Move to real LaTeX rendering

annotating.py

@@ -219,6 +219,71 @@ def render_latex_text(text, width_px, bg_color=(255, 255, 255, 255), max_lines=N
     final_img.alpha_composite(img)
     return final_img
 
+import os
+import tempfile
+import subprocess
+import PIL.ImageOps
+
+
+def render_real_latex_text(text, width_px, bg_color=(255, 255, 255, 255), max_lines=None, fontsize=19):
+    dpi = 100
+    width_in = width_px / dpi
+    line_spacing = int(fontsize * 1.2)
+
+    # Use the 'standalone' class with 'varwidth' to auto-crop height while restricting width
+    latex_template = f"""\\documentclass[varwidth={width_in}in,margin=0.2cm]{{standalone}}
+\\usepackage[utf8]{{inputenc}}
+\\usepackage[T1]{{fontenc}}
+\\usepackage{{lmodern}}  % Enables arbitrary font scaling
+\\usepackage{{amsmath, amssymb}}
+%\\usepackage{{anyfontsize}} % replaces by lmodern
+\\begin{{document}}
+\\fontsize{{{fontsize}}}{{{line_spacing}}}\\selectfont
+{text}
+\\end{{document}}
+"""
+
+    with tempfile.TemporaryDirectory() as temp_dir:
+        tex_path = os.path.join(temp_dir, 'text.tex')
+        pdf_path = os.path.join(temp_dir, 'text.pdf')
+
+        with open(tex_path, 'w', encoding='utf-8') as f:
+            f.write(latex_template)
+
+        # Compile to PDF
+        result = subprocess.run(
+            ['pdflatex', '-interaction=nonstopmode', 'text.tex'],
+            cwd=temp_dir,
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL
+        )
+
+        if not os.path.exists(pdf_path):
+            raise RuntimeError("LaTeX compilation failed. Check your LaTeX syntax.")
+
+        # Convert PDF to grayscale (ignoring pdf2image's broken transparency)
+        images = convert_from_path(pdf_path, dpi=dpi)
+        gray_img = images[0].convert("L")
+
+    # 1. Invert grayscale to create an alpha mask (white bg = 0, black text = 255)
+    alpha_mask = PIL.ImageOps.invert(gray_img)
+
+    # 2. Create a transparent image with black text using the mask
+    text_img = Image.new("RGBA", gray_img.size, (0, 0, 0, 255))
+    text_img.putalpha(alpha_mask)
+
+    # 3. Create the requested background and composite the text over it
+    final_img = Image.new("RGBA", text_img.size, bg_color)
+    final_img.alpha_composite(text_img)
+
+    # (Optional) Truncate image height if max_lines is strictly enforced
+    if max_lines:
+        max_height_px = int((fontsize * 1.2 / 72.0) * dpi * max_lines) # Points to pixels
+        if final_img.height > max_height_px:
+            final_img = final_img.crop((0, 0, final_img.width, max_height_px))
+
+    return final_img
+
 import io
 from PIL import Image
 import matplotlib.pyplot as plt
@@ -376,7 +441,7 @@ def compose_label_image(base_img, label, result, hmin,
 
         # Render Text
         txt_img = render_fn(fb['text'], width_px=ANNOT_WIDTH,
-                            bg_color=(255, 200, 200, 180), max_lines=3)
+                            bg_color=(255, 200, 200, 180), max_lines=None)
 
         # Calculate Position
         center_y = (target_ymin + target_ymax) / 2
@@ -458,7 +523,8 @@ def process_student(student_id, labels_data, root_dir, all_labels, overwrite):
         d_notes[label] = str(score)
 
         final_img, _ = compose_label_image(base_img, label, result, coordinates[0],
-                                           with_empty=True)
+                                           with_empty=True,
+                                           render_fn=render_real_latex_text)
         # 7. Save Image
         save_path = os.path.join(output_dir, f"{label}.jpg")
         final_img.save(save_path)