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Rectangular Circle Drawing

1. Drawing a Rectangle

rectangle(img, pt1, pt2, color, thickness=None, lineType=None, shift=None)

Parameter description:

img: The canvas or carrier image.

pt1, pt2: Required parameters. Vertices of the rectangle, representing the top-left corner and bottom-right corner respectively (these two vertices define a unique rectangle).

color: Required parameter. Used to set the color of the rectangle.

thickness: Optional parameter. Used to set the width of the rectangle border. When negative, it indicates filling the rectangle.

lineType: Optional parameter. Used to set the type of the line segment. Options are 8 (8-connected line - default), 4 (4-connected line), and cv2.LINE_AA for anti-aliasing.

2. Drawing a Circle

cv2.circle(img, center, radius, color[, thickness[, lineType]])

Parameter description:

img: The canvas or carrier image.

center: The center coordinates of the circle, format: (50,50)

radius: The radius.

color: The color.

thickness: Line thickness. Default is 1. If -1, it fills the circle solid.

lineType: Line type. Default is 8 (connected type). As described in the table below:

3. Drawing an Ellipse

cv2.ellipse(img, center, axes, angle, StartAngle, endAngle, color[, thickness[, lineType]])

center: The center point of the ellipse, (x, x)

axes: Refers to the minor radius and major radius, (x, x)

angle: Refers to the angle of counterclockwise rotation

StartAngle: The start angle of the arc

endAngle: The end angle of the arc

img, color: Refer to the circle description.

# The fifth parameter refers to the angle at which the drawing starts counterclockwise, and the sixth refers to the angle at which the drawing ends counterclockwise

# If the fourth, fifth, and sixth parameters are added with a symbol, it means the opposite direction, that is, the clockwise direction

4. Drawing a Polygon

cv2.polylines(img, [pts], isClosed, color[, thickness[, lineType]])

pts: The vertices of the polygon

isClosed: Whether it is closed (True/False)

Other parameters refer to the circle drawing parameters.

Code path:

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~/dofbot_opencv/scripts/3.draw_picture/05_rectangle_circle.ipynb

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import cv2
import numpy as np
newImageInfo = (500,500,3)
dst = np.zeros(newImageInfo,np.uint8)
# 1 2 top-left corner 3 bottom-right corner 4 5 fill -1 >0 line w
cv2.rectangle(dst,(350,100),(400,270),(0,255,0),3)
# 2 center 3 r
cv2.circle(dst,(250,250),(50),(255,0,0),2)
# 2 center 3 axes 4 angle 5 begin 6 end 7
cv2.ellipse(dst, (256,256), (150,100), 0, 0, 180, (0,255,255), -1)
points = np.array([[150,50], [140,140], [200,170], [250,250], [150,50]], np.int32)
#print(points.shape)
points = points.reshape((-1,1,2))
#print(points.shape)
cv2.polylines(dst,[points],True,(255,255,0))
# cv2.imshow('dst',dst)
    # cv2.waitKey(0)

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import matplotlib.pyplot as plt
dst = cv2.cvtColor(dst, cv2.COLOR_BGR2RGB)
plt.imshow(dst)
plt.show()