[GSoC] Full Screen Mode (#5032)

* Gesture detection implemented

* Left and right swipe

* Selection implemented

* onDown implemented

* onDown implemented

* FS mode implemented

* OnSwipe doc

* Scope cancel

* Added label in Manifest

app/src/main/AndroidManifest.xml

@@ -46,7 +46,10 @@
             android:finishOnTaskLaunch="true" />
 
         <activity
-            android:name=".media.ZoomableActivity" />
+            android:name=".media.ZoomableActivity"
+            android:label="Zoomable Activity"
+            android:configChanges="screenSize|keyboard|orientation"
+            android:parentActivityName=".customselector.ui.selector.CustomSelectorActivity" />
 
         <activity android:name=".auth.LoginActivity">
             <intent-filter>

app/src/main/java/fr/free/nrw/commons/customselector/database/UploadedDao.kt

@@ -66,4 +66,18 @@ abstract class UploadedStatusDao {
     suspend fun getUploadedFromImageSHA1(imageSHA1: String):UploadedStatus? {
         return getFromImageSHA1(imageSHA1)
     }
+
+    /**
+     * Check whether the imageSHA1 is present in database
+     */
+    @Query("SELECT COUNT() FROM uploaded_table WHERE imageSHA1 = (:imageSHA1) AND imageResult = (:imageResult) ")
+    abstract suspend fun findByImageSHA1(imageSHA1 : String, imageResult: Boolean): Int
+
+    /**
+     * Check whether the modifiedImageSHA1 is present in database
+     */
+    @Query("SELECT COUNT() FROM uploaded_table WHERE modifiedImageSHA1 = (:modifiedImageSHA1) AND modifiedImageResult = (:modifiedImageResult) ")
+    abstract suspend fun findByModifiedImageSHA1(modifiedImageSHA1 : String,
+                                                 modifiedImageResult: Boolean): Int
+
 }

app/src/main/java/fr/free/nrw/commons/customselector/helper/CustomSelectorConstants.kt

@@ -0,0 +1,10 @@
+package fr.free.nrw.commons.customselector.helper
+
+object CustomSelectorConstants {
+
+    const val TOTAL_IMAGES = "total_images"
+    const val TOTAL_SELECTED_IMAGES = "total_selected_images"
+    const val PRESENT_POSITION = "present_position"
+    const val NEW_SELECTED_IMAGES = "new_selected_images"
+
+}

app/src/main/java/fr/free/nrw/commons/customselector/helper/OnSwipeTouchListener.kt

@@ -0,0 +1,72 @@
+package fr.free.nrw.commons.customselector.helper
+
+import android.content.Context
+import android.view.GestureDetector
+import android.view.MotionEvent
+import android.view.View
+import kotlin.math.abs
+
+/**
+ * Class for detecting swipe gestures
+ */
+open class OnSwipeTouchListener(context: Context?) : View.OnTouchListener {
+
+    private val gestureDetector: GestureDetector
+
+    override fun onTouch(view: View?, motionEvent: MotionEvent?): Boolean {
+        return gestureDetector.onTouchEvent(motionEvent)
+    }
+
+    private inner class GestureListener : GestureDetector.SimpleOnGestureListener() {
+
+        private val SWIPE_THRESHOLD = 100
+        private val SWIPE_VELOCITY_THRESHOLD = 100
+
+        override fun onDown(e: MotionEvent?): Boolean {
+            return true
+        }
+
+        override fun onFling(
+            event1: MotionEvent,
+            event2: MotionEvent,
+            velocityX: Float,
+            velocityY: Float
+        ): Boolean {
+            try {
+                val diffY: Float = event2.y - event1.y
+                val diffX: Float = event2.x - event1.x
+                if (abs(diffX) > abs(diffY)) {
+                    if (abs(diffX) > SWIPE_THRESHOLD && abs(velocityX) >
+                        SWIPE_VELOCITY_THRESHOLD) {
+                        if (diffX > 0) {
+                            onSwipeRight()
+                        } else {
+                            onSwipeLeft()
+                        }
+                    }
+                } else {
+                    if (abs(diffY) > SWIPE_THRESHOLD && abs(velocityY) >
+                        SWIPE_VELOCITY_THRESHOLD) {
+                        if (diffY > 0) {
+                            onSwipeDown()
+                        } else {
+                            onSwipeUp()
+                        }
+                    }
+                }
+            } catch (exception: Exception) {
+                exception.printStackTrace()
+            }
+            return false
+        }
+    }
+
+    open fun onSwipeRight() {}
+    open fun onSwipeLeft() {}
+    open fun onSwipeUp() {}
+    open fun onSwipeDown() {}
+
+    init {
+        gestureDetector = GestureDetector(context, GestureListener())
+    }
+}

