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OpenCV(四)-图形的绘制

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一、直线

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(function) def line(
    img: MatLike,	# img: 在哪个图像上画线
    pt1: Point,		# 开始点、结束点：指定线的开始与结束位置
    pt2: Point,
    color: Scalar,
    thickness: int = ...,
    lineType: int = ...,	# 线类型：-1，4，8，16，16最光滑
    shift: int = ...	# Shift:坐标缩放比例
) -> MatLike
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import cv2
import numpy as np

img = np.zeros((300, 400, 3), np.uint8)

# 画线坐标（x, y)，不是设置页面的（y,x)


cv2.line(img, (10, 20), (300, 100), (0, 0, 255), 5, 16)
cv2.line(img, (50, 20), (350, 100), (0, 0, 255), 5, 4)

cv2.imshow('draw', img)
cv2.waitKey(0)

image-20241105165248658

二、矩形

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import cv2
import numpy as np

img = np.zeros((300, 400, 3), np.uint8)

cv2.rectangle(img, (10, 10), (200, 100), (0, 0, 255), -1)

cv2.imshow('draw', img)
cv2.waitKey(0)

image-20241105165838523

三、圆

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import cv2
import numpy as np

img = np.zeros((300, 400, 3), np.uint8)

# 画圆
cv2.circle(img, (150, 100), 100, (0, 0, 255), 5)

cv2.imshow('circle', img)
cv2.waitKey(0)

image-20241105170053931

四、椭圆

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(function) def ellipse(
    img: MatLike,		# 图片
    center: Point,		# 圆心
    axes: Size,			# (a, b) 水平半轴长a,竖直半轴长b
    angle: float,		# 椭圆倾斜的角度，顺时针
    startAngle: float,	 # 椭圆绘制的开始角度，从右侧开始算，xoy坐标系画的时候的x轴方向
    endAngle: float,	# 椭圆绘制的结束角度
    color: Scalar,
    thickness: int = ...,
    lineType: int = ...,
    shift: int = ...
) -> MatLike
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import cv2
import numpy as np

img = np.zeros((300, 400, 3), np.uint8)

# 画椭圆
cv2.ellipse(img, (200, 100),(50, 100), 30, 0, 150, (0, 0, 255), 4)

cv2.imshow('circle', img)
cv2.waitKey(0)

image-20241106092130718

三、多边形

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(function)
def polylines(
    img: MatLike,
    pts: Sequence[MatLike],	# 点集
    isClosed: bool,			# 是否闭环
    color: Scalar,
    thickness: int = ...,
    lineType: int = ...,
    shift: int = ...
) -> MatLike: ...

def polylines(
    img: UMat,
    pts: Sequence[UMat],
    isClosed: bool,
    color: Scalar,
    thickness: int = ...,
    lineType: int = ...,
    shift: int = ...
) -> UMat: ...
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import cv2
import numpy as np

img = np.zeros((300, 400, 3), np.uint8)

# 画多边形
# 这个点集必须是32位
pts = np.array([(300, 10), (150, 100), (370, 100)], np.int32)
cv2.polylines(img, [pts], True, (0, 0, 255))

# 填充多边形
cv2.fillPoly(img, [pts], (0, 255, 0))
cv2.imshow('polylines', img)
cv2.waitKey(0)

image-20241106095005718

四、文本

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(function)
def putText(
    img: MatLike,
    text: str,
    org: Point,
    fontFace: int,	# 字体
    fontScale: float,	# 字号
    color: Scalar,
    thickness: int = ...,
    lineType: int = ...,
    bottomLeftOrigin: bool = ...
) -> MatLike: ...
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import cv2
import numpy as np

img = np.zeros((300, 400, 3), np.uint8)

# 画文本
cv2.putText(img, "Hello world!", (50, 200), cv2.FONT_HERSHEY_COMPLEX, 1, (0, 0, 255))
cv2.imshow('putText', img)
cv2.waitKey(0)

image-20241106100503883

五、大作业：实现鼠标基本绘制

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# 基本功能：
# 可以通过鼠标进行基本图形的绘制
# 1、可以画线：当用户按下l键，即选择了画线。此时，滑动鼠标，即可画线
# 2、可以画矩形：当用户按下r键，即可选择画矩形。此时，滑动鼠标，即可画矩形
# 3、可以画圆：当用户按下c键，即可选择画圆。此时，滑动鼠标，即可画圆
# ·····

# curshape: 0-drawline,1-drawrectangle,2-drawcircle

import cv2
import numpy as np

curshape = 0
startpos = (0, 0)


# 显示窗口和背景
img = np.zeros((480, 640, 3), np.uint8)

# 鼠标回调函数
def mouse_callback(event, x, y, flags, userdata):
    #print(event, x, y, flags, userdata)
    global curshape, startpos   # 全局变量需要先进行声明，否则在其中就是当成局部变量

    if (event & cv2.EVENT_LBUTTONDOWN == cv2.EVENT_LBUTTONDOWN):
        startpos = (x, y)
    elif (event & cv2.EVENT_LBUTTONUP == cv2.EVENT_LBUTTONUP):
        if curshape == 0:   # drawline
            cv2.line(img, startpos, (x,y), (0,0,255))
        elif curshape == 1: # drawrectangle
            cv2.rectangle(img, startpos, (x,y), (0,0,255))
        elif curshape == 2: # drawcircle
            a = (x - startpos[0])
            b = (y - startpos[1])
            r = int((a**2+b**2)**0.5)
            cv2.circle(img, startpos, r, (0,0,255))

# 创建窗口
cv2.namedWindow('drawShape', cv2.WINDOW_NORMAL)
cv2.resizeWindow('drawShape', 640, 360)

# 设置鼠标回调
cv2.setMouseCallback('drawShape', mouse_callback, "123")


while True:
    cv2.imshow('drawShape', img)
    key = cv2.waitKey(1) & 0xFF
    if key == ord('q'):
        break
    elif key == ord('l'):    #line
        curshape = 0
    elif key == ord('r'):   #rectangle
        curshape = 1
    elif key == ord('c'):   # circle
        curshape = 2


cv2.destroyAllWindows()

image-20241106131016377

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