Add bounding box primitive (#251)

* Add bounding box primitive

Signed-off-by: Ashwin Vaidya <ashwinnitinvaidya@gmail.com>

* Add docstring

Signed-off-by: Ashwin Vaidya <ashwinnitinvaidya@gmail.com>

---------

Signed-off-by: Ashwin Vaidya <ashwinnitinvaidya@gmail.com>

model_api/python/model_api/visualizer/__init__.py

@@ -1,11 +1,11 @@
 """Visualizer."""
 
-# Copyright (C) 2024 Intel Corporation
+# Copyright (C) 2024-2025 Intel Corporation
 # SPDX-License-Identifier: Apache-2.0
 
 from .layout import Flatten, HStack, Layout
-from .primitive import Overlay
+from .primitive import BoundingBox, Overlay
 from .scene import Scene
 from .visualizer import Visualizer
 
-__all__ = ["Overlay", "Scene", "Visualizer", "Layout", "Flatten", "HStack"]
+__all__ = ["BoundingBox", "Overlay", "Scene", "Visualizer", "Layout", "Flatten", "HStack"]

model_api/python/model_api/visualizer/primitive.py

@@ -9,16 +9,70 @@
 
 import numpy as np
 import PIL
+from PIL import Image, ImageDraw
 
 
 class Primitive(ABC):
     """Primitive class."""
 
     @abstractmethod
-    def compute(self, image: PIL.Image) -> PIL.Image:
+    def compute(self, image: Image) -> Image:
         pass
 
 
+class BoundingBox(Primitive):
+    """Bounding box primitive.
+
+    Args:
+        x1 (int): x-coordinate of the top-left corner of the bounding box.
+        y1 (int): y-coordinate of the top-left corner of the bounding box.
+        x2 (int): x-coordinate of the bottom-right corner of the bounding box.
+        y2 (int): y-coordinate of the bottom-right corner of the bounding box.
+        label (str | None): Label of the bounding box.
+        color (str | tuple[int, int, int]): Color of the bounding box.
+
+    Example:
+        >>> bounding_box = BoundingBox(x1=10, y1=10, x2=100, y2=100, label="Label Name")
+        >>> bounding_box.compute(image)
+    """
+
+    def __init__(
+        self,
+        x1: int,
+        y1: int,
+        x2: int,
+        y2: int,
+        label: str | None = None,
+        color: str | tuple[int, int, int] = "blue",
+    ) -> None:
+        self.x1 = x1
+        self.y1 = y1
+        self.x2 = x2
+        self.y2 = y2
+        self.label = label
+        self.color = color
+        self.y_buffer = 5  # Text at the bottom of the text box is clipped. This prevents that.
+
+    def compute(self, image: Image) -> Image:
+        draw = ImageDraw.Draw(image)
+        # draw rectangle
+        draw.rectangle((self.x1, self.y1, self.x2, self.y2), outline=self.color, width=2)
+        # add label
+        if self.label:
+            # draw the background of the label
+            textbox = draw.textbbox((0, 0), self.label)
+            label_image = Image.new(
+                "RGB",
+                (textbox[2] - textbox[0], textbox[3] + self.y_buffer - textbox[1]),
+                self.color,
+            )
+            draw = ImageDraw.Draw(label_image)
+            # write the label on the background
+            draw.text((0, 0), self.label, fill="white")
+            image.paste(label_image, (self.x1, self.y1))
+        return image
+
+
 class Overlay(Primitive):
     """Overlay primitive.
 

tests/python/unit/visualizer/test_primitive.py

@@ -5,8 +5,9 @@
 
 import numpy as np
 import PIL
+from PIL import ImageDraw
 
-from model_api.visualizer import Overlay
+from model_api.visualizer import BoundingBox, Overlay
 
 
 def test_overlay(mock_image: PIL.Image):
@@ -22,3 +23,12 @@ def test_overlay(mock_image: PIL.Image):
     data *= 255
     overlay = Overlay(data)
     assert overlay.compute(empty_image) == expected_image
+
+
+def test_bounding_box(mock_image: PIL.Image):
+    """Test if the bounding box is created correctly."""
+    expected_image = mock_image.copy()
+    draw = ImageDraw.Draw(expected_image)
+    draw.rectangle((10, 10, 100, 100), outline="blue", width=2)
+    bounding_box = BoundingBox(x1=10, y1=10, x2=100, y2=100)
+    assert bounding_box.compute(mock_image) == expected_image