How to capture whole screen in Corona SDK

You can use the following lines of code to capture the device screen in Corona SDK. This will save the screenshot as: Picture 1.png, Picture 2.png, etc in the sandbox, and will show it on the screen with half size(if you do not need this, you can remove it by calling captured_image:removeSelf() and captured_image=nil). It can save upto 10000 files.

Syntax:

    local function captureDeviceScreen()
       local captured_image = display.captureScreen( true )
       captured_image:scale(.5,.5)
       local alert = native.showAlert( "Success", "Captured Image is Saved to Library", { "OK" } )
    end
    Runtime:addEventListener("tap",captureDeviceScreen)


And if you want to save the image with desired name, then you can refer the following post:

How to mail a screen captured image using corona SDK

How to mail a screen captured image using corona SDK

For doing this, you have to:

• First create a localgroup.
• Then add the screen objects to that group.
• Return the display group
• Use display.save to save the entire group displayed.
• Create mail option and add attachment image from baseDirectory
• Call mail Popup

Example: 

-- creating the display group --
local localGroup = display.newGroup()  

-- creating display objects and adding it to the group --
local bg = display.newRect(0,0,320,480)
bg.x = 160
bg.y = 240
bg:setFillColor(150)
localGroup:insert(bg)

local rect = display.newRect(0,0,50,50)
rect.x = 30+math.random(260)
rect.y = 30+math.random(420)
localGroup:insert(rect)

-- Then do as follows --
local function takePhotoAndSendMail()
  -- take screen shot to baseDirectory --
  local baseDir = system.DocumentsDirectory
  display.save( localGroup, "myScreenshot.jpg", baseDir )

  -- Create mail options --
  local options =
  {
    to = { "devblogdk@gmail.com",},
    subject = "My Level",
    body = "Add this...",
    attachment =
    {
      { baseDir=system.DocumentsDirectory, filename="myScreenshot.jpg", 

        type="image" },
    },
  }

  -- Send mail --
  native.showPopup("mail", options)
end
rect:addEventListener("tap",takePhotoAndSendMail)

Using camera to take picture and save that to file: cocos2d

/* Using camera to take a photo */

    // in .h File //
        @interface HelloWorld : CCLayer <UIImagePickerControllerDelegate, UINavigationControllerDelegate>{
   
            UIImagePickerController *uip;
            UIImage *profileImage;
        }

    // in .m File //
        #import "AppDelegate.h"

        -(void)takePhoto{
            AppDelegate *appdel = [UIApplication sharedApplication].delegate;
   
            @try {
       
                uip = [[UIImagePickerController alloc] init] ;
                uip.sourceType = UIImagePickerControllerSourceTypeCamera;
                uip.allowsEditing = YES;
                uip.delegate = self;
            }
            @catch (NSException * e) {
                [uip release];
                uip = nil;
            }
            @finally {
                if(uip) {
                    [appdel.viewController presentModalViewController:uip animated:YES];
                }
            }
        }



    - (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{
   
        profileImage=[info objectForKey:UIImagePickerControllerEditedImage];
        AppDelegate *appdel = [UIApplication sharedApplication].delegate;
        [appdel.viewController dismissModalViewControllerAnimated:YES];
        [uip release];
       
        [NSThread detachNewThreadSelector:@selector(writeImgToPath:) toTarget:self withObject:profileImage]; 
         
       
    }


// To write the image to file //
    -(void)writeImgToPath:(id)sender
    {
       
        NSAutoreleasePool *pool = [NSAutoreleasePool new];
        UIImage *image = sender;
        NSArray *pathArr = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                           NSUserDomainMask,
                                                           YES);
        CGSize size;
        int currentProfileIndex = 1
        NSString *path = [[pathArr objectAtIndex:0]
                      stringByAppendingPathComponent:[NSString stringWithFormat:@"Img_%d.png",currentProfileIndex]];           
       
        size = CGSizeMake(120, 120);
        UIGraphicsBeginImageContext(size);
        [image drawInRect:CGRectMake(0, 0, 120, 120)];
        image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
   
        NSData *data = UIImagePNGRepresentation(image);
        [data writeToFile:path atomically:YES];
        NSLog(@"Saved.....");
       
        CGRect r = CGRectMake(0, 0, 80, 80);
        UIGraphicsBeginImageContext(r.size);
   
        UIImage *img1;
   
        [image drawInRect:r];
        img1 = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
       
        [pool release];
    }