Develop Reference

Android ViewPager2 not dynamically wrapping height of different sized fragments

I have a ViewPager2 that has different height fragments as children, the height of the children change after data is loaded
<com.google.android.material.appbar.CollapsingToolbarLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
app:expandedTitleGravity="top"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<com.google.android.material.tabs.TabLayout
android:id="#+id/tabs_header"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/prospect_detail_tab_prospect" />
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/prospect_detail_tab_influencers" />
<com.google.android.material.tabs.TabItem
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:text="#string/prospect_detail_tab_sales" />
</com.google.android.material.tabs.TabLayout>
<androidx.viewpager2.widget.ViewPager2
android:id="#+id/pager_header"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</com.google.android.material.appbar.CollapsingToolbarLayout>
I've tried a few different solutions but nothing has worked for resizing the viewpager2 if it goes back to a smaller fragment, it just stays the same height as the tallest fragment

What happen is the ViewPager2 doesn't refresh its own height when your fragment's height changes (if you are using a RecyclerView inside for instance).
In order to solve this, we need to calculate the height when the user select the tab. This can be done using registerOnPageChangeCallback and onPageSelected
registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
override fun onPageSelected(position: Int) {
super.onPageSelected(position)
// Here we need to calculate height
}
})
Now, we need to calculate the height of the fragment. To do so, we need to access the fragment and its root view. This can be done using the fragmentManager provided to your ViewPagerAdapter, when creating it, e.g. here we are using childFragmentManager:
PagerViewAdapter(childFragmentManager, lifecycle)
registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
override fun onPageSelected(position: Int) {
super.onPageSelected(position)
// Because the fragment might or might not be created yet,
// we need to check for the size of the fragmentManager
// before accessing it.
if (childFragmentManager.fragments.size > position) {
val fragment = childFragmentManager.fragments.get(position)
fragment.view?.let {
// Now we've got access to the fragment Root View
// we will use it to calculate the height and
// apply it to the ViewPager2
updatePagerHeightForChild(it, binding.viewPager)
}
}
}
})
// This function can sit in an Helper file, so it can be shared across your project.
fun updatePagerHeightForChild(view: View, pager: ViewPager2) {
view.post {
val wMeasureSpec =
View.MeasureSpec.makeMeasureSpec(view.width, View.MeasureSpec.EXACTLY)
val hMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
view.measure(wMeasureSpec, hMeasureSpec)
if (pager.layoutParams.height != view.measuredHeight) {
pager.layoutParams = (pager.layoutParams)
.also { lp ->
// applying Fragment Root View Height to
// the pager LayoutParams, so they match
lp.height = view.measuredHeight
}
}
}
}
Notice: We are accessing the viewPager using binding, if you do not use binding, provide the viewPager your own way, maybe with findViewById()
Limitation: Async Loading Content
if you've got some dynamic loading content, you might need to couple with solution with ViewTreeObserver.OnGlobalLayoutListener, I haven't tested that yet.
Reference: https://issuetracker.google.com/u/0/issues/143095219

You need to custom ViewPager a little bit:
public class WrapHeightViewPager extends ViewPager {
private int currentPosition = 0;
public WrapHeightViewPager(#NonNull Context context) {
super(context);
}
public WrapHeightViewPager(#NonNull Context context, #Nullable AttributeSet attrs) {
super(context, attrs);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
if (currentPosition < getChildCount()) {
View child = getChildAt(currentPosition);
child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
int height = child.getMeasuredHeight();
if (height != 0) {
heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
}
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
public void measureViewPager(int currentPosition) {
this.currentPosition = currentPosition;
requestLayout();
}
}
After that, when init tabLayout, just call measureViewPager(currentPosition) in onTabSelected function
tabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
#Override
public void onTabSelected(TabLayout.Tab tab) {
viewPager.measureViewPager(tab.getPosition());
}
#Override
public void onTabUnselected(TabLayout.Tab tab) {
}
#Override
public void onTabReselected(TabLayout.Tab tab) {
}
});

How to add sticky header to parallax ScrollView?