app/src/main/java/fr/free/nrw/commons/customselector/listeners/ImageSelectListener.kt

@@ -19,5 +19,9 @@ interface ImageSelectListener {
      * onLongPress
      * @param imageUri : uri of image
      */
-    fun onLongPress(imageUri: Uri)
+    fun onLongPress(
+        position: Int,
+        images: ArrayList<Image>,
+        selectedImages: ArrayList<Image>
+    )
 }

app/src/main/java/fr/free/nrw/commons/customselector/listeners/PassDataListener.kt

@@ -0,0 +1,7 @@
+package fr.free.nrw.commons.customselector.listeners
+
+import fr.free.nrw.commons.customselector.model.Image
+
+interface PassDataListener {
+    fun passSelectedImages(selectedImages: ArrayList<Image>)
+}

app/src/main/java/fr/free/nrw/commons/customselector/ui/adapter/ImageAdapter.kt

@@ -228,7 +228,7 @@ class ImageAdapter(
 
             // launch media preview on long click.
             holder.itemView.setOnLongClickListener {
-                imageSelectListener.onLongPress(image.uri)
+                imageSelectListener.onLongPress(position, images, selectedImages)
                 true
             }
         }
@@ -317,6 +317,13 @@ class ImageAdapter(
         diffResult.dispatchUpdatesTo(this)
     }
 
+    /**
+     * Set new selected images
+     */
+    fun setSelectedImages(newSelectedImages: ArrayList<Image>){
+        selectedImages = ArrayList(newSelectedImages)
+        imageSelectListener.onSelectedImagesChanged(selectedImages, 0)
+    }
     /**
      * Refresh the data in the adapter
      */

app/src/main/java/fr/free/nrw/commons/customselector/ui/selector/CustomSelectorActivity.kt

@@ -4,7 +4,6 @@ import android.app.Activity
 import android.app.Dialog
 import android.content.Intent
 import android.content.SharedPreferences
-import android.net.Uri
 import android.os.Bundle
 import android.view.View
 import android.view.Window
@@ -16,6 +15,7 @@ import androidx.lifecycle.ViewModelProvider
 import fr.free.nrw.commons.R
 import fr.free.nrw.commons.customselector.database.NotForUploadStatus
 import fr.free.nrw.commons.customselector.database.NotForUploadStatusDao
+import fr.free.nrw.commons.customselector.helper.CustomSelectorConstants
 import fr.free.nrw.commons.customselector.listeners.FolderClickListener
 import fr.free.nrw.commons.customselector.listeners.ImageSelectListener
 import fr.free.nrw.commons.customselector.model.Image
@@ -112,6 +112,18 @@ class CustomSelectorActivity: BaseActivity(), FolderClickListener, ImageSelectLi
         }
     }
 
