Paginate photo-only PDF pages by capacity

Compute the max number of images that can fit on a photo-only page based on available height and minimum cell size.
Chunk overflow photos across additional continued pages instead of shrinking frames too far.
Align spacing constants for photo grids so continued pages match the main template.

server/app/services/pdf_reportlab.py

@@ -224,9 +224,12 @@ def render_report_pdf(
     footer_h = 8 * mm
     gap = 4 * mm
     photo_col_gap = 6 * mm
+    photo_row_gap = 6 * mm
+    photos_header_gap = 8 * mm
     min_photo_cell_w = 80 * mm
+    min_photo_cell_h = 60 * mm
     two_col_cell_w = (width - 2 * margin - photo_col_gap) / 2
-    max_photos_per_page = 6 if two_col_cell_w >= min_photo_cell_w else 2
+    columns_for_photos = 2 if two_col_cell_w >= min_photo_cell_w else 1
 
     gray_50 = colors.HexColor("#f9fafb")
     gray_200 = colors.HexColor("#e5e7eb")
@@ -260,6 +263,15 @@ def render_report_pdf(
     uploads = (session.get("uploads") or {}).get("photos") or []
     by_id = {item.get("id"): item for item in uploads if item.get("id")}
 
+    content_top = height - margin - header_h - gap
+    content_bottom = margin + footer_h + gap
+    photo_area_height_photos = max(0, content_top - photos_header_gap - content_bottom)
+    max_rows_photos = max(
+        1,
+        int((photo_area_height_photos + photo_row_gap) // (min_photo_cell_h + photo_row_gap)),
+    )
+    max_photos_photos = max(1, max_rows_photos * columns_for_photos)
+
     sections: List[dict]
     if sections_or_pages and isinstance(sections_or_pages[0], dict) and "pages" in sections_or_pages[0]:
         sections = sections_or_pages
@@ -286,21 +298,35 @@ def render_report_pdf(
                 if path and path.exists():
                     label = _safe_text(item.get("name") or path.name)
                     photo_entries.append({"path": path, "label": label})
-            chunks = _chunk(photo_entries, max_photos_per_page) or [[]]
-            for chunk_index, chunk in enumerate(chunks):
-                if base_variant == "photos":
-                    variant = "photos"
-                else:
+            if base_variant == "photos":
+                chunks = _chunk(photo_entries, max_photos_photos) or [[]]
+                for chunk in chunks:
+                    print_pages.append(
+                        {
+                            "page_index": page_index,
+                            "template": template,
+                            "photos": chunk,
+                            "variant": "photos",
+                            "section_index": section_index,
+                        }
+                    )
+            else:
+                first_chunk = photo_entries[:2]
+                remainder = photo_entries[2:]
+                chunks = [first_chunk]
+                if remainder:
+                    chunks.extend(_chunk(remainder, max_photos_photos))
+                for chunk_index, chunk in enumerate(chunks):
                     variant = "full" if chunk_index == 0 else "photos"
-                print_pages.append(
-                    {
-                        "page_index": page_index,
-                        "template": template,
-                        "photos": chunk,
-                        "variant": variant,
-                        "section_index": section_index,
-                    }
-                )
+                    print_pages.append(
+                        {
+                            "page_index": page_index,
+                            "template": template,
+                            "photos": chunk,
+                            "variant": variant,
+                            "section_index": section_index,
+                        }
+                    )
 
     if not print_pages:
         print_pages = [
@@ -378,7 +404,7 @@ def render_report_pdf(
             pdf.drawString(margin, y, "Observations and Findings")
             pdf.setStrokeColor(gray_200)
             pdf.line(margin, y - 2, width - margin, y - 2)
-            y -= 8 * mm
+            y -= photos_header_gap
 
             ref = _safe_text(template.get("reference"))
             area = _safe_text(template.get("area"))
@@ -578,7 +604,7 @@ def render_report_pdf(
             pdf.drawString(margin, y, "Photo Documentation (continued)")
             pdf.setStrokeColor(gray_200)
             pdf.line(margin, y - 2, width - margin, y - 2)
-            y -= 8 * mm
+            y -= photos_header_gap
 
         if variant == "full":
             y -= 2 * mm
@@ -595,16 +621,16 @@ def render_report_pdf(
         if photos:
             columns = 1 if len(photos) == 1 else 2
             rows = math.ceil(len(photos) / columns)
-            cell_w = (width - 2 * margin - (columns - 1) * 6 * mm) / columns
-            cell_h = (photo_area_height - (rows - 1) * 6 * mm) / rows
+            cell_w = (width - 2 * margin - (columns - 1) * photo_col_gap) / columns
+            cell_h = (photo_area_height - (rows - 1) * photo_row_gap) / rows
 
             for idx, photo in enumerate(photos):
                 photo_path = photo["path"]
                 label = photo.get("label") or photo_path.name
                 row = idx // columns
                 col = idx % columns
-                x = margin + col * (cell_w + 6 * mm)
-                y = photo_area_top - (row + 1) * cell_h - row * 6 * mm
+                x = margin + col * (cell_w + photo_col_gap)
+                y = photo_area_top - (row + 1) * cell_h - row * photo_row_gap
                 pdf.setStrokeColor(gray_200)
                 pdf.setFillColor(gray_50)
                 pdf.roundRect(x, y, cell_w, cell_h, 3 * mm, stroke=1, fill=1)