I've created ParallaxScrollView based on this answer and parallax effect works great with the ImageView.
public class ParallaxScrollView extends ScrollView {
private Activity activity;
private View imgContainer;
private ImageView imageView;
private float parallaxValue;
public ParallaxScrollView(final Context context) {
this(context, null);
}
public ParallaxScrollView(final Context context, final AttributeSet attrs) {
this(context, attrs, 0);
}
public ParallaxScrollView(final Context context, final AttributeSet attrs, final int defStyle) {
super(context, attrs, defStyle);
}
public void setParallaxParams(final Activity activity, final View imgContainer, final ImageView imageView, final float parallaxValue) {
this.activity = activity;
this.imgContainer = imgContainer;
this.imageView = imageView;
this.parallaxValue = parallaxValue;
}
#Override
protected void onScrollChanged(final int l, final int t, final int oldl, final int oldt) {
super.onScrollChanged(l, t, oldl, oldt);
if (activity == null || imgContainer == null || imageView == null) {
throw new IllegalStateException("Please set parallax parameters via setParallaxParams() method!");
}
if (imageView.getTop() == 0) {
imageView.setTranslationY(getScrollY() * parallaxValue);
return;
}
// Get scroll view screen bound
final Rect scrollBounds = new Rect();
getHitRect(scrollBounds);
// Check if image container is visible in the screen
// so to apply the translation only when the container is visible to the user
if (imgContainer.getLocalVisibleRect(scrollBounds)) {
final Display display = activity.getWindowManager().getDefaultDisplay();
final DisplayMetrics outMetrics = new DisplayMetrics ();
display.getMetrics(outMetrics);
// Get screen density
final float density = getResources().getDisplayMetrics().density;
// Get screen height in pixels
final float dpHeight = outMetrics.heightPixels / density;
final float screenHeightPixels = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dpHeight, getResources().getDisplayMetrics());
final float halfScreenHeight = screenHeightPixels / 2;
// Get image container height in pixels
final float containerHeightPixels = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, imgContainer.getHeight(), getResources().getDisplayMetrics());
// Get the location that consider a vertical center for the image (where the translation should be zero)
final float center = halfScreenHeight - (containerHeightPixels / 2);
// get the location (x,y) of the image container in pixels
final int[] locScreen = {0,0};
imgContainer.getLocationOnScreen(locScreen);
// trying to transform the current image container location into percentage
// so when the image container is exaclty in the middle of the screen percentage should be zero
// and as the image container getting closer to the edges of the screen should increase to 100%
final float finalLoc = ((locScreen[1]-center) * 100)/ halfScreenHeight;
// translate the inner image taking consideration also the density of the screen
imageView.setTranslationY(-finalLoc * parallaxValue * density);
}
}
}
And here is how I use it:
parallaxScrollView.setParallaxParams(getActivity(), imageContainer, image, 0.5f);
Now, I would like to add a sticky header to the Toolbar, so when the user would scroll down and the header will be on top of the screen below Toolbar it will "stick" to the Toolbar and when the user scrolls up and the content below header reaches it's top it should "unstick". Hard to explain, but I hope it is clear :)
Here is how the layout looks like:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">
<ParallaxScrollView
android:id="#+id/scroll_view"
android:fillViewport="true"
android:overScrollMode="never"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<FrameLayout
android:id="#+id/image_container"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<ImageView
android:id="#+id/image"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:adjustViewBounds="true"
android:scaleType="centerCrop" />
</FrameLayout>
<FrameLayout
android:id="#+id/sticky_header"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<!-- Content -->
</FrameLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:paddingTop="#dimen/padding_big"
android:paddingBottom="#dimen/padding_big"
android:paddingEnd="#dimen/padding_big"
android:paddingStart="#dimen/padding_big"
android:paddingLeft="#dimen/padding_big"
android:paddingRight="#dimen/padding_big">
<!-- Content -->
So, here basically I want to "stick" FrameLayout with id #+id/stickyHeader to the top when user scrolls.
Very similar approach AirBnb uses in their Android application (take a look at sticky tab bar at this link).
Any ideas how to do that?
Ideally, without using third-party libraries.

windowSoftInputMode="adjustResize" not working with translucent action/navbar

I have problems with the translucent actionbar/navbar in the new Android KitKat (4.4) and the windowSoftInputMode="adjustResize".
Normaly, changing the InputMode to adjustResize, the app should resize itself when keyboard is shown, but here it won't! If I delete the lines for the transparent effect, the resize is working.
So if the keyboard is visible, my ListView is under it and I can't access the last few items (only by hiding the keyboard manually).
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="XYZ"
android:versionCode="23"
android:versionName="0.1" >
<uses-sdk
android:minSdkVersion="9"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/Theme.XYZStyle" >
<activity
android:name="XYZ"
android:label="#string/app_name"
android:windowSoftInputMode="adjustResize" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
values-v19/styles.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<style name="Theme.XYZStyle" parent="#style/Theme.AppCompat.Light">
<item name="android:windowTranslucentStatus">true</item>
<item name="android:windowTranslucentNavigation">true</item>
</style>
</resources>
fragment.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<ListView
android:id="#+id/listView_contacts"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:clipToPadding="false"
android:divider="#null"
android:dividerHeight="0dp"
android:drawSelectorOnTop="true"
android:fastScrollAlwaysVisible="true"
android:fastScrollEnabled="true"
android:paddingBottom="#dimen/navigationbar__height" >
</ListView>
</RelativeLayout>
Any ideas for fixing this?

You are missing the following property:
android:fitsSystemWindows="true"
in the root RelativeLayout of the fragment .xml layout.
Update:
Last year there was an interesting talk by Chris Bane that explains in good detail how this works:
https://www.youtube.com/watch?v=_mGDMVRO3iE

There's a related bug report here. I've found a workaround that, from limited testing, seems to do the trick with no repercussions. Add a custom implementation of your root ViewGroup (I almost always am using FrameLayout, so this is what I've tested with) with the logic below. Then, use this custom layout in place of your root layout, and ensure you set android:fitsSystemWindows="true". You can then just call getInsets() any time after layout (e.g. add an OnPreDrawListener) to adjust the rest of your layout to account for the system insets, if desired.
import android.content.Context;
import android.graphics.Rect;
import android.os.Build;
import android.util.AttributeSet;
import android.widget.FrameLayout;
import org.jetbrains.annotations.NotNull;
/**
* #author Kevin
* Date Created: 3/7/14
*
* https://code.google.com/p/android/issues/detail?id=63777
*
* When using a translucent status bar on API 19+, the window will not
* resize to make room for input methods (i.e.
* {#link android.view.WindowManager.LayoutParams#SOFT_INPUT_ADJUST_RESIZE} and
* {#link android.view.WindowManager.LayoutParams#SOFT_INPUT_ADJUST_PAN} are
* ignored).
*
* To work around this; override {#link #fitSystemWindows(android.graphics.Rect)},
* capture and override the system insets, and then call through to FrameLayout's
* implementation.
*
* For reasons yet unknown, modifying the bottom inset causes this workaround to
* fail. Modifying the top, left, and right insets works as expected.
*/
public final class CustomInsetsFrameLayout extends FrameLayout {
private int[] mInsets = new int[4];
public CustomInsetsFrameLayout(Context context) {
super(context);
}
public CustomInsetsFrameLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomInsetsFrameLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public final int[] getInsets() {
return mInsets;
}
#Override
protected final boolean fitSystemWindows(#NotNull Rect insets) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
// Intentionally do not modify the bottom inset. For some reason,
// if the bottom inset is modified, window resizing stops working.
// TODO: Figure out why.
mInsets[0] = insets.left;
mInsets[1] = insets.top;
mInsets[2] = insets.right;
insets.left = 0;
insets.top = 0;
insets.right = 0;
}
return super.fitSystemWindows(insets);
}
}
Since fitSystemWindows was deprecated, please refer to the answer below to complete the workaround.

