前言
以前的文章《C OpenCV视频操作之图像输出文字》介绍了OpenCV中的putText函数可以输出文字，但是这个函数只能输出英文，如果输入的是中文会变为乱码，今天我们就来实现OpenCV输出中文（只在windows环境下）。
核心代码
微卡智享
建一个putText的类，里面的putTextZH设置为静态方法
putText.h
代码语言：javascript复制#pragma once
#ifndef PUTTEXT_H_
#define PUTTEXT_H_
#include <Windows.h>
#include <string>
#include <opencv2/opencv.hpp>
using namespace cv;
class putText
{
private:
static void GetStringSize(HDC hdc, const char* str, int* w, int* h);
public:
static void putTextZH(Mat& dst, const char* str, Point org, Scalar color, int fontsize,
const char* fn = "Arial", bool italic = false, bool underline = false);
};
#endif // !PUTTEXT_H_
putText.cpp
代码语言：javascript复制#include "putText.h"
void putText::GetStringSize(HDC hdc, const char* str, int* w, int* h)
{
SIZE size;
GetTextExtentPoint32A(hdc, str, strlen(str), &size);
if (w != 0) *w = size.cx;
if (h != 0) *h = size.cy;
}
void putText::putTextZH(Mat& dst, const char* str, Point org, Scalar color, int fontsize, const char* fn, bool italic, bool underline)
{
CV_Assert(dst.data != 0 && (dst.channels() == 1 || dst.channels() == 3));
int x, y, r, b;
//坐标点大于图像宽和高直接返回
if (org.x > dst.cols || org.y > dst.rows) return;
x = org.x < 0 ? -org.x : 0;
y = org.y < 0 ? -org.y : 0;
LOGFONTA lf;
lf.lfHeight = -fontsize; //字体高度
lf.lfWidth = 0; //平均宽度
lf.lfEscapement = 0; //字符排列角度
lf.lfOrientation = 0; //字符本身旋转的角度
lf.lfWeight = 5; //设置字体线条的宽度
lf.lfItalic = italic; //斜体
lf.lfUnderline = underline; //下划线
lf.lfStrikeOut = 0; //是否字符中央加横线
lf.lfCharSet = DEFAULT_CHARSET; //字符集
lf.lfOutPrecision = 0; //字体的精确度
lf.lfQuality = PROOF_QUALITY; //字体质量
lf.lfPitchAndFamily = 0; //选择字体的间距和字体家族
strcpy_s(lf.lfFaceName, fn); //字体的名称
HFONT hf = CreateFontIndirectA(&lf);
HDC hdc = CreateCompatibleDC(0);
HFONT holdfont = (HFONT)SelectObject(hdc, hf);
int strBaseW = 0, strBaseH = 0;
int singleRow = 0;
char buf[1 << 12];
strcpy_s(buf, str);
char* bufT[1 << 12]; //这个用于分隔字符串后剩余的字符，可能会超出。
//处理多行
{
int nnh = 0;
int cw, ch;
const char* ln = strtok_s(buf, "n", bufT);
while (ln != 0)
{
GetStringSize(hdc, ln, &cw, &ch);
strBaseW = max(strBaseW, cw);
strBaseH = max(strBaseH, ch);
ln = strtok_s(0, "n", bufT);
nnh ;
}
singleRow = strBaseH;
strBaseH *= nnh;
}
if (org.x strBaseW < 0 || org.y strBaseH < 0)
{
SelectObject(hdc, holdfont);
DeleteObject(hf);
DeleteObject(hdc);
return;
}
r = org.x strBaseW > dst.cols ? dst.cols - org.x - 1 : strBaseW - 1;
b = org.y strBaseH > dst.rows ? dst.rows - org.y - 1 : strBaseH - 1;
org.x = org.x < 0 ? 0 : org.x;
org.y = org.y < 0 ? 0 : org.y;
BITMAPINFO bmp = { 0 };
BITMAPINFOHEADER& bih = bmp.bmiHeader;
int strDrawLineStep = strBaseW * 3 % 4 == 0 ? strBaseW * 3 : (strBaseW * 3 4 - ((strBaseW * 3) % 4));
bih.biSize = sizeof(BITMAPINFOHEADER);