+    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
+        super.onActivityResult(requestCode, resultCode, data)
+        if (requestCode == 101) {
+            if (resultCode == Activity.RESULT_OK) {
+                val selectedImages: ArrayList<Image> =
+                    data!!
+                        .getParcelableArrayListExtra(CustomSelectorConstants.NEW_SELECTED_IMAGES)!!
+                imageFragment!!.passSelectedImages(selectedImages)
+            }
+        }
+    }
+
     /**
      * Show Custom Selector Welcome Dialog.
      */
@@ -305,9 +317,19 @@ class CustomSelectorActivity: BaseActivity(), FolderClickListener, ImageSelectLi
      * onLongPress
      * @param imageUri : uri of image
      */
-    override fun onLongPress(imageUri: Uri) {
-        val intent = Intent(this, ZoomableActivity::class.java).setData(imageUri);
-        startActivity(intent)
+    override fun onLongPress(
+        position: Int,
+        images: ArrayList<Image>,
+        selectedImages: ArrayList<Image>
+    ) {
+        val intent = Intent(this, ZoomableActivity::class.java)
+        intent.putExtra(CustomSelectorConstants.PRESENT_POSITION, position);
+        intent.putParcelableArrayListExtra(CustomSelectorConstants.TOTAL_IMAGES, images)
+        intent.putParcelableArrayListExtra(
+            CustomSelectorConstants.TOTAL_SELECTED_IMAGES,
+            selectedImages
+        )
+        startActivityForResult(intent, 101)
     }
 
     /**

app/src/main/java/fr/free/nrw/commons/customselector/ui/selector/ImageFragment.kt

@@ -19,6 +19,7 @@ import fr.free.nrw.commons.R
 import fr.free.nrw.commons.customselector.database.NotForUploadStatusDao
 import fr.free.nrw.commons.customselector.database.UploadedStatusDao
 import fr.free.nrw.commons.customselector.helper.ImageHelper
+import fr.free.nrw.commons.customselector.listeners.PassDataListener
 import fr.free.nrw.commons.customselector.helper.ImageHelper.CUSTOM_SELECTOR_PREFERENCE_KEY
 import fr.free.nrw.commons.customselector.helper.ImageHelper.SWITCH_STATE_PREFERENCE_KEY
 import fr.free.nrw.commons.customselector.listeners.ImageSelectListener
@@ -42,7 +43,7 @@ import kotlin.collections.ArrayList
 /**
  * Custom Selector Image Fragment.
  */
-class ImageFragment: CommonsDaggerSupportFragment(), RefreshUIListener {
+class ImageFragment: CommonsDaggerSupportFragment(), RefreshUIListener, PassDataListener {
 
     /**
      * Current bucketId.
@@ -293,6 +294,7 @@ class ImageFragment: CommonsDaggerSupportFragment(), RefreshUIListener {
      * notifyDataSetChanged, rebuild the holder views to account for deleted images.
      */
     override fun onResume() {
+        Log.d("haha", "onResume: ")
         imageAdapter.notifyDataSetChanged()
         super.onResume()
     }
@@ -327,4 +329,8 @@ class ImageFragment: CommonsDaggerSupportFragment(), RefreshUIListener {
     override fun refresh() {
         imageAdapter.refresh(filteredImages, allImages)
     }
+
+    override fun passSelectedImages(selectedImages: ArrayList<Image>){
+        imageAdapter.setSelectedImages(selectedImages)
+    }
 }

app/src/main/java/fr/free/nrw/commons/di/ActivityBuilderModule.java

@@ -13,6 +13,7 @@ import fr.free.nrw.commons.customselector.ui.selector.CustomSelectorActivity;
 import fr.free.nrw.commons.description.DescriptionEditActivity;
 import fr.free.nrw.commons.explore.depictions.WikidataItemDetailsActivity;
 import fr.free.nrw.commons.explore.SearchActivity;
+import fr.free.nrw.commons.media.ZoomableActivity;
 import fr.free.nrw.commons.notification.NotificationActivity;
 import fr.free.nrw.commons.profile.ProfileActivity;
 import fr.free.nrw.commons.review.ReviewActivity;
@@ -75,4 +76,7 @@ public abstract class ActivityBuilderModule {
 
     @ContributesAndroidInjector
     abstract DescriptionEditActivity bindDescriptionEditActivity();
+
+    @ContributesAndroidInjector
+    abstract ZoomableActivity bindZoomableActivity();
 }

