I think the project you are looking for is: https://github.com/sarxos/webcam-capture (I&#39;m the author)

There is an example working exactly as you&#39;ve described - after it&#39;s run, the window appear where, after you press &quot;Start&quot; button, you can see live image from webcam device and save it to file after you click on &quot;Snapshot&quot; ([source code available][2], please note that FPS counter in the corner can be disabled):

![snapshot][1]

The project is portable (WinXP, Win7, Win8, Linux, Mac, Raspberry Pi) and does not require any additional software to be installed on the PC.

API is really nice and easy to learn. Example how to capture single image and save it to PNG file:

    Webcam webcam = Webcam.getDefault();
    webcam.open();
    ImageIO.write(webcam.getImage(), &quot;PNG&quot;, new File(&quot;test.png&quot;));

  [1]: http://i.stack.imgur.com/u9ZJN.png
  [2]: https://github.com/sarxos/webcam-capture/blob/master/webcam-capture/src/example/java/TakeSnapshotFromVideoExample.java

Undefining a method in Ruby is pretty simple, I can just use `undef METHOD_NAME`.

Is there anything similar for a class? I am on `MRI 1.9.2`. 

I have to undefine an ActiveRecord Model, run two lines of code, and restore the model back to its original form.

The problem is, I have an model `Contact` and I am using a company&#39;s API and it happens that they have some class called `Contact`, and changing my model name would be lot of work for me. 

What can I do in this situation?

How to undefine class in Ruby?

&gt; **Possible Duplicate:**  
&gt; [How to write Python sort key functions for descending values](https://stackoverflow.com/questions/11206884/how-to-write-python-sort-key-functions-for-descending-values)  

&lt;!-- End of automatically inserted text --&gt;

In Python 3, it&#39;s pretty easy to sort a list of objects lexicographically using multiple keys.  For example:

`items.sort(key = lambda obj: obj.firstname, obj.lastname)`

The `reverse` argument lets you specify whether you want ascending or descending order.  But what do you do in the case where you want to sort by multiple keys, but you want to sort using descending order for the first key, and ascending order for the second?

For example, suppose we have an object with two attributes, `points` and `name`, where `points` is an `int` and `name` is a `str`.  We want to sort a list of these objects by `points` in *descending* order (so that the object with the greatest number of points comes first), but for objects with an equal number of `points`, we want to sort these by `name` in alphabetical (*ascending*) order.

How can this be achieved?

Sort by multiple keys using different orderings

I need to access web camera using Java. This is what I want to do

1. Access web cam 

2. Now the user can see web cam working because his face is visible on screen
(have heard some libs are there which doesn&#39;t show the video output of webcam) 

3. when user click save button, take a snapshot and save it



I have tried number of ways to do this, from a long time.

1. JMF - Now it is dead
2. FMJ - Now it is dead too
3. VLCJ - too much because I am not creating a music/video player and it expect VLC to be installed
4. Xuggler - too much and hard work
5. JMyron - didn&#39;t work
6. JavaFX - I thought it could do it, but seems like it can&#39;t


I am even satisfied if the library is just ONLY doing the above mentioned, because that&#39;s enough for me. But I expect it to be simple too. Really great if it is not using DLLs, because it is not platform independent if it does. Really appreciate if it can DETECT the camera, without manually passing the camera name and other info as have do in VLCJ (because there might be thousands of camera brands, so I can&#39;t create a list of thousand elements in it). And, I am creating a desktop application, not web app.

If you know a library like this, please be kind enough to let me know. Other libraries (which might not suit to all of my requirements, but suits to the basic requirement) also welcome. Please help




Best way to access web camera in Java

I need to access web camera using Java. This is what I want to do
<ol>
<li>
Access web cam
</li>
<li>
Now the user can see web cam working because his face is visible on screen
(have heard some libs are there which doesn't show the video output of webcam)
</li>
<li>
when user click save button, take a snapshot and save it
</li>
</ol>
I have tried number of ways to do this, from a long time.
<ol>
<li>JMF - Now it is dead</li>
<li>FMJ - Now it is dead too</li>
<li>VLCJ - too much because I am not creating a music/video player and it expect VLC to be installed</li>
<li>Xuggler - too much and hard work</li>
<li>JMyron - didn't work</li>
<li>JavaFX - I thought it could do it, but seems like it can't</li>
</ol>
I am even satisfied if the library is just ONLY doing the above mentioned, because that's enough for me. But I expect it to be simple too. Really great if it is not using DLLs, because it is not platform independent if it does. Really appreciate if it can DETECT the camera, without manually passing the camera name and other info as have do in VLCJ (because there might be thousands of camera brands, so I can't create a list of thousand elements in it). And, I am creating a desktop application, not web app.
If you know a library like this, please be kind enough to let me know. Other libraries (which might not suit to all of my requirements, but suits to the basic requirement) also welcome. Please help

