【python】opencv教程CV2模块——画图，来左边跟我一起画星星在右边画彩虹

opencv教程CV2模块——画图，来左边跟我一起画星星在右边画彩虹

import numpy as np
import cv2

# 定义一块宽600，高400的画布，初始化为白色
canvas = np.zeros((400, 600, 3), dtype=np.uint8) + 255

# 画一条纵向的正中央的黑色分界线
cv2.line(canvas, (300, 0), (300, 399), (0, 0, 0), 2)

# 画一条右半部份画面以150为界的横向分界线
cv2.line(canvas, (300, 149), (599, 149), (0, 0, 0), 2)

# 左半部分的右下角画个红色的圆
cv2.circle(canvas, (200, 300), 75, (0, 0, 255), 5)

# 左半部分的左下角画个蓝色的矩形
cv2.rectangle(canvas, (20, 240), (100, 360), (255, 0, 0), thickness=3)

# 定义两个三角形，并执行内部绿色填充
triangles = np.array([
    [(200, 240), (145, 333), (255, 333)],
    [(60, 180), (20, 237), (100, 237)]])
cv2.fillPoly(canvas, triangles, (0, 255, 0))

# 画一个黄色五角星
# 第一步通过旋转角度的办法求出五个顶点
phi = 4 * np.pi / 5
rotations = [[[np.cos(i * phi), -np.sin(i * phi)], [i * np.sin(phi), np.cos(i * phi)]] for i in range(1, 5)]
pentagram = np.array([[[[0, -1]] + [np.dot(m, (0, -1)) for m in rotations]]], dtype=np.float)

# 定义缩放倍数和平移向量把五角星画在左半部分画面的上方
pentagram = np.round(pentagram * 80 + np.array([160, 120])).astype(np.int)

# 将5个顶点作为多边形顶点连线，得到五角星
cv2.polylines(canvas, pentagram, True, (0, 255, 255), 9)

# 按像素为间隔从左至右在画面右半部份的上方画出HSV空间的色调连续变化
for x in range(302, 600):
    color_pixel = np.array([[[round(180*float(x-302)/298), 255, 255]]], dtype=np.uint8)
    line_color = [int(c) for c in cv2.cvtColor(color_pixel, cv2.COLOR_HSV2BGR)[0][0]]
    cv2.line(canvas, (x, 0), (x, 147), line_color)

# 如果定义圆的线宽大于半斤，则等效于画圆点，随机在画面右下角的框内生成坐标
np.random.seed(42)
n_pts = 30
pts_x = np.random.randint(310, 590, n_pts)
pts_y = np.random.randint(160, 390, n_pts)
pts = zip(pts_x, pts_y)

# 画出每个点，颜色随机
for pt in pts:
    pt_color = [int(c) for c in np.random.randint(0, 255, 3)]
    cv2.circle(canvas, pt, 3, pt_color, 5)

# 在左半部分最上方打印文字
cv2.putText(canvas,
            'Drawing Example',
            (5, 15),
            cv2.FONT_HERSHEY_SIMPLEX,
            0.5,
            (0, 0, 0),
            1)

cv2.imshow('Example of basic drawing functions', canvas)
cv2.waitKey()

效果图：

不过，论画图哪家强，还是推荐python龟，啊哈哈哈哈！