实时视频工具，展示HTML5 video, canvas, Ext 特性

HTML5 知识库

阅读:982次评论:3条更新时间:2011-09-15

EXT HTML5

David Davis创建了一个Live video示例，用于展示HTML5 video和Canvas的特性。<video> 标签是为了原生的视频渲染，这样的话就不用那些第三方的如Flash的插件。至于<canvas> 标签，则是为了在像素级别，这么细的一个级别中“画出”复杂的图形图像，而且是一个清晰而强大的API。

作为HTML5的一部分，<video> 可以通用CSS和JavaScript来定制和操作，使得我们能够用一种不错的方式对用户观看的视频加以处理。以此为题材，我们可以做出一个很实用的组件——live video ，以下为截图：

首先扩展Ext.Panel使其可以播放HTML5的视频：

Ext.ns('Ext.ux');
 
/* -NOTICE-
 * For HTML5 video to work, your server must
 * send the right content type, for more info see:
 * https://developer.mozilla.org/En/HTML/Element/Video
 */
Ext.ux.HTML5VideoPanel = Ext.extend(Ext.Panel, {
 
  constructor: function(config) {
    Ext.ux.HTML5VideoPanel.superclass.constructor.call(this, Ext.applyIf(config, {
      width    : '100%',
      height   : '100%',
      autoplay : false,
      controls : true,
      bodyStyle: 'background-color:#000;color:#fff',
      html     : '',
      suggestChromeFrame: false
    }));
 
    this.on({
      scope        : this,
      render       : this._render,
      beforedestroy: function() {
        this.video = null;
      },
      bodyresize   : function(panel, width, height) {
        if (this.video)
        this.video.setSize(width, height);
      }
    });
  },
 
  _render: function() {
    var fallback = '';
 
    if (this.fallbackHTML) {
      fallback = this.fallbackHTML;
    } else {
      fallback = "Your browser doesn't support html5 video. ";
 
      if (Ext.isIE && this.suggestChromeFrame) {
        /* chromeframe requires that your site have a special tag in the header
         * see http://code.google.com/chrome/chromeframe/ for details
         */
        fallback += '<a>Get Google Chrome Frame for IE</a>';
      } else if (Ext.isChrome) {
        fallback += '<a>Upgrade Chrome</a>';
      } else if (Ext.isGecko) {
        fallback += '<a>Upgrade to Firefox 3.5</a>';
      } else {
        fallback += '<a>Get Firefox 3.5</a>';
      }
    }
 
    /* match the video size to the panel dimensions */
    var size = this.getSize();
 
    var cfg = Ext.copyTo({
      tag   : 'video',
      width : size.width,
      height: size.height
    },
    this, 'poster,start,loopstart,loopend,playcount,autobuffer,loop');
 
    /* just having the params exist enables them */
    if (this.autoplay) cfg.autoplay = 1;
    if (this.controls) cfg.controls = 1;
 
    /* handle multiple sources */
    if (Ext.isArray(this.src)) {
      cfg.children = [];
 
      for (var i = 0, len = this.src.length; i < len; i++) {
        if (!Ext.isObject(this.src[i])) {
          throw "source list passed to html5video panel must be an array of objects";
        }
 
        cfg.children.push(
          Ext.applyIf({tag: 'source'}, this.src[i])
        );
      }
 
      cfg.children.push({
        html: fallback
      });
 
    } else {
      cfg.src  = this.src;
      cfg.html = fallback;
    }
 
    this.video = this.body.createChild(cfg);
  }
 
});
 
Ext.reg('html5video', Ext.ux.HTML5VideoPanel);

将html5video panel添加到一个web desktop window，canvas preview 添加到taskbar按钮：

Desktop.VideoWindow = Ext.extend(Ext.app.Module, {
  id: 'video-win',
 
  init: function() {
    this.launcher = {
      text   : 'Video Window',
      iconCls: 'icon-grid',
      handler: this.createWindow,
      scope  : this
    };
  },
 
  createWindow: function() {
    var win,
        tipWidth  = 160,
        tipHeight = 96;
 
    /* createWindow uses renderTo, so it is immediately rendered */
    win = this.app.getDesktop().createWindow({
      animCollapse   : false,
      constrainHeader: true,
 
      title  : 'Video Window',
      width  : 740,
      height : 480,
      iconCls: 'icon-grid',
      shim   : false,
      border : false,
      layout : 'fit',
      items: [{
        xtype: 'html5video',
        src: [
        // firefox (ogg theora)
        {
          src : 'http://xant.us/files/google_main.ogv',
          type: 'video/ogg'
        },
        // chrome and webkit-nightly (h.264)
        {
          src : 'http://xant.us/files/google_main.mgv',
          type: 'video/mp4'
        }
        ],
        autobuffer: true,
        autoplay : true,
        controls : true,
        /* default */
        listeners: {
          afterrender: function() {
            var win = this.ownerCt;
            win.videoEl = this.video.dom;
 
            win.tip = new Ext.ToolTip({
              anchor   : 'bottom',
              autoHide : true,
              hideDelay: 300,
              height   : tipHeight,
              width    : tipWidth,
              bodyCfg  : {
                tag    : 'canvas',
                width  : tipWidth,
                height : tipHeight
              },
              listeners: {
                afterrender: function() {
                  /* get the canvas 2d context */
                  win.ctx = this.body.dom.getContext('2d');
                }
              }
            });
          }
        }
      }],
      listeners: {
        beforedestroy: function() {
          win.tip = win.ctx = win.videoEl = null;
        }
      }
    });
 
    win.show();
 
    win.tip.initTarget(win.taskButton.el);
    win.tip.on('show', this.renderPreview.createDelegate(this, [win]));
  },
 
  renderPreview: function(win) {
    if ((win.tip && ! win.tip.isVisible()) || !win.videoEl) return;
 
    if (win.ctx) {
      win.ctx.drawImage(win.videoEl, 0, 0, win.tip.width, win.tip.height);      
    }
 
    /* 20ms to keep the tooltip video smooth */
    this.renderPreview.defer(20, this, [win]);
  }
 
});

在靠近sample.js顶部的位置，为getModules添加app constructor：

getModules : function(){
  return [
    new MyDesktop.GridWindow(),
    new MyDesktop.TabWindow(),
    new MyDesktop.AccordionWindow(),
    new MyDesktop.BogusMenuModule(),
    new MyDesktop.BogusModule(),
    /* add the line below, and don't forget the comma above */
    new MyDesktop.VideoWindow()
  ];
}