Offscreen QML for Node.js

This is a part of Node3D project.

npm i -s qml-raub

QML interoperation addon for Node.js. See Qt Documentation for QML features and syntax.

Note: this addon uses N-API, and therefore is ABI-compatible across different Node.js versions. Addon binaries are precompiled and there is no compilation step during the npm i command.

const { View } = require('qml-raub');
View.init(process.cwd(), hwnd, ctx, device);

const ui = new View({ width, height, file: 'gui.qml' });

The QML engine must be initialized first. Then, new View instances can be created.

• See TypeScript declarations for more details.
• See example for a complete setup.

QML views can process input events. Mouse and keyboard events can be sent to a view. Unhandled (unused) events are re-emitted by the view. Changing the event flow from window -> app to window -> ui -> app allows blocking the handled events. For example, when a QML button is pressed, a 3D scene behind the button won't receive any mouse event. Or when a QML input is focused, the app's hotkeys won't be triggered by typing text.

View

Main class that loads and manages a QML file.

When the file is loaded and whenever the QML scene is resized a new GL Texture (id) is created and reported in an event (type 'reset'). Then the texture can be placed onto any drawable surface.

For example a screen-sized rectangle with this texture would look as if it is the app's UI, which it already almost is. Also some in-scene quads, e.g. a PC display in the distant corner of 3d room, can be textured this way.

const ui = new View({ width, height, file: 'gui.qml' });

See TypeScript declarations for more details.

Events:

• 'destroy' - emitted when the scene is destroyed.
• 'load' - emitted when the scene is fully loaded.
• 'reset', textureId - emitted when a new texture is generated.
• <ANY_EVENTS> - being an EventEmitter, views can emit anything. On QML side, a special global function eventEmit(type, data) is present. Using this function any event can be generated from QML side.

Property

Helper class to access QML data. Automates reading and writing QML objects. A QML object should have objectName and the target property. The value must be serializable.

const x1 = new Property({ view, name: 'obj1', key: 'x1' });
x1.value = 10;

See TypeScript declarations for more details.

Method

Helper class to call a QML method. A QML object should have objectName and the target method.

const f1 = new Method({ view, name: 'obj1', key: 'f1' });
const y = f1(a, b, c);

Instances of this class are actually functions on their own. Up to 10 arguments can be used for the call. Functions may immediately return a value.