#kcoppock answer is really helpful, but fitSystemWindows was deprecated in API level 20
So since API 20 (KITKAT_WATCH) you should override onApplyWindowInsets
#Override
public final WindowInsets onApplyWindowInsets(WindowInsets insets) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT_WATCH) {
return super.onApplyWindowInsets(insets.replaceSystemWindowInsets(0, 0, 0,
insets.getSystemWindowInsetBottom()));
} else {
return insets;
}
}

If you want to customize the insets and you are targeting API level >=21 you can accomplish this without having to create a custom view group. By just setting fitsSystemWindows padding will be applied to your container view by default, which you may not want.
The version checks are built into this method and only devices >= 21 will execute the code inside the lambda. Kotlin example:
ViewCompat.setOnApplyWindowInsetsListener(container) { view, insets ->
insets.replaceSystemWindowInsets(0, 0, 0, insets.systemWindowInsetBottom).apply {
ViewCompat.onApplyWindowInsets(view, this)
}
}
Make sure your layout still sets the fitsSystemWindows flag otherwise the window insets listener will not be called.
<FrameLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
/>
These sources are helpful:
https://medium.com/google-developers/why-would-i-want-to-fitssystemwindows-4e26d9ce1eec
https://medium.com/#azizbekian/windowinsets-24e241d4afb9

This worked for me to have translucent status bar and adjustResize in fragment:
Make a custom RelativeLayout as #Victor91 and #kcoppock said.
Use CustomRelativeLayout as parent layout for your fragment.
Declare theme with android:windowTranslucentStatus = true
The container Activity must be declared in Manifest with
android:windowSoftInputMode="adjustResize" and use the declared
theme
Please Use fitsSystemWindows on fragment root layout!
public class CustomRelativeLayout extends RelativeLayout {
private int[] mInsets = new int[4];
public CustomRelativeLayout(Context context) {
super(context);
}
public CustomRelativeLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public CustomRelativeLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
#Override
public final WindowInsets onApplyWindowInsets(WindowInsets insets) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT_WATCH) {
mInsets[0] = insets.getSystemWindowInsetLeft();
mInsets[1] = insets.getSystemWindowInsetTop();
mInsets[2] = insets.getSystemWindowInsetRight();
return super.onApplyWindowInsets(insets.replaceSystemWindowInsets(0, 0, 0,
insets.getSystemWindowInsetBottom()));
} else {
return insets;
}
}
}
Then in xml,
<com.blah.blah.CustomRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
</com.blah.blah.CustomRelativeLayout>

A small update on the helpful #Victor Rendina's answer caused by the replaceSystemWindowInsets and systemWindowInsetBottom methods deprecation.
Prerequisites:
API >= 21
implementation 'androidx.core:core-ktx:1.5.0-alpha02' at least
Kotlin extension:
fun View?.fitSystemWindowsAndAdjustResize() = this?.let { view ->
ViewCompat.setOnApplyWindowInsetsListener(view) { v, insets ->
view.fitsSystemWindows = true
val bottom = insets.getInsets(WindowInsetsCompat.Type.ime()).bottom
WindowInsetsCompat
.Builder()
.setInsets(
WindowInsetsCompat.Type.systemBars(),
Insets.of(0, 0, 0, bottom)
)
.build()
.apply {
ViewCompat.onApplyWindowInsets(v, this)
}
}
}
Usage:
rootView.fitSystemWindowsAndAdjustResize()
where rootView is literally the root view of the layout :)
Note: if the extension does not work for your root view (I ran into this when having ConstraintLayout as the rootView) wrap the entire layout with a FrameLayout so that the FrameLayout becomes the new root view.

I had the same problem,
My Activity had a ScrollView as root view and with translucent statusbar activated it didn't resize correctly when keyboard showed... and conseguently the screen didn't scrolled hiding the input views.
Solution:
Moved everything (layout and activity logic) inside a new Fragment.
Then changed the Activity to only include this Fragment. Now everything works as expected!
This is the layout of the activity:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/contentView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true" />

Add this first at your root layout.
android:fitsSystemWindows="true"
When you use this approach, it becomes your responsibility to ensure that critical parts of your app's UI (for example, the built-in controls in a Maps application) don't end up getting covered by system bars. This could make your app unusable. In most cases you can handle this by adding the android:fitsSystemWindows attribute to your XML layout file, set to true. This adjusts the padding of the parent ViewGroup to leave space for the system windows. This is sufficient for most applications.
In some cases, however, you may need to modify the default padding to get the desired layout for your app. To directly manipulate how your content lays out relative to the system bars (which occupy a space known as the window's "content insets"), override fitSystemWindows(Rect insets). The fitSystemWindows() method is called by the view hierarchy when the content insets for a window have changed, to allow the window to adjust its content accordingly. By overriding this method you can handle the insets (and hence your app's layout) however you want.
https://developer.android.com/training/system-ui/status#behind
If you want to become a master window fitter, please watch the video from the android developer.
https://www.youtube.com/watch?v=_mGDMVRO3iE

