Blend out bottom bar

app/src/main/java/com/github/dfa/diaspora_android/ui/BottomBarBehavior.java

@@ -0,0 +1,102 @@
+package com.github.dfa.diaspora_android.ui;
+
+import android.content.Context;
+import android.os.Build;
+import android.support.design.widget.CoordinatorLayout;
+import android.support.v4.view.ViewCompat;
+import android.support.v4.view.ViewPropertyAnimatorListener;
+import android.support.v4.view.animation.FastOutSlowInInterpolator;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.animation.Animation;
+import android.view.animation.AnimationUtils;
+import android.widget.LinearLayout;
+
+import com.github.dfa.diaspora_android.R;
+
+/**
+ * Created by vanitas on 21.06.16.
+ */
+public class BottomBarBehavior extends CoordinatorLayout.Behavior<LinearLayout> {
+    private static final FastOutSlowInInterpolator INTERPOLATOR = new FastOutSlowInInterpolator();
+    private boolean mIsAnimatingOut = false;
+
+    public BottomBarBehavior(Context context, AttributeSet attrs) {
+        super();
+    }
+
+    @Override
+    public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final LinearLayout child,
+                                       final View directTargetChild, final View target, final int nestedScrollAxes) {
+        return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
+                || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
+    }
+
+    @Override
+    public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final LinearLayout child,
+                               final View target, final int dxConsumed, final int dyConsumed,
+                               final int dxUnconsumed, final int dyUnconsumed) {
+
+        super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed);
+        if (dyConsumed < 0 && !this.mIsAnimatingOut && child.getVisibility() == View.VISIBLE) {
+            // User scrolled down and the FAB is currently visible -> hide the FAB
+            animateOut(child);
+        } else if (dyConsumed > 0 && child.getVisibility() != View.VISIBLE) {
+            // User scrolled up and the FAB is currently not visible -> show the FAB
+            animateIn(child);
+        }
+    }
+
+    private void animateOut(final LinearLayout linearLayout) {
+        if (Build.VERSION.SDK_INT >= 14) {
+            ViewCompat.animate(linearLayout).translationY(168F).alpha(0.0F).setInterpolator(INTERPOLATOR).withLayer()
+                    .setListener(new ViewPropertyAnimatorListener() {
+                        public void onAnimationStart(View view) {
+                            BottomBarBehavior.this.mIsAnimatingOut = true;
+                        }
+
+                        public void onAnimationCancel(View view) {
+                            BottomBarBehavior.this.mIsAnimatingOut = false;
+                        }
+
+                        public void onAnimationEnd(View view) {
+                            BottomBarBehavior.this.mIsAnimatingOut = false;
+                            view.setVisibility(View.GONE);
+                        }
+                    }).start();
+        } else {
+            Animation anim = AnimationUtils.loadAnimation(linearLayout.getContext(), R.anim.bottom_bar_up);
+            anim.setInterpolator(INTERPOLATOR);
+            anim.setDuration(200L);
+            anim.setAnimationListener(new Animation.AnimationListener() {
+                public void onAnimationStart(Animation animation) {
+                    BottomBarBehavior.this.mIsAnimatingOut = true;
+                }
+
+                public void onAnimationEnd(Animation animation) {
+                    BottomBarBehavior.this.mIsAnimatingOut = false;
+                    linearLayout.setVisibility(View.GONE);
+                }
+
+                @Override
+                public void onAnimationRepeat(final Animation animation) {
+                }
+            });
+            linearLayout.startAnimation(anim);
+        }
+    }
+
+    private void animateIn(LinearLayout linearLayout) {
+        linearLayout.setVisibility(View.VISIBLE);
+        if (Build.VERSION.SDK_INT >= 14) {
+            ViewCompat.animate(linearLayout).translationY(0).scaleX(1.0F).scaleY(1.0F).alpha(1.0F)
+                    .setInterpolator(INTERPOLATOR).withLayer().setListener(null)
+                    .start();
+        } else {
+            Animation anim = AnimationUtils.loadAnimation(linearLayout.getContext(), R.anim.bottom_bar_down);
+            anim.setDuration(200L);
+            anim.setInterpolator(INTERPOLATOR);
+            linearLayout.startAnimation(anim);
+        }
+    }
+}

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

@@ -42,13 +42,15 @@
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:layout_gravity="bottom"
-        android:theme="@style/AppTheme.AppBarOverlay">
+        android:theme="@style/AppTheme.AppBarOverlay"
+        app:layout_behavior=".ui.BottomBarBehavior">
 
         <android.support.v7.widget.ActionMenuView
             android:id="@+id/toolbar2"
             android:layout_width="match_parent"
             android:layout_height="45dp"
             android:background="?attr/colorPrimary"
+            app:layout_scrollFlags="scroll|enterAlways|snap"
             app:popupTheme="@style/AppTheme.PopupOverlay" />
 
     </android.support.design.widget.AppBarLayout>