47 lines
1.7 KiB
JavaScript
47 lines
1.7 KiB
JavaScript
'use strict';
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// This polyfill prepares a child context to be attached to a parent context.
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// The parent must call navigator.usb.test.attachToContext() to attach to the
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// child context.
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(() => {
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if (this.constructor.name === 'DedicatedWorkerGlobalScope' ||
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this !== window.top) {
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// Run Chromium specific set up code.
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if (typeof MojoInterfaceInterceptor !== 'undefined') {
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let messageChannel = new MessageChannel();
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messageChannel.port1.onmessage = async (messageEvent) => {
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if (messageEvent.data.type === 'Attach') {
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messageEvent.data.interfaces.forEach(interfaceName => {
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let interfaceInterceptor =
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new MojoInterfaceInterceptor(interfaceName);
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interfaceInterceptor.oninterfacerequest =
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e => messageChannel.port1.postMessage({
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type: interfaceName,
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handle: e.handle
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}, [e.handle]);
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interfaceInterceptor.start();
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});
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// Wait for a call to GetDevices() to ensure that the interface
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// handles are forwarded to the parent context.
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try {
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await navigator.usb.getDevices();
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} catch (e) {
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// This can happen in case of, for example, testing usb disallowed
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// iframe.
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console.error(`getDevices() throws error: ${e.name}: ${e.message}`);
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}
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messageChannel.port1.postMessage({ type: 'Complete' });
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}
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};
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let message = { type: 'ReadyForAttachment', port: messageChannel.port2 };
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if (typeof Window !== 'undefined')
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parent.postMessage(message, '*', [messageChannel.port2]);
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else
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postMessage(message, [messageChannel.port2]);
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}
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}
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})();
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