I am really sorry. Posting again with correct formatting this time :
I would like to pass a protobuf message from Javascript to a C++
WebAssembly module.
I do receive, and can successfully parse the simpler protobuf messages on
the C++ side, however, protobuf is failing to parse the less-simple
protobuf messages.
Here is the code that I am using :
```javascript
goog.module('protobufMessageGenerator');
goog.require('proto.my_proto.MyMessage');
function generateMyMessage() {
var msg = new proto.my_proto.MyMessage()
var internal = new proto.my_proto.MyMessageInternal()
internal.setAccentColor("#CC1D24")
internal.setLogo("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")
msg.setInternal(internal)
return msg
}
```
Using the google-closure-compiler, I compile this protobuf message
generator to pure Javascript.
I use this code to pass the message to the C++ WebAssembly module :
```javascript
function sendMessage() {
Module.self().setMyMessage(module$contents$protobufMessageGenerator_generateMyMessage().serializeBinary())
}
sendMessage()
```
I receive the message on the C++ side using this code :
```cpp
void JavascriptPublicInterface::setMyMessage(const QString &myMessage)
{
if (_myMessage != myMessage)
{
_myMessage = myMessage;
emit myMessageChanged();
}
}
void JavascriptPublicInterface::setMyMessageEMS(const std::string
&myMessage)
{
setMyMessage(QString::fromStdString(myMessage));
}
//...
void startListeningToMyMessage(std::function<void(euf_proto::MyMessage
myMessage)> listener)
{
const auto changedListener = [listener]() {
const auto newMyMessageString =
JavascriptPublicInterface::self()->myMessage();
my_proto::MyMessage myMessagePb;
if
(myMessagePb.ParseFromString(newMyMessageString.toStdString()))
{
qDebug() << "C++ : Successfully parsed new
MyMessage: " << newMyMessageString;
}
else
{
qDebug() << "C++ : Failed to parse new MyMessage: "
<< newMyMessageString;
}
qDebug() << "MyMessage received: " <<
QString::fromStdString(myMessagePb.DebugString());
listener(myMessagePb);
};
if (!QObject::connect(JavascriptPublicInterface::self(),
&JavascriptPublicInterface::myMessageChanged, changedListener))
{
throw std::runtime_error("Failed to connect to
JavascriptPublicInterface myMessageChanged");
}
}
```
In the Javascript console I see : "C++ : Failed to parse new MyMessage: ..."
I guess that it can be related to the fact that Javascript is using UTF-16
and C++ is using UTF-8 encoding (because the messages that are UTF-8 only
can be successfully parsed), so I tried to fix the sending and receiving
like this:
```javascript
//For more info see :
https://emscripten.org/docs/api_reference/emscripten.h.html?highlight=stringtoutf8
function convertUtf16ToUtf8(input) {
var uint8Arr = input
var jsString = String.fromCharCode.apply(null, uint8Arr)
var lengthBytes = lengthBytesUTF8(jsString)+1
var stringOnWasmHeap = _malloc(lengthBytes)
stringToUTF8(jsString, stringOnWasmHeap, lengthBytes)
return stringOnWasmHeap
}
function sendMessage() {
var myMessage =
convertUtf16ToUtf8(module$contents$protobufMessageGenerator_generateMyMessage().serializeBinary())
Module.self().setMyMessage(myMessage)
_free(myMessage)
}
sendMessage()
```
And I modified the parsing on the C++ side like this :
```cpp
void JavascriptPublicInterface::setMyMessageEMS(const int pointer)
{
const char* msg = (char*)pointer;
setMyMessage(QString::fromStdString(msg));
}
```
But I still get this error : "C++ : Failed to parse new MyMessage: ..."
How could I fix this?
(I am using protobuf 3.19.1 (same version on both the Javascript and the
C++ side).)
On Thursday, February 17, 2022 at 8:25:26 PM UTC+1 Csaba Szigeti wrote:
> I would like to pass a protobuf message from Javascript to a C++
> WebAssembly module.
>
> I do receive, and can successfully parse the simpler protobuf messages on
> the C++ side, however, protobuf is failing to parse the less-simple
> protobuf messages.
>
> Here is the code that I am using :
> ```
> goog.module('protobufMessageGenerator');
> goog.require('proto.my_proto.MyMessage'); function generateMyMessage() {
> var msg = new proto.my_proto.MyMessage() var internal = new
> proto.my_proto.MyMessageInternal() internal.setAccentColor("#CC1D24")
> internal.setLogo("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")
>
> msg.setInternal(internal) return msg }
> ```
> Using the google-closure-compiler, I compile this protobuf message
> generator to pure Javascript. I use this code to pass the message to the
> C++ WebAssembly module :
> ```
> function sendMessage() {
> Module.self().setMyMessage(module$contents$protobufMessageGenerator_generateMyMessage().serializeBinary())
>
> } sendMessage()
> ```
> I receive the message on the C++ side using this code :
> ```
> void JavascriptPublicInterface::setMyMessage(const QString &myMessage) {
> if (_myMessage != myMessage) { _myMessage = myMessage; emit
> myMessageChanged(); } } void
> JavascriptPublicInterface::setMyMessageEMS(const std::string &myMessage) {
> setMyMessage(QString::fromStdString(myMessage)); } //... void
> startListeningToMyMessage(std::function<void(euf_proto::MyMessage
> myMessage)> listener) { const auto changedListener = [listener]() { const
> auto newMyMessageString = JavascriptPublicInterface::self()->myMessage();
> my_proto::MyMessage myMessagePb; if
> (myMessagePb.ParseFromString(newMyMessageString.toStdString())) { qDebug()
> << "C++ : Successfully parsed new MyMessage: " << newMyMessageString; }
> else { qDebug() << "C++ : Failed to parse new MyMessage: " <<
> newMyMessageString; } qDebug() << "MyMessage received: " <<
> QString::fromStdString(myMessagePb.DebugString()); listener(myMessagePb);
> }; if (!QObject::connect(JavascriptPublicInterface::self(),
> &JavascriptPublicInterface::myMessageChanged, changedListener)) { throw
> std::runtime_error("Failed to connect to JavascriptPublicInterface
> myMessageChanged"); } }
> ```
>
>
> In the Javascript console I see : "C++ : Failed to parse new MyMessage:
> ..."
>
> I guess that it can be related to the fact that Javascript is using UTF-16
> and C++ is using UTF-8 encoding (because the messages that are UTF-8 only
> can be successfully parsed), so I tried to fix the sending and receiving
> like this:
>
> ```
> //For more info see :
> https://emscripten.org/docs/api_reference/emscripten.h.html?highlight=stringtoutf8
>
> function convertUtf16ToUtf8(input) { var uint8Arr = input var jsString =
> String.fromCharCode.apply(null, uint8Arr) var lengthBytes =
> lengthBytesUTF8(jsString)+1 var stringOnWasmHeap = _malloc(lengthBytes)
> stringToUTF8(jsString, stringOnWasmHeap, lengthBytes) return
> stringOnWasmHeap } function sendMessage() { var myMessage =
> convertUtf16ToUtf8(module$contents$protobufMessageGenerator_generateMyMessage().serializeBinary())
>
> Module.self().setMyMessage(myMessage) _free(myMessage) } sendMessage()
> ```
> And I modified the parsing on the C++ side like this :
> ```
> void JavascriptPublicInterface::setMyMessageEMS(const int pointer) { const
> char* msg = (char*)pointer; setMyMessage(QString::fromStdString(msg)); }
> ```
>
> But I still get this error : "C++ : Failed to parse new MyMessage: ..."
>
> How could I fix this?
>
> (I am using protobuf 3.19.1 (same version on both the Javascript and the
> C++ side).)
>
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