Introduction
In this article I describe how to create a Windows Store App to capture an image using JavaScript. In this article we capture a photo from a webcam. For this app it is necessary that you have a webcam in your system and all the drivers of the webcam are Correctly installed. If you don't have a webcam or your webcam does not work then this app will still run but it cannot capture images from the webcam.
I assume you can create a simple Windows Store App using JavaScript. For more help visit Simple Windows Store Apps using JavaScript.
To start the creation of the app, add two JavaScript pages by right-clicking on the js folder in the Solution Explorer and select Add > new item > JavaScript Page and then give an appropriate name. In the same way, add one HTML page to your project.
Write the following code in default.html:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title> app</title>
<link rel="stylesheet" href="//Microsoft.WinJS.1.0/css/ui-light.css" />
<script src="//Microsoft.WinJS.1.0/js/base.js"></script>
<script src="//Microsoft.WinJS.1.0/js/ui.js"></script>
<link rel="stylesheet" href="/css/default.css" />
<script src="/js/script1.js"></script>
<script src="/js/default.js"></script>
</head>
<body role="application" style="background-color: lightblue">
<center> <div id="rootGrid">
<div id="content">
<h1 id="featureLabel"></h1>
<div id="contentHost"></div>
</div>
</div></center>
</body>
</html>
Write the following code in default.js:
(function () {
"use strict";
var appTitle = "Photo capture";
var pages = [
{ url: "page.html" }
];
function activated(eventObject) {
if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) {
eventObject.setPromise(WinJS.UI.processAll().then(function () {
var url = WinJS.Application.sessionState.lastUrl || pages[0].url;
return WinJS.Navigation.navigate(url);
}));
}
}
WinJS.Navigation.addEventListener("navigated", function (eventObject) {
var url = eventObject.detail.location;
var host = document.getElementById("contentHost");
host.winControl && host.winControl.unload && host.winControl.unload();
WinJS.Utilities.empty(host);
eventObject.detail.setPromise(WinJS.UI.Pages.render(url, host, eventObject.detail.state).then(function () {
WinJS.Application.sessionState.lastUrl = url;
}));
});
WinJS.Namespace.define("App", {
appTitle: appTitle,
pages: pages
});
WinJS.Application.addEventListener("activated", activated, false);
WinJS.Application.start();
})();
Write the following code in page.html:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<link rel="stylesheet" href="/css/capturephoto.css" />
<script src="/js/script.js"></script>
</head>
<body>
<div data-win-control="App.pageInput">
<button id="captureButton">Capture Photo</button>
<button id="resetButton">Reset</button>
<br />
<br />
</div>
<div data-win-control="App.pageOutput">
<img class="imageHolder" id="capturedPhoto" alt="image holder" src="/images/1.jpg" />
</div>
</body>
</html>
Write the following code in script.js:
(function () {
"use strict";
var photoKey = "capturedPhoto";
var localSettings = Windows.Storage.ApplicationData.current.localSettings;
var page = WinJS.UI.Pages.define("page.html", {
ready: function (element, options) {
document.getElementById("captureButton").addEventListener("click", capturePhoto, false);
document.getElementById("resetButton").addEventListener("click", reset, false);
document.getElementById("resetButton").style.visibility = "hidden";
if (localSettings.values[photoKey]) {
document.getElementById("captureButton").disabled = true;
reloadPhoto();
}
}
});
function capturePhoto() {
WinJS.log && WinJS.log("", "app", "status");
var dialog = new Windows.Media.Capture.CameraCaptureUI();
var aspectRatio = { width: 1, height: 1 };
dialog.photoSettings.croppedAspectRatio = aspectRatio;
dialog.captureFileAsync(Windows.Media.Capture.CameraCaptureUIMode.photo).done(function (file) {
if (file) {
var photoBlobUrl = URL.createObjectURL(file, { oneTimeOnly: true });
document.getElementById("capturedPhoto").src = photoBlobUrl;
document.getElementById("resetButton").style.visibility = "visible";
localSettings.values[photoKey] = file.path;
} else {
WinJS.log && WinJS.log("No photo captured.", "app", "status");
}
}, function (err) {
WinJS.log && WinJS.log(err, "app", "error");
});
}
function reset() {
WinJS.log && WinJS.log("", "app", "status");
document.getElementById("capturedPhoto").src = "/images/placeholder-sdk.png";
document.getElementById("resetButton").style.visibility = "hidden";
localSettings.values.remove(photoKey);
}
function reloadPhoto() {
Windows.Storage.StorageFile.getFileFromPathAsync(localSettings.values[photoKey]).done(function (file) {
document.getElementById("capturedPhoto").src = URL.createObjectURL(file, { oneTimeOnly: true });
document.getElementById("resetButton").style.visibility = "visible";
document.getElementById("captureButton").disabled = false;
}, function (err) {
localSettings.values.remove(photoKey);
document.getElementById("captureButton").disabled = false;
WinJS.log && WinJS.log(err, "app", "error");
});
}
})();
Write the following code in script1.js:
(function () {
var pageOutput = WinJS.Class.define(
function (element, options) {
element.winControl = this;
this.element = element;
new WinJS.Utilities.QueryCollection(element)
.setAttribute("role", "region")
.setAttribute("aria-labelledby", "outputLabel")
.setAttribute("aria-live", "assertive");
element.id = "output";
this._addOutputLabel(element);
this._addStatusOutput(element);
}, {
_addOutputLabel: function (element) {
var label = document.createElement("h2");
label.id = "outputLabel";
label.textContent = "Output";
element.parentNode.insertBefore(label, element);
},
_addStatusOutput: function (element) {
var statusDiv = document.createElement("div");
statusDiv.id = "statusMessage";
element.insertBefore(statusDiv, element.childNodes[0]);
}
}
);
var currentpageUrl = null;
WinJS.Navigation.addEventListener("navigating", function (evt) {
currentpageUrl = evt.detail.location;
});
WinJS.log = function (message, tag, type) {
var statusDiv = document.getElementById("statusMessage");
};
function activated(e) {
WinJS.Utilities.query("#featureLabel")[0].textContent = App.appTitle;
}
WinJS.Application.addEventListener("activated", activated, false);
WinJS.Namespace.define("App", {
pageOutput: pageOutput
});
})();
Output:
Summary
In this app I described how to capture a photo in a Windows Store App using JavaScript. I hope this article has helped you to understand this topic. Please share if you know more about this. Your feedback and constructive contributions are welcome.
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