Based on Joseph Johnson's workaround in Android How to adjust layout in Full Screen Mode when softkeyboard is visible
call this in onCreate() after setContentView() in your activity.
AndroidBug5497Workaround.assistActivity(this);
a litte different from original replace return (r.bottom - r.top); with return r.bottom; in computeUsableHeight()
for some reason, i must set my activity fitsSystemWindows attribute to false.
this workaround saved me. it's works well for me. hope can help you.
the implementation class is:
public class AndroidBug5497Workaround {
// For more information, see https://code.google.com/p/android/issues/detail?id=5497
// To use this class, simply invoke assistActivity() on an Activity that already has its content view set.
public static void assistActivity (Activity activity) {
new AndroidBug5497Workaround(activity);
}
private View mChildOfContent;
private int usableHeightPrevious;
private FrameLayout.LayoutParams frameLayoutParams;
private AndroidBug5497Workaround(Activity activity) {
FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
mChildOfContent = content.getChildAt(0);
mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
public void onGlobalLayout() {
possiblyResizeChildOfContent();
}
});
frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
}
private void possiblyResizeChildOfContent() {
int usableHeightNow = computeUsableHeight();
if (usableHeightNow != usableHeightPrevious) {
int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
int heightDifference = usableHeightSansKeyboard - usableHeightNow;
if (heightDifference > (usableHeightSansKeyboard/4)) {
// keyboard probably just became visible
frameLayoutParams.height = usableHeightSansKeyboard - heightDifference;
} else {
// keyboard probably just became hidden
frameLayoutParams.height = usableHeightSansKeyboard;
}
mChildOfContent.requestLayout();
usableHeightPrevious = usableHeightNow;
}
}
private int computeUsableHeight() {
Rect r = new Rect();
mChildOfContent.getWindowVisibleDisplayFrame(r);
return r.bottom;
}
}

It shouldn't work with the translucent status bar; that setting forces the window into fullscreen mode which does not work with adjustResize.
You can either use adjustPan or use the fitsSystemWindows properties. I would suggest reading about the feature though, it has significant side effects:
https://medium.com/google-developers/why-would-i-want-to-fitssystemwindows-4e26d9ce1eec

I had like a problem.
I set windowDrawsSystemBarBackgrounds to 'true' and my app should show under status bar.
It's my activity theme.
<item name="android:windowTranslucentStatus" tools:targetApi="KITKAT">false</item>
<item name="android:windowDrawsSystemBarBackgrounds">true</item>
<item name="android:windowTranslucentNavigation">true</item>
<item name="android:statusBarColor">#android:color/transparent</item>
and I got help from jianshu's blog.
you can read code but text like me.
I add few code more.
public final class ZeroInsetsFrameLayout extends FrameLayout {
private int[] mInsets = new int[4];
public ZeroInsetsFrameLayout(Context context) {
super(context);
}
public ZeroInsetsFrameLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public ZeroInsetsFrameLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public final int[] getInsets() {
return mInsets;
}
#Override
public WindowInsets computeSystemWindowInsets(WindowInsets in, Rect outLocalInsets) {
outLocalInsets.left = 0;
outLocalInsets.top = 0;
outLocalInsets.right = 0;
return super.computeSystemWindowInsets(in, outLocalInsets);
}
#Override
protected final boolean fitSystemWindows(#NonNull Rect insets) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
// Intentionally do not modify the bottom inset. For some reason,
// if the bottom inset is modified, window resizing stops working.
// TODO: Figure out why.
mInsets[0] = insets.left;
mInsets[1] = insets.top;
mInsets[2] = insets.right;
insets.left = 0;
insets.top = 0;
insets.right = 0;
}
return super.fitSystemWindows(insets);
}
}
This is my fragment layout.
<com.dhna.widget.ZeroInsetsFrameLayout 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"
android:background="#color/white">
<!-- your xml code -->
</ZeroInsetsFrameLayout>
I want it to be helpful to you.
good luck!

