QML Debug

WARNING !!!

This is a beta release. It may contain bugs and problems.

Please be patient while using it and report back any problem you have encountered to https://github.com/orcun-gokbulut/qml-debug/issuess

Thank you for using Qml-Debug Beta.

Description

Short Description: QML Debuger for VSCode.

Detailed Description: Debug Adapter Protocol (DAP), which is used by Visual Studio Code to interface with various debuggers, implementation for Qt QML debugger.

https://microsoft.github.io/debug-adapter-protocol/

Usage

Right now only attach mode debugging is supported which means you have to launch your application (by hand or through another Visual Studio Code launch configuration) and then attach Qml Debugger.

This limitation will be lifted in future releases. Qml Debug will eventually gain the ability to launch your application.

Attach Mode

Attach mode attaches Qml Debugger in the already running application instance.

Sample launch.json Configuration:

{

    "version": "0.2.0",
    "configurations": [
        {
            "name": "QML Debug: Attach",
            "type": "qml",
            "request": "attach",
            "host": "localhost",
            "port": 12150,
            "paths": {
                "qrc:/qml-debug-test-app/qml": "${workspaceFolder}/qml"
            }
        },
    ]
}

Configuration Properties

name: Name of your configuration.
type: Type of your debugger extension. This should be qml.
request (Default: attach): Debugger mode. Only attach mode is supported for now. Therefore this should be attach.
host (Default: 127.0.0.1): Hostname/IP Address of the computer that debugee will be run.
port (Default: 12150): Port number of the debugger.
paths: List of Qml paths that will be matched to physical paths for debugger to load correct source code.

Mapping Virtual paths to Physical Paths

In order to Qml Debuger find your source code, you should have one or more path matching options in your configuration. These mapping tuples are contained in configuration's path property.

Example:

"paths": {
    "qrc:/qml-debug-test-app": "${workspaceFolder}/src/qml",
    "qrc:/qml-debug-test-app/ui": "${workspaceFolder}/src/ui/qml"
}

Launching Your Application

In order to debug your Qml based application in attach mode you have to start your binary with debug parameters;

./your_qml_app -qmljsdebugger=host:127.0.0.1,port:12150,block,services:DebugMessages,QmlDebugger,V8Debugger,QmlInspector

These parameters will instruct Qt to load necessary debugger plugins and extensions. On launch mode Qml Debugger extension will add these paramters automaticly but in attach mode you have to add it yourself when you are launching your application by hand.

You can also use VSCode launch.json configuration to append the parameters by adding flowing lines to your configration;;

"args": [
    "-qmljsdebugger=host:localhost,port:12150,services:DebugMessages,QmlDebugger,V8Debugger"
]

Attach with C++ Debugger

If you want use multiple debugger (C++ and Qml) at the same time you should crate compatable one Qml Debug configuıration and one cppdbg configuration then combine them into launch compound.

You should make sure that cppdbg launch configration launches application with debugging command line arguments with correct hostname and port values that matches with your Qml Debug launch configuration.

Command Line Arguments:

-qmljsdebugger=host:localhost,port:12150,services:DebugMessages,QmlDebugger,V8Debugger

Launch Configuration:

"host": "localhost",
"port": 12150,

Example compund launch configration;

{
    "version": "0.2.0",
    "configurations": [
        // C++ Launcher
        {
            "name": "C++ Debug: Launch",
            "type": "cppdbg",
            "request": "launch",
            "program": "${workspaceFolder}/your_qml_application",
            "args": [
                "-qmljsdebugger=host:localhost,port:12150,services:DebugMessages,QmlDebugger,V8Debugger"
            ]
        },
        // Qml Attacher
        {
            "name": "QML Debug: Attach",
            "type": "qml",
            "request": "attach",
            "host": "localhost",
            "port": 12150,
            "paths": {
                "qrc:/qml": "${workspaceFolder}/qml"
            }
        },
    ],
    "compounds": [
        {
          "name": "C++/QML Debug: Launch",
          "configurations": ["C++ Debug: Launch", "QML Debug: Attach"]
        }
    ]
}

Current State

Project is still in development. Current version is fully functional but unstable with lots of potential bugs. In addition to that, there are rooms for improvements in various places. Therefore, still work in progress...

Initial Release Features

[x] Qt Datastream Protocol Implementation.
[x] Debugging and logging support tools and utilities.
[x] Main structure of the application.
[x] Handshaking and snakeoil code.
[x] Breakpoints
[x] Flow Control (Pause, Step, StepIn, StepOut, Continue)
[x] Backtrace and Stack Viewer
[x] Editor Variable Evaluators
[x] Exception Breakpoints
[x] Settings
[x] Documentation
[ ] Extended Documentation
[ ] Polishing, Bugfixing, Improving Stability and Hardening for Initial Release
[ ] Automatic Attach (Automaticly find Qml application and attach it)
[ ] Automatic C++ Debug Launcher (Launch C++ debuger before starting Qml Debug Session)
[ ] Automated Unit Tests

Next Major Version Features

[ ] Qml Scene Graph Profiler and Debugger

Really R&D Stuff (Far Future, Requires VSCode future contribution)

[ ] Mixed Mode Debugging (Merging Qml and C++ debug sessions into one)

Author

👤 Y. Orçun Gökbulut

Website: https://www.github.com/orcun-gokbulut
Github: @orcun-gokbulut

🤝 Contributing

Contributions, issues and feature requests are welcome!
Feel free to check issues page. You can also take a look at the contributing guide.

Y. Orçun GÖKBULUT