WebkitSpeech

readme.md

Simple demo on how to write JS plugins for Corona

Tiny sample of using JavaScript with Corona HTML5 builds. JavaScript plugin_speech.js exposes Lua module plugin.speech with APIs to access browser's Web Speech capabilities: speech.start(...), speech.stop() and speech.isRunning().

Live Demo:

• https://vlad-test.s3.amazonaws.com/WebkitSpeech/index.html

Guide on using JavaScript in Corona:

• https://docs.coronalabs.com/guide/html5/plugins/index.html

Web Speech API info:

• https://www.google.com/intl/en/chrome/demos/speech.html
• https://developers.google.com/web/updates/2013/01/Voice-Driven-Web-Apps-Introduction-to-the-Web-Speech-API
• https://w3c.github.io/speech-api/speechapi.html

build.settings

settings =
{
	orientation =
	{
		default = "portrait",
		supported = { "portrait", },
	},
}

config.lua

application =
{
	content =
	{
		width = 320,
		height = 480, 
		scale = "letterbox",
	},
}

main.lua

-- using protected call because plugin is only in browser, no Lua wrapper
local imported, speech = pcall(require, "plugin.speech")
if not imported then speech = {isRunning=function()end,start=function()end,stop=function()end,} end

-- text objects to hold results or instructions
local phase = display.newText {
    text="event phase goes here", fontSize = 12,
    x = display.contentCenterX, y = 20, width = display.contentWidth*0.9, height = 20,
}

local text = display.newText{
    text="Click to start/stop/restart. Note mic access request!", fontSize = 12,
    width = display.contentWidth*0.9, x = display.contentCenterX, y = display.contentCenterY,
}

Runtime:addEventListener("tap", function()
    if speech.isRunning() then
        speech.stop()
    else
        if not speech.start{
            lang = "en-US",
            continuous = true,
            interimResults = true,
            listener = function(event)
                -- print(require('json').encode(event))
                phase.text = event.phase
                if event.phase == "result" then
                    text.text = event.final .. event.interim
                elseif event.phase == "started" then
                    text.text = "Start talking!"
                end
            end
        } then 
            text.text = "Error while starting speech recognition!"
        end
    end
end)

plugin_speech.js

plugin_speech = {
    start: function(params) {
        var self = this;
        if (!('webkitSpeechRecognition' in window)) {
            return null;
        }
        if(!params || !LuaIsFunction(params.listener)) {
            console.error("No listener passed to params table")
            return null;
        }
        self.callback = LuaCreateFunction( params.listener );

        self.final_transcript = "";
        self.recognition = new webkitSpeechRecognition();
        self.recognition.continuous = params.continuous || false;
        self.recognition.interimResults = params.interimResults || false;
        if(params.lang) {
            self.recognition.lang = params.lang;
        }
    
        self.recognition.onstart = function() {
            self.callback({
                name: "speech",
                phase: "started",
            })
        };

        self.recognition.onerror = function(event) {
            self.callback({
                name: "speech",
                phase: "error",
                error: event.error,
                isError: true,
            })
            self.recognition = null;
        };

        self.recognition.onend = function() {
            self.callback({
                name: "speech",
                phase: "ended",
                final: self.final_transcript,
            })
            self.recognition = null;
            LuaReleaseFunction(self.callback);
        };

        self.recognition.onresult = function(event) {
            var interim_transcript = '';
            for (var i = event.resultIndex; i < event.results.length; ++i) {
                if (event.results[i].isFinal) {
                    self.final_transcript += event.results[i][0].transcript;
                } else {
                    interim_transcript += event.results[i][0].transcript;
                }
            }
            self.callback({
                name: "speech",
                phase: "result",
                interim: interim_transcript,
                final: self.final_transcript,
            })
        };
        self.recognition.start();
        return true;
    },
    isRunning: function() {
        return this.recognition != null;
    },
    stop: function() {
        if(this.recognition) {
            this.recognition.stop()
        }
        this.recognition = null;
    }
}