qtprotobuf

QtProtobuf

gRPC and Protobuf generator and bindings for Qt framework

see Protobuf and gRPC for more information

Table of contents

API Reference

Linux Build

Windows Build

Usage

CMake functions reference

qmake integration

Running tests

Linux Build

Prerequesties

Check installation of following packages in your system:

• protobuf 3.6.0 or higher
• grpc 1.15.0 or higher
• golang 1.10 or higher (Mandatory dependency for any type of build)

Note: Older versions could be supported as well but not officially tested.

For Ubuntu

Install GRPC packages in system:

sudo apt-get install libgrpc++-dev protobuf-compiler-grpc libgrpc++1 libgrpc-dev libgrpc6

All-in-one build

If required versions of libraries are not found in your system, you may use all-in-one build procedure for prerequesties

Update submodules to fetch 3rdparty dependencies:

git submodule update --init --recursive

Build

mkdir build
cd build

#In case Qt installed in system, use:
cmake ..

#In case you have Qt installed from qt installer, use:
cmake .. -DCMAKE_PREFIX_PATH="<path/to/qt/installation>/Qt<qt_version>/<qt_version>/gcc_64/lib/cmake"

cmake --build . [--config <RELEASE|DEBUG>] -- -j<N>

Windows Build

Prerequesties

Download and install:

• Qt 5.12.3 or higher 1
• cmake-3.1 or higher 2
• Strawberry perl 5.28 3
• GoLang 1.10 or higher 4
• Yasm 1.3 or higher 5
• Actual Visual Studio Compiler with cmake support that required by Qt 6

Note: All applications should be in PATH

Update submodules to fetch 3rdparty dependencies:

git submodule update --init --recursive

Build

Open Qt MSVC command line and follow steps:

"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat" <x86|x64>
cd <directory with qtprotobuf project>
mkdir build
cd build
cmake ..
cmake --build . [--config <RELEASE|DEBUG>] -- /m:<N>

Usage

Direct usage of generator

protoc --plugin=protoc-gen-qtprotobuf=<path/to/bin>/qtprotobufgen --qtprotobuf_out=<output_dir> <protofile>.proto [--qtprotobuf_opt=out=<output_dir>]

Integration with project

You can integrate QtProtobuf as submodule in your project or as installed in system package. Add following line in your project CMakeLists.txt:

...
find_package(QtProtobufProject CONFIG REQUIRED COMPONENTS QtProtobuf QtGrpc)
file(GLOB PROTO_FILES ABSOLUTE ${CMAKE_CURRENT_SOURCE_DIR}/path/to/protofile1.proto
                               ${CMAKE_CURRENT_SOURCE_DIR}/path/to/protofile2.proto
                               ...
                               ${CMAKE_CURRENT_SOURCE_DIR}/path/to/protofileN.proto)
# Function below generates source files for specified PROTO_FILES,
# writes result to STATIC library target and saves its name to 
# ${QtProtobuf_GENERATED} variable
generate_qtprotobuf(TARGET MyTarget
    OUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/generated
    PROTO_FILES ${PROTO_FILES})
add_executable(MyTarget main.cpp) # Add your target here
target_link_libraries(MyTarget ${QtProtobuf_GENERATED})

Optional:

You also may pre-specify expected generated headers to prevent dummy-parser mistakes

...
set(GENERATED_HEADERS
    # List of artifacts expected after qtprotobufgen job done.
    # Usually it's full list of messages in all packages with .h header suffix
    ...
    )
...
generate_qtprotobuf(TARGET MyTarget
    OUT_DIR ${CMAKE_CURRENT_BINARY_DIR}/generated
    PROTO_FILES ${PROTO_FILES}
    GENERATED_HEADERS ${GENERATED_HEADERS})
...

Usage

To enable QtProtobuf project you need to register protobuf types. It's good practice to make it in 'main' function.

...
#include <QtProtobufTypes>
...
int main(int argc, char *argv[])
{
    QtProtobuf::qRegisterProtobufTypes();
    ... //Qt application initialization and run
}

Code exceptions

If any prohibited Qt/QML keyword is used as field name, generator appends 'Proto' suffix to generated filed name. It's required to omit overloading for example QML reserved names like 'id' or 'objectName'.