app/src/main/java/fr/free/nrw/commons/media/ZoomableActivity.java

@@ -1,92 +0,0 @@
-package fr.free.nrw.commons.media;
-
-import android.graphics.drawable.Animatable;
-import android.net.Uri;
-import android.os.Bundle;
-import android.view.View;
-import android.widget.ProgressBar;
-import androidx.annotation.Nullable;
-import androidx.appcompat.app.AppCompatActivity;
-import butterknife.BindView;
-import butterknife.ButterKnife;
-import com.facebook.drawee.backends.pipeline.Fresco;
-import com.facebook.drawee.controller.BaseControllerListener;
-import com.facebook.drawee.controller.ControllerListener;
-import com.facebook.drawee.drawable.ProgressBarDrawable;
-import com.facebook.drawee.drawable.ScalingUtils;
-import com.facebook.drawee.generic.GenericDraweeHierarchy;
-import com.facebook.drawee.generic.GenericDraweeHierarchyBuilder;
-import com.facebook.drawee.interfaces.DraweeController;
-import com.facebook.imagepipeline.image.ImageInfo;
-import fr.free.nrw.commons.R;
-import fr.free.nrw.commons.media.zoomControllers.zoomable.DoubleTapGestureListener;
-import fr.free.nrw.commons.media.zoomControllers.zoomable.ZoomableDraweeView;
-import timber.log.Timber;
-
-
-public class ZoomableActivity extends AppCompatActivity {
-    private Uri imageUri;
-
-    @BindView(R.id.zoomable)
-    ZoomableDraweeView photo;
-    @BindView(R.id.zoom_progress_bar)
-    ProgressBar spinner;
-
-    @Override
-    protected void onCreate(Bundle savedInstanceState) {
-        super.onCreate(savedInstanceState);
-
-        imageUri = getIntent().getData();
-        if (null == imageUri) {
-            throw new IllegalArgumentException("No data to display");
-        }
-        Timber.d("URl = " + imageUri);
-
-        setContentView(R.layout.activity_zoomable);
-        ButterKnife.bind(this);
-        init();
-    }
-
-    /**
-     * Two types of loading indicators have been added to the zoom activity:
-     *  1.  An Indeterminate spinner for showing the time lapsed between dispatch of the image request
-     *      and starting to receiving the image.
-     *  2.  ProgressBarDrawable that reflects how much image has been downloaded
-     */
-    private final ControllerListener loadingListener = new BaseControllerListener<ImageInfo>() {
-        @Override
-        public void onSubmit(String id, Object callerContext) {
-            // Sometimes the spinner doesn't appear when rapidly switching between images, this fixes that
-            spinner.setVisibility(View.VISIBLE);
-        }
-
-        @Override
-        public void onIntermediateImageSet(String id, @Nullable ImageInfo imageInfo) {
-            spinner.setVisibility(View.GONE);
-        }
-        @Override
-        public void onFinalImageSet(String id, @Nullable ImageInfo imageInfo, @Nullable Animatable animatable) {
-            spinner.setVisibility(View.GONE);
-        }
-    };
-    private void init() {
-        if( imageUri != null ) {
-            GenericDraweeHierarchy hierarchy = GenericDraweeHierarchyBuilder.newInstance(getResources())
-                    .setActualImageScaleType(ScalingUtils.ScaleType.FIT_CENTER)
-                    .setProgressBarImage(new ProgressBarDrawable())
-                    .setProgressBarImageScaleType(ScalingUtils.ScaleType.FIT_CENTER)
-                    .build();
-            photo.setHierarchy(hierarchy);
-            photo.setAllowTouchInterceptionWhileZoomed(true);
-            photo.setIsLongpressEnabled(false);
-            photo.setTapListener(new DoubleTapGestureListener(photo));
-            DraweeController controller = Fresco.newDraweeControllerBuilder()
-                    .setUri(imageUri)
-                    .setControllerListener(loadingListener)
-                    .build();
-            photo.setController(controller);
-        }
-    }
-
-
-}

