Add Java and Python code for the following imgproc tutorials: Finding contours in your image, Convex Hull, Creating Bounding boxes and circles for contours, Creating Bounding rotated boxes and ellipses for contours, Image Moments, Point Polygon Test.

samples/python/tutorial_code/ShapeDescriptors/find_contours/findContours_demo.py

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+from __future__ import print_function
+import cv2 as cv
+import numpy as np
+import argparse
+import random as rng
+
+rng.seed(12345)
+
+def thresh_callback(val):
+    threshold = val
+
+    # Detect edges using Canny
+    canny_output = cv.Canny(src_gray, threshold, threshold * 2)
+
+    # Find contours
+    _, contours, hierarchy = cv.findContours(canny_output, cv.RETR_TREE, cv.CHAIN_APPROX_SIMPLE)
+
+    # Draw contours
+    drawing = np.zeros((canny_output.shape[0], canny_output.shape[1], 3), dtype=np.uint8)
+    for i in range(len(contours)):
+        color = (rng.randint(0,256), rng.randint(0,256), rng.randint(0,256))
+        cv.drawContours(drawing, contours, i, color, 2, cv.LINE_8, hierarchy, 0)
+
+    # Show in a window
+    cv.imshow('Contours', drawing)
+
+# Load source image
+parser = argparse.ArgumentParser(description='Code for Finding contours in your image tutorial.')
+parser.add_argument('--input', help='Path to input image.', default='../data/HappyFish.jpg')
+args = parser.parse_args()
+
+src = cv.imread(args.input)
+if src is None:
+    print('Could not open or find the image:', args.input)
+    exit(0)
+
+# Convert image to gray and blur it
+src_gray = cv.cvtColor(src, cv.COLOR_BGR2GRAY)
+src_gray = cv.blur(src_gray, (3,3))
+
+# Create Window
+source_window = 'Source'
+cv.namedWindow(source_window)
+cv.imshow(source_window, src)
+max_thresh = 255
+thresh = 100 # initial threshold
+cv.createTrackbar('Canny Thresh:', source_window, thresh, max_thresh, thresh_callback)
+thresh_callback(thresh)
+
+cv.waitKey()