Fully implement imagepicker and create play store showcase (#12)3.1.1

* Update changelog

* Add uri to imagemodel

* Revamp image pickers

* Prepare play store showcase

* Add encrypted files

* Test showcase

* Clean elastic recycler activity

7 files changed, 345 insertions, 146 deletions

diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItem.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItem.kt
index 2bfc57f..ffeb560 100644
--- a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItem.kt
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItem.kt
@@ -1,22 +1,16 @@
 package ca.allanwang.kau.imagepicker
 
-import android.content.Context
-import android.graphics.Color
 import android.graphics.drawable.Drawable
 import android.support.v7.widget.RecyclerView
 import android.view.View
 import ca.allanwang.kau.iitems.KauIItem
 import ca.allanwang.kau.utils.bindView
-import ca.allanwang.kau.utils.gone
 import com.bumptech.glide.Glide
 import com.bumptech.glide.load.DataSource
 import com.bumptech.glide.load.engine.GlideException
 import com.bumptech.glide.request.RequestListener
 import com.bumptech.glide.request.target.Target
 import com.mikepenz.fastadapter.FastAdapter
-import com.mikepenz.google_material_typeface_library.GoogleMaterial
-import com.mikepenz.iconics.IconicsDrawable
-import com.mikepenz.iconics.typeface.IIcon
 
 /**
  * Created by Allan Wang on 2017-07-04.
@@ -25,7 +19,6 @@ class ImageItem(val data: ImageModel)
     : KauIItem<ImageItem, ImageItem.ViewHolder>(R.layout.kau_iitem_image, { ViewHolder(it) }) {
 
     private var failedToLoad = false
-    var withFade = true
 
     companion object {
         fun bindEvents(fastAdapter: FastAdapter<ImageItem>) {
@@ -45,50 +38,28 @@ class ImageItem(val data: ImageModel)
 
     override fun bindView(holder: ViewHolder, payloads: List<Any>?) {
         super.bindView(holder, payloads)
-        if (withFade) holder.container.alpha = 0f
         Glide.with(holder.itemView)
                 .load(data.data)
                 .listener(object : RequestListener<Drawable> {
                     override fun onLoadFailed(e: GlideException?, model: Any, target: Target<Drawable>, isFirstResource: Boolean): Boolean {
-                        failedToLoad = true;
-                        holder.container.setIcon(GoogleMaterial.Icon.gmd_error);
-                        if (withFade) holder.container.animate().alpha(1f).start();
+                        failedToLoad = true
+                        holder.container.imageBase.setImageDrawable(ImagePickerCore.getErrorDrawable(holder.itemView.context))
                         return true;
                     }
 
                     override fun onResourceReady(resource: Drawable, model: Any, target: Target<Drawable>, dataSource: DataSource, isFirstResource: Boolean): Boolean {
                         holder.container.imageBase.setImageDrawable(resource)
                         if (isSelected) holder.container.blurInstantly()
-                        if (withFade) holder.container.animate().alpha(1f).start();
                         return true;
                     }
                 })
                 .into(holder.container.imageBase)
     }
 
-    private fun BlurredImageView.setIcon(icon: IIcon) {
-        val sizePx = computeViewSize(context)
-        imageBase.setImageDrawable(IconicsDrawable(context, icon)
-                .sizePx(sizePx)
-                .paddingPx(sizePx / 3)
-                .color(Color.WHITE))
-        imageBase.setBackgroundColor(ImagePickerActivityBase.accentColor)
-        imageForeground.gone()
-    }
-
-    private fun computeViewSize(context: Context): Int {
-        val screenWidthPx = context.resources.displayMetrics.widthPixels
-        return screenWidthPx / ImagePickerActivityBase.computeColumnCount(context)
-    }
-
     override fun unbindView(holder: ViewHolder) {
         super.unbindView(holder)
-        if (!failedToLoad) {
-            Glide.with(holder.itemView).clear(holder.container.imageBase)
-            holder.container.removeBlurInstantly()
-        } else {
-            holder.container.fullReset()
-        }
+        Glide.with(holder.itemView).clear(holder.container.imageBase)
+        holder.container.removeBlurInstantly()
         failedToLoad = false
     }
 
diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItemBasic.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItemBasic.kt
new file mode 100644
index 0000000..62a0b09
--- /dev/null
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageItemBasic.kt
@@ -0,0 +1,71 @@
+package ca.allanwang.kau.imagepicker
+
+import android.annotation.SuppressLint
+import android.app.Activity
+import android.content.Intent
+import android.graphics.drawable.Drawable
+import android.support.v7.app.AppCompatActivity
+import android.support.v7.widget.RecyclerView
+import android.view.View
+import ca.allanwang.kau.iitems.KauIItem
+import ca.allanwang.kau.ui.views.MeasuredImageView
+import ca.allanwang.kau.utils.bindView
+import ca.allanwang.kau.utils.buildIsLollipopAndUp
+import com.bumptech.glide.Glide
+import com.bumptech.glide.load.DataSource
+import com.bumptech.glide.load.engine.GlideException
+import com.bumptech.glide.request.RequestListener
+import com.bumptech.glide.request.target.Target
+import com.mikepenz.fastadapter.FastAdapter
+
+/**
+ * Created by Allan Wang on 2017-07-04.
+ */
+class ImageItemBasic(val data: ImageModel)
+    : KauIItem<ImageItem, ImageItemBasic.ViewHolder>(R.layout.kau_iitem_image_basic, { ViewHolder(it) }) {
+
+    companion object {
+        @SuppressLint("NewApi")
+        fun bindEvents(activity: Activity, fastAdapter: FastAdapter<ImageItemBasic>) {
+            fastAdapter.withSelectable(false)
+                    //add image data and return right away
+                    .withOnClickListener { v, _, item, _ ->
+                        val intent = Intent()
+                        val data = arrayListOf(item.data)
+                        intent.putParcelableArrayListExtra(IMAGE_PICKER_RESULT, data)
+                        activity.setResult(AppCompatActivity.RESULT_OK, intent)
+                        if (buildIsLollipopAndUp) activity.finishAfterTransition()
+                        else activity.finish()
+                        true
+                    }
+        }
+    }
+
+    override fun isSelectable(): Boolean = false
+
+    override fun bindView(holder: ViewHolder, payloads: List<Any>?) {
+        super.bindView(holder, payloads)
+        Glide.with(holder.itemView)
+                .load(data.data)
+                .listener(object : RequestListener<Drawable> {
+                    override fun onLoadFailed(e: GlideException?, model: Any, target: Target<Drawable>, isFirstResource: Boolean): Boolean {
+                        holder.image.setImageDrawable(ImagePickerCore.getErrorDrawable(holder.itemView.context))
+                        return true;
+                    }
+
+                    override fun onResourceReady(resource: Drawable, model: Any, target: Target<Drawable>, dataSource: DataSource, isFirstResource: Boolean): Boolean {
+                        return false
+                    }
+                })
+                .into(holder.image)
+    }
+
+    override fun unbindView(holder: ViewHolder) {
+        super.unbindView(holder)
+        Glide.with(holder.itemView).clear(holder.image)
+    }
+
+    class ViewHolder(v: View) : RecyclerView.ViewHolder(v) {
+        val image: MeasuredImageView by bindView(R.id.kau_image)
+    }
+}
\ No newline at end of file
diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageModel.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageModel.kt
index d744650..202805c 100644
--- a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageModel.kt
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImageModel.kt
@@ -1,10 +1,12 @@
 package ca.allanwang.kau.imagepicker
 
 import android.database.Cursor
+import android.net.Uri
 import android.os.Parcel
 import android.os.Parcelable
 import android.provider.MediaStore
 import android.support.annotation.NonNull
+import java.io.File
 
 
 /**
@@ -34,6 +36,8 @@ data class ImageModel(val size: Long, val dateModified: Long, val data: String,
         parcel.writeString(this.displayName)
     }
 
+    val uri: Uri by lazy { Uri.fromFile(File(data)) }
+
     override fun describeContents(): Int {
         return 0
     }
diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityBase.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityBase.kt
index 9d988d1..3a9809c 100644
--- a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityBase.kt
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityBase.kt
@@ -1,40 +1,27 @@
 package ca.allanwang.kau.imagepicker
 
