[CollapsingToolbarLayout] Wrong height for wrap_content while children have fitSystemWindows set to true

Description: At onMeasure() in CollapsingToolbarLayout, it adds topInset to the measured height, which can be unnecessary and cause a gap to appear at the bottom if children have fitSystemWindow set to true.

ImageView with fitSystemWindow = false

ImageView with fitSystemWindow = true

Expected behavior: View height should be measured considering fitSystemWindow of children.

Source code:

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  xmlns:tools="http://schemas.android.com/tools"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:fitsSystemWindows="true">

  <com.google.android.material.appbar.AppBarLayout
    android:id="@+id/app_bar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:fitsSystemWindows="true"
    android:theme="@style/AppTheme.AppBarOverlay">

    <com.google.android.material.appbar.CollapsingToolbarLayout
      android:id="@+id/toolbar_layout"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:fitsSystemWindows="true"
      app:contentScrim="?colorPrimary"
      app:layout_scrollFlags="scroll|exitUntilCollapsed"
      app:toolbarId="@+id/toolbar">

      <ImageView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:adjustViewBounds="true"
        android:fitsSystemWindows="true"
        android:src="@drawable/hero"/>

      <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?actionBarSize"
        app:layout_collapseMode="pin"
        app:popupTheme="@style/AppTheme.PopupOverlay"/>

    </com.google.android.material.appbar.CollapsingToolbarLayout>
  </com.google.android.material.appbar.AppBarLayout>

  <androidx.core.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/activity_scrolling">

    <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_margin="16dp"
      android:text="@string/large_text"/>

  </androidx.core.widget.NestedScrollView>
</androidx.coordinatorlayout.widget.CoordinatorLayout>

Android API version: 28

Material Library version: 1.1.0-alpha09

Device: Pixel 2 XL / Pixel 2 Emulator

[ogndman]

I’ve solved the issue as follow.

class CustomCollapsingToolbarLayout
@JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0
) : CollapsingToolbarLayout(context, attrs, defStyleAttr) {

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        if (ViewCompat.getFitsSystemWindows(this)) {
            val mode = MeasureSpec.getMode(heightMeasureSpec)
            val topInset = getTopSystemInset()

            if (mode == MeasureSpec.UNSPECIFIED && topInset > 0) {
                val hasFitsSystemWindowsFlagInChild = (0 until childCount)
                    .map { index -> getChildAt(index) }
                    .any { ViewCompat.getFitsSystemWindows(it) }
                if (hasFitsSystemWindowsFlagInChild) {
                    val heightSpec = MeasureSpec.makeMeasureSpec(measuredHeight - topInset, MeasureSpec.EXACTLY)
                    super.onMeasure(widthMeasureSpec, heightSpec)
                }
            }
        }
    }

    private fun getTopSystemInset(): Int {
        val field = CollapsingToolbarLayout::class.java.getDeclaredField("lastInsets")
            .apply { isAccessible = true }
        val windowsInsetsCompat = field.get(this) as? WindowInsetsCompat
        return windowsInsetsCompat?.systemWindowInsetTop ?: 0
    }
}

[droplet-js]

i have solve it.

remove “android:fitsSystemWindows=true” from CollapsingToolbarLayout.