Android insets: dealing with fears and getting ready for Android Q

Typical tasks

 <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    ...
    <item name="colorPrimaryDark">@color/colorAccent</item>
    ...
</style>

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    ...
    <item name="android:statusBarColor">@color/colorAccent</item>
    ...
</style>

override fun onCreateView(...): View {
    requireActivity().window.statusBarColor = requireContext().getColor(R.color.colorPrimary)
    ...
}

<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">    
    ...
    <item name="android:windowTranslucentStatus">true</item>
    ...
</style>

<activity
    ...
    android:windowSoftInputMode="adjustResize">
    ...
</activity>

boolean isOpened = false;

public void setListenerToRootView() {
    final View activityRootView = getWindow().getDecorView().findViewById(android.R.id.content);
    activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
    
            int heightDiff = activityRootView.getRootView().getHeight() - activityRootView.getHeight();      
            if (heightDiff > 100) { // 99% of the time the height diff will be due to a keyboard.       
                Toast.makeText(getApplicationContext(), "Gotcha!!! softKeyboardup", 0).show();

                if (isOpened == false) {
                   //Do two things, make the view top visible and the editText smaller
                }
                isOpened = true;
            } else if (isOpened == true) {
                Toast.makeText(getApplicationContext(), "softkeyborad Down!!!", 0).show();
                isOpened = false;
            }    
        }
    });
}

What did we do before Android 10

Why does it work?

@Override
public void onAttachedToWindow() {   
    super.onAttachedToWindow();
    ...    
    if (mLastInsets == null && ViewCompat.getFitsSystemWindows(this)) {         
        // We're set to fitSystemWindows but we haven't had any insets yet...
        // We should request a new dispatch of window insets
        ViewCompat.requestApplyInsets(this);
    }     
    ...
}

@Override
public WindowInsets dispatchApplyWindowInsets(WindowInsets insets) {    
    insets = super.dispatchApplyWindowInsets(insets);     
    if (!insets.isConsumed()) {         
        final int count = getChildCount();        
        for (int i = 0; i < count; i++) {
            insets = getChildAt(i).dispatchApplyWindowInsets(insets);             
            if (insets.isConsumed()) {          
                break;
            }
        }
    }
    return insets;
}

We write our own ViewGroup

class WindowInsetFrameLayout @JvmOverloads constructor(
    context: Context,      
    attrs: AttributeSet? = null,     
    defStyleRes: Int = 0
) : FrameLayout(context, attrs, defStyleRes) {

    override fun dispatchApplyWindowInsets(insets: WindowInsets): WindowInsets { 
        for (child in (0 until childCount)) {
            getChildAt(child).dispatchApplyWindowInsets(insets)
        }
        return insets.consumeSystemWindowInsets()
    }
}

Android 10

Insets What do you need to know about them?

Insets were created to scare developers.

System window insets

Tappable element insets

System gesture insets

Mandatory system gesture insets

Stable insets

Bangs and necklines

• LAYOUT_IN_DISPLAY_CUTOUT_MODE_DEFAULT. In portrait - there is, and in landscape - a black bar by default.
• LAYOUT_IN_DISPLAY_CUTOUT_MODE_NEVER. Not at all - a black stripe.
• LAYOUT_IN_DISPLAY_CUTOUT_MODE_SHORT_EDGES - always is.

insets.displayCutout
    .boundingRects
    .forEach { rect -> ... }

How it works

Spread insets

Handling insets

We handle Insets through delegation or inheritance.

Why return something?

Practice

Turn on transparency

<style name="AppTheme" parent="Theme.MaterialComponents.Light">
    <item name="android:windowTranslucentStatus">true</item>
    <item name="android:windowTranslucentNavigation">true</item>
</style>

Turn on transparency with color

rootView.systemUiVisibility = View.SYSTEM_UI_FLAG_LAYOUT_STABLE or  
    View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION

<style name="AppTheme" parent="Theme.MaterialComponents.Light">
    <!-- Set the navigation bar to 50% translucent white -->
    <item name="android:navigationBarColor">#80FFFFFF</item> 
</style>

What could be easier than handling insets?