E.g. for message:

message MessageReserved {
    sint32 import = 1;
    sint32 property = 2;
    sint32 id = 3;
}

Following properties will be generated:

...
    Q_PROPERTY(QtProtobuf::sint32 importProto READ importProto WRITE setImport NOTIFY importProtoChanged)
    Q_PROPERTY(QtProtobuf::sint32 propertyProto READ propertyProto WRITE setProperty NOTIFY propertyProtoChanged)
    Q_PROPERTY(QtProtobuf::sint32 idProto READ idProto WRITE setId NOTIFY idProtoChanged)
...

Note: List of exceptions might be extended in future releases.

CMake functions reference

generate_qtprotobuf

generate_qtprotobuf is cmake helper function that automatically generates STATIC library target from your .proto files

Due to cmake restrictions it's required to specify resulting artifacts manually as list of header files expected after generator job finished.

Parameters:

TARGET - name of you target that will be base for generated target name

OUT_DIR - output directory that will contain generated artifacts. Usually subfolder in build directory should be used

GENERATED_HEADERS - List of header files expected after generator job finished

EXCLUDE_HEADERS - List of header files to be excluded from pre-parsed list of expected header files (e.g. nested messages that are not supported by QtProtobuf generator)

PROTO_FILES - List of .proto files that will be used in generation procedure

MULTI - Enables/disables multi-files generation mode. In case if this property is set to TRUE generator will create pair of header/source files for each message

Note: multi-files generation mode is defined as deprecated by QtProtobuf team, and might have poor support in future

QML - Enables/disables QML code generation in protobuf classes. If set to TRUE qml related code for lists and qml registration to be generated.

Outcome:

QtProtobuf_GENERATED - variable that will contain generated STATIC library target name

qtprotobuf_link_archive

qtprotobuf_link_archive is cmake helper function that links whole archive to your library or executable target. It's useful when you try to link generated target to shared library or/and to executable that doesn't utilize all protobuf generated classes directly from C++ code, but requires them from QML.

Parameters

TARGET - name of target to link to

GENERATED_TARGET - protobuf generated target name

Usefull definitions

QTPROTOBUF_MAKE_COVERAGE - if TRUE/ON, QtProtobuf will be built with gcov intergration, to collect code coverage reports(usefull for developers). FALSE by default

QTPROTOBUF_MAKE_TESTS - if TRUE/ON, tests for QtProtobuf will be built. TRUE by default

QTPROTOBUF_MAKE_EXAMPLES - if TRUE/ON, built-in examples will be built. TRUE by default

QTPROTOBUF_EXECUTABLE - contains full path to QtProtobuf generator add_executable

qmake integration

Note: Available in QtProtobuf version >=0.2.0

QtProtobuf has limited qmake build procedures support. It's only available and tested on linux platforms. To use it in your qmake project, first you need build and install QtProtobuf as standalone project in your system paths:

mkdir build
cd build
cmake .. [-DCMAKE_PREFIX_PATH="<path/to/qt/installation>/Qt<qt_version>/<qt_version>/gcc_64/lib/cmake"] -DCMAKE_INSTALL_PREFIX=/usr -DQTPROTOBUF_MAKE_TESTS=OFF -DQTPROTOBUF_MAKE_EXAMPLES=OFF
sudo cmake --build . [--config <RELEASE|DEBUG>] -- -j<N> install

Commands above will install qt protobuf into you system paths prefixed with /usr folder.

Once build and installation is finished, you may use QtProtobuf and QtGrpc in qmake project by adding following lines in .pro file:

QT += protobuf #for protobuf libraries support
QT += grpc #for grpc libraries support

To generate source code and link it to you project use predefined qtprotobuf_generate function

qtprotobuf_generate([generate_qml=false])

qtprotobuf_generate is qmake helper test function that generates QtProtobuf source code based on files provided by PROTO_FILES global context variable

Parameters:

generate_qml - Enables/disables QML code generation in protobuf classes. If set to true qml related code for lists and qml registration to be generated.

Note: see examples/qmakeexample for details

Running tests

cd <build directory>
ctest

Documentation generation

Project uses doxygen for documentation generation.

For Windows additionally install:

• doxygen
• graphviz

You can generate documentation:

mkdir build
cd build
cmake ..
cmake --build . --target doc