做图像识别的时候需要在图片中画出特定大小和角度的矩形框，自己写了一个函数，给定的输入是图片名称，矩形框的位置坐标,长宽和角度，直接输出画好矩形框的图片。
主要思想是先根据x,y坐标和长宽得到矩形，然后通过数学计算得到旋转angle角度后的新矩形框的四个顶点位置坐标，再利用draw.line()函数画出来。
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import math
import matplotlib.pyplot as plt
import numpy as np
from PIL import Image, ImageDraw
def draw(filename,result):
img = Image.open(filename)
w,h=img.size
draw = ImageDraw.Draw(img)
result=np.array(result)
x=result[0][0]
y=result[0][1]
angle=result[0][2]
height=result[0][3]
width=result[0][4]
anglePi = -angle*math.pi/180.0
cosA = math.cos(anglePi)
sinA = math.sin(anglePi)
x1=x-0.5*width
y1=y-0.5*height
x0=x+0.5*width
y0=y1
x2=x1
y2=y+0.5*height
x3=x0
y3=y2
x0n= (x0 -x)*cosA -(y0 - y)*sinA + x
y0n = (x0-x)*sinA + (y0 - y)*cosA + y
x1n= (x1 -x)*cosA -(y1 - y)*sinA + x
y1n = (x1-x)*sinA + (y1 - y)*cosA + y
x2n= (x2 -x)*cosA -(y2 - y)*sinA + x
y2n = (x2-x)*sinA + (y2 - y)*cosA + y
x3n= (x3 -x)*cosA -(y3 - y)*sinA + x
y3n = (x3-x)*sinA + (y3 - y)*cosA + y
draw.line([(x0n, y0n),(x1n, y1n)], fill=(0, 0, 255))
draw.line([(x1n, y1n),(x2n, y2n)], fill=(255, 0, 0))
draw.line([(x2n, y2n),(x3n, y3n)],fill= (0,0,255))
draw.line([(x0n, y0n), (x3n, y3n)],fill=(255,0,0))
plt.imshow(img)
plt.show()
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改写成c++
由于c++程序也需要用到这个程序，改写一下
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void CopentestDlg::OnBnClickedAnaly()
{
CString x,y,angle,width;
float xRaw[4], yRaw[4];
float xNew[4], yNew[4];
float height = 33;
if (imageCut==NULL) {
AfxMessageBox(_T("未打开图片不能分析"));
return;
}
GetDlgItem(IDC_EX)->GetWindowText(x);
GetDlgItem(IDC_EY)->GetWindowText(y);
GetDlgItem(IDC_ANGLE)->GetWindowText(angle);
GetDlgItem(IDC_WIDTH)->GetWindowText(width);
float xf = _tstof(x); //将Cstring转成float类型
float yf = _tstof(y);
float widthf= _tstof(width);
float anglef= _tstof(angle);
xRaw[1] = xf - 0.5*widthf;
yRaw[1] = yf - 0.5*height;
xRaw[0] = xf + 0.5*widthf;
yRaw[0] = yRaw[1];
xRaw[2] = xRaw[1];
yRaw[2] = yf + 0.5*height;
xRaw[3] = xRaw[0];
yRaw[3] = yRaw[2];
float anglePi = -anglef*pi / 180.0;
float cosA = cos(anglePi);
float sinA = sin(anglePi);
xNew[0] = (xRaw[0] - xf)*cosA - (yRaw[0] - yf)*sinA + xf;
yNew[0] = (xRaw[0] - xf)*sinA + (yRaw[0] - yf)*cosA + yf;
xNew[1] = (xRaw[1] - xf)*cosA - (yRaw[1] - yf)*sinA + xf;
yNew[1] = (xRaw[1] - xf)*sinA + (yRaw[1] - yf)*cosA + yf;
xNew[2] = (xRaw[2] - xf)*cosA - (yRaw[2] - yf)*sinA + xf;
yNew[2] = (xRaw[2] - xf)*sinA + (yRaw[2] - yf)*cosA + yf;
xNew[3] = (xRaw[3] - xf)*cosA - (yRaw[3] - yf)*sinA + xf;
yNew[3] = (xRaw[3] - xf)*sinA + (yRaw[3] - yf)*cosA + yf;
cvLine(imageCut, cvPoint(xNew[0], yNew[0]), cvPoint(xNew[1], yNew[1]), cvScalar(0, 0, 255), 3);
cvLine(imageCut, cvPoint(xNew[1], yNew[1]), cvPoint(xNew[2], yNew[2]), cvScalar(255, 0, 0), 3);
cvLine(imageCut, cvPoint(xNew[2], yNew[2]), cvPoint(xNew[3], yNew[3]), cvScalar(0, 0, 255), 3);
cvLine(imageCut, cvPoint(xNew[0], yNew[0]), cvPoint(xNew[3], yNew[3]), cvScalar(255, 0, 0), 3);
DrawPicToHDC(imageCut, IDC_Cut);
pEdit->ReplaceSel(_T("图片已修改\r\n"));
}
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效果图
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/u013948010/article/details/78318894