我喜欢使用 windows.WindowState API，但收到错误“windows is not defined”。
const windowstate = windows.windowstate;我正在开发一个使用语音合成 API 的 WebExtension。它的问题是，当语音暂停时，该 API 不能再用于其他选项卡！为了防止这种情况发生，演讲必须停止而不是暂停。但在这种情况下，如果用户想再次恢复第一个选项卡上的文本，则必须从头开始重复整个段落。也就是说，为什么我想区分不同的可见性变化（我为此使用了 'visibilitychange'、'blur' 和 'focus' 事件）：
- TabLeave ➔ 停止发言
- TabEnter ➔ 再次开始语音，如果用户进行了此设置
- LostFocus 和 WndMinimized ➔ 暂停语音，如果用户进行了此设置
- GotFocus & WndRestored/WndMaximized ➔ 恢复语音，如果之前暂停并且用户进行了此设置
我的“manifest.json”：
{
"description": "My extension.","manifest_version": 2,"name": "Lesehilfe","version": "1.0","homepage_url": "https://dummy.de","icons": {
"32": "icons/aero_arrow_reading_aid_32x32.cur"
},"content_scripts": [
{
"matches": ["<all_urls>"],"js": ["lib/tinycolor.js","lib/input_action.js","lib/state_change.js","lib/print.js","lib/xlabs_library.js","options.js","content.js"],"css": ["style.css","resources.css"]
}
],"background": {
"scripts": ["background.js"]
},"options_ui": {
"page": "options.html","browser_style": true,"chrome_style": true,"_comment": "browser_style is for Firefox,non-standard chrome_style for Chrome and Opera"
},"permissions": [
"storage","notifications","activetab"
]
}
问题演示：
<html>
<body style="text-align: center;">
<strong>Speech Synthesis API Test</strong>
<p id="SOquestion">
I am developing a WebExtension,which makes use of the speech synthesis API. The problem with it is,when speech is paused,that API can’t be used on other tabs anymore! To prevent this,that speech has to be stopped instead of paused. But in this case,the whole paragraph has to be repeated from start,if the user wants to resume the text on the first tab again. That is,why I want to distinguish between different visability changes (I am using the 'visibilitychange','blur' and 'focus' event for this):
</p>
<button id="btnPlayPause">▶</button><!-- Play sign -->
<button id="btnStop">⏹</button> <!-- Stop sign -->
<script>
function onCompletion(e) {
btnPlayPause.innerText = "▶"; // Play sign
}
var btnPlayPause = document.getElementById("btnPlayPause");
var btnStop = document.getElementById("btnStop");
var text = document.getElementById("SOquestion").innerText;
var synth = window.speechSynthesis;
var utterThis = new SpeechSynthesisUtterance(text);
utterThis.onend = onCompletion;
utterThis.lang = 'en-UK';
btnPlayPause.addEventListener('click',(e) => {
if (synth.paused) {
btnPlayPause.innerText = "⏸"; // Pause sign
synth.resume();
return;
}
if (synth.speaking) {
btnPlayPause.innerText = "▶"; // Play sign
synth.pause();
return;
}
btnPlayPause.innerText = "⏸"; // Pause sign
synth.speak(utterThis);
},false);
btnStop.addEventListener('click',(e) => {
onCompletion();
synth.cancel();
},false);
</script>
</body>
</html>请按照以下步骤操作：
- 运行代码片段
- 点击播放按钮
- 点击暂停（同一个按钮）
- 导航到其他包含文章的标签
- 进入 Firefox 阅读器模式
- 从那里开始语音合成
➔ 它不应该播放任何语音输出（至少这发生在我身上）
- 现在与停止演讲而不是暂停演讲进行比较
我的问题是：
- windows.windowstate API 是否仅限于后台脚本，还是也可以用于内容脚本？
- 它需要什么权限？