Set starting height of CollapsingToolbarLayout

Question

I want to be able to scroll on the ImageView inside the CollapsingToolbarLayout. So how that would be possible, and How to set a starting height of that Image view?

Answer 1

cheesesquare implement your Request

this is a layout in cheesesquare

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/detail_backdrop_height"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar"
        android:fitsSystemWindows="true">

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

            <ImageView
                android:id="@+id/backdrop"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:scaleType="centerCrop"
                android:fitsSystemWindows="true"
                app:layout_collapseMode="parallax" />

            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:layout_collapseMode="pin" />

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

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

    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical"
            android:paddingTop="24dp">

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_margin="@dimen/card_margin">

                <LinearLayout
                    style="@style/Widget.CardContent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="Info"
                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="@string/cheese_ipsum" />

                </LinearLayout>

            </android.support.v7.widget.CardView>

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="@dimen/card_margin"
                android:layout_marginLeft="@dimen/card_margin"
                android:layout_marginRight="@dimen/card_margin">

                <LinearLayout
                    style="@style/Widget.CardContent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="Friends"
                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="@string/cheese_ipsum" />

                </LinearLayout>

            </android.support.v7.widget.CardView>

            <android.support.v7.widget.CardView
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginBottom="@dimen/card_margin"
                android:layout_marginLeft="@dimen/card_margin"
                android:layout_marginRight="@dimen/card_margin">

                <LinearLayout
                    style="@style/Widget.CardContent"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content">

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="Related"
                        android:textAppearance="@style/TextAppearance.AppCompat.Title" />

                    <TextView
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:text="@string/cheese_ipsum" />

                </LinearLayout>

            </android.support.v7.widget.CardView>

        </LinearLayout>

    </android.support.v4.widget.NestedScrollView>

    <android.support.design.widget.FloatingActionButton
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        app:layout_anchor="@id/appbar"
        app:layout_anchorGravity="bottom|right|end"
        android:src="@drawable/ic_discuss"
        android:layout_margin="@dimen/fab_margin"
        android:clickable="true"/>

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

Answer 2

Actually AppBarLayout has special method to apply such offset:

final int setAppBarTopBottomOffset(CoordinatorLayout coordinatorLayout, AppBarLayout appBarLayout, int newOffset, int minOffset, int maxOffset)

Unfortunately it has package-private access level, but we can invoke it through such intermediate chain:

private void setAppBarOffset(int offsetPx){
    CoordinatorLayout.LayoutParams params = (CoordinatorLayout.LayoutParams) mAppBarLayout.getLayoutParams();
    AppBarLayout.Behavior behavior = (AppBarLayout.Behavior) params.getBehavior();
    behavior.onNestedPreScroll(mCoordinatorLayour, mAppBarLayout, null, 0, offsetPx, new int[]{0, 0});
}

One thing to be mentioned - this method should be called after mAppBarLayout is already prepared and measured. So the right way is to call it via view's post method.

mCoordinatorLayour = (CoordinatorLayout) findViewById(R.id.root_coordinator);
mAppBarLayout = (AppBarLayout) findViewById(R.id.app_bar_layout);

mAppBarLayout.post(new Runnable() {
    @Override
    public void run() {
        int heightPx = findViewById(R.id.iv_header).getHeight();
        setAppBarOffset(heightPx/2);
    }
});

Answer 3

Just add:

android:fitsSystemWindows="true"
app:layout_collapseMode="parallax"

to the ImageView in the CollapsingToolbarLayout.

You can find more here.