Capturing images in web application on Windows 8.1 tablets

问题

I am about to develop an application that is to run on Windows 8.1 tablets. An important feature is to be able to click on a button to access the camera to take some pictures. Ideally I would like to create it as a Web application rather than a native application due to a number of reasons (licences, cross-platform, development time: have no experience in native apps, etc.).

I have looked at the options for capturing images from HTML 5 and have found HTML Media Capture which allows me to write:

<input type="file" accept="image/*" capture="camera" />

To get access to the camera. This works great on iPads and on Android tablets, but I can't get it to work on Windows 8 tablets. I have tried using Chrome on the Windows 8 tablet, but still no effect. All it does is that it opens a file dialog in which I can choose a file to upload. What I want to do is to be able to capture a new image. This standard is not supported by IE (an apparently the other browsers cannot access the device's camera either).

I have also stumbled across Media Capture and Streams which seems to be mostly related to showing streams from e.g. the web cam, but probably could be used to capture images and is supported by Chrome and Firefox among other browsers, but still not by Internet Explorer (even IE11). None of the three browsers' implementations seem to work on my Windows 8.1 test machine though. If someone has gotten getUserMedia to work on Windows 8 tablets in any browser I'm interested in hearing about it.

Anyway, my main question is: Is there any way to access the camera on a Windows 8 tablet using HTML5 from a web application? The only working examples I have seen have relied on a prototype implementation for IE using Active X or solutions that use flash.

EDIT: I would very much prefer to keep it in HTML5/javascript as it has to work offline (using HTML5 Application Cache)

回答1:

I struggled very much for this solution, at the end I find good a solution. But only can use in windows store apps like chrome windows 8 mode (chrome settings -> relaunch chrome in windows 8 mode) then you can use the normal file input tag in html. when you hit "choose file" u see the image below. Then u can choose camera to add take image from camera.

if you can not see camera in the list, u can install app below.

https://www.microsoft.com/en-US/store/apps/Camera-File-Open-Picker/9WZDNCRFJQVN

回答2:

So I was running into the exactly same issue. My web app is similar, except I have to do some bar code scanning with the tablet's camera.

I'm using the HTML 5 media api as you commented. In order to make it work in chrome in a Windows 8 Surface Pro, I had to do this:

To enable getUserMedia in Chrome type ‘chrome://flags/’ in URL bar and enable “Enable screen capture support in getUserMedia(). Mac, Windows, Linux, Chrome OS” option.

It was working in my laptop but not in the tablet, after making that change and restarting chrome it worked. Good luck.

回答3:

Here is the code I ended up using to get around this situation... It appears to work in chrome very well however still no support for Internet Explorer which is known not support getUserMedia. Again I wish this wasn't necessary and windows just supported the take picture feature like iOS and android but it works for now.

Credit: http://davidwalsh.name/browser-camera

    // Put event listeners into place
    window.addEventListener("DOMContentLoaded", function() {
    // Grab elements, create settings, etc.
    var canvas = document.getElementById("canvas"),
        context = canvas.getContext("2d"),
        video = document.getElementById("video"),
        videoObj = { "video": true },
        errBack = function(error) {
            console.log("Video capture error: ", error.code);
        };

    // Put video listeners into place
    if(navigator.getUserMedia) { // Standard
        navigator.getUserMedia(videoObj, function(stream) {
            video.src = stream;
            video.play();
        }, errBack);
    } else if(navigator.webkitGetUserMedia) { // WebKit-prefixed
        navigator.webkitGetUserMedia(videoObj, function(stream){
            video.src = window.webkitURL.createObjectURL(stream);
            video.play();
        }, errBack);
    }
    else if(navigator.mozGetUserMedia) { // Firefox-prefixed
        navigator.mozGetUserMedia(videoObj, function(stream){
            video.src = window.URL.createObjectURL(stream);
            video.play();
        }, errBack);
    }
    document.getElementById("snap").addEventListener("click", function() {
        context.drawImage(video, 0, 0, 640, 480);
    });
}, false);

回答4:

getUserMedia interface works in Chrome on my Surface 2, prove:

I've implemented solution described here: http://www.html5rocks.com/en/tutorials/getusermedia/intro/ Btw, there is a working example on their site as well:

getUserMedia doesn't work in IE
getUserMedia probably works in FF, but I didn't test
access to the camera from [Browse] button doesn't work in any browser on my Surface 2

EDIT: Just realized, my approach doesn't work on Surface any more. Same story for the html5rocks page, the example given doesn't work on Surface. I guess, new Chrome version stopped to support something. BUT I've found the example which works on Surface for Chrome and Firefox, here you are: http://www.ceng.metu.edu.tr/~e1559848/demos/qrdecode/index.html

来源：https://stackoverflow.com/questions/20471561/capturing-images-in-web-application-on-windows-8-1-tablets

标签

html

mobile

camera

tablet

windows-8.1