基于Qt的工业名牌识别系统遇到的问题

2020.04.14

Note1

  将QString转换为std::string：

std::string QStringToCharArray(QString str) {
	QTextCodec *code = QTextCodec::codecForName("gb18030");
	std::string stdstr = code->fromUnicode(str).data();
	return stdstr;
}

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Note2

  cv::Mat与QImage之间的转换：

QImage转cvMat

Mat QImage2cvMat(QImage image)
{
	cv::Mat mat;
	switch (image.format())
	{
	case QImage::Format_ARGB32:
	case QImage::Format_RGB32:
	case QImage::Format_ARGB32_Premultiplied:
		mat = cv::Mat(image.height(), image.width(), CV_8UC4, (void*)image.bits(), image.bytesPerLine());
		break;
	case QImage::Format_RGB888:
		mat = cv::Mat(image.height(), image.width(), CV_8UC3, (void*)image.bits(), image.bytesPerLine());
		cv::cvtColor(mat, mat, CV_BGR2RGB);
		break;
	case QImage::Format_Indexed8:
		mat = cv::Mat(image.height(), image.width(), CV_8UC1, (void*)image.bits(), image.bytesPerLine());
		break;
	}
	return mat;
}

cvMat转QImage

QImage cvMat2QImage(const cv::Mat& mat)
{
	// 8-bits unsigned, NO. OF CHANNELS = 1
	if (mat.type() == CV_8UC1)
	{
		QImage image(mat.cols, mat.rows, QImage::Format_Indexed8);
		// Set the color table (used to translate colour indexes to qRgb values)
		image.setColorCount(256);
		for (int i = 0; i < 256; i++)
		{
			image.setColor(i, qRgb(i, i, i));
		}
		// Copy input Mat
		uchar *pSrc = mat.data;
		for (int row = 0; row < mat.rows; row++)
		{
			uchar *pDest = image.scanLine(row);
			memcpy(pDest, pSrc, mat.cols);
			pSrc += mat.step;
		}
		return image;
	}
	// 8-bits unsigned, NO. OF CHANNELS = 3
	else if (mat.type() == CV_8UC3)
	{
		// Copy input Mat
		const uchar *pSrc = (const uchar*)mat.data;
		// Create QImage with same dimensions as input Mat
		QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_RGB888);
		return image.rgbSwapped();
	}
	else if (mat.type() == CV_8UC4)
	{
		// Copy input Mat
		const uchar *pSrc = (const uchar*)mat.data;
		// Create QImage with same dimensions as input Mat
		QImage image(pSrc, mat.cols, mat.rows, mat.step, QImage::Format_ARGB32);
		return image.copy();
	}
	else
	{
		return QImage();
	}
}

---

Note3

void QImage::setNumColors(int n)

  该函数为老版Qt的函数，在Qt5中已被淘汰，可使用numColors()、setColorCount()代替。

参考资料:https://doc.qt.io/qt-5/qimage-obsolete.html#setNumColors