app/src/main/java/fr/free/nrw/commons/media/ZoomableActivity.kt

@@ -0,0 +1,387 @@
+package fr.free.nrw.commons.media
+
+import android.app.Activity
+import android.content.Intent
+import android.graphics.drawable.Animatable
+import android.net.Uri
+import android.os.Bundle
+import android.view.View
+import android.widget.ProgressBar
+import android.widget.TextView
+import android.widget.Toast
+import butterknife.BindView
+import butterknife.ButterKnife
+import com.facebook.drawee.backends.pipeline.Fresco
+import com.facebook.drawee.controller.BaseControllerListener
+import com.facebook.drawee.controller.ControllerListener
+import com.facebook.drawee.drawable.ProgressBarDrawable
+import com.facebook.drawee.drawable.ScalingUtils
+import com.facebook.drawee.generic.GenericDraweeHierarchyBuilder
+import com.facebook.drawee.interfaces.DraweeController
+import com.facebook.imagepipeline.image.ImageInfo
+import fr.free.nrw.commons.R
+import fr.free.nrw.commons.customselector.database.NotForUploadStatus
+import fr.free.nrw.commons.customselector.database.NotForUploadStatusDao
+import fr.free.nrw.commons.customselector.database.UploadedStatusDao
+import fr.free.nrw.commons.customselector.helper.CustomSelectorConstants
+import fr.free.nrw.commons.customselector.helper.OnSwipeTouchListener
+import fr.free.nrw.commons.customselector.model.Image
+import fr.free.nrw.commons.media.zoomControllers.zoomable.DoubleTapGestureListener
+import fr.free.nrw.commons.media.zoomControllers.zoomable.ZoomableDraweeView
+import fr.free.nrw.commons.theme.BaseActivity
+import fr.free.nrw.commons.upload.FileProcessor
+import fr.free.nrw.commons.upload.FileUtilsWrapper
+import fr.free.nrw.commons.utils.CustomSelectorUtils
+import kotlinx.coroutines.*
+import timber.log.Timber
+import javax.inject.Inject
+
+class ZoomableActivity : BaseActivity() {
+
+    private lateinit var imageUri: Uri
+
+    @JvmField
+    @BindView(R.id.zoomable)
+    var photo: ZoomableDraweeView? = null
+
+    @JvmField
+    @BindView(R.id.zoom_progress_bar)
+    var spinner: ProgressBar? = null
+
+    @JvmField
+    @BindView(R.id.selection_count)
+    var selectedCount: TextView? = null
+
+    /**
+     * Total images present in folder
+     */
+    private var images: ArrayList<Image>? = null
+
+    /**
+     * Total selected images present in folder
+     */
+    private var selectedImages: ArrayList<Image>? = null
+
+    /**
+     * Present position of the image
+     */
+    private var position = 0
+
+    /**
+     * FileUtilsWrapper class to get imageSHA1 from uri
+     */
+    @Inject
+    lateinit var fileUtilsWrapper: FileUtilsWrapper
+
+    /**
+     * FileProcessor to pre-process the file.
+     */
+    @Inject
+    lateinit var fileProcessor: FileProcessor
+
+    /**
+     * NotForUploadStatus Dao class for database operations
+     */
+    @Inject
+    lateinit var notForUploadStatusDao: NotForUploadStatusDao
+
+    /**
+     * UploadedStatus Dao class for database operations
+     */
+    @Inject
+    lateinit var uploadedStatusDao: UploadedStatusDao
+
+    /**
+    * Coroutine Dispatchers and Scope.
+    */
+    private var defaultDispatcher : CoroutineDispatcher = Dispatchers.Default
+    private var ioDispatcher : CoroutineDispatcher = Dispatchers.IO
+    private val scope : CoroutineScope = MainScope()
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        images = intent.getParcelableArrayListExtra(
+            CustomSelectorConstants.TOTAL_IMAGES
+        )
+        selectedImages = intent.getParcelableArrayListExtra(
+            CustomSelectorConstants.TOTAL_SELECTED_IMAGES
+        )
+        position = intent.getIntExtra(CustomSelectorConstants.PRESENT_POSITION, 0)
+        imageUri = if (images.isNullOrEmpty()) {
+            intent.data as Uri
+        } else {
+            images!![position].uri
+        }
+        Timber.d("URl = $imageUri")
+        setContentView(R.layout.activity_zoomable)
+        ButterKnife.bind(this)
+        init(imageUri)
+        onSwap()
+    }
+
+    /**
+     * Handle swap gestures. Ex. onSwipeLeft, onSwipeRight, onSwipeUp, onSwipeDown
+     */
+    private fun onSwap() {
+        if (!images.isNullOrEmpty()) {
+            photo!!.setOnTouchListener(object : OnSwipeTouchListener(this) {
+                override fun onSwipeLeft() {
+                    super.onSwipeLeft()
+                    if (position < images!!.size - 1) {
+                        position++
+                        init(images!![position].uri)
+                    } else {
+                        Toast.makeText(
+                            this@ZoomableActivity,
+                            "No more images found",
+                            Toast.LENGTH_SHORT
+                        ).show()
