[This answers your problem](https://stackoverflow.com/questions/4912092/using-html5-canvas-javascript-to-take-screenshots/6678156#6678156).

You can use JavaScript/Canvas to do the job but it is still experimental.

**Update:** 

There is a library for this now https://html2canvas.hertzen.com/

I needed to snapshot a div on the page (for a webapp I wrote) that is protected by JWT&#39;s and makes very heavy use of Angular.

I had no luck with any of the above methods.

I ended up taking the outerHTML of the div I needed, cleaning it up a little (*) and then sending it to the server where I run wkhtmltopdf against it.

This is working _very_ well for me.

(*) various input devices in my pages didn&#39;t render as checked or have their text values when viewed in the pdf...  So I run a little bit of jQuery on the html before I send it up for rendering.  ex: for text input items -- I copy their .val()&#39;s into &#39;value&#39; attributes, which then can be seen by wkhtmlpdf

I&#39;d really like to be able to print out valid SQL for my application, including values, rather than bind parameters, but it&#39;s not obvious how to do this in SQLAlchemy (by design, I&#39;m fairly sure). 

Has anyone solved this problem in a general way?

SQLAlchemy: print the actual query

I am reading an development guide of Facebook Developers at [here][1] 

It says that I must use keytool to export the signature for my app such as:

```cmd
keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64
```

I do not know how to find the keytool in order to run it. I tried to open a Windows command prompt and paste the above command, but it did not work.

  [1]: http://developers.facebook.com/docs/guides/mobile/#android.

How can I find and run the keytool

I&#39;m working on web application that needs to render a page and make a screenshot on the client (browser) side. 

I don&#39;t need the screenshot to be saved on the local HDD though, just kept it in RAM and send it to the application server later.

I researched:

1. BrowserShots alike services...
2. Mechanized browsers...
3. wkhtmltoimage...
4. Python WebKit2PNG...

But none of those gives me all I need, which is:

1. Processing at browser side (generate screenshot of page). Don&#39;t need to be saved on HDD! Just...
2. ...send image to Server for further processing.
3. Capturing whole page (not only visible part)

Eventually I came upon Google&#39;s Feedback Tool (click &quot;feedback&quot; on YouTube footer to see this). It contains [JavaScript for JPG encoding](http://code.google.com/p/closure-library/source/browse/trunk/third_party/closure/goog/jpeg_encoder/jpeg_encoder_basic.js?spec=svn463&amp;r=440) and two other huge scripts which I can&#39;t determine what exactly they do... 

But it&#39;s processed on the Client side - otherwise there would be no point putting this huge JPEG encoder in the code!

Anyone have any idea how did they made it / how I can make it?

Here is an example of the feedback (report a bug on some screens)

![Feedback/report bug example][1]


  [1]: http://i.stack.imgur.com/9Wj0x.jpg

How to screenshot website in JavaScript client-side / how Google did it? (no need to access HDD)

I'm working on web application that needs to render a page and make a screenshot on the client (browser) side.
I don't need the screenshot to be saved on the local HDD though, just kept it in RAM and send it to the application server later.
I researched:
<ol>
<li>BrowserShots alike services...</li>
<li>Mechanized browsers...</li>
<li>wkhtmltoimage...</li>
<li>Python WebKit2PNG...</li>
</ol>
But none of those gives me all I need, which is:
<ol>
<li>Processing at browser side (generate screenshot of page). Don't need to be saved on HDD! Just...</li>
<li>...send image to Server for further processing.</li>
<li>Capturing whole page (not only visible part)</li>
</ol>
Eventually I came upon Google's Feedback Tool (click "feedback" on YouTube footer to see this). It contains <a href="http://code.google.com/p/closure-library/source/browse/trunk/third_party/closure/goog/jpeg_encoder/jpeg_encoder_basic.js?spec=svn463&#x26;r=440" target="_blank" rel="noopener noreferrer">JavaScript for JPG encoding</a> and two other huge scripts which I can't determine what exactly they do...
But it's processed on the Client side - otherwise there would be no point putting this huge JPEG encoder in the code!
Anyone have any idea how did they made it / how I can make it?
Here is an example of the feedback (report a bug on some screens)
<img src="http://i.stack.imgur.com/9Wj0x.jpg" alt="Feedback/report bug example">

How to convert colors in RGB format to hex format and vice versa?