-import android.Manifest
-import android.app.Activity
-import android.content.Context
 import android.content.Intent
 import android.database.Cursor
 import android.os.Bundle
-import android.provider.MediaStore
 import android.support.design.widget.AppBarLayout
 import android.support.design.widget.CoordinatorLayout
 import android.support.design.widget.FloatingActionButton
-import android.support.v4.app.LoaderManager
-import android.support.v4.content.CursorLoader
 import android.support.v4.content.Loader
-import android.support.v7.app.AppCompatActivity
-import android.support.v7.widget.GridLayoutManager
 import android.support.v7.widget.LinearLayoutManager
 import android.support.v7.widget.RecyclerView
 import android.support.v7.widget.Toolbar
 import android.widget.TextView
-import ca.allanwang.kau.animators.FadeScaleAnimatorAdd
-import ca.allanwang.kau.animators.KauAnimator
-import ca.allanwang.kau.permissions.kauRequestPermissions
 import ca.allanwang.kau.utils.*
-import com.mikepenz.fastadapter.commons.adapters.FastItemAdapter
 import com.mikepenz.google_material_typeface_library.GoogleMaterial
 
-
 /**
  * Created by Allan Wang on 2017-07-04.
  *
  * Base activity for selecting images from storage
+ * Images are blurred when selected, and multiple images can be selected at a time.
+ * Having three layered images makes this slightly slower than [ImagePickerActivityOverlayBase]
  */
-abstract class ImagePickerActivityBase : AppCompatActivity(), LoaderManager.LoaderCallbacks<Cursor> {
-
-    val imageAdapter = FastItemAdapter<ImageItem>()
+abstract class ImagePickerActivityBase : ImagePickerCore<ImageItem>() {
 
     val coordinator: CoordinatorLayout by bindView(R.id.kau_coordinator)
     val toolbar: Toolbar by bindView(R.id.kau_toolbar)
@@ -42,28 +29,6 @@ abstract class ImagePickerActivityBase : AppCompatActivity(), LoaderManager.Load
     val recycler: RecyclerView by bindView(R.id.kau_recyclerview)
     val fab: FloatingActionButton by bindView(R.id.kau_fab)
 
-    companion object {
-        /**
-         * Given the dimensions of our device and a minimum image size,
-         * Computer the optimal column count for our grid layout
-         *
-         * @return column count
-         */
-        fun computeColumnCount(context: Context): Int {
-            val minImageSizePx = context.dimenPixelSize(R.dimen.kau_image_minimum_size)
-            val screenWidthPx = context.resources.displayMetrics.widthPixels
-            return screenWidthPx / minImageSizePx
-        }
-
-        var accentColor: Int = 0xff666666.toInt()
-
-        fun onImagePickerResult(resultCode: Int, data: Intent?): List<ImageModel> {
-            if (resultCode != Activity.RESULT_OK || data == null || !data.hasExtra(IMAGE_PICKER_RESULT))
-                return emptyList()
-            return data.getParcelableArrayListExtra(IMAGE_PICKER_RESULT)
-        }
-    }
-
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
@@ -79,12 +44,7 @@ abstract class ImagePickerActivityBase : AppCompatActivity(), LoaderManager.Load
         }
         toolbar.setNavigationOnClickListener { onBackPressed() }
 
-        recycler.apply {
-            layoutManager = GridLayoutManager(context, computeColumnCount(context))
-            adapter = imageAdapter
-            setHasFixedSize(true)
-            itemAnimator = KauAnimator(FadeScaleAnimatorAdd(0.8f))
-        }
+        initializeRecycler(recycler)
 
         ImageItem.bindEvents(imageAdapter)
         imageAdapter.withSelectionListener({ _, _ -> selectionCount.text = imageAdapter.selections.size.toString() })
@@ -110,24 +70,7 @@ abstract class ImagePickerActivityBase : AppCompatActivity(), LoaderManager.Load
         loadImages()
     }
 
-    /**
-     * Request read permissions and load all external images
-     * The result will be filtered through {@link #onLoadFinished(Loader, Cursor)}
-     * Call this to make sure that we request permissions each time
-     * The adapter will be cleared on each successful call
-     */
-    private fun loadImages() {
-        kauRequestPermissions(Manifest.permission.READ_EXTERNAL_STORAGE) {
-            granted, _ ->
-            if (granted) {
-                supportLoaderManager.initLoader(LOADER_ID, null, this)
-                setToolbarScrollable(true)
-            } else {
-                toast(R.string.kau_permission_denied)
-                setToolbarScrollable(false)
-            }
-        }
-    }
+    override fun converter(model: ImageModel): ImageItem = ImageItem(model)
 
     /**
      * Decide whether the toolbar can hide itself
@@ -145,56 +88,13 @@ abstract class ImagePickerActivityBase : AppCompatActivity(), LoaderManager.Load
             params.scrollFlags = 0
     }
 