+                    }
+                }
+
+                override fun onSwipeRight() {
+                    super.onSwipeRight()
+                    if (position > 0) {
+                        position--
+                        init(images!![position].uri)
+                    } else {
+                        Toast.makeText(
+                            this@ZoomableActivity,
+                            "No more images found",
+                            Toast.LENGTH_SHORT
+                        ).show()
+                    }
+                }
+
+                override fun onSwipeUp() {
+                    super.onSwipeUp()
+                    scope.launch {
+                        val imageSHA1 = CustomSelectorUtils.getImageSHA1(
+                            images!![position].uri,
+                            ioDispatcher,
+                            fileUtilsWrapper,
+                            contentResolver
+                        )
+                        var isNonActionable = notForUploadStatusDao.find(imageSHA1)
+                        if (isNonActionable > 0) {
+                            Toast.makeText(
+                                this@ZoomableActivity,
+                                "Can't select this image for upload", Toast.LENGTH_SHORT
+                            ).show()
+                        } else {
+                            isNonActionable =
+                                uploadedStatusDao.findByImageSHA1(imageSHA1, true)
+                            if (isNonActionable > 0) {
+                                Toast.makeText(
+                                    this@ZoomableActivity,
+                                    "Can't select this image for upload", Toast.LENGTH_SHORT
+                                ).show()
+                            } else {
+                                val imageModifiedSHA1 = CustomSelectorUtils.generateModifiedSHA1(
+                                    images!![position],
+                                    defaultDispatcher,
+                                    this@ZoomableActivity,
+                                    fileProcessor,
+                                    fileUtilsWrapper
+                                )
+                                isNonActionable = uploadedStatusDao.findByModifiedImageSHA1(
+                                    imageModifiedSHA1,
+                                    true
+                                )
+                                if (isNonActionable > 0) {
+                                    Toast.makeText(
+                                        this@ZoomableActivity,
+                                        "Can't select this image for upload",
+                                        Toast.LENGTH_SHORT
+                                    ).show()
+                                } else {
+                                    if (!selectedImages!!.contains(images!![position])) {
+                                        selectedImages!!.add(images!![position])
+                                    }
+                                    position = getNextActionableImage(position + 1)
+                                    init(images!![position].uri)
+                                }
+                            }
+                        }
+                    }
+                }
+
+                override fun onSwipeDown() {
+                    super.onSwipeDown()
+                    scope.launch {
+                        insertInNotForUpload(images!![position])
+                        if (position < images!!.size - 1) {
+                            position++
+                            init(images!![position].uri)
+                        } else {
+                            Toast.makeText(
+                                this@ZoomableActivity,
+                                "No more images found",
+                                Toast.LENGTH_SHORT
+                            ).show()
+                        }
+                    }
+                }
+            })
+        }
+    }
+
+    /**
+     * Gets next actionable image
+     */
+    private suspend fun getNextActionableImage(index: Int): Int {
+        var nextPosition = position
+        for(i in index until images!!.size){
+            nextPosition = i
+            val imageSHA1 = CustomSelectorUtils.getImageSHA1(
+                images!![i].uri,
+                ioDispatcher,
+                fileUtilsWrapper,
+                contentResolver
+            )
+            var isNonActionable = notForUploadStatusDao.find(imageSHA1)
+            if (isNonActionable <= 0) {
+                isNonActionable = uploadedStatusDao.findByImageSHA1(imageSHA1, true)