ViewCompat
    .setOnApplyWindowInsetsListener(bottomNav) { view, insets ->  
        view.updatePadding(bottom = insets.systemWindowInsetBottom) 
        insets
    }

val bottomNavBottomPadding = bottomNav.paddingBottom
ViewCompat
    .setOnApplyWindowInsetsListener(bottomNav) { view, insets ->                 
        view.updatePadding(
        bottom = bottomNavBottomPadding + insets.systemWindowInsetBottom
    )
    Insets
}

Add Kotlin!

fun View.doOnApplyWindowInsets(block: (View, WindowInsetsCompat, Rect) -> WindowInsetsCompat) {    

    val initialPadding = recordInitialPaddingForView(this)

    ViewCompat.setOnApplyWindowInsetsListener(this) { v, insets ->        
        block(v, insets, initialPadding)
    }
    
    requestApplyInsetsWhenAttached()
}

private fun recordInitialPaddingForView(view: View) =
   Rect(view.paddingLeft, view.paddingTop, view.paddingRight, view.paddingBottom)

  .

bottomNav.doOnApplyWindowInsets { view, insets, padding ->   
    view.updatePadding(
        bottom = padding.bottom + insets.systemWindowInsetBottom
    ) 
    insets
}

Something forgotten!

fun View.doOnApplyWindowInsets(block: (View, WindowInsetsCompat, Rect) -> WindowInsetsCompat) {

    val initialPadding = recordInitialPaddingForView(this)
     
    ViewCompat.setOnApplyWindowInsetsListener(this) { v, insets ->        
        block(v, insets, initialPadding)
    }
      
    requestApplyInsetsWhenAttached() 
}

private fun recordInitialPaddingForView(view: View) =
      Rect(view.paddingLeft, view.paddingTop, view.paddingRight, view.paddingBottom)

fun View.requestApplyInsetsWhenAttached() {    
    if (isAttachedToWindow) {        
        requestApplyInsets()
    } else {
        addOnAttachStateChangeListener(object : View.OnAttachStateChangeListener {            
            override fun onViewAttachedToWindow(v: View) {
                v.removeOnAttachStateChangeListener(this)
                v.requestApplyInsets()           
            }

            override fun onViewDetachedFromWindow(v: View) = Unit
        })
    }
}

Refining RecyclerView

<androidx.recyclerview.widget.RecyclerView 
        android:id="@+id/recyclerView"        
    android:layout_width="match_parent"    
    android:layout_height="match_parent"             
    android:clipToPadding="false" />

recyclerView.doOnApplyWindowInsets { view, insets, padding ->    
    view.updatePadding(
        bottom = padding.bottom + insets.systemWindowInsetBottom
    )
}

Application bug

doOnApplyWindowInsets { view, insets, initialPadding ->    
    view.updatePadding(
        bottom = initialPadding.bottom + insets.systemWindowInsetBottom
    )
    insets.replaceSystemWindowInsets(
        Rect(
            insets.systemWindowInsetLeft,            
            insets.systemWindowInsetTop,            
            insets.systemWindowInsetRight,
            0
        )
    )
}

Redefine All

@Override
public WindowInsets dispatchApplyWindowInsets(WindowInsets insets) {     
    insets = super.dispatchApplyWindowInsets(insets);     
    if (!insets.isConsumed()) {        
        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            insets = getChildAt(i).dispatchApplyWindowInsets(insets);
            if (insets.isConsumed()) {
                break;
            }
        }
    }
    return insets;
}

fun View.addSystemBottomPadding(    
    targetView: View = this
) {
    doOnApplyWindowInsets { _, insets, initialPadding ->           
        targetView.updatePadding(
            bottom = initialPadding.bottom + insets.systemWindowInsetBottom
        )
        insets.replaceSystemWindowInsets(
            Rect(
                insets.systemWindowInsetLeft,
                insets.systemWindowInsetTop,     
                insets.systemWindowInsetRight,
                0
            )
        )
    }
}

• First he will give insets Bottom Navigation Bar. 
• That will process insets, will return zero bottom.
• Further, by default, they will go from top to bottom: Toolbar, fragment with RecyclerView.
• Then, perhaps, he will again send insets Bottom Navigation Bar. But this is no longer important, everything will work so well.

Important

Android 10 Preparation Checklist

• @rmr_spb in a telegram - records of internal mitaps of Redmadrobot SPb.
• All source code in this article and even more in GitFox . There is a separate Android 10 branch, where you can see by commit how I got to all this and how I supported the new Android.
• Chris Bane's Insetter Library . It contains 5-6 extensions that I showed. To use in your project, contact the library, most likely it will move to Android Jetpack. I developed them in my project and, it seems to me, they got better.
• Chris Bane's article .
• FunCorn, , .
• «Why would I want to fitsSystemWindows?» .

AppConf, youtube- . , - . AppsConf , . , , stay tuned!