QPainter.drawImage in paintGL not work

[Anima]

I have a widget subclass QOpenGLWidget and I want to combine openGL and QPainter in the paintGL function, but it not work. Here is the code:

void paintGL()
{	
        glEnable(GL_MULTISAMPLE);
	glEnable(GL_BLEND);
	glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE);
	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
	glClear(GL_COLOR_BUFFER_BIT);

	m_pImageRender->paint();

	glDisable(GL_BLEND);
	glDisable(GL_MULTISAMPLE);
        
        QPainter painter(this);
        painter.fillRect(QRect(100, 100, 100, 100), QColor("#ff0000"); // without the following line,  this line work
        painter.drawImage(rect(), m_oImage, QRect(0, 0, m_oImage.width(), m_oImage.height()); // after add this line, the screen display nothing, just black
}

The openGL painting code is like below:

m_pShaderProgram->bind();
	m_pVertexBuffer->bind();
	m_pIndexBuffer->bind();
	
	m_pShaderProgram->setUniformValue("projection", m_mtProjection);
	m_pShaderProgram->setUniformValue("scale", m_fScale);
	m_pShaderProgram->setUniformValue("offset", m_vecOffset);

	int textureUnits[m_nImageCount], display[m_nImageCount];
	float cmin[m_nImageCount], cmax[m_nImageCount];
	QVector4D color[m_nImageCount];
	for (int i = 0;i < m_nImageCount;i++)
	{
		textureUnits[i] = i;
		display[i] = m_vecDisplay[i];
		cmin[i] = m_vecClipMin[i];
		cmax[i] = m_vecClipMax[i];
		color[i] = QVector4D(m_vecColor[i].red() / 255.0, m_vecColor[i].green() / 255.0, m_vecColor[i].blue() / 255.0, 1.0);
	}

	m_pShaderProgram->setUniformValueArray("utexture", textureUnits, m_nImageCount);
	m_pShaderProgram->setUniformValueArray("display", display, m_nImageCount);
	m_pShaderProgram->setUniformValueArray("rgbcolor", color, m_nImageCount);
	m_pShaderProgram->setUniformValueArray("cmin", cmin, m_nImageCount, 1);
	m_pShaderProgram->setUniformValueArray("cmax", cmax, m_nImageCount, 1);
	for (int i = 0;i < m_nImageCount;i++)
	{
		if (m_vecTexture[i])
		{
			m_vecTexture[i]->bind(i);
		}
	}

	m_pShaderProgram->enableAttributeArray(0);
	m_pShaderProgram->setAttributeBuffer(0, GL_FLOAT, 0, 2, 4 * sizeof(GLfloat));
	m_pShaderProgram->enableAttributeArray(1);
	m_pShaderProgram->setAttributeBuffer(1, GL_FLOAT, 2 * sizeof(GLfloat), 2, 4 * sizeof(GLfloat));

	m_pOpenGLCore->glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

	for (int i = 0;i < m_nImageCount;i++)
	{
		if (m_vecTexture[i])
		{
			m_vecTexture[i]->release(i);
		}
	}
	m_pShaderProgram->release();
	m_pVertexBuffer->release();
	m_pIndexBuffer->release();

So, what may cause the problem?