如何在移动web浏览器中使用输入[type='file']，在捕获照片后在画布上正确地绘制照片?

I am making a simple web app in mobile which allow visitor to capture photo by using html5 input[type=file] element. Then I will display it on the web for preview, and then visitor can choose to upload the photo to my server for other purpose(ie: upload to FB)I am making a simple web app in mobile which al