使用cv::putText写中文字符时输出结果为"？？？？？？"。。。。。。这怎么能忍？

        python方法中可以将opencv图片转化为PIL，写中文之后再转回opencv格式。

        C++方法中通常利用freetype库来实现，freetype打包的win32静态库可以在C#通过dll引用进行调用，这需要其版本跟CvxText对应，否则会出现错误，其在x64平台也一样。

        本文采用windows的GDI显示系统的TrueType字体，没有封装，就两个函数，分成h和cpp文件，可以自己编辑文件名和函数名，也可以直接将cpp的代码复制到你需要的程序中。

 【putText.h】

#ifndef PUTTEXT_H_
#define PUTTEXT_H_

#include <windows.h>
#include <string>
#include <opencv2/opencv.hpp>

using namespace cv;

void GetStringSize(HDC hDC, const char* str, int* w, int* h);
void putTextHusky(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】

#include "putText.h"

void 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 putTextHusky(Mat &dst, const char* str, Point org, Scalar color, int fontSize, const char* fn, bool italic, bool underline)//后俩参数：斜体，下划线
{
	CV_Assert(dst.data != 0 && (dst.channels() == 1 || dst.channels() == 3));

	int x, y, r, b;
	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;
	lf.lfWidth = 0;
	lf.lfEscapement = 0;
	lf.lfOrientation = 0;
	lf.lfWeight = 5;
	lf.lfItalic = italic;   //斜体
	lf.lfUnderline = underline; //下划线
	lf.lfStrikeOut = 0;
	lf.lfCharSet = DEFAULT_CHARSET;
	lf.lfOutPrecision = 0;
	lf.lfClipPrecision = 0;
	lf.lfQuality = PROOF_QUALITY;
	lf.lfPitchAndFamily = 0;
	strcpy_s(lf.lfFaceName, fn);

	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);
}

        第二个函数putTextHusky()，默认使用Arial字体，也可以设置成操作系统中已经安装的字体，如“宋体”、“微软雅黑”、“Times New Roman”等；默认显示非斜体、非下划线。

【示例】

#include <opencv2/opencv.hpp>
#include "putText.h"

using namespace std;
using namespace cv;

int main()//自己写库解决putText无法显示中文字符问题
{
	Mat img = imread("lyf.png");

	putText(img, "中文无法显示...", Point(50, 50), 2, 1, Scalar(0, 0, 255), 1, 8, false);
	putTextHusky(img, "Arial字体...", Point(50, 100), Scalar(0, 0, 255), 30, "Arial");
	putTextHusky(img, "微软雅黑字体...", Point(50, 150), Scalar(0, 255, 0), 30, "微软雅黑", true, true);
	putTextHusky(img, "楷体字体...\n", Point(50, 200), Scalar(128, 255, 0), 30, "楷体", true, true);
	//imwrite("lyfWrite.png", img);
	imshow("test", img);
	waitKey(0);
	
	system("pause");
	return 0;
}