-    override fun onCreateLoader(id: Int, args: Bundle?): Loader<Cursor> {
-        val columns = arrayOf(
-                MediaStore.Images.Media._ID,
-                MediaStore.Images.Media.TITLE,
-                MediaStore.Images.Media.DATA,
-                MediaStore.Images.Media.SIZE,
-                MediaStore.Images.Media.DISPLAY_NAME,
-                MediaStore.Images.Media.DATE_MODIFIED
-        )
-        return CursorLoader(this,
-                MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
-                columns,
-                null,
-                null,
-                //Sort by descending date
-                MediaStore.Images.Media.DATE_MODIFIED + " DESC")
-    }
-
-    override fun onLoadFinished(loader: Loader<Cursor>, data: Cursor?) {
-        reset()
-        if (data == null || !data.moveToFirst()) {
-            toast(R.string.kau_no_images_found)
-            setToolbarScrollable(false)
-            return
-        }
-        do {
-            val model = ImageModel(data)
-            if (!shouldLoad(model)) continue
-            imageAdapter.add(ImageItem(model))
-        } while (data.moveToNext())
+    override fun onLoadFinished(loader: Loader<Cursor>?, data: Cursor?) {
+        super.onLoadFinished(loader, data)
         setToolbarScrollable((recycler.layoutManager as LinearLayoutManager).findLastCompletelyVisibleItemPosition() < imageAdapter.getItemCount() - 1)
     }
 
-    /**
-     * Optional filter to decide which images get displayed
-     * Defaults to checking their sizes to filter out
-     * very small images such as lurking drawables/icons
-     *
-     * Returns true if model should be displayed, false otherwise
-     */
-    open fun shouldLoad(model: ImageModel): Boolean = model.size > 10000L
-
-    private fun reset() {
-        imageAdapter.clear();
+    override fun onStatusChange(loaded: Boolean) {
+        setToolbarScrollable(loaded)
     }
 
-    override fun onLoaderReset(loader: Loader<Cursor>) = reset()
-
-    override fun onBackPressed() {
-        setResult(RESULT_CANCELED)
-        super.onBackPressed()
-    }
 }
\ No newline at end of file
diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityOverlayBase.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityOverlayBase.kt
new file mode 100644
index 0000000..ed8eee4
--- /dev/null
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerActivityOverlayBase.kt
@@ -0,0 +1,51 @@
+package ca.allanwang.kau.imagepicker
+
+import android.os.Build
+import android.os.Bundle
+import android.support.annotation.RequiresApi
+import android.support.v7.widget.RecyclerView
+import ca.allanwang.kau.ui.widgets.ElasticDragDismissFrameLayout
+import ca.allanwang.kau.utils.bindView
+import ca.allanwang.kau.utils.toast
+
+/**
+ * Created by Allan Wang on 2017-07-23.
+ *
+ * Base activity for selecting images from storage
+ * This variant is an overlay and selects one image only before returning directly
+ * It is more efficient than [ImagePickerActivityBase], as all images are one layer deep
+ * as opposed to three layers deep
+ */
+@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
+abstract class ImagePickerActivityOverlayBase : ImagePickerCore<ImageItemBasic>() {
+
+    val draggable: ElasticDragDismissFrameLayout by bindView(R.id.kau_draggable)
+    val recycler: RecyclerView by bindView(R.id.kau_recyclerview)
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.kau_activity_image_picker_overlay)
+        initializeRecycler(recycler)
+        ImageItemBasic.bindEvents(this, imageAdapter)
+
+        draggable.addExitListener(this, R.transition.kau_image_exit_bottom, R.transition.kau_image_exit_top)
+        draggable.setOnClickListener { finishAfterTransition() }
+
+        loadImages()
+    }
+
+    override fun finishAfterTransition() {
+        recycler.stopScroll()
+        super.finishAfterTransition()
+    }
+
+    override fun onStatusChange(loaded: Boolean) {
+        if (!loaded) toast(R.string.kau_no_images_loaded)
+    }
+
+    override fun converter(model: ImageModel): ImageItemBasic = ImageItemBasic(model)
+
+    override fun onBackPressed() {
+        finishAfterTransition()
+    }
+}
\ No newline at end of file
diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerBinder.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerBinder.kt
index 8e8a69c..db8d113 100644
--- a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerBinder.kt
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerBinder.kt
@@ -2,6 +2,7 @@ package ca.allanwang.kau.imagepicker
 
 import android.app.Activity
 import android.content.Intent
+import ca.allanwang.kau.utils.startActivityForResult
 
 /**
  * Created by Allan Wang on 2017-07-21.
@@ -11,10 +12,11 @@ import android.content.Intent
  */
 
