allow selecting multiple items by dragging

app/src/main/kotlin/com/simplemobiletools/applauncher/activities/MainActivity.kt

@@ -18,6 +18,7 @@ import com.simplemobiletools.commons.helpers.LICENSE_KOTLIN
 import com.simplemobiletools.commons.helpers.LICENSE_MULTISELECT
 import com.simplemobiletools.commons.helpers.LICENSE_STETHO
 import com.simplemobiletools.commons.models.Release
+import com.simplemobiletools.commons.views.MyScalableRecyclerView
 import kotlinx.android.synthetic.main.activity_main.*
 import java.util.*
 
@@ -29,6 +30,7 @@ class MainActivity : SimpleActivity(), RecyclerAdapter.AppLaunchersListener {
         setContentView(R.layout.activity_main)
         setupLaunchers()
         checkWhatsNewDialog()
+        setupGridLayoutManager()
 
         fab.setOnClickListener {
             AddAppLauncherDialog(this, launchers) {
@@ -65,10 +67,29 @@ class MainActivity : SimpleActivity(), RecyclerAdapter.AppLaunchersListener {
         startAboutActivity(R.string.app_name, LICENSE_KOTLIN or LICENSE_MULTISELECT or LICENSE_STETHO, BuildConfig.VERSION_NAME)
     }
 
+    private fun getGridAdapter() = (launchers_grid.adapter as RecyclerAdapter)
+
+    private fun setupGridLayoutManager() {
+        launchers_grid.isDragSelectionEnabled = true
+        launchers_grid.listener = object : MyScalableRecyclerView.MyScalableRecyclerViewListener {
+            override fun zoomIn() {}
+
+            override fun zoomOut() {}
+
+            override fun selectItem(position: Int) {
+                getGridAdapter().selectItem(position)
+            }
+
+            override fun selectRange(initialSelection: Int, lastDraggedIndex: Int, minReached: Int, maxReached: Int) {
+                getGridAdapter().selectRange(initialSelection, lastDraggedIndex, minReached, maxReached)
+            }
+        }
+    }
+
     private fun setupLaunchers() {
         launchers = dbHelper.getLaunchers()
         checkInvalidApps()
-        launchers_holder.adapter = RecyclerAdapter(this, launchers, this) {
+        launchers_grid.adapter = RecyclerAdapter(this, launchers, this) {
             val launchIntent = packageManager.getLaunchIntentForPackage(it.packageName)
             if (launchIntent != null) {
                 startActivity(launchIntent)
@@ -97,6 +118,10 @@ class MainActivity : SimpleActivity(), RecyclerAdapter.AppLaunchersListener {
         setupLaunchers()
     }
 
+    override fun itemLongClicked(position: Int) {
+        launchers_grid.setDragSelectActive(position)
+    }
+
     private fun checkWhatsNewDialog() {
         arrayListOf<Release>().apply {
             checkWhatsNew(this, BuildConfig.VERSION_CODE)

app/src/main/kotlin/com/simplemobiletools/applauncher/adapters/RecyclerAdapter.kt

@@ -147,6 +147,45 @@ class RecyclerAdapter(val activity: SimpleActivity, val launchers: MutableList<A
         actMode?.finish()
     }
 
+    fun selectItem(pos: Int) {
+        toggleItemSelection(true, pos)
+    }
+
+    fun selectRange(from: Int, to: Int, min: Int, max: Int) {
+        if (from == to) {
+            (min..max).filter { it != from }
+                    .forEach { toggleItemSelection(false, it) }
+            return
+        }
+
+        if (to < from) {
+            for (i in to..from)
+                toggleItemSelection(true, i)
+
+            if (min > -1 && min < to) {
+                (min until to).filter { it != from }
+                        .forEach { toggleItemSelection(false, it) }
+            }
+            if (max > -1) {
+                for (i in from + 1..max)
+                    toggleItemSelection(false, i)
+            }
+        } else {
+            for (i in from..to)
+                toggleItemSelection(true, i)
+
+            if (max > -1 && max > to) {
+                (to + 1..max).filter { it != from }
+                        .forEach { toggleItemSelection(false, it) }
+            }
+
+            if (min > -1) {
+                for (i in min until from)
+                    toggleItemSelection(false, i)
+            }
+        }
+    }
+
     class ViewHolder(view: View, val adapterListener: MyAdapterListener, val activity: SimpleActivity, val multiSelectorCallback: ModalMultiSelectorCallback,
                      val multiSelector: MultiSelector, val listener: AppLaunchersListener?, val itemClick: (AppLauncher) -> (Unit)) : SwappingHolder(view, MultiSelector()) {
         fun bindView(launcher: AppLauncher, textColor: Int): View {
@@ -176,11 +215,15 @@ class RecyclerAdapter(val activity: SimpleActivity, val launchers: MutableList<A
                     activity.startSupportActionMode(multiSelectorCallback)
                     adapterListener.toggleItemSelectionAdapter(true, adapterPosition)
                 }
+
+                listener.itemLongClicked(adapterPosition)
             }
         }
     }
 
     interface AppLaunchersListener {
         fun refreshLaunchers()
+
+        fun itemLongClicked(position: Int)
     }
 }

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

@@ -6,8 +6,8 @@
     android:layout_width="match_parent"
     android:layout_height="match_parent">
 
-    <android.support.v7.widget.RecyclerView
-        android:id="@+id/launchers_holder"
+    <com.simplemobiletools.commons.views.MyScalableRecyclerView
+        android:id="@+id/launchers_grid"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:clipToPadding="false"