bih.biWidth = strBaseW;
bih.biHeight = strBaseH;
bih.biPlanes = 1;
bih.biBitCount = 24;
bih.biCompression = BI_RGB;
bih.biSizeImage = strBaseH * strDrawLineStep;
bih.biClrUsed = 0;
bih.biClrImportant = 0;
void* pDibData = 0;
HBITMAP hBmp = CreateDIBSection(hdc, &bmp, DIB_RGB_COLORS, &pDibData, 0, 0);
CV_Assert(pDibData != 0);
HBITMAP hOldBmp = (HBITMAP)SelectObject(hdc, hBmp);
//color.val[2], color.val[1], color.val[0]
SetTextColor(hdc, RGB(255, 255, 255));
SetBkColor(hdc, 0);
//SetStretchBltMode(hDC, COLORONCOLOR);
strcpy_s(buf, str);
const char* ln = strtok_s(buf, "n", bufT);
int outTextY = 0;
while (ln != 0)
{
TextOutA(hdc, 0, outTextY, ln, strlen(ln));
outTextY = singleRow;
ln = strtok_s(0, "n", bufT);
}
uchar* dstData = (uchar*)dst.data;
int dstStep = dst.step / sizeof(dstData[0]);
unsigned char* pImg = (unsigned char*)dst.data org.x * dst.channels() org.y * dstStep;
unsigned char* pStr = (unsigned char*)pDibData x * 3;
for (int tty = y; tty <= b; tty)
{
unsigned char* subImg = pImg (tty - y) * dstStep;
unsigned char* subStr = pStr (strBaseH - tty - 1) * strDrawLineStep;
for (int ttx = x; ttx <= r; ttx)
{
for (int n = 0; n < dst.channels(); n) {
double vtxt = subStr[n] / 255.0;
int cvv = vtxt * color.val[n] (1 - vtxt) * subImg[n];
subImg[n] = cvv > 255 ? 255 : (cvv < 0 ? 0 : cvv);
}
subStr = 3;
subImg = dst.channels();
}
}
SelectObject(hdc, hOldBmp);
SelectObject(hdc, holdfont);
DeleteObject(hf);
DeleteObject(hBmp);
DeleteDC(hdc);
}
调用方式
代码语言：javascript复制 //输出中文显示
putText::putTextZH(src, "我是Vaccae,请关注微卡智享", Point(rect.x-40, rect.y-23),
Scalar(0, 0, 255), 20, "微软雅黑");代码演示
微卡智享
新建一个opencvputtextzh的项目，配置参见《VS2017配置OpenCV通用属性》。
上图中的putText.h和putText.cpp就是上面的核心代码，接下来我们看一下main的代码。
main.cpp
代码语言：javascript复制#include <iostream>
#include <opencv2/opencv.hpp>
#include "putText.h"
using namespace std;
using namespace cv;
int main(int argc, char** argv) {
Mat src = imread("E:/DCIM/test3.jpg");
if (!src.data) {
cout << "could not find src" << endl;
return -1;
}
Mat tmpsrc, dst;
//转为灰度图
cvtColor(src, tmpsrc, COLOR_BGR2GRAY);
//二值化
threshold(tmpsrc, tmpsrc, 0, 255, THRESH_BINARY_INV | THRESH_OTSU);
//发现轮廓
vector<vector<Point>> contours;
findContours(tmpsrc, contours, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);
//用于存放拆线点集
vector<vector<Point>> contours_poly(contours.size());
for (int i=0; i < contours.size(); i) {
//将多边形进行拟合
approxPolyDP(Mat(contours[i]), contours_poly[i], 3, true);
//获取矩形并在源图上画出来
Rect rect = boundingRect(contours_poly[i]);
rectangle(src, rect, Scalar(0, 0, 255));
//输出中文显示
putText::putTextZH(src, "我是Vaccae,请关注微卡智享", Point(rect.x-40, rect.y-23),
Scalar(0, 0, 255), 20, "微软雅黑");
}
imshow("src", src);
waitKey(0);
return 0;
}实现效果
完
