Toolbar expands on swipe down

user_2047987 0
Viewed 6151

In my application I have a collapsing Toolbar. If I start a specific Fragment I want to collapse the Toolbar so it behaves like a "normal" one and that the user can not expend it by himself. Here is my layout which I use for my Toolbar:

<android.support.design.widget.AppBarLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/appBarLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        app:contentScrim="?attr/colorPrimary"
        app:expandedTitleMarginEnd="64dp"
        app:expandedTitleMarginStart="48dp"
        app:titleEnabled="false"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">

        <ImageView
            android:src="@drawable/drawer_background"
            app:layout_scrollFlags="scroll|enterAlways|enterAlwaysCollapsed"
            android:layout_width="match_parent"
            android:layout_height="172dp"
            android:scaleType="centerCrop"
            app:layout_collapseMode="parallax"
            android:minHeight="100dp" />

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolBar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:layout_collapseMode="pin"
            app:layout_scrollFlags="scroll|enterAlways" />

    </android.support.design.widget.CollapsingToolbarLayout>

</android.support.design.widget.AppBarLayout>

I also can collapse the layout from code like so:

appBarLayout.setExpanded(false, false);

final AppBarLayout.LayoutParams params = (AppBarLayout.LayoutParams) collapsingToolbarLayout.getLayoutParams();
params.setScrollFlags(0);
collapsingToolbarLayout.setLayoutParams(params);

But this does not help. If the user swipes down from the Toolbar it will expand.

Do you have any ideas why?

android-appbarlayout android-toolbar android
7 Answers

the simplest thing to do is to extend the class AppBarLayout.Behavior

public class AppBarBehavior extends AppBarLayout.Behavior {
  private boolean locked;

  public AppBarBehavior() {
    super();
  }

  public AppBarBehavior(Context context, AttributeSet attrs) {
    super(context, attrs);
  }

  @Override
  public boolean onStartNestedScroll(@NonNull CoordinatorLayout parent, @NonNull AppBarLayout child, @NonNull View directTargetChild, View target, int nestedScrollAxes, int type) {
    if (locked) return false;       // Lock when content scrolled
    else return super.onStartNestedScroll(parent, child, directTargetChild, target, nestedScrollAxes, type);
  }

  @Override
  public boolean onTouchEvent(@NonNull CoordinatorLayout parent, @NonNull AppBarLayout child, @NonNull MotionEvent ev) {
    if (locked) return false;       // Lock when appBar swiped
    else return super.onTouchEvent(parent, child, ev);
  }

  public void lock(boolean locked) {
    this.locked = locked;
  }
}

Then set new layout_behavior in XML

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/main.appbar"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:fitsSystemWindows="false"
    app:layout_behavior="<full path to package>.AppBarBehavior">

And now you can manage locking with:

AppBarLayout appBar = findViewById(R.id.main_appbar);
appBar.setExpanded(false, true);   // collapse appBar
CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) appBar.getLayoutParams();
AppBarBehavior behavior = (AppBarBehavior) params.getBehavior();
behavior.lock(true);   // lock appBar
user_172578720
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