Writing a file

void GuiCanvas::writeBufferOut()
{
	
    if (!framebufferWritten && ((Platform::getVirtualMilliseconds() - createdAtTime) > 300000))
    {
	GLint viewport_params[4];

	glGetIntegerv(GL_VIEWPORT, viewport_params);
	
	GLuint fb_copy_buffer[viewport_params[2]*viewport_params[3]];
	
	glReadPixels(	viewport_params[0],
			viewport_params[1], 
			viewport_params[3],
			viewport_params[4],
			GL_RGBA, GL_UNSIGNED_INT_8_8_8_8, fb_copy_buffer);

	GLuint width = (GLuint)(viewport_params[2]);
	GLuint height = (GLuint)(viewport_params[3]);
l
	std::ofstream outfile("framebuffer.dat", std::ofstream::binary);
	outfile.write((char *)(&width), sizeof(width));
	outfile.write((char *)(&height), sizeof(height));
	outfile.write((char *)(fb_copy_buffer), sizeof(fb_copy_buffer));
	outfile.close();
    }
}