 /**
- * Image picker launcher
+ * Image picker launchers
  */
-fun Activity.kauLaunchImagePicker(clazz: Class<out ImagePickerActivityBase>, requestCode: Int) {
-    startActivityForResult(Intent(this, clazz), requestCode)
+fun Activity.kauLaunchImagePicker(clazz: Class<out ImagePickerCore<*>>, requestCode: Int) {
+//    startActivityForResult(clazz, requestCode, true)
+    startActivityForResult(clazz, requestCode, transition = ImagePickerActivityOverlayBase::class.java.isAssignableFrom(clazz))
 }
 
 /**
@@ -22,7 +24,7 @@ fun Activity.kauLaunchImagePicker(clazz: Class<out ImagePickerActivityBase>, req
  * call under [Activity.onActivityResult]
  * and make sure that the requestCode matches first
  */
-fun Activity.kauOnImagePickerResult(resultCode: Int, data: Intent?) = ImagePickerActivityBase.onImagePickerResult(resultCode, data)
+fun Activity.kauOnImagePickerResult(resultCode: Int, data: Intent?) = ImagePickerCore.onImagePickerResult(resultCode, data)
 
 internal const val LOADER_ID = 42
 internal const val IMAGE_PICKER_RESULT = "image_picker_result"
diff --git a/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerCore.kt b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerCore.kt
new file mode 100644
index 0000000..f197a5e
--- /dev/null
+++ b/imagepicker/src/main/kotlin/ca/allanwang/kau/imagepicker/ImagePickerCore.kt
@@ -0,0 +1,200 @@
+package ca.allanwang.kau.imagepicker
+
+import android.Manifest
+import android.app.Activity
+import android.content.Context
+import android.content.Intent
+import android.database.Cursor
+import android.graphics.Color
+import android.graphics.drawable.Drawable
+import android.os.Bundle
+import android.provider.MediaStore
+import android.support.v4.app.LoaderManager
+import android.support.v4.content.CursorLoader
+import android.support.v4.content.Loader
+import android.support.v7.app.AppCompatActivity
+import android.support.v7.widget.GridLayoutManager
+import android.support.v7.widget.RecyclerView
+import ca.allanwang.kau.animators.FadeScaleAnimatorAdd
+import ca.allanwang.kau.animators.KauAnimator
+import ca.allanwang.kau.permissions.kauRequestPermissions
+import ca.allanwang.kau.utils.dimenPixelSize
+import ca.allanwang.kau.utils.toast
+import com.mikepenz.fastadapter.IItem
+import com.mikepenz.fastadapter.commons.adapters.FastItemAdapter
+import com.mikepenz.google_material_typeface_library.GoogleMaterial
+import com.mikepenz.iconics.IconicsDrawable
+
+/**
+ * Created by Allan Wang on 2017-07-23.
+ *
+ * Container for the main logic behind the image pickers
+ */
+abstract class ImagePickerCore<T : IItem<*, *>> : AppCompatActivity(), LoaderManager.LoaderCallbacks<Cursor> {
+
+    companion object {
+        /**
+         * Given the dimensions of our device and a minimum image size,
+         * Computer the optimal column count for our grid layout
+         *
+         * @return column count
+         */
+        fun computeColumnCount(context: Context): Int {
+            val minImageSizePx = context.dimenPixelSize(R.dimen.kau_image_minimum_size)
+            val screenWidthPx = context.resources.displayMetrics.widthPixels
+            return screenWidthPx / minImageSizePx
+        }
+
+        /**
+         * Compute our resulting image size
+         */
+        fun computeViewSize(context: Context): Int {
+            val screenWidthPx = context.resources.displayMetrics.widthPixels
+            return screenWidthPx / computeColumnCount(context)
+        }
+
+        /**
+         * Create error tile for a given item
+         */
+        fun getErrorDrawable(context: Context): Drawable {
+            val sizePx = ImagePickerCore.computeViewSize(context)
+            return IconicsDrawable(context, GoogleMaterial.Icon.gmd_error)
+                    .sizePx(sizePx)
+                    .backgroundColor(accentColor)
+                    .paddingPx(sizePx / 3)
+                    .color(Color.WHITE)
+        }
+
+        var accentColor: Int = 0xff666666.toInt()
+
+        /**
+         * Helper method to retrieve the images from our iamge picker
+         * This is used for both single and multiple photo picks
+         */
+        fun onImagePickerResult(resultCode: Int, data: Intent?): List<ImageModel> {
+            if (resultCode != Activity.RESULT_OK || data == null || !data.hasExtra(IMAGE_PICKER_RESULT))