Shortly, I have an `NSDictionary` with urls for images that I need to show in my `UITableView`. Each cell has a title and an image. I had successfully made this happen, although the scrolling was lagging, as it seemed like the cells downloaded their image every time they came into the screen.
I searched for a bit, and found `SDWebImage` on github. This made the scroll-lagg go away. I am not completely sure what it did, but I believed it did some caching. 
But! Every time I open the app for the first time, I see NO images, and I have to scroll down, and back up for them to arrive. And if I exit the app with home-button, and open again, then it seemes like the caching is working, because the images on the screen are visible, however, if I scroll one cell down, then the next cell has no image. Until i scroll past it and back up, or if I click on it. Is this how caching is supposed to work? Or what is the best way to cache images downloaded from the web? The images are being updated rarily, so I was close to just import them to the project, but I like to have the possibility to update images without uploading an update..

Is it impossible to load all the images for the whole tableview form the cache(given that there is something in the cache) at launch? Is that why I sometimes see cells without images?

And yes, I&#39;m having a hard time understanding what cache is.



**--EDIT--**

I tried this with only images of the same size (500x150), and the aspect-error is gone, however when I scroll up or down, there are images on all cells, but at first they are wrong. After the cell has been in the view for some milliseconds, the right image appears. This is amazingly annoying, but maybe how it has to be?.. It seemes like it chooses the wrong index from the cache at first. If I scroll slow, then I can see the images blink from wrong image to the correct one. If I scroll fast, then I believe the wrong images are visible at all times, but I can&#39;t tell due to the fast scrolling. When the fast scrolling slows down and eventually stops, the wrong images still appear, but immediately after it stops scrolling, it updates to the right images. I also have a custom `UITableViewCell` class, but I haven&#39;t made any big changes.. I haven&#39;t gone through my code very much yet, but I can&#39;t think of what may be wrong.. Maybe I have something in the wrong order.. I have programmed much in java, c#, php etc, but I&#39;m having a hard time understanding Objective-c, with all the `.h` and `.m` ...
I have also `
    
    @interface FirstViewController : UITableViewController{
    
    /**/
    NSCache *_imageCache;
    }
(among other variables) in `FirstViewController.h`. Is this not correct?

Here&#39;s my `cellForRowAtIndexPath`.

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
    static NSString *CellIdentifier = @&quot;hallo&quot;;
    CustomCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    
    if (cell == nil)
    {
        cell = [[CustomCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }
    
    NSMutableArray *marr = [hallo objectAtIndex:indexPath.section];
    NSDictionary *dict = [marr objectAtIndex:indexPath.row];
    
    NSString* imageName = [dict objectForKey:@&quot;Image&quot;];
    //NSLog(@&quot;url: %@&quot;, imageURL);
    
    UIImage *image = [_imageCache objectForKey:imageName];
    
    if(image)
    {
        cell.imageView.image = image;
    }
    else
    {
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
            
            NSString* imageURLString = [NSString stringWithFormat:@&quot;example.com/%@&quot;, imageName];
            NSURL *imageURL = [NSURL URLWithString:imageURLString];
            UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:imageURL]];
            
            if(image)
            {
                dispatch_async(dispatch_get_main_queue(), ^{
                    CustomCell *cell =(CustomCell*)[self.tableView cellForRowAtIndexPath:indexPath];
                    if(cell)
                    {
                        cell.imageView.image = image;
                    }
                });
                [_imageCache setObject:image forKey:imageName];
            }
        });
    }
    
    cell.textLabel.text = [dict objectForKey:@&quot;Name&quot;];
    
    return cell;
    }

Best way to cache images on ios app?

Does OpenCV support the comparison of two images, returning some value (maybe a percentage) that indicates how similar these images are? E.g. 100% would be returned if the same image was passed twice, 0% would be returned if the images were totally different.

I already read a lot of similar topics here on StackOverflow. I also did quite some Googling. Sadly I couldn&#39;t come up with a satisfying answer.

Checking images for similarity with OpenCV

Is there a general way to define the size, in percent or pixels, for an image that is linked in `org-mode`?

Say I have the following link in my `.org` file:

    [[~/images/example.jpg]]

This JPG is way too large, so if I export it to HTML or LaTeX or open it in `org-mode` with &lt;kbd&gt;C-c C-o i&lt;/kbd&gt; will only see a fraction of the image. 

How to resize images in org-mode

I have a site with many pages and different background pictures, and I display them from CSS like:

&lt;!-- language-all: lang-css --&gt;
    
    body.page-8 {
	    background: url(&quot;../img/pic.jpg&quot;) no-repeat scroll center top #000;
	    background-size: cover;
    }

However, I want to show different (fullscreen) pictures on one page using `&lt;img&gt;` elements, and I want them to have the same properties as the above  `background-image: cover;` property (the images cant be displayed from CSS, they must be displayed from the HTML document).

Normally I use:

    div.mydiv img {
	    width: 100%;
    }

Or:

    div.mydiv img {
	    width: auto;
    }

to make the picture full and responsive. However the picture shrinks too much (`width: 100%`) when the screen gets too narrow, and shows the body&#39;s background-color in the bottom screen. The other method, `width: auto;`, only makes the image full size and does not respond to the screen size.

Is there a way to display the image the same way that `background-size: cover` does?

Is there an equivalent to background-size: cover and contain for image elements?

I am using the tooltip. But I want that on image tag, like when I mouseover the image then the tooltip should work. I have tried but not working for me on image tag.

Tooltip on image

I&#39;ve been trying to implement an application that requires camera preview on a surface.
As I see the things, both activity and surface lifecycles consist of the following states:

1. When I first launch my Activity: `onResume()-&gt;onSurfaceCreated()-&gt;onSurfaceChanged()`
2. When I leave my Activity: `onPause()-&gt;onSurfaceDestroyed()`

In this scheme, I can do corresponding calls like open/release camera and start/stop preview in `onPause/onResume` and `onSurfaceCreated()/onSurfaceDestroyed()`.

It works fine, unless I lock the screen. When I launch the app, then lock the screen and unlock it later I see:

`onPause()` - and nothing else after the screen is locked - then `onResume()` after unlock - and no surface callbacks after then. Actually, `onResume()` is called after the power button is pressed and the screen is on, but the lock screen is still active, so, it&#39;s before the activity becomes even visible.

With this scheme, I get a black screen after unlock, and no surface callbacks are called.

Here&#39;s a code fragment that doesn&#39;t involve actual work with the camera, but the `SurfaceHolder` callbacks. The issue above is reproduced even with this code on my phone (callbacks are called in a normal sequence when you press &quot;Back&quot; button, but are missing when you lock the screen):

    class Preview extends SurfaceView implements SurfaceHolder.Callback {
    
    	private static final String tag= &quot;Preview&quot;;
    
    	public Preview(Context context) {
    		super(context);
    		Log.d(tag, &quot;Preview()&quot;);
    		SurfaceHolder holder = getHolder();
    		holder.addCallback(this);
    		holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    	}
    
    	public void surfaceCreated(SurfaceHolder holder) {
    		Log.d(tag, &quot;surfaceCreated&quot;);
    	}
    
    	public void surfaceDestroyed(SurfaceHolder holder) {
    		Log.d(tag, &quot;surfaceDestroyed&quot;);
    	}
    
    	public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    		Log.d(tag, &quot;surfaceChanged&quot;);
    	}
    }

Any ideas on why the surface remains undestroyed after the Activity is paused? Also, how do you handle camera lifecycle in such cases?

How SurfaceHolder callbacks are related to Activity lifecycle?

Is it possible to access the camera (built-in on Apples) from a browser? 

Optimal solution would be client-side javascript. Looking to avoid using Java or Flash.

Access camera from a browser

I&#39;m capturing an image and setting it to image view.

    public void captureImage() {

        Intent intentCamera = new Intent(&quot;android.media.action.IMAGE_CAPTURE&quot;);
        File filePhoto = new File(Environment.getExternalStorageDirectory(), &quot;Pic.jpg&quot;);
        imageUri = Uri.fromFile(filePhoto);
        MyApplicationGlobal.imageUri = imageUri.getPath();
        intentCamera.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
        startActivityForResult(intentCamera, TAKE_PICTURE);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent intentFromCamera) {
        super.onActivityResult(requestCode, resultCode, intentFromCamera);

        if (resultCode == RESULT_OK &amp;&amp; requestCode == TAKE_PICTURE) {

            if (intentFromCamera != null) {
                Bundle extras = intentFromCamera.getExtras();
                if (extras.containsKey(&quot;data&quot;)) {
                    bitmap = (Bitmap) extras.get(&quot;data&quot;);
                }
                else {
                    bitmap = getBitmapFromUri();
                }
            }
            else {
                bitmap = getBitmapFromUri();
            }
            // imageView.setImageBitmap(bitmap);
            imageView.setImageURI(imageUri);
        }
        else {
        }
    }

    public Bitmap getBitmapFromUri() {

        getContentResolver().notifyChange(imageUri, null);
        ContentResolver cr = getContentResolver();
        Bitmap bitmap;

        try {
            bitmap = android.provider.MediaStore.Images.Media.getBitmap(cr, imageUri);
            return bitmap;
        }
        catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

But the problem is, the image on some devices every time it gets rotated. For example, on a Samsung device it works good, but on a [Sony Xperia][1] the image gets rotated by 90 degrees and on [Toshiba Thrive][2] (tablet) by 180 degrees.

  [1]: https://en.wikipedia.org/wiki/Sony_Xperia
  [2]: https://en.wikipedia.org/wiki/Toshiba_Thrive


Why does an image captured using camera intent gets rotated on some devices on Android?

I have created an app with a button and wrote onClickListener for that button. I have tried several sample code examples and none of them worked. They all bring up the Android camera app and don&#39;t take photographs. I want some code which I can put in my onClickListener so when I press the button on the screen, a picture will be taken.

How can I make the camera take a picture when I press a button in an Android activity?


Taking pictures with camera on Android programmatically

I am getting this error only in iOS 7 and the application crashed. 
In iOS 6, I never get any error, just once of memory warning when opening the camera.

    Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.

Here is what I am doing.

    imagePicker = [[UIImagePickerController alloc] init];
    [imagePicker setDelegate:self];
    [imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
    [imagePicker setAllowsEditing:YES];
            
    [self presentModalViewController:imagePicker animated:YES];

I did tried to delay the `presentModalViewController`, but I am still getting the same message. After few seconds (7-10), the application crashed.

This error is only present in iOS 7. 

Anybody has the clue?



UIImagePickerController error: Snapshotting a view that has not been rendered results in an empty snapshot in iOS 7

I have a html file and i run it on localhost. But, this file includes mirror using webcam. Example, how can i run [this html file][1] on localhost? Webcam starting on this example when check to live checkbox. Thanx for your reply.


  [1]: http://myprojectguide.org/p/flash-videoio/test.html

How to run html file on localhost?

I have a generic interface like this:

    interface A&lt;T&gt; {
        T getValue();
    }

This interface has limited instances, hence it would be best to implement them as enum values. The problem is those instances have different type of values, so I tried the following approach but it does not compile:

    public enum B implements A {
        A1&lt;String&gt; {
            @Override
            public String getValue() {
                return &quot;value&quot;;
            }
        },
        A2&lt;Integer&gt; {
            @Override
            public Integer getValue() {
                return 0;
            }
        };
    }

Any idea about this?

How to implement enum with generics?

I am trying to understand PrintWriter for a small program I&#39;m making, and I cant seem to get java to make the file and then write on it. When I execute the program below it gives me a Filenotfoundexeption error on line 9. It also fails to make the file in the directory that I specified. I am new to this so please try and keep the answers simple. I am using Eclipse.

    import java.io.PrintWriter;
    import java.io.File;

    public class Testing {
	
	  public static void main(String[] args) {
		
		File file = new File (&quot;C:/Users/Me/Desktop/directory/file.txt&quot;);
		PrintWriter printWriter = new PrintWriter (&quot;file.txt&quot;);
		printWriter.println (&quot;hello&quot;);
		printWriter.close ();		
	  }
    }






How to use PrintWriter and File classes in Java?

What is the difference between these 2 functions?
 
    static void gPrint(List&lt;? extends Number&gt; l) {
	    for (Number n : l) {
			System.out.println(n);
		}
	}
	
	static &lt;T extends Number&gt; void gPrintA(List&lt;T&gt; l) {
		for (Number n : l) {
			System.out.println(n);
		}
	}

I see the same output.

Java Generics WildCard: &lt;? extends Number&gt; vs &lt;T extends Number&gt;

Source Wikipedia:   

&gt; **Question mark** (?) is used instead of &#39;*&#39; for leaving either day-of-month or day-of-week blank.

The above statement is not making much sense to me.

So if I write some cron as **`0 0 0 ? * *`** then does it mean first of every month or it means it will execute daily?

It is a bit confusing as Java crons start with seconds while other crons start with minute.

Significance of question mark in Java cron

How do I access maven properties defined in the pom in a normal maven project, and in a maven plugin project?

Content Type	Original Author	Original Content on Stackoverflow
Question	PeakGen	View Question on Stackoverflow
Solution 1 - Image	Bartosz Firyn	View Answer on Stackoverflow

Best way to access web camera in Java

Image Problem Overview

Image Solutions

Solution 1 - Image

Sort by multiple keys using different orderings

How to undefine class in Ruby?

Attributions