android html5, how to get a photo from the Gallery app and put it into a canvas

I need the following:

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  I have a html5 application on android

  
  


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  When the user clicks on the button "Select image", android shows the default Gallery app (or any other app of the user), and the user selects one of this photos

  
  


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  android returns back to my html5 page, passing the userImage, and the html5 page puts the image into a canvas (instead of uploading the photo to a server through a web form):

  
  

  var ctx = document.getElementById("myCanvas").getContext("2d"); ctx.drawImage(userImage, 0, 0);

  
  

how to do this with HTML5 getUserMedia API?