Use of video tags and canvas drawings in HTML5

Use of video tags

The video tag defines the movie, which is a new label in HTML5, and its properties are as follows (refer to the documentation):

　　

Domo01

<! DOCTYPE html>"en">"UTF-8"> <title>demo01</title>"Madashuai.mp4"loop="Loop"autoplay="AutoPlay"controls="Controls"Width=" -"height=" -"></video></body>
 
 

  
  
 
   
SRC is the path to the video
 
   
Loop is looping, that is, playback continues after the play is finished
 
   
AutoPlay is ready to play
 
   
Controls appear as control controls, and no start-pause buttons if not
 
   
Width and height to control the video widths and heights
 
  
 
 
Use of DrawImage in canvas
The first parameter that is accepted can be an IMG, or video, or a canvas, and the following parameters are used for clipping and controlling the width of the height.
DOMO02:
<! DOCTYPE html>"en">"UTF-8"> <title>demo01</title>"Myvideo"Src="Madashuai.mp4"loop="Loop"autoplay="AutoPlay"controls="Controls"></video> <br> <button id="Snapscreen"> screenshot </button> <canvas id="MyCanvas"Width=" -"height=" -"></canvas> <script>varMyCanvas = document.getElementById ('MyCanvas'). GetContext ('2d'), Snapscreen= document.getElementById ('Snapscreen'), Video= document.getElementById ('Myvideo'); Snapscreen.onclick=function () {mycanvas.drawimage (video,0,0, -, -); } </script></body>

 
  

  
   
 
    
We get to the canvas environment first and then click the button to take the current video screenshot.
 
   
 
  
Navigator.mediaDevices.getUserMedia ()
By this method, we can get the right to use the local webcam, official documentation.
When used, it is usually combined with the video tag, that is, the camera is displayed on video.
DEMO03:
<! DOCTYPE html>"en">"UTF-8"> <title>demo01</title>"Myvideo"Src=""></video> <script>Navigator.mediaDevices.getUserMedia ({//Audio:true,//You can also open the sound here .Videotrue}). Then (function (mediastream) {varMyvideo = document.getElementById ('Myvideo'); Myvideo.srcobject=MediaStream; Myvideo.onloadedmetadata=function () {Myvideo.controls="Controls";    Myvideo.play (); }  }); </script></body>

 
   

  
    
 
     
Note: The use of MediaStream here is similar to the usage of promise in ES6, which is passed to then as a parameter after the result is obtained.
 
     
The srcobject tag that assigns the video source to the visual tag can be displayed in video.
 
     
The Onloadedmetadata event is triggered after the video file has been loaded.
 
    
 
   
Now we can combine the camera with video and canvas so we can take a screenshot.
demo04
<! DOCTYPE html>"en">"UTF-8"> <title>demo01</title>"Myvideo"Width=" -"height=" -"Src=""></video> <button id="Snapscreen"> screenshot </button> <canvas id="MyCanvas"Width=" -"height=" -"></canvas> <script>varMyvideo = document.getElementById ('Myvideo'); Navigator.mediaDevices.getUserMedia ({video:true}). Then (function (mediastream) {Myvideo.srcobject=MediaStream; Myvideo.onloadedmetadata=function () {Myvideo.controls="Controls";    Myvideo.play ();  }  }); varSnapscreen = document.getElementById ('Snapscreen'), Canvas= document.getElementById ('MyCanvas'). GetContext ('2d'); Snapscreen.onclick=function () {canvas.drawimage (Myvideo,0,0); } </script></body>
The following is quite interesting:
Demo05
<! DOCTYPE html>"en">"UTF-8"> <title>demo01</title>class="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <videoclass="Myvideos"Src=""></video> <script>varMyvideos = Document.getelementsbyclassname ('Myvideos'); Navigator.mediaDevices.getUserMedia ({video:true}). Then (function (mediastream) { for(vari =0; i < myvideos.length; i++) {Myvideos[i].srcobject=MediaStream; Myvideos[i].width= -;    Myvideos[i].play (); }  }); </script></body>
Use of video tags and canvas drawings in HTML5