For example, convert `&#39;#0080C0&#39;` to `(0, 128, 192)`.

RGB to hex and hex to RGB

How should a view&#39;s `el` be handled?
It has to be set, otherwise events don&#39;t fire (see [here][1]).

But should it be an element that is already on the page?
In my app, I render a (jQuery Templates) template into a Fancybox. What should the `el` be in that case?

  [1]: https://stackoverflow.com/questions/4909564/backbone-js-why-isnt-this-event-bound

Backbone.View &quot;el&quot; confusion

I have an app.js node application. As this file is starting to grow, I would like to move some part of the code in some other files that I would &quot;require&quot; or &quot;include&quot; in the app.js file.

I&#39;m trying things like:

    // Declare application
    var app = require(&#39;express&#39;).createServer();

    // Declare usefull stuff for DB purposes
    var mongoose = require(&#39;mongoose&#39;);
    var Schema = mongoose.Schema;
    var ObjectId = Schema.ObjectId;

    // THE FOLLOWING REQUIRE DOES NOT WORK
    require(&#39;./models/car.js&#39;);

in car.js:

    // Define Car model
    CarSchema = new Schema({
      brand        : String,
      type : String
    });
    mongoose.model(&#39;Car&#39;, CarSchema);


I got the error:

    ReferenceError: Schema is not defined

I&#39;m just looking to have the content of car.js loaded (instead of having everything in the same app.js file) Is there a particuliar way to do this in node.js ?


include external .js file in node.js app

Here&#39;s an contrived example of what&#39;s going on: http://jsfiddle.net/adamjford/YNGcm/20/

HTML:

    &lt;a href=&quot;#&quot;&gt;Click me!&lt;/a&gt;
    &lt;div&gt;&lt;/div&gt;

JavaScript:

    function getSomeDeferredStuff() {
        var deferreds = [];
    
        var i = 1;
        for (i = 1; i &lt;= 10; i++) {
            var count = i;
    
            deferreds.push(
            $.post(&#39;/echo/html/&#39;, {
                html: &quot;&lt;p&gt;Task #&quot; + count + &quot; complete.&quot;,
                delay: count
            }).success(function(data) {
                $(&quot;div&quot;).append(data);
            }));
        }
        
        return deferreds;
    }
    
    $(function() {
        $(&quot;a&quot;).click(function() {
            var deferreds = getSomeDeferredStuff();
    
            $.when(deferreds).done(function() {
                $(&quot;div&quot;).append(&quot;&lt;p&gt;All done!&lt;/p&gt;&quot;);
            });
        });
    });

I want &quot;All done!&quot; to appear after all of the deferred tasks have completed, but `$.when()` doesn&#39;t appear to know how to handle an array of Deferred objects. &quot;All done!&quot; is happening first because the array is not a Deferred object, so jQuery goes ahead and assumes it&#39;s just done.

I know one could pass the objects into the function like `$.when(deferred1, deferred2, ..., deferredX)` but it&#39;s unknown how many Deferred objects there will be at execution in the actual problem I&#39;m trying to solve.

Pass in an array of Deferreds to $.when()

How do you test an element for existence without the use of the `getElementById` method?

I have set up a [live demo][1] for reference. I will also print the code on here as well:

    &lt;!DOCTYPE html&gt;
    &lt;html&gt;
    &lt;head&gt;
        &lt;script&gt;
        var getRandomID = function (size) {
                var str = &quot;&quot;,
                    i = 0,
                    chars = &quot;0123456789abcdefghijklmnopqurstuvwxyzABCDEFGHIJKLMNOPQURSTUVWXYZ&quot;;
                while (i &lt; size) {
                    str += chars.substr(Math.floor(Math.random() * 62), 1);
                    i++;
                }
                return str;
            },
            isNull = function (element) {
                var randomID = getRandomID(12),
                    savedID = (element.id)? element.id : null;
                element.id = randomID;
                var foundElm = document.getElementById(randomID);
                element.removeAttribute(&#39;id&#39;);
                if (savedID !== null) {
                    element.id = savedID;
                }
                return (foundElm) ? false : true;
            };
        window.onload = function () {
            var image = document.getElementById(&quot;demo&quot;);
            console.log(&#39;undefined&#39;, (typeof image === &#39;undefined&#39;) ? true : false); // false
            console.log(&#39;null&#39;, (image === null) ? true : false); // false
            console.log(&#39;find-by-id&#39;, isNull(image)); // false
            image.parentNode.removeChild(image);
            console.log(&#39;undefined&#39;, (typeof image === &#39;undefined&#39;) ? true : false); // false ~ should be true?
            console.log(&#39;null&#39;, (image === null) ? true : false); // false ~ should be true?
            console.log(&#39;find-by-id&#39;, isNull(image)); // true ~ correct but there must be a better way than this?
        };
        &lt;/script&gt;
    &lt;/head&gt;
    &lt;body&gt;
        &lt;div id=&quot;demo&quot;&gt;&lt;/div&gt;
    &lt;/body&gt;
    &lt;/html&gt;