+                if (isNonActionable <= 0) {
+                    val imageModifiedSHA1 = CustomSelectorUtils.generateModifiedSHA1(
+                        images!![i],
+                        defaultDispatcher,
+                        this@ZoomableActivity,
+                        fileProcessor,
+                        fileUtilsWrapper
+                    )
+                    isNonActionable = uploadedStatusDao.findByModifiedImageSHA1(
+                        imageModifiedSHA1,
+                        true
+                    )
+                    if (isNonActionable <= 0) {
+                        return i
+                    } else {
+                        continue
+                    }
+                } else {
+                    continue
+                }
+            } else {
+                continue
+            }
+        }
+        return nextPosition
+    }
+
+    /**
+     * Unselect item UI
+     */
+    private fun itemUnselected() {
+        selectedCount!!.visibility = View.INVISIBLE
+    }
+
+    /**
+     * Select item UI
+     */
+    private fun itemSelected(i: Int) {
+        selectedCount!!.visibility = View.VISIBLE
+        selectedCount!!.text = i.toString()
+    }
+
+    /**
+     * Get index from list
+     */
+    private fun getIndex(list: ArrayList<Image>?, image: Image): Int {
+        return list!!.indexOf(image)
+    }
+
+    /**
+     * Two types of loading indicators have been added to the zoom activity:
+     * 1.  An Indeterminate spinner for showing the time lapsed between dispatch of the image request
+     * and starting to receiving the image.
+     * 2.  ProgressBarDrawable that reflects how much image has been downloaded
+     */
+    private val loadingListener: ControllerListener<ImageInfo?> =
+        object : BaseControllerListener<ImageInfo?>() {
+            override fun onSubmit(id: String, callerContext: Any) {
+                // Sometimes the spinner doesn't appear when rapidly switching between images, this fixes that
+                spinner!!.visibility = View.VISIBLE
+            }
+
+            override fun onIntermediateImageSet(id: String, imageInfo: ImageInfo?) {
+                spinner!!.visibility = View.GONE
+            }
+
+            override fun onFinalImageSet(
+                id: String,
+                imageInfo: ImageInfo?,
+                animatable: Animatable?
+            ) {
+                spinner!!.visibility = View.GONE
+            }
+        }
+
+    private fun init(imageUri: Uri?) {
+        if (imageUri != null) {
+            val hierarchy = GenericDraweeHierarchyBuilder.newInstance(resources)
+                .setActualImageScaleType(ScalingUtils.ScaleType.FIT_CENTER)
+                .setProgressBarImage(ProgressBarDrawable())
+                .setProgressBarImageScaleType(ScalingUtils.ScaleType.FIT_CENTER)
+                .build()
+            photo!!.hierarchy = hierarchy
+            photo!!.setAllowTouchInterceptionWhileZoomed(true)
+            photo!!.setIsLongpressEnabled(false)
+            photo!!.setTapListener(DoubleTapGestureListener(photo))
+            val controller: DraweeController = Fresco.newDraweeControllerBuilder()
+                .setUri(imageUri)
+                .setControllerListener(loadingListener)
+                .build()
+            photo!!.controller = controller
+
+            if (!images.isNullOrEmpty()) {
+                val selectedIndex = getIndex(selectedImages, images!![position])
+                val isSelected = selectedIndex != -1
+                if (isSelected) {
+                    itemSelected(selectedIndex + 1)
+                } else {
+                    itemUnselected()
+                }
+            }
+        }
+    }
+
+    /**
+     * Inserts an image in Not For Upload Database
+     */
+    private suspend fun insertInNotForUpload(it: Image) {
+        val imageSHA1 = CustomSelectorUtils.getImageSHA1(
+            it.uri,
+            ioDispatcher,
+            fileUtilsWrapper,
+            contentResolver
+        )
+        notForUploadStatusDao.insert(
+            NotForUploadStatus(
+                imageSHA1,
+                true
+            )
+        )
+    }
+
+    /**
+     * Send selected images in fragment
+     */
+    override fun onBackPressed() {
+        if (!images.isNullOrEmpty()) {
+            val returnIntent = Intent()
+            returnIntent.putParcelableArrayListExtra(
+                CustomSelectorConstants.NEW_SELECTED_IMAGES,
+                selectedImages
+            )
+            setResult(Activity.RESULT_OK, returnIntent)
+            finish()
+        }
+        super.onBackPressed()
+    }
+
+    override fun onDestroy() {
+        scope.cancel()
+        super.onDestroy()
+    }
+}

