Cache loaded fonts

Author: tybulewicz

src/model_api/visualizer/primitive/bounding_box.py

@@ -5,9 +5,10 @@
 
 from __future__ import annotations
 
-from PIL import Image, ImageDraw, ImageFont
+from PIL import Image, ImageDraw
 
 from model_api.visualizer.defaults import DEFAULT_FONT_SIZE, DEFAULT_OUTLINE_WIDTH
+from model_api.visualizer.utils import default_font
 
 from .primitive import Primitive
 
@@ -49,7 +50,7 @@ def __init__(
         self.color = color
         self.outline_width = outline_width
         self.font_size = font_size
-        self.font = ImageFont.load_default(size=self.font_size)
+        self.font = default_font(size=self.font_size)
         self.y_buffer = max(3, font_size // 3)  # Text at the bottom of the text box is clipped. This prevents that.
 
     def compute(self, image: Image) -> Image:

src/model_api/visualizer/primitive/keypoints.py

@@ -6,9 +6,10 @@
 from typing import Union
 
 import numpy as np
-from PIL import Image, ImageDraw, ImageFont
+from PIL import Image, ImageDraw
 
 from model_api.visualizer.defaults import DEFAULT_FONT_SIZE, DEFAULT_KEYPOINT_SIZE
+from model_api.visualizer.utils import default_font
 
 from .primitive import Primitive
 
@@ -51,7 +52,7 @@ def compute(self, image: Image) -> Image:
             )
 
         if self.scores is not None:
-            font = ImageFont.load_default(size=self.font_size)
+            font = default_font(size=self.font_size)
             for score, keypoint in zip(self.scores, self.keypoints):
                 textbox = draw.textbbox((0, 0), f"{score:.2f}", font=font)
                 draw.text(

src/model_api/visualizer/primitive/label.py

@@ -6,9 +6,10 @@
 from io import BytesIO
 from typing import Union
 
-from PIL import Image, ImageDraw, ImageFont
+from PIL import Image, ImageDraw
 
 from model_api.visualizer.defaults import DEFAULT_FONT_SIZE
+from model_api.visualizer.utils import default_font, truetype_font
 
 from .primitive import Primitive
 
@@ -53,7 +54,7 @@ def __init__(
         self.label = f"{label} ({score:.2f})" if score is not None else label
         self.fg_color = fg_color
         self.bg_color = bg_color
-        self.font = ImageFont.load_default(size=size) if font_path is None else ImageFont.truetype(font_path, size)
+        self.font = default_font(size=size) if font_path is None else truetype_font(font_path, size)
 
     def compute(self, image: Image, buffer_y: int = 5) -> Image:
         """Generate label on top of the image.

src/model_api/visualizer/primitive/overlay.py

@@ -9,9 +9,9 @@
 
 import numpy as np
 import PIL
-from PIL import ImageFont
 
 from model_api.visualizer.defaults import DEFAULT_FONT_SIZE, DEFAULT_OPACITY
+from model_api.visualizer.utils import default_font
 
 from .primitive import Primitive
 
@@ -66,7 +66,7 @@ def overlay_labels(
         """
         if labels is not None:
             labels = [labels] if isinstance(labels, str) else labels
-            font = ImageFont.load_default(size=font_size)
+            font = default_font(size=font_size)
             buffer_y = max(3, font_size // 3)
             dummy_image = PIL.Image.new("RGB", (1, 1))
             draw = PIL.ImageDraw.Draw(dummy_image)

src/model_api/visualizer/scene/detection.py

@@ -12,9 +12,9 @@
 from model_api.visualizer.defaults import DEFAULT_FONT_SIZE, DEFAULT_OUTLINE_WIDTH
 from model_api.visualizer.layout import Flatten, HStack, Layout
 from model_api.visualizer.primitive import BoundingBox, Label, Overlay
+from model_api.visualizer.utils import get_label_color_mapping
 
 from .scene import Scene
-from .utils import get_label_color_mapping
 
 
 class DetectionScene(Scene):

src/model_api/visualizer/scene/segmentation/instance_segmentation.py

@@ -13,7 +13,7 @@
 from model_api.visualizer.layout import Flatten, HStack, Layout
 from model_api.visualizer.primitive import BoundingBox, Label, Overlay, Polygon
 from model_api.visualizer.scene import Scene
-from model_api.visualizer.scene.utils import get_label_color_mapping
+from model_api.visualizer.utils import get_label_color_mapping
 
 
 class InstanceSegmentationScene(Scene):

src/model_api/visualizer/scene/utils.py src/model_api/visualizer/utils.pysrc/model_api/visualizer/scene/utils.py renamed to src/model_api/visualizer/utils.py

@@ -1,5 +1,9 @@
 """Visualizer utilities."""
 
+from functools import lru_cache
+
+from PIL import ImageFont
+
 # Copyright (C) 2026 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
@@ -38,3 +42,28 @@ def get_label_color_mapping(labels: list[str]) -> dict[str, str]:
     """
     unique_labels = sorted(set(labels))
     return {label: COLOR_PALETTE[i % len(COLOR_PALETTE)] for i, label in enumerate(unique_labels)}
+
+
+@lru_cache(maxsize=5)
+def default_font(size: int = 10):
+    """Get the default font with the specified size using cache to store the object.
+
+    Args:
+        size: Font size.
+
+    Returns:
+        A PIL ImageFont instance with the default font and specified size.
+    """
+    return ImageFont.load_default(size=size)
+
+
+@lru_cache(maxsize=5)
+def truetype_font(font_path: str, size: int = 10):
+    """Get a TrueType font from the specified path and size using cache to store the object.
+
+    Args:
+        font_path: Path to the .ttf font file.
+        size: Font size.
+    """
+
+    return ImageFont.truetype(font_path, size)