AndroidBug5497Workaround.java take care memory leak. need below code
getViewTreeObserver().removeOnGlobalLayoutListener(listener);
My sample using RxJava that automatically call removeOnGlobalLayoutListener() when onPause() in Activity's lifecycle
public class MyActivity extends RxAppCompatActivity {
// ...
protected void onStart(){
super.onStart();
TRSoftKeyboardVisibility
.changes(this) // activity
.compose(this.<TRSoftKeyboardVisibility.ChangeEvent>bindUntilEvent(ActivityEvent.PAUSE))
.subscribe(keyboardEvent -> {
FrameLayout content = (FrameLayout) findViewById(android.R.id.content);
View firstChildView = content.getChildAt(0);
firstChildView.getLayoutParams().height = keyboardEvent.viewHeight();
firstChildView.requestLayout();
// keyboardEvent.isVisible = keyboard visible or not
// keyboardEvent.keyboardHeight = keyboard height
// keyboardEvent.viewHeight = fullWindowHeight - keyboardHeight
});
//...
}
package commonlib.rxjava.keyboard;
import android.app.Activity;
import android.view.View;
import android.widget.FrameLayout;
import kr.ohlab.android.util.Assert;
import rx.Observable;
public class TRSoftKeyboardVisibility {
public static Observable<ChangeEvent> changes(Activity activity) {
Assert.notNull(activity, "activity == null");
FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
View childOfContent = content.getChildAt(0);
return Observable.create(
new TRSoftKeyboardVisibilityEventOnSubscribe(childOfContent));
}
public static final class ChangeEvent {
private final int keyboardHeight;
private final boolean visible;
private final int viewHeight;
public static ChangeEvent create(boolean visible, int keyboardHeight,
int windowDisplayHeight) {
return new ChangeEvent(visible, keyboardHeight, windowDisplayHeight);
}
private ChangeEvent(boolean visible, int keyboardHeight, int viewHeight) {
this.keyboardHeight = keyboardHeight;
this.visible = visible;
this.viewHeight = viewHeight;
}
public int keyboardHeight() {
return keyboardHeight;
}
public boolean isVisible() {
return this.visible;
}
public int viewHeight() {
return viewHeight;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof ChangeEvent)) return false;
ChangeEvent that = (ChangeEvent) o;
if (keyboardHeight != that.keyboardHeight) return false;
if (visible != that.visible) return false;
return viewHeight == that.viewHeight;
}
#Override
public int hashCode() {
int result = keyboardHeight;
result = 31 * result + (visible ? 1 : 0);
result = 31 * result + viewHeight;
return result;
}
#Override
public String toString() {
return "ChangeEvent{" +
"keyboardHeight=" + keyboardHeight +
", visible=" + visible +
", viewHeight=" + viewHeight +
'}';
}
}
}
package commonlib.rxjava.keyboard;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewTreeObserver;
import kr.ohlab.android.util.Assert;
import rx.Observable;
import rx.Subscriber;
import rx.android.MainThreadSubscription;
import timber.log.Timber;
public class TRSoftKeyboardVisibilityEventOnSubscribe
implements Observable.OnSubscribe<TRSoftKeyboardVisibility.ChangeEvent> {
private final View mTopView;
private int mLastVisibleDecorViewHeight;
private final Rect mWindowVisibleDisplayFrame = new Rect();
public TRSoftKeyboardVisibilityEventOnSubscribe(View topView) {
mTopView = topView;
}
private int computeWindowFrameHeight() {
mTopView.getWindowVisibleDisplayFrame(mWindowVisibleDisplayFrame);
return (mWindowVisibleDisplayFrame.bottom - mWindowVisibleDisplayFrame.top);
}
private TRSoftKeyboardVisibility.ChangeEvent checkKeyboardVisibility() {
int windowFrameHeightNow = computeWindowFrameHeight();
TRSoftKeyboardVisibility.ChangeEvent event = null;
if (windowFrameHeightNow != mLastVisibleDecorViewHeight) {
int mTopViewHeight = mTopView.getHeight();
int heightDiff = mTopViewHeight - windowFrameHeightNow;
Timber.e("XXX heightDiff=" + heightDiff);
if (heightDiff > (mTopViewHeight / 4)) {
event = TRSoftKeyboardVisibility.ChangeEvent.create(true, heightDiff, windowFrameHeightNow);
} else {
event = TRSoftKeyboardVisibility.ChangeEvent.create(false, 0, windowFrameHeightNow);
}
mLastVisibleDecorViewHeight = windowFrameHeightNow;
return event;
}
return null;
}
public void call(final Subscriber<? super TRSoftKeyboardVisibility.ChangeEvent> subscriber) {
Assert.checkUiThread();
final ViewTreeObserver.OnGlobalLayoutListener listener =
new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
TRSoftKeyboardVisibility.ChangeEvent event = checkKeyboardVisibility();
if( event == null)
return;
if (!subscriber.isUnsubscribed()) {
subscriber.onNext(event);
}
}
};
mTopView.getViewTreeObserver().addOnGlobalLayoutListener(listener);
subscriber.add(new MainThreadSubscription() {
#Override
protected void onUnsubscribe() {
mTopView.getViewTreeObserver().removeOnGlobalLayoutListener(listener);
}
});
}
}

After I had researched on all forum. thoese ways can not help find point out. Lucky when i tried doing this way. It helps me resolved problem
XML
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<!-- Your xml -->
</RelativeLayout>
Activity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView("Your Activity");
setAdjustScreen();
}
Created Func
protected void setAdjustScreen(){
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE);
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);
/*android:windowSoftInputMode="adjustPan|adjustResize"*/
}
Finally adding some lines to your mainifest
<activity
android:name="Your Activity"
android:windowSoftInputMode="adjustPan|adjustResize"
android:screenOrientation="portrait"></activity>

I had the same problem. I have solved using coordinatorlayout
activity.main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout
android:layout_height="match_parent" android:layout_width="match_parent"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:android="http://schemas.android.com/apk/res/android">
<android.support.design.widget.AppBarLayout
android:layout_height="wrap_content"
android:layout_width="match_parent"
android:theme="#style/AppTheme.AppBarOverlay">
<android.support.v7.widget.Toolbar
android:layout_height="?attr/actionBarSize"
android:layout_width="match_parent"
app:popupTheme="#style/AppTheme.PopupOverlay"
android:background="?attr/colorPrimary"
android:id="#+id/toolbar"/>
</android.support.design.widget.AppBarLayout>
<include layout="#layout/content_main2"/>
</android.support.design.widget.CoordinatorLayout>
content_main2.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<android.support.v7.widget.RecyclerView
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_marginTop="30dp"
android:layout_marginBottom="30dp"
app:layout_scrollFlags="scroll|exitUntilCollapsed"
android:id="#+id/post_msg_recyclerview">
</android.support.v7.widget.RecyclerView>
<EditText
android:layout_width="match_parent"
android:layout_height="50dp"
app:layout_constraintBottom_toBottomOf="parent"
android:background="#color/colorPrimary"
/>
</android.support.constraint.ConstraintLayout>
MainActivity.java
now add this line linearLayoutManager.setStackFromEnd(true);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setStackFromEnd(true);
recyclerView.setLayoutManager(linearLayoutManager);
Adapter adapter1=new Adapter(arrayList);
recyclerView.setAdapter(adapter1);

