How to use PercentRelativeLayout in a CollapsingToolbarLayout?

Question

I would like to use PercentRelativeLayout throughout my projects, and have been able to do so successfully with Views that don't require scrolling. When using ScrollView's however, attributes such as layout_heightPercent and layout_marginTopPercent don't work.

My problem specifically is when I'm using a CollapsingToolbarLayout and a NestedScrollView. I have found some clues as to why this isn't working as desired here.

A solution (second answer) to the question is to extend the ScrollView and override the onMeasure method. I tried doing this with several of the views but haven't been successful.

Here's the Layout I need to get working:

<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/sign_in_coordinator_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#000000"
android:fitsSystemWindows="true"
android:animateLayoutChanges="true">

<android.support.design.widget.AppBarLayout
    android:id="@+id/sign_in_app_bar_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:fitsSystemWindows="true"
    android:animateLayoutChanges="true">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/sign_in_collapsing_toolbar_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        android:animateLayoutChanges="true"
        app:expandedTitleMarginStart="48dp"
        app:expandedTitleMarginEnd="64dp"
        app:contentScrim="@color/primaryBackground"
        app:layout_scrollFlags="exitUntilCollapsed|scroll"
        >

        <android.support.percent.PercentRelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent">

            <ImageView
                android:layout_width="0dp"
                android:layout_height="0dp"

                app:layout_widthPercent="50%"
                app:layout_heightPercent="80%"
                app:layout_marginLeftPercent="33%"

                android:scaleType="centerCrop"
                android:src="@drawable/picture"
                android:fitsSystemWindows="true"
                app:layout_collapseMode="parallax"/>

        </android.support.percent.PercentRelativeLayout>

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="58dp"
            app:layout_collapseMode="pin"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"/>

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

<android.support.v4.widget.NestedScrollView
    android:id="@+id/scroll_view"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:clipToPadding="false"
    android:animateLayoutChanges="true"
    app:behavior_overlapTop="315dp"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <android.support.percent.PercentRelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            android:layout_width="0dp"
            android:layout_height="0dp"

            app:layout_widthPercent="50%"
            app:layout_heightPercent="80%"
            app:layout_marginLeftPercent="33%"

            android:scaleType="centerCrop"
            android:src="@drawable/picture"
            android:fitsSystemWindows="true" />

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

Any help would be appreciated.

Answer 1

I messed around with the code from here a bit and found a solution. Whenever you want to use a PercentRelativeLayout inside a view that scrolls, you can do the following:

Extend the view, override its onMeasure method, get the measured height and width and pass those to the setMeasuredDimension method.

For example, when using an AppBarLayout, create a custom view as follows:

public class MyAppBarLayout extends AppBarLayout {

  public MyAppBarLayout(Context context) {
      super(context);
  }

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

  // For some scrolling views, this method isn't defined, so just comment it out
  public MyAppBarLayout(Context context, AttributeSet attrs, int defStyleAttr) {
      super(context, attrs, defStyleAttr);
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
      super.onMeasure(widthMeasureSpec, heightMeasureSpec);

      int width = getMeasuredWidth();
      int height = getMeasuredHeight();

      setMeasuredDimension(width, height);
  }
}

Then you can use a PercentRelativeLayout inside the custom view as follows:

<com.mydomain.myapp.MyAppBarLayout           
    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="match_parent">

    <android.support.percent.PercentRelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <ImageView
            app:layout_widthPercent="50%"
            app:layout_heightPercent="50%"
            app:layout_marginTopPercent="25%"
            app:layout_marginLeftPercent="25%"/>

    </android.support.percent.PercentFrameLayout>      
</com.mydomain.myapp.MyAppBarLayout>

The same procedure can be followed for NestedScrollView, ScrollView, etc.