Basically the above code demonstrates an element being stored into a variable and then removed from the DOM. Even though the element has been removed from the DOM, the variable retains the element as it was when first declared. In other words, it is not a live reference to the element itself, but rather a replica. As a result, checking the variable&#39;s value (the element) for existence will provide an unexpected result.

The `isNull` function is my attempt to check for an elements existence from a variable, and it works, but I would like to know if there is an easier way to accomplish the same result.

PS: I&#39;m also interested in why JavaScript variables behave like this if anyone knows of some good articles related to the subject.

  [1]: http://jsbin.com/apawi5/3





How can I check if an element exists in the visible DOM?

How do I obtain a `java.awt.Image` of a JFrame?

I want to obtain a screen shot of a `JFrame` (for later use within my application). This is presently accomplished using the robot to take a screen shot specifying the coordinates and dimensions of the `JFrame` involved.

However, I believe that there is a better way: Swing components, by default, render themselves as images into a double buffer prior to painting themselves onto the screen.

Is there a way to obtain these images from the component?


Swing: Obtain Image of JFrame

I want to take a screenshot of my iOS application when it is running in the simulator, and save the screenshot on my Mac. How can I do this?

Take screenshots in the iOS simulator

I have saved some screenshots in the iPhone Simulator running iOS 5, but I can&#39;t find them. 

I had this problem before, and it took me frickin&#39; ages to find them in the file system. Is this so simple that I am just a dullard, or does no-one use this feature or what?

I know I can get the screenshots off my real phone, but I don&#39;t want retina screenshots - I want normal screenshots.

Where are iOS simulator screenshots stored?

I&#39;m running Firefox on a Xvfb in a VPS. What I want to do is to take a full page screenshot of the page.

I can redirect Firefox to particular page using

    firefox http://google.com

and take a screenshot (inside X) using ImageMagick

    import root -window output.jpg

The problem is, most of the page need scrolling and I can&#39;t know the height beforehand.

The other way is to pick a very big height (like 4000px) and then process the image and remove the useless part. But that&#39;s unnecessary processing.

I found many Firefox add-ons, but I&#39;m looking for a solution that can be programmed using the Shell Command line.

Edit: I ended up writing my own [FireFox extension][1] for doing this.


  [1]: https://github.com/omarabid/CmdShots

Take a full page screenshot with Firefox on the command-line

I want to [take screenshots](https://stackoverflow.com/questions/7092613/take-screenshots-in-the-ios-simulator?rq=1) of my iOS apps running from Xcode in the iPhone Simulator and iPad Simulator.

However, when I take screenshots, only the screen is captured. The device frame (which *is* shown on my desktop surrounding the iOS Simulator window) is not included in the screenshot.

How can I take screenshots of Xcode&#39;s iOS Simulator app and include the bounding hardware device frame?

Take iOS Simulator screenshots including device frame?

I want to write a module where on a click of a button the camera opens and I can click and capture an image.  If I don&#39;t like the image I can delete it and click one more image and then select the image and it should return back and display that image in the activity.

Capture Image from Camera and Display in Activity

When I write a lambda with `[=]`, does it mean that all my local variables will be copied into members of the created struct or can I assume that only those will that are actually used in the lambda? For example:

    void f()
    {
        vector&lt;int&gt; v(10000);
        const int n = 5;
        const int DivByNCnt = count_if(istream_iterator&lt;int&gt;(cin), istream_iterator&lt;int&gt;(), 
              [=](int i)
              {
                 return i % n == 0;
              });
    }

Which of the following, if any, is true?

 - both n and v will be copied
 - n will be copied, v will not
 - n will be copied, v may or may not be copied depending on the implmenentation/optimization settings.

