Chromium是支持Video對象的,這個是HTML5的新特性,如今爲了在JavaScript中能夠調用到底層的一些特性,需要給其添加一個新的方法,即: 如何使JavaScript能夠調用到Chromium底層的一些特性。
首先看一下Video Play方法的調用堆棧,
通過調用堆棧我們可以看到,Play方法最初是應該屬於HTMLMediaElement,這個也是HTML5的一個元素,Video繼承至它。
我們再來看看相關一些類的關係,
這樣就更清晰了,通過調查可以得知,我們只有在HTMLMediaElement中定義相應的接口,然後一路調用下去,最後就可以調用到WebMediaPlayerImpl,這個類具體實現Player的相應功能,這個類中可以調用到PipeLine,這樣我們就可以調用我們任意想調用的東西了,例如: demux,decoder,render等。要想把相應的接口Export到JavaScript層,在HTMLMediaElement.idl中定義是關鍵,其他的事情框架就給我做了。下面講一個小例子。
----------------------------------------------------Sample--------------------------------------------
We implement a specialcall interface on HTMLMediaElementand it call WebMediaPlayerImpl’s function finally.
First we prepare a sample.html to triggerthe call as below:
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Second, we add implemented code in Chromiumproject as below:
1, Add specialcall function inHTMLMediaElement classvoidHTMLMediaElement::specialcall() {
printf("Good , called my function in HTMLMediaElement! \n");
if(m_player)
m_player->myspecialcall();
else
printf("can't get m_player in HTMLMediaElement \n");
}
2, Export specialcall funciton inHTMLMediaElement.idl file
void specialcall();
3, Add specialcall in MediaPlayer classvoid MediaPlayer::specialcall(){
printf("myspecialcall is called in MediaPlayer class \n");
m_private->myspecialcall();
}
4, Add a virtual function in WebMediaPlayerclass in WebMediaPlayer.hvirtual void myspecialcall() { }
5, Add a virtual function in MediaPlayerPrivateclass in WebMediaPlayer.hvirtual void specialcall() { }
6, Add a virtual function in WebMediaPlayerClientImplclass
void WebMediaPlayerClientImpl::specialcall(){
printf("specialcall is called in WebMediaPlayerClientImpl class\n");
if (m_webMediaPlayer.get())
m_webMediaPlayer->specialcall();
else
printf("can't get web media player at this moment \n");
}
7, Add a virtual function in WebMediaPlayerImpl class
voidWebMediaPlayerImpl::specialcall(){
printf("myspecialcall is called in WebMediaPlayerImpl class\n");
printf("Here,i think it's enough,you can get what you want becauseyou can get pipeline here \n");
}
Third, build theChromium project and run Chrome and load sample.html, click pay button afterload. The result is as below: