Animated skip button.

app/src/main/java/org/thoughtcrime/securesms/groups/ui/creategroup/CreateGroupActivity.java

@@ -1,17 +1,19 @@
 package org.thoughtcrime.securesms.groups.ui.creategroup;
 
+import android.animation.ValueAnimator;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 import android.util.Pair;
 import android.view.MenuItem;
-import android.view.View;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.appcompat.app.AlertDialog;
 
 import com.annimon.stream.Stream;
+import com.google.android.material.button.MaterialButton;
+import com.google.android.material.floatingactionbutton.ExtendedFloatingActionButton;
 
 import org.signal.core.util.logging.Log;
 import org.thoughtcrime.securesms.ContactSelectionActivity;
@@ -28,6 +30,7 @@ import org.thoughtcrime.securesms.recipients.RecipientId;
 import org.thoughtcrime.securesms.util.FeatureFlags;
 import org.thoughtcrime.securesms.util.Stopwatch;
 import org.thoughtcrime.securesms.util.TextSecurePreferences;
+import org.thoughtcrime.securesms.util.ViewUtil;
 import org.thoughtcrime.securesms.util.concurrent.SimpleTask;
 import org.thoughtcrime.securesms.util.views.SimpleProgressDialog;
 import org.whispersystems.libsignal.util.guava.Optional;
@@ -43,7 +46,9 @@ public class CreateGroupActivity extends ContactSelectionActivity {
 
   private static final short REQUEST_CODE_ADD_DETAILS = 17275;
 
-  private View next;
+  private ExtendedFloatingActionButton next;
+  private ValueAnimator                padStart;
+  private ValueAnimator                padEnd;
 
   public static Intent newIntent(@NonNull Context context) {
     Intent intent = new Intent(context, CreateGroupActivity.class);
@@ -67,6 +72,7 @@ public class CreateGroupActivity extends ContactSelectionActivity {
     getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 
     next = findViewById(R.id.next);
+    extendSkip();
 
     next.setOnClickListener(v -> handleNextPressed());
   }
@@ -96,7 +102,7 @@ public class CreateGroupActivity extends ContactSelectionActivity {
       getToolbar().clear();
     }
 
-    enableNext();
+    shrinkSkip();
 
     return true;
   }
@@ -106,16 +112,40 @@ public class CreateGroupActivity extends ContactSelectionActivity {
     if (contactsFragment.hasQueryFilter()) {
       getToolbar().clear();
     }
+
+    if (contactsFragment.getSelectedContactsCount() == 0) {
+      extendSkip();
+    }
   }
 
-  private void enableNext() {
-    next.setEnabled(true);
-    next.animate().alpha(1f);
+  private void extendSkip() {
+    next.setIconGravity(MaterialButton.ICON_GRAVITY_END);
+    next.extend();
+    animatePadding(24, 18);
   }
 
-  private void disableNext() {
-    next.setEnabled(false);
-    next.animate().alpha(0.5f);
+  private void shrinkSkip() {
+    next.setIconGravity(MaterialButton.ICON_GRAVITY_START);
+    next.shrink();
+    animatePadding(16, 16);
+  }
+
+  private void animatePadding(int startDp, int endDp) {
+    if (padStart != null) padStart.cancel();
+
+    padStart = ValueAnimator.ofInt(next.getPaddingStart(), ViewUtil.dpToPx(startDp)).setDuration(200);
+    padStart.addUpdateListener(animation -> {
+      ViewUtil.setPaddingStart(next, (Integer) animation.getAnimatedValue());
+    });
+    padStart.start();
+
+    if (padEnd != null) padEnd.cancel();
+
+    padEnd = ValueAnimator.ofInt(next.getPaddingEnd(), ViewUtil.dpToPx(endDp)).setDuration(200);
+    padEnd.addUpdateListener(animation -> {
+      ViewUtil.setPaddingEnd(next, (Integer) animation.getAnimatedValue());
+    });
+    padEnd.start();
   }
 
   private void handleNextPressed() {

app/src/main/java/org/thoughtcrime/securesms/util/ViewUtil.java

@@ -247,6 +247,22 @@ public final class ViewUtil {
     view.setPadding(padding, padding, padding, padding);
   }
 
+  public static void setPaddingStart(@NonNull View view, int padding) {
+    if (view.getLayoutDirection() == View.LAYOUT_DIRECTION_LTR) {
+      view.setPadding(padding, view.getPaddingTop(), view.getPaddingRight(), view.getPaddingBottom());
+    } else {
+      view.setPadding(view.getPaddingLeft(), view.getPaddingTop(), padding, view.getPaddingBottom());
+    }
+  }
+
+  public static void setPaddingEnd(@NonNull View view, int padding) {
+    if (view.getLayoutDirection() != View.LAYOUT_DIRECTION_LTR) {
+      view.setPadding(padding, view.getPaddingTop(), view.getPaddingRight(), view.getPaddingBottom());
+    } else {
+      view.setPadding(view.getPaddingLeft(), view.getPaddingTop(), padding, view.getPaddingBottom());
+    }
+  }
+
   public static boolean isPointInsideView(@NonNull View view, float x, float y) {
     int[] location = new int[2];