이미지 주변에 투명 padding을 추가하는 Service.

일단 핵심 기능에 필요한 부분만 구현

back-end2/src/services/padding_service.py

+import numpy as np
+import cv2
+
+from models.builders.composited_image_builer import CompositedImageBuilder
+from utils.image.image_compositer import ImageCompister
+
+class PaddingService:
+    """
+    mask에 있는 객체를 모두 포함하는 직사각형이 장변이 ratio(%) 만큼
+    """
+    def add_square_padding_according_to_mask(self, inner_np_image, mask, ratio = 50) -> "CompsitedImage":
+        if mask is None:
+            if inner_np_image.shape[0] >= inner_np_image.shape[0]:
+                long_length = inner_np_image.shape[0]
+            else:
+                long_length = inner_np_image.shape[1]
+        else:
+            long_length = mask.get_long_side_length()
+
+        new_length = int(100 * long_length / ratio)
+
+
+        inner_np_image_width = inner_np_image.shape[1]
+        inner_np_image_height = inner_np_image.shape[0]
+
+        x_offset = int((new_length - inner_np_image_width) / 2)
+        y_offset = int((new_length - inner_np_image_height) / 2)
+
+        transparent_image = np.zeros((new_length, new_length, 4), dtype=np.uint8)
+        inner_np_image = cv2.cvtColor(inner_np_image, cv2.COLOR_RGB2RGBA)
+        padded_np_image = ImageCompister().composite(transparent_image, inner_np_image, x_offset, y_offset)
+
+        padded_image = (
+            CompositedImageBuilder()
+            .set_outer_image(transparent_image)
+            .set_inner_image(inner_np_image)
+            .set_composited_image(padded_np_image)
+            .set_x_offset(x_offset)
+            .set_y_offset(y_offset)
+            .build())
+        return padded_image
+    
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