<androidx.constraintlayout.widget.ConstraintLayout
android:fitsSystemWindows="true">
<androidx.coordinatorlayout.widget.CoordinatorLayout>
<com.google.android.material.appbar.AppBarLayout>
<com.google.android.material.appbar.CollapsingToolbarLayout/>
</com.google.android.material.appbar.AppBarLayout>
<androidx.core.widget.NestedScrollView>
<Editext/>
<androidx.core.widget.NestedScrollView/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
</androidx.constraintlayout.widget.ConstraintLayout>

here is what i use
in the main view in the xml file you will add this
android:animateLayoutChanges="true"
then in the "onCreate" function you will before every thing get the status bar size like this
int resourceId = getResources().getIdentifier("status_bar_height", "dimen", "android");
if (resourceId > 0)
{
status_bar=getResources().getDimensionPixelSize(resourceId);
}
then finally in "onCreate" you will add this to update the size
main_view= findViewById(R.id.the_main);
main_view.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener()
{
#Override
public void onGlobalLayout()
{
Rect r = new Rect();
View view = getWindow().getDecorView();
view.getWindowVisibleDisplayFrame(r);
if (Math.abs(old_size - r.height()) > 100)
{
ViewGroup.LayoutParams params = main_view.getLayoutParams();
params.height = r.height()+ status_bar ;
main_view.setLayoutParams(params);
}
old_size = r.height();
}
});

I don't why but option adjustResize doesn't work with fullscreen. I've just added titleBar and works ( android:theme="#style/AppTheme"). Insted that I use in code " getSupportActionBar().hide();"
<activity
android:name=".ChatActivity"
android:launchMode="singleInstance"
android:screenOrientation="portrait"
android:windowSoftInputMode="adjustResize"
android:theme="#style/AppTheme"
/>

The best practice allows user scroll content when the keyboard is shown.
So to add this functionality you need put your root layout inside the ScrollView and use windowSoftInputMode="adjustResize" activity method.
But if you want to use this functionality with <item name="android:windowTranslucentStatus">true</item>
flag on Android 5 content won't be scrollable and will overlaps with keyboard.
To solve this issue check this answer

Align the child views in center of the ViewPager android

I need to set the child view as center of the ViewPager and also I would like to show some part of the next and previous views to the current view sides(like current screen below 1). But currently the current view is starting at left side of the ViewPager(like expected screen below 2). How can I achieve that?
Here is my code..
MyViewPagerAdapter
public class MyViewPagerAdapter extends PagerAdapter {
private Activity mActivity;
private int mPageCount;
public MyViewPagerAdapter(Activity activity,int pageCount) {
mActivity = activity;
mPageCount = pageCount;
}
#Override
public int getCount() {
return mPageCount;
}
#Override
public boolean isViewFromObject(View view, Object obj) {
return (view ==(View)obj);
}
#Override
public Object instantiateItem(ViewGroup container,final int position) {
ViewGroup viewGroup = (ViewGroup)mActivity.getLayoutInflater().inflate(
R.layout.item_view, null);
viewGroup.setBackgroundColor(randomColor());
TextView textView = (TextView)viewGroup.findViewById(R.id.textView1);
textView.setText("Page: "+(position+1));
Button button = (Button) viewGroup.findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Toast.makeText(mActivity, "Hey, Its clicked!!! at page "+(position+1), Toast.LENGTH_LONG).show();
}
});
container.addView(viewGroup);
return viewGroup;
}
Random rnd = new Random();
private int randomColor(){
return Color.argb(255, rnd.nextInt(256), rnd.nextInt(256), rnd.nextInt(256));
}
#Override
public void destroyItem(ViewGroup collection, int position, Object view) {
//must be overridden else throws exception as not overridden.
Log.d("Tag", collection.getChildCount()+"");
collection.removeView((View) view);
}
#Override
public float getPageWidth(int position) {
return 0.8f;
}
}
MainActivity
public class MainActivity extends Activity {
private ViewPager viewPager;
LinearLayout linearLayout;
private int ID = 100;
private final int count = 8;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
viewPager = (ViewPager) findViewById(R.id.viewPager);
linearLayout = (LinearLayout) findViewById(R.id.indicator_layout);
generateIndicators(count);
MyViewPagerAdapter adapter = new MyViewPagerAdapter(this, count);
viewPager.setAdapter(adapter);
viewPager.setOnPageChangeListener(new OnPageChangeListener() {
int oldPosition = 0;
#Override
public void onPageSelected(int position) {
//this changes the old position's view state image
((TextView)linearLayout.getChildAt(oldPosition)).setText("");
oldPosition = position;
//this changes the current position's view state image
((TextView)linearLayout.getChildAt(position)).setText((position+1)+"");
}
//this method will be called repeatedly upto another item comes as front one(active one)
#Override
public void onPageScrolled(int arg0, float arg1, int arg2) {
}
//this will be called as per scroll state
#Override
public void onPageScrollStateChanged(int arg0) {
}
});
viewPager.setOffscreenPageLimit(4);
}
private void generateIndicators(int count) {
/// Converts 14 dip into its equivalent px
int padd = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 3, getResources().getDisplayMetrics());
for(int i=0;i<count;i++){
TextView textView = new TextView(this);
textView.setId(ID+i);
final int currentItem = i;
textView.setBackgroundResource(R.drawable.white_cell);
textView.setPadding(padd,padd,padd,padd);
/// Converts 14 dip into its equivalent px
int size = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 10, getResources().getDisplayMetrics());
textView.setTextSize(size);
textView.setGravity(Gravity.CENTER);
/// Converts 14 dip into its equivalent px
int px = (int)TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 30, getResources().getDisplayMetrics());
LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(px, px);
linearLayout.addView(textView,params);
}
((TextView)linearLayout.getChildAt(0)).setText("1");
}
}
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<android.support.v4.view.ViewPager
android:id="#+id/viewPager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" >
</android.support.v4.view.ViewPager>
<LinearLayout
android:id="#+id/indicator_layout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="19dp" >
</LinearLayout>
</RelativeLayout>
item_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="100dp"
android:layout_height="match_parent"
android:id="#+id/root_view"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:text="Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="click me" />
</LinearLayout>
Current screen
expected screen

For one app I implemented similar the following way, with standard ViewPager:
Make pages full-screen with the actual content in an inner layout. For example, make the full-screen layout a RelativeLayout with transparent background and the actual content another RelativeLayout centered in the parent. If I remember right, the reason for this was that with just the inner layout as a page, the ViewPager would not have taken all the screen width on some devices such as Galaxy Nexus.
Use ViewPager.setPageMargin() to set up a negative page margin i.e. how much of the next/previous page you want to show. Make sure it only overlaps the transparent region of the parent full-screen layout.
Call ViewPager.setOffscreenPageLimit() to adjust the off-screen page count to at least 2 from the default 1 to ensure smooth paging by really creating the pages off-screen. Otherwise you will see next/previous pages being drawn while already partially showing on screen.

For anyone upset that the OP didn't update his question with the solution here is a link that explains, with minimal effort, how to pull this off in XML: http://blog.neteril.org/blog/2013/10/14/android-tip-viewpager-with-protruding-children/
Basically when you declare your viewpager in XML, give it the same left and right padding and set android:clipToPadding="false". (The clipToPadding is missing in his xml sample and necessary to achieve this effect)

Finally, I have added my solution for this question in GitHub. I have done some pretty tricks to get the workaround solution. You can get the project from the below link(Actually I have planned to create a blog with the explanation , but I dint have that much time to do).
Here is the link(https://github.com/noundla/Sunny_Projects/tree/master/CenterLockViewPager)
You have to copy the files from com.noundla.centerviewpagersample.comps package to your project. And you can see the usage of that Viewpager in MainActivity class.
Please let me know if anyone has problems with this.

I found solution in this post, below the code i used:
// Offset between sibling pages in dp
int pageOffset = 20;
// Visible part of sibling pages at the edges in dp
int sidePageVisibleWidth = 10;
// Horizontal padding will be
int horPadding = pageOffset + sidePageVisibleWidth;
// Apply parameters
viewPager.setClipToPadding(false);
viewPager.setPageMargin(UIUtil.dpToPx(pageOffset, getContext()));
viewPager.setPadding(UIUtil.dpToPx(horPadding, getContext()), 0, UIUtil.dpToPx(horPadding, getContext()), 0);
dpToPx code:
public static int dpToPx(int dp, Context context) {
float density = context.getResources().getDisplayMetrics().density;
return Math.round((float) dp * density);
}
This is all you need

You can use padding for viewPager and set clipToPadding false
Java
viewPager.setClipToPadding(false);
viewPager.setPadding(50, 0, 50, 0);
Kotlin
viewPager.clipToPadding = false
viewPager.setPadding(50, 0, 50, 0)

I had to center current page in view pager with different page widths, so solution with paddings was not suitable. Also user scrolling was disabled (it was tab bar view pager, scrolled by another view pager). Here is a very simple solution to do that - just override ViewPager.ScrollTo method just like this (C# code, Xamarin):
public override void ScrollTo(int x, int y)
{
x -= (int) (MeasuredWidth * (1 - Adapter.GetPageWidth(CurrentItem)) / 2);
base.ScrollTo(x, y);
}
And if you calculate page width for each fragment don't forget to cache them in array.

Extend HorizontalScrollView class as the parent for the scrolling view. In the onMeasure() method you can specify the width and height of each child. Little cumbersome way but the effect will be good and you can have a good hold on your child view.

