400))
+    if max_dimension <= 0:
+        return image
+    height, width = image.shape[:2]
+    longest = max(width, height)
+    if longest <= max_dimension:
+        return image
+    scale = max_dimension / float(longest)
+    next_size = (max(1, int(round(width * scale))), max(1, int(round(height * scale))))
+    return cv2.resize(image, next_size, interpolation=cv2.INTER_AREA).astype(np.uint8)
+
+
 def image_state_create(*, session, parent, image, operation, params, label=None, prefix="state"):
     relative_path = save_image_array(image, prefix)
-    sequence = session.states.count()
+    max_sequence = session.states.aggregate(value=Max("sequence"))["value"]
+    sequence = 0 if max_sequence is None else max_sequence + 1
     state = ImageState.objects.create(
         session=session,
         parent=parent,
@@ -101,6 +117,15 @@ def image_states_payload(*, states):
     return [image_state_payload(state=state, include_image=True) for state in states]
 
 
+def image_state_delete(*, state):
+    if state.sequence == 0 or state.operation == "upload":
+        raise ProcessingError("The original S0 upload state cannot be deleted.")
+    image_path = state.image
+    state.children.update(parent=None)
+    state.delete()
+    delete_relative_file(image_path)
+
+
 def image_state_apply_operation(*, state, operation, params):
     if state.session.expired:
         raise ProcessingError("Image session has expired.")