qskinny/doc/html/qtloader.js

277 lines
10 KiB
JavaScript

// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
/**
* Loads the instance of a WASM module.
*
* @param config May contain any key normally accepted by emscripten and the 'qt' extra key, with
* the following sub-keys:
* - environment: { [name:string] : string }
* environment variables set on the instance
* - onExit: (exitStatus: { text: string, code?: number, crashed: bool }) => void
* called when the application has exited for any reason. There are two cases:
* aborted: crashed is true, text contains an error message.
* exited: crashed is false, code contians the exit code.
*
* Note that by default Emscripten does not exit when main() returns. This behavior
* is controlled by the EXIT_RUNTIME linker flag; set "-s EXIT_RUNTIME=1" to make
* Emscripten tear down the runtime and exit when main() returns.
*
* - containerElements: HTMLDivElement[]
* Array of host elements for Qt screens. Each of these elements is mapped to a QScreen on
* launch.
* - fontDpi: number
* Specifies font DPI for the instance
* - onLoaded: () => void
* Called when the module has loaded.
* - entryFunction: (emscriptenConfig: object) => Promise<EmscriptenModule>
* Qt always uses emscripten's MODULARIZE option. This is the MODULARIZE entry function.
* - module: Promise<WebAssembly.Module>
* The module to create the instance from (optional). Specifying the module allows optimizing
* use cases where several instances are created from a single WebAssembly source.
* - qtdir: string
* Path to Qt installation. This path will be used for loading Qt shared libraries and plugins.
* The path is set to 'qt' by default, and is relative to the path of the web page's html file.
* This property is not in use when static linking is used, since this build mode includes all
* libraries and plugins in the wasm file.
* - preload: [string]: Array of file paths to json-encoded files which specifying which files to preload.
* The preloaded files will be downloaded at application startup and copied to the in-memory file
* system provided by Emscripten.
*
* Each json file must contain an array of source, destination objects:
* [
* {
* "source": "path/to/source",
* "destination": "/path/to/destination"
* },
* ...
* ]
* The source path is relative to the html file path. The destination path must be
* an absolute path.
*
* $QTDIR may be used as a placeholder for the "qtdir" configuration property (see @qtdir), for instance:
* "source": "$QTDIR/plugins/imageformats/libqjpeg.so"
*
* @return Promise<{
* instance: EmscriptenModule,
* exitStatus?: { text: string, code?: number, crashed: bool }
* }>
* The promise is resolved when the module has been instantiated and its main function has been
* called. The returned exitStatus is defined if the application crashed or exited immediately
* after its entry function has been called. Otherwise, config.onExit will get called at a
* later time when (and if) the application exits.
*
* @see https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/emscripten for
* EmscriptenModule
*/
async function qtLoad(config)
{
const throwIfEnvUsedButNotExported = (instance, config) =>
{
const environment = config.environment;
if (!environment || Object.keys(environment).length === 0)
return;
const isEnvExported = typeof instance.ENV === 'object';
if (!isEnvExported)
throw new Error('ENV must be exported if environment variables are passed');
};
const throwIfFsUsedButNotExported = (instance, config) =>
{
const environment = config.environment;
if (!environment || Object.keys(environment).length === 0)
return;
const isFsExported = typeof instance.FS === 'object';
if (!isFsExported)
throw new Error('FS must be exported if preload is used');
};
if (typeof config !== 'object')
throw new Error('config is required, expected an object');
if (typeof config.qt !== 'object')
throw new Error('config.qt is required, expected an object');
if (typeof config.qt.entryFunction !== 'function')
config.qt.entryFunction = window.createQtAppInstance;
config.qt.qtdir ??= 'qt';
config.qt.preload ??= [];
config.qtContainerElements = config.qt.containerElements;
delete config.qt.containerElements;
config.qtFontDpi = config.qt.fontDpi;
delete config.qt.fontDpi;
// Used for rejecting a failed load's promise where emscripten itself does not allow it,
// like in instantiateWasm below. This allows us to throw in case of a load error instead of
// hanging on a promise to entry function, which emscripten unfortunately does.
let circuitBreakerReject;
const circuitBreaker = new Promise((_, reject) => { circuitBreakerReject = reject; });
// If module async getter is present, use it so that module reuse is possible.