+                return emptyList()
+            return data.getParcelableArrayListExtra(IMAGE_PICKER_RESULT)
+        }
+
+        /**
+         * Number of loaded images we should cache
+         * This is arbitrary
+         */
+        const val CACHE_SIZE = 80
+
+        /**
+         * We know that Glide takes a while to initially fetch the images
+         * My as well make it look pretty
+         */
+        const val INITIAL_LOAD_DELAY = 600L
+    }
+
+    val imageAdapter: FastItemAdapter<T> = FastItemAdapter()
+
+    /**
+     * Further improve preloading by extending the layout space
+     */
+    val extraSpace: Int by lazy { resources.displayMetrics.heightPixels }
+
+    fun initializeRecycler(recycler: RecyclerView) {
+        recycler.apply {
+            val manager = object : GridLayoutManager(context, computeColumnCount(context)) {
+                override fun getExtraLayoutSpace(state: RecyclerView.State?): Int {
+                    return extraSpace
+                }
+            }
+            setItemViewCacheSize(CACHE_SIZE)
+            isDrawingCacheEnabled = true
+            layoutManager = manager
+            adapter = imageAdapter
+            setHasFixedSize(true)
+            itemAnimator = object : KauAnimator(FadeScaleAnimatorAdd(0.8f)) {
+                override fun startDelay(holder: RecyclerView.ViewHolder, duration: Long, factor: Float): Long {
+                    return super.startDelay(holder, duration, factor) + INITIAL_LOAD_DELAY
+                }
+            }
+        }
+    }
+
+    //Sort by descending date
+    var sortQuery = MediaStore.Images.Media.DATE_MODIFIED + " DESC"
+
+    /**
+     * Request read permissions and load all external images
+     * The result will be filtered through {@link #onLoadFinished(Loader, Cursor)}
+     * Call this to make sure that we request permissions each time
+     * The adapter will be cleared on each successful call
+     */
+    open fun loadImages() {
+        kauRequestPermissions(Manifest.permission.READ_EXTERNAL_STORAGE) {
+            granted, _ ->
+            if (granted) {
+                supportLoaderManager.initLoader(LOADER_ID, null, this)
+                onStatusChange(true)
+            } else {
+                toast(R.string.kau_permission_denied)
+                onStatusChange(false)
+            }
+        }
+    }
+
+    override fun onCreateLoader(id: Int, args: Bundle?): Loader<Cursor> {
+        val columns = arrayOf(
+                MediaStore.Images.Media._ID,
+                MediaStore.Images.Media.TITLE,
+                MediaStore.Images.Media.DATA,
+                MediaStore.Images.Media.SIZE,
+                MediaStore.Images.Media.DISPLAY_NAME,
+                MediaStore.Images.Media.DATE_MODIFIED
+        )
+        return CursorLoader(this, MediaStore.Images.Media.EXTERNAL_CONTENT_URI, columns, null, null, sortQuery)
+    }
+
+    override fun onLoadFinished(loader: Loader<Cursor>?, data: Cursor?) {
+        reset()
+        if (data == null || !data.moveToFirst()) {
+            toast(R.string.kau_no_images_found)
+            onStatusChange(false)
+            return
+        }
+        val items = mutableListOf<T>()
+        do {
+            val model = ImageModel(data)
+            if (!shouldLoad(model)) continue
+            items.add(converter(model))
+        } while (data.moveToNext())
+        addItems(items)
+    }
+
+    abstract fun converter(model: ImageModel): T
+
+    override fun onLoaderReset(loader: Loader<Cursor>?) = reset()
+
+    /**
+     * Called at the end of [onLoadFinished]
+     * when the adapter should add the items
+     */
+    open fun addItems(items: List<T>) {
+        imageAdapter.add(items)
+    }
+
+    /**
+     * Clears the adapter to prepare for a new load
+     */
+    open fun reset() {
+        imageAdapter.clear()
+    }
+
+    /**
+     * Optional filter to decide which images get displayed
+     * Defaults to checking their sizes to filter out
+     * very small images such as lurking drawables/icons
+     *
+     * Returns true if model should be displayed, false otherwise
+     */
+    open fun shouldLoad(model: ImageModel): Boolean = model.size > 10000L
+
+    open fun onStatusChange(loaded: Boolean) {}
+
+}
\ No newline at end of file