Suppose for the argument&#39;s sake that vector&#39;s copy constructor has side effects. 

Does [=] imply that all local variables will be copied?

I&#39;m using a Python library that does something to an object
```python
do_something(my_object)
```
and changes it. While doing so, it prints some statistics to stdout, and I&#39;d like to get a grip on this information. The proper solution would be to change `do_something()` to return the relevant information,
```python
out = do_something(my_object)
```
but it will be a while before the devs of `do_something()` get to this issue. As a workaround, I thought about parsing whatever `do_something()` writes to stdout.

How can I capture stdout output between two points in the code, e.g.,
```python
start_capturing()
do_something(my_object)
out = end_capturing()
```
?

How to capture stdout output from a Python function call?

I often search documents (mainly PDFs) using Google. But when I right click the link, or just hang the mouse cursor over it. What I get is NOT the real link, but some thing long and confusing like the following:

    http://www.google.com/url?sa=t&amp;source=web&amp;cd=1&amp;ved=0CCUQFjAA&amp;url=http%3A%2F%2Fwww.marxists.org%2Freference%2Farchive%2Feinstein%2Fworks%2F1910s%2Frelative%2Frelativity.pdf&amp;ei=Fai1TZq-Acugtgenw6DqDg&amp;usg=AFQjCNFzYOTqpf68rQnuwW9K7wp39WL6Rg&amp;sig2=z4RqvOLEEJsPohBqr1ghxQ

I have no idea what this is but I know this nonsense is not what I want, I want the real link (for the one above: `http://www.marxists.org/reference/archive/einstein/works/1910s/relative/relativity.pdf`), not something with Google&#39;s intervention.

How do I get the “Real” link to file in Google search results?

&quot;Real&quot; link to file in Google search results?

I have come across an interview question &quot;If you were designing a web crawler, how would you avoid getting into infinite loops? &quot; and I am trying to answer it.

How does it all begin from the beginning.
Say Google started with some hub pages say hundreds of them (How these hub pages were found in the first place is a different sub-question).
As Google follows links from a page and so on, does it keep making  a hash table to make sure that it doesn&#39;t follow the earlier visited pages.

What if the same page has 2 names (URLs) say in these days when we have URL shorteners etc..

I have taken Google as an example. Though Google doesn&#39;t leak how its web crawler algorithms and page ranking etc work, but any guesses?


Designing a web crawler

I see two issues with AngularJS application regarding search engines and SEO:

1) What happens with custom tags? Do search engines ignore the whole content within those tags? i.e. suppose I have

    &lt;custom&gt;
      &lt;h1&gt;Hey, this title is important&lt;/h1&gt;
    &lt;/custom&gt;

would `&lt;h1&gt;` be indexed despite being inside custom tags?

&lt;br&gt;

2) Is there a way to avoid search engines of indexing {{}} binds literally? i.e.

    &lt;h2&gt;{{title}}&lt;/h2&gt;

I know I could do something like

    &lt;h2 ng-bind=&quot;title&quot;&gt;&lt;/h2&gt;

but what if I want to actually let the crawler &quot;see&quot; the title? Is server-side rendering the only solution?



How do search engines deal with AngularJS applications?

Some will think this is not related to programming but I think it is, because most of the time when I encounter programming issues I search on Google to find solutions or ways to do what I plan to do before I start writing it from scratch. Let&#39;s face it, we all copy pasters...

I don&#39;t like to remove my hands from the keyboard. Google had a feature after you submit a query and press &lt;kbd&gt;Tab&lt;/kbd&gt; it will start navigating within the search results. Most likely because they had a tabindex attribute which was was removed.

Does anyone know why sometimes this works and sometimes it doesn&#39;t? I&#39;m starting to think I should create a Chrome app that will add the tab index to the results, but I don&#39;t want to do it before I am 100% sure this feature was removed.


Content Type	Original Author	Original Content on Stackoverflow
Question	Paweł Szymański	View Question on Stackoverflow
Solution 1 - Javascript	Vaibhav Garg	View Answer on Stackoverflow
Solution 2 - Javascript	Al Joslin	View Answer on Stackoverflow

How to screenshot website in JavaScript client-side / how Google did it? (no need to access HDD)

Javascript Problem Overview

Javascript Solutions

Solution 1 - Javascript

Solution 2 - Javascript

How can I find and run the keytool

SQLAlchemy: print the actual query

Attributions