if (config.qt.module) {
config.instantiateWasm = async (imports, successCallback) =>
{
try {
const module = await config.qt.module;
successCallback(
await WebAssembly.instantiate(module, imports), module);
} catch (e) {
circuitBreakerReject(e);
}
}
}
const qtPreRun = (instance) => {
// Copy qt.environment to instance.ENV
throwIfEnvUsedButNotExported(instance, config);
for (const [name, value] of Object.entries(config.qt.environment ?? {}))
instance.ENV[name] = value;
// Copy self.preloadData to MEMFS
const makeDirs = (FS, filePath) => {
const parts = filePath.split("/");
let path = "/";
for (let i = 0; i < parts.length - 1; ++i) {
const part = parts[i];
if (part == "")
continue;
path += part + "/";
try {
FS.mkdir(path);
} catch (error) {
const EEXIST = 20;
if (error.errno != EEXIST)
throw error;
}
}
}
throwIfFsUsedButNotExported(instance, config);
for ({destination, data} of self.preloadData) {
makeDirs(instance.FS, destination);
instance.FS.writeFile(destination, new Uint8Array(data));
}
}
if (!config.preRun)
config.preRun = [];
config.preRun.push(qtPreRun);
config.onRuntimeInitialized = () => config.qt.onLoaded?.();
const originalLocateFile = config.locateFile;
config.locateFile = filename =>
{
const originalLocatedFilename = originalLocateFile ? originalLocateFile(filename) : filename;
if (originalLocatedFilename.startsWith('libQt6'))
return `${config.qt.qtdir}/lib/${originalLocatedFilename}`;
return originalLocatedFilename;
}
const originalOnExit = config.onExit;
config.onExit = code => {
originalOnExit?.();
config.qt.onExit?.({
code,
crashed: false
});
}
const originalOnAbort = config.onAbort;
config.onAbort = text =>
{
originalOnAbort?.();
aborted = true;
config.qt.onExit?.({
text,
crashed: true
});
};
const fetchPreloadFiles = async () => {
const fetchJson = async path => (await fetch(path)).json();
const fetchArrayBuffer = async path => (await fetch(path)).arrayBuffer();
const loadFiles = async (paths) => {
const source = paths['source'].replace('$QTDIR', config.qt.qtdir);
return {
destination: paths['destination'],
data: await fetchArrayBuffer(source)
};
}
const fileList = (await Promise.all(config.qt.preload.map(fetchJson))).flat();
self.preloadData = (await Promise.all(fileList.map(loadFiles))).flat();
}
await fetchPreloadFiles();
// Call app/emscripten module entry function. It may either come from the emscripten
// runtime script or be customized as needed.
let instance;
try {
instance = await Promise.race(
[circuitBreaker, config.qt.entryFunction(config)]);
} catch (e) {
config.qt.onExit?.({
text: e.message,
crashed: true
});
throw e;
}
return instance;
}
// Compatibility API. This API is deprecated,
// and will be removed in a future version of Qt.
function QtLoader(qtConfig) {
const warning = 'Warning: The QtLoader API is deprecated and will be removed in ' +
'a future version of Qt. Please port to the new qtLoad() API.';
console.warn(warning);
let emscriptenConfig = qtConfig.moduleConfig || {}
qtConfig.moduleConfig = undefined;
const showLoader = qtConfig.showLoader;
qtConfig.showLoader = undefined;
const showError = qtConfig.showError;
qtConfig.showError = undefined;
const showExit = qtConfig.showExit;
qtConfig.showExit = undefined;
const showCanvas = qtConfig.showCanvas;
qtConfig.showCanvas = undefined;
if (qtConfig.canvasElements) {
qtConfig.containerElements = qtConfig.canvasElements
qtConfig.canvasElements = undefined;
} else {
qtConfig.containerElements = qtConfig.containerElements;
qtConfig.containerElements = undefined;
}
emscriptenConfig.qt = qtConfig;
let qtloader = {
exitCode: undefined,
exitText: "",
loadEmscriptenModule: _name => {
try {
qtLoad(emscriptenConfig);
} catch (e) {
showError?.(e.message);
}
}
}
qtConfig.onLoaded = () => {
showCanvas?.();
}
qtConfig.onExit = exit => {
qtloader.exitCode = exit.code
qtloader.exitText = exit.text;
showExit?.();
}
showLoader?.("Loading");
return qtloader;
};