Merge PIL and OpenCV in `plot_one_box(use_pil=False)` (#4416)

* Merge PIL and OpenCV box plotting functions

* Add ASCII check to plot_one_box

* Cleanup

* Cleanup2

detect.py

                     if save_img or save_crop or view_img:  # Add bbox to image
                         c = int(cls)  # integer class
                         label = None if hide_labels else (names[c] if hide_conf else f'{names[c]} {conf:.2f}')
-                        plot_one_box(xyxy, im0, label=label, color=colors(c, True), line_thickness=line_thickness)
+                        im0 = plot_one_box(xyxy, im0, label=label, color=colors(c, True), line_width=line_thickness)
                         if save_crop:
                             save_one_box(xyxy, imc, file=save_dir / 'crops' / names[c] / f'{p.stem}.jpg', BGR=True)
 

models/common.py

                         if crop:
                             save_one_box(box, im, file=save_dir / 'crops' / self.names[int(cls)] / self.files[i])
                         else:  # all others
-                            plot_one_box(box, im, label=label, color=colors(cls))
+                            im = plot_one_box(box, im, label=label, color=colors(cls))
             else:
                 str += '(no detections)'
 

utils/general.py

     return 'site-packages' in Path(__file__).absolute().parts
 
 
+def is_ascii(str=''):
+    # Is string composed of all ASCII (no UTF) characters?
+    return len(str.encode().decode('ascii', 'ignore')) == len(str)
+
+
 def emojis(str=''):
     # Return platform-dependent emoji-safe version of string
-    return str.encode().decode(encoding='ascii', errors='ignore') if platform.system() == 'Windows' else str
+    return str.encode().decode('ascii', 'ignore') if platform.system() == 'Windows' else str
 
 
 def file_size(file):

utils/plots.py

 # Plotting utils
 
+import math
 from copy import copy
 from pathlib import Path
 
 import cv2
-import math
 import matplotlib
 import matplotlib.pyplot as plt
 import numpy as np
 import pandas as pd
 import seaborn as sn
 import torch
-import yaml
 from PIL import Image, ImageDraw, ImageFont
 
-from utils.general import xywh2xyxy, xyxy2xywh
+from utils.general import is_ascii, xyxy2xywh, xywh2xyxy
 from utils.metrics import fitness
 
 # Settings
     return filtfilt(b, a, data)  # forward-backward filter
 
 
-def plot_one_box(x, im, color=(128, 128, 128), label=None, line_thickness=3):
-    # Plots one bounding box on image 'im' using OpenCV
+def plot_one_box(box, im, color=(128, 128, 128), txt_color=(255, 255, 255), label=None, line_width=3, use_pil=False):
+    # Plots one xyxy box on image im with label
     assert im.data.contiguous, 'Image not contiguous. Apply np.ascontiguousarray(im) to plot_on_box() input image.'
-    tl = line_thickness or round(0.002 * (im.shape[0] + im.shape[1]) / 2) + 1  # line/font thickness
-    c1, c2 = (int(x[0]), int(x[1])), (int(x[2]), int(x[3]))
-    cv2.rectangle(im, c1, c2, color, thickness=tl, lineType=cv2.LINE_AA)
-    if label:
-        tf = max(tl - 1, 1)  # font thickness
-        t_size = cv2.getTextSize(label, 0, fontScale=tl / 3, thickness=tf)[0]
-        c2 = c1[0] + t_size[0], c1[1] - t_size[1] - 3
-        cv2.rectangle(im, c1, c2, color, -1, cv2.LINE_AA)  # filled
-        cv2.putText(im, label, (c1[0], c1[1] - 2), 0, tl / 3, [225, 255, 255], thickness=tf, lineType=cv2.LINE_AA)
-
-
-def plot_one_box_PIL(box, im, color=(128, 128, 128), label=None, line_thickness=3):
-    # Plots one bounding box on image 'im' using PIL
-    im = Image.fromarray(im)
-    draw = ImageDraw.Draw(im)
-    line_thickness = line_thickness or max(int(min(im.size) / 200), 2)
-    draw.rectangle(box, width=line_thickness, outline=color)  # plot
-    if label:
-        font = ImageFont.truetype("Arial.ttf", size=max(round(max(im.size) / 40), 12))
-        txt_width, txt_height = font.getsize(label)
-        draw.rectangle([box[0], box[1] - txt_height + 4, box[0] + txt_width, box[1]], fill=color)
-        draw.text((box[0], box[1] - txt_height + 1), label, fill=(255, 255, 255), font=font)
-    return np.asarray(im)
+    lw = line_width or max(int(min(im.size) / 200), 2)  # line width
+
+    if use_pil or not is_ascii(label):  # use PIL
+        im = Image.fromarray(im)
+        draw = ImageDraw.Draw(im)
+        draw.rectangle(box, width=lw + 1, outline=color)  # plot
+        if label:
+            font = ImageFont.truetype("Arial.ttf", size=max(round(max(im.size) / 40), 12))
+            txt_width, txt_height = font.getsize(label)
+            draw.rectangle([box[0], box[1] - txt_height + 4, box[0] + txt_width, box[1]], fill=color)
+            draw.text((box[0], box[1] - txt_height + 1), label, fill=txt_color, font=font)
+        return np.asarray(im)
+    else:  # use OpenCV
+        c1, c2 = (int(box[0]), int(box[1])), (int(box[2]), int(box[3]))
+        cv2.rectangle(im, c1, c2, color, thickness=lw, lineType=cv2.LINE_AA)
+        if label:
+            tf = max(lw - 1, 1)  # font thickness
+            txt_width, txt_height = cv2.getTextSize(label, 0, fontScale=lw / 3, thickness=tf)[0]
+            c2 = c1[0] + txt_width, c1[1] - txt_height - 3
+            cv2.rectangle(im, c1, c2, color, -1, cv2.LINE_AA)  # filled
+            cv2.putText(im, label, (c1[0], c1[1] - 2), 0, lw / 3, txt_color, thickness=tf, lineType=cv2.LINE_AA)
+        return im
 
 
 def plot_wh_methods():  # from utils.plots import *; plot_wh_methods()
                 cls = names[cls] if names else cls
                 if labels or conf[j] > 0.25:  # 0.25 conf thresh
                     label = '%s' % cls if labels else '%s %.1f' % (cls, conf[j])
-                    plot_one_box(box, mosaic, label=label, color=color, line_thickness=tl)
+                    mosaic = plot_one_box(box, mosaic, label=label, color=color, line_width=tl)
 
         # Draw image filename labels
         if paths: