Storage for Pages (SBSDKIndexedImageStorage, SBSDKKeyedImageStorage)

The document pages display the scanned images, and these images can be stored using SBSDKIndexedImageStorage or SBSDKKeyedImageStorage.

• SBSDKIndexedImageStorage and SBSDKKeyedImageStorage are thread-safe and persistent storages for images.
• They can be used to store and retrieve images in an array-fashioned style (indexed) or dictionary-fashioned style (keyed) to and from the device disk.
• Both allow the usage of an encrypter which encrypts the data when writing it to the disk and decrypts the data when reading it from the disk.
• These classes conform to the SBSDKImageStoring protocol. Custom image storages can be implemented and used within Scanbot SDK by conforming to this protocol.

Swift

import UIKit
import ScanbotSDK

class ImageStoringSwiftViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Initialize a folder URL to persist the images to. 
        let documentsURL = SBSDKStorageLocation.applicationDocumentsFolderURL.appendingPathComponent("Images", isDirectory: true)
        
        // Create a storage location object. This will create the folder on the filesystem if neccessary.
        let documentsLocation = SBSDKStorageLocation(baseURL: documentsURL)
        
        // Initialize an indexed image storage at this location.
        // The indexed image storage is an array-like storage.
        let imageStorage = SBSDKIndexedImageStorage(storageLocation: documentsLocation, 
                                                    fileFormat: .PNG, 
                                                    encrypter: nil)!
        
        if let image = UIImage(named: "testDocument") {
            // Save an image to the storage.
            let isAdded = imageStorage.add(image)
            // Check the result.
            print("Image added successfully: \(isAdded)")
        }
        // Check the number of images in the storage.
        print("Images in storage: \(imageStorage.imageCount)")
        
        
        // Create and attach an encrypter to the storage. This will encrypt the image data, before it is written to disk 
        // and decrypt it after it is read from disk. 
        // Setting the encrypter does not encrypt existing images in the storage, only the images that are added to the 
        // storage after setting the encrypter. 
        imageStorage.encrypter = SBSDKAESEncrypter(password: "xxxxx", mode: .AES256)
        
        // Store an image from a URL. This does not load the image and has a very low memory footprint.
        if let url = Bundle.main.url(forResource: "imageDocument", withExtension: "png") {
            // Copy the image from the URL to the storage.
            let isAdded = imageStorage.addImage(from: url)
            // Check the result.
            print("Image from URL was added successfully : \(isAdded)")
        }
        
        // Make sure that the indices are valid before moving an image from one index to another.
        if imageStorage.imageCount > 1 {
            // Move the image at index 1 to index 0.
            let isMoved = imageStorage.moveImage(from: 1, to: 0)
            print("Image was moved successfully: \(isMoved)")
        }
        
        // Make sure that the index is valid.
        if imageStorage.imageCount > 1 {
            // Remove the image at index 1.
            imageStorage.removeImage(at: 1)
        }
        
        // The image storage is persisted on disk. 
        // When the images are no longer needed they should be removed to free the disk space. 
        // Remove all images from the storage.
        imageStorage.removeAll()
    }
}

Objective-C

#import "ImageStoringObjcViewController.h"
@import ScanbotSDK;

@interface ImageStoringObjcViewController ()

@end

@implementation ImageStoringObjcViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    // Initialize a folder URL to persist the images to. 
    NSURL *documentsURL = [[SBSDKStorageLocation applicationDocumentsFolderURL] URLByAppendingPathComponent:@"Images"];
    
    // Create a storage location object. This will create the folder on the filesystem if neccessary.
    SBSDKStorageLocation *documentsLocation = [[SBSDKStorageLocation alloc] initWithBaseURL:documentsURL];
    
    // Initialize an indexed image storage at this location.
    // The indexed image storage is an array-like storage.
    SBSDKIndexedImageStorage *imageStorage 
    = [[SBSDKIndexedImageStorage alloc] initWithStorageLocation:documentsLocation
                                                     fileFormat:SBSDKImageFileFormatPNG
                                                      encrypter:nil];
    
    UIImage *image = [UIImage imageNamed:@"testDocument"];
    
    // Save an image to our location.
    BOOL isAdded = [imageStorage addImage:image];
    
    // Check the result.
    NSLog(@"Image added successfully : %@", isAdded ? @"YES" : @"NO");
    
    // Check the number of images in the storage.
    NSLog(@"Image Count: %lu", (unsigned long)[imageStorage imageCount]);
    
    // Create and attach an encrypter to the storage. This will encrypt the image data, before it it written to disk 
    // and decrypt it after it is read from disk. 
    // Setting the encrypter does not encrypt existing images in the storage, only the images that are added to the 
    // storage after setting the encrypter. 
    imageStorage.encrypter = [[SBSDKAESEncrypter alloc] initWithPassword:@"xxxxx" mode:SBSDKAESEncrypterModeAES256];
    
    // Store an image from a URL. This does not load the image and has a very low memory footprint.
    NSURL *url = [[NSBundle mainBundle] URLForResource:@"imageDocument" withExtension:@"png"];

    // Copy the image from the URL to the storage.
    BOOL isAddedFromURL = [imageStorage addImageFromURL:url];
    
    // Check the result.
    NSLog(@"Image from URL was added successfully : %@", isAddedFromURL ? @"YES" : @"NO");
    
    // Make sure that the indices are valid before moving an image from one index to another.
    if (imageStorage.imageCount > 1) {
        // Move the image at index 1 to index 0.
        BOOL isMoved = [imageStorage moveImageFromIndex:1 toIndex:0];
        NSLog(@"Image was moved successfully : %@", isMoved ? @"YES" : @"NO");
    }

    // Make sure that the index is valid.
    if (imageStorage.imageCount > 1) {
        // Remove the image at index 1.
        [imageStorage removeImageAtIndex:1];
    }
    
    // The image storage is persisted on disk. 
    // When the images are no longer needed they should be removed to free the disk space. 
    // Remove all images from the storage.
    [imageStorage removeAllImages];
}
@end

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