FlatBuffers 的 直接上手C++示例 之二

1、fbs文件

namespace FACECAPTURE;

attribute "priority";
//---------------------------------------------------------------------------------------------
//採集設備向PC發送圖片相關
table ImgMsg {
    colorImg              : [ubyte];   // 彩圖
    irImg                 : [ubyte];   // IR圖
    dotImg                : [ubyte];   // 散斑圖
    depthImg              : [ubyte];   // 深度圖
}

table ImgData {
    imgMsgs               : [ImgMsg];  // 一幀數據裏面的圖片數據
    tsNow                 : long;      // 圖片採集時的時間戳
}

//---------------------------------------------------------------------------------------
enum MSG_TYPE: int
{   
    ZMQ_MSGTYPE_NEED_INTERRUPT = 0,            // 消息類型爲採集設備通知已建立連接的PC端平臺中斷連接
    ZMQ_MSGTYPE_NEED_INTERRUPT_RETURN = 1,     // 消息類型爲PC端中斷REQ後應答採集設備
    ZMQ_MSGTYPE_GET_IMGDATA = 2,                // 消息類型爲PC端向採集設備發起採集圖片請求
 	ZMQ_MSGTYPE_GET_IMGDATA_RETURN = 3,         // 消息類型爲抓拍機已知曉可以發送數據了
}

table JsonMsg {
    json       : string;
}

union Content {
    JsonMsg,
    ImgData
 }

table TransMsg {
    type : MSG_TYPE;
	content : Content;
	//聯合體，如果只是發送格式化的json，就選用JsonMsg結構，
	//其他按照函數名,選取對應結構。
}//每個消息包含一個消息類型，一個具體內容

root_type TransMsg;

2、序列化反序列化

char* generateBuffer()
{
	int len = 0;
	{
		int ret = 0;
		char* p = NULL;
		int zmqRet = 0;
		flatbuffers::FlatBufferBuilder builder;
		flatbuffers::Offset<FACECAPTURE::JsonMsg> content;
		flatbuffers::Offset<FACECAPTURE::TransMsg> zmqData;

		builder.Clear();

		char buffer[128] = { "Hello world!" };

		content = FACECAPTURE::CreateJsonMsgDirect(builder, "{'a':1}");

		//content = builder.CreateString(buffer, strlen("Hello world!") + 1);

		FACECAPTURE::TransMsgBuilder msgData(builder);
		msgData.add_type(FACECAPTURE::MSG_TYPE_ZMQ_MSGTYPE_GET_IMGDATA);
		msgData.add_content_type(FACECAPTURE::Content_JsonMsg);
		msgData.add_content(*(flatbuffers::Offset<void> *) &content);
		zmqData = msgData.Finish();
		builder.Finish(zmqData);

		//flatbuffers::Offset<FACECAPTURE::TransMsg> msg = FACECAPTURE::CreateTransMsg(builder, FACECAPTURE::MSG_TYPE_ZMQ_MSGTYPE_NEED_INTERRUPT, FACECAPTURE::Content_NONE, content);

		len = builder.GetSize();
		p = new char[len];
		memcpy(p, builder.GetBufferPointer(), builder.GetSize());

		const FACECAPTURE::TransMsg* pTransMsg = FACECAPTURE::GetTransMsg(p);
		printf("type is %d, msg is %s\n", pTransMsg->type(), pTransMsg->content_as_JsonMsg()->json()->c_str());
	}
	return 0;
}