app/src/main/java/fr/free/nrw/commons/utils/CustomSelectorUtils.kt

@@ -5,6 +5,7 @@ import android.content.Context
 import android.net.Uri
 import androidx.exifinterface.media.ExifInterface
 import fr.free.nrw.commons.customselector.model.Image
+import fr.free.nrw.commons.filepicker.PickedFiles
 import fr.free.nrw.commons.customselector.ui.selector.ImageLoader
 import fr.free.nrw.commons.filepicker.PickedFiles
 import fr.free.nrw.commons.media.MediaClient
@@ -26,17 +27,18 @@ class CustomSelectorUtils {
         /**
          * Get image sha1 from uri, used to retrieve the original image sha1.
          */
-        suspend fun getImageSHA1(uri: Uri,
-                                 ioDispatcher : CoroutineDispatcher,
-                                 fileUtilsWrapper: FileUtilsWrapper,
-                                 contentResolver: ContentResolver
+        suspend fun getImageSHA1(
+            uri: Uri,
+            ioDispatcher: CoroutineDispatcher,
+            fileUtilsWrapper: FileUtilsWrapper,
+            contentResolver: ContentResolver
         ): String {
             return withContext(ioDispatcher) {
 
                 try {
                     val result = fileUtilsWrapper.getSHA1(contentResolver.openInputStream(uri))
                     result
-                } catch (e: FileNotFoundException){
+                } catch (e: FileNotFoundException) {
                     e.printStackTrace()
                     ""
                 }
@@ -44,16 +46,15 @@ class CustomSelectorUtils {
         }
 
         /**
-         * Generate Modified SHA1 using present Exif settings.
-         *
-         * @return modified sha1
+         * Generates modified SHA1 of an image
          */
-        suspend fun generateModifiedSHA1(image: Image,
-                                         defaultDispatcher : CoroutineDispatcher,
-                                         context: Context,
-                                         fileProcessor: FileProcessor,
-                                         fileUtilsWrapper: FileUtilsWrapper
-        ) : String {
+        suspend fun generateModifiedSHA1(
+            image: Image,
+            defaultDispatcher: CoroutineDispatcher,
+            context: Context,
+            fileProcessor: FileProcessor,
+            fileUtilsWrapper: FileUtilsWrapper
+        ): String {
             return withContext(defaultDispatcher) {
                 val uploadableFile = PickedFiles.pickedExistingPicture(context, image.uri)
                 val exifInterface: ExifInterface? = try {
@@ -64,7 +65,9 @@ class CustomSelectorUtils {
                 }
                 fileProcessor.redactExifTags(exifInterface, fileProcessor.getExifTagsToRedact())
                 val sha1 =
-                    fileUtilsWrapper.getSHA1(fileUtilsWrapper.getFileInputStream(uploadableFile.filePath))
+                    fileUtilsWrapper.getSHA1(
+                        fileUtilsWrapper.getFileInputStream(uploadableFile.filePath)
+                    )
                 uploadableFile.file.delete()
                 sha1
             }

app/src/main/res/layout/activity_zoomable.xml

@@ -23,4 +23,21 @@
         app:layout_constraintTop_toTopOf="parent"
         />
 
+    <TextView
+      android:id="@+id/selection_count"
+      android:layout_width="@dimen/dimen_20"
+      android:layout_height="@dimen/dimen_20"
+      app:layout_constraintDimensionRatio="H,1:1"
+      android:textSize="11sp"
+      android:textStyle="bold"
+      android:textColor="@color/black"
+      android:layout_margin="@dimen/dimen_6"
+      android:gravity="center|center_vertical"
+      style="@style/TextAppearance.AppCompat.Small"
+      android:text="12"
+      android:visibility="gone"
+      android:background="@drawable/circle_shape"
+      app:layout_constraintStart_toStartOf="parent"
+      app:layout_constraintTop_toTopOf="parent"/>
+
 </androidx.constraintlayout.widget.ConstraintLayout>