Replacement for the linearLayout weights mechanism

Background:
Google suggests to avoid using nested weighted linearLayouts because of performance.
using nested weighted linearLayout is awful to read, write and maintain.
there is still no good alternative for putting views that are % of the available size. Only solutions are weights and using OpenGL. There isn't even something like the "viewBox" shown on WPF/Silverlight to auto-scale things.
This is why I've decided to create my own layout which you tell for each of its children exactly what should be their weights (and surrounding weights) compared to its size.
It seems I've succeeded , but for some reason I think there are some bugs which I can't track down.
One of the bugs is that textView, even though I give a lot of space for it, it puts the text on the top instead of in the center. imageViews on the other hand work very well. Another bug is that if I use a layout (for example a frameLayout) inside my customized layout, views within it won't be shown (but the layout itself will).
Please help me figure out why it occurs.
How to use: instead of the next usage of linear layout (I use a long XML on purpose, to show how my solution can shorten things):
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:orientation="vertical">
<View android:layout_width="wrap_content" android:layout_height="0px"
android:layout_weight="1" />
<LinearLayout android:layout_width="match_parent"
android:layout_height="0px" android:layout_weight="1"
android:orientation="horizontal">
<View android:layout_width="0px" android:layout_height="wrap_content"
android:layout_weight="1" />
<TextView android:layout_width="0px" android:layout_weight="1"
android:layout_height="match_parent" android:text="#string/hello_world"
android:background="#ffff0000" android:gravity="center"
android:textSize="20dp" android:textColor="#ff000000" />
<View android:layout_width="0px" android:layout_height="wrap_content"
android:layout_weight="1" />
</LinearLayout>
<View android:layout_width="wrap_content" android:layout_height="0px"
android:layout_weight="1" />
</LinearLayout>
What I do is simply (the x is where to put the view itself in the weights list):
<com.example.weightedlayouttest.WeightedLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res/com.example.weightedlayouttest"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" tools:context=".MainActivity">
<TextView android:layout_width="0px" android:layout_height="0px"
app:horizontalWeights="1,1x,1" app:verticalWeights="1,1x,1"
android:text="#string/hello_world" android:background="#ffff0000"
android:gravity="center" android:textSize="20dp" android:textColor="#ff000000" />
</com.example.weightedlayouttest.WeightedLayout>
My code of the special layout is:
public class WeightedLayout extends ViewGroup
{
#Override
protected WeightedLayout.LayoutParams generateDefaultLayoutParams()
{
return new WeightedLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT);
}
#Override
public WeightedLayout.LayoutParams generateLayoutParams(final AttributeSet attrs)
{
return new WeightedLayout.LayoutParams(getContext(),attrs);
}
#Override
protected ViewGroup.LayoutParams generateLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
return new WeightedLayout.LayoutParams(p.width,p.height);
}
#Override
protected boolean checkLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
final boolean isCorrectInstance=p instanceof WeightedLayout.LayoutParams;
return isCorrectInstance;
}
public WeightedLayout(final Context context)
{
super(context);
}
public WeightedLayout(final Context context,final AttributeSet attrs)
{
super(context,attrs);
}
public WeightedLayout(final Context context,final AttributeSet attrs,final int defStyle)
{
super(context,attrs,defStyle);
}
#Override
protected void onLayout(final boolean changed,final int l,final int t,final int r,final int b)
{
for(int i=0;i<this.getChildCount();++i)
{
final View v=getChildAt(i);
final WeightedLayout.LayoutParams layoutParams=(WeightedLayout.LayoutParams)v.getLayoutParams();
//
final int availableWidth=r-l;
final int totalHorizontalWeights=layoutParams.getLeftHorizontalWeight()+layoutParams.getViewHorizontalWeight()+layoutParams.getRightHorizontalWeight();
final int left=l+layoutParams.getLeftHorizontalWeight()*availableWidth/totalHorizontalWeights;
final int right=r-layoutParams.getRightHorizontalWeight()*availableWidth/totalHorizontalWeights;
//
final int availableHeight=b-t;
final int totalVerticalWeights=layoutParams.getTopVerticalWeight()+layoutParams.getViewVerticalWeight()+layoutParams.getBottomVerticalWeight();
final int top=t+layoutParams.getTopVerticalWeight()*availableHeight/totalVerticalWeights;
final int bottom=b-layoutParams.getBottomVerticalWeight()*availableHeight/totalVerticalWeights;
//
v.layout(left+getPaddingLeft(),top+getPaddingTop(),right+getPaddingRight(),bottom+getPaddingBottom());
}
}
// ///////////////
// LayoutParams //
// ///////////////
public static class LayoutParams extends ViewGroup.LayoutParams
{
int _leftHorizontalWeight =0,_rightHorizontalWeight=0,_viewHorizontalWeight=0;
int _topVerticalWeight =0,_bottomVerticalWeight=0,_viewVerticalWeight=0;
public LayoutParams(final Context context,final AttributeSet attrs)
{
super(context,attrs);
final TypedArray arr=context.obtainStyledAttributes(attrs,R.styleable.WeightedLayout_LayoutParams);
{
final String horizontalWeights=arr.getString(R.styleable.WeightedLayout_LayoutParams_horizontalWeights);
//
// handle horizontal weight:
//
final String[] words=horizontalWeights.split(",");
boolean foundViewHorizontalWeight=false;
int weight;
for(final String word : words)
{
final int viewWeightIndex=word.lastIndexOf('x');
if(viewWeightIndex>=0)
{
if(foundViewHorizontalWeight)
throw new IllegalArgumentException("found more than one weights for the current view");
weight=Integer.parseInt(word.substring(0,viewWeightIndex));
setViewHorizontalWeight(weight);
foundViewHorizontalWeight=true;
}
else
{
weight=Integer.parseInt(word);
if(weight<0)
throw new IllegalArgumentException("found negative weight:"+weight);
if(foundViewHorizontalWeight)
_rightHorizontalWeight+=weight;
else _leftHorizontalWeight+=weight;
}
}
if(!foundViewHorizontalWeight)
throw new IllegalArgumentException("couldn't find any weight for the current view. mark it with 'x' next to the weight value");
}
//
// handle vertical weight:
//
{
final String verticalWeights=arr.getString(R.styleable.WeightedLayout_LayoutParams_verticalWeights);
final String[] words=verticalWeights.split(",");
boolean foundViewVerticalWeight=false;
int weight;
for(final String word : words)
{
final int viewWeightIndex=word.lastIndexOf('x');
if(viewWeightIndex>=0)
{
if(foundViewVerticalWeight)
throw new IllegalArgumentException("found more than one weights for the current view");
weight=Integer.parseInt(word.substring(0,viewWeightIndex));
setViewVerticalWeight(weight);
foundViewVerticalWeight=true;
}
else
{
weight=Integer.parseInt(word);
if(weight<0)
throw new IllegalArgumentException("found negative weight:"+weight);
if(foundViewVerticalWeight)
_bottomVerticalWeight+=weight;
else _topVerticalWeight+=weight;
}
}
if(!foundViewVerticalWeight)
throw new IllegalArgumentException("couldn't find any weight for the current view. mark it with 'x' next to the weight value");
}
//
arr.recycle();
}
public LayoutParams(final int width,final int height)
{
super(width,height);
}
public LayoutParams(final ViewGroup.LayoutParams source)
{
super(source);
}
public int getLeftHorizontalWeight()
{
return _leftHorizontalWeight;
}
public void setLeftHorizontalWeight(final int leftHorizontalWeight)
{
_leftHorizontalWeight=leftHorizontalWeight;
}
public int getRightHorizontalWeight()
{
return _rightHorizontalWeight;
}
public void setRightHorizontalWeight(final int rightHorizontalWeight)
{
if(rightHorizontalWeight<0)
throw new IllegalArgumentException("negative weight :"+rightHorizontalWeight);
_rightHorizontalWeight=rightHorizontalWeight;
}
public int getViewHorizontalWeight()
{
return _viewHorizontalWeight;
}
public void setViewHorizontalWeight(final int viewHorizontalWeight)
{
if(viewHorizontalWeight<0)
throw new IllegalArgumentException("negative weight:"+viewHorizontalWeight);
_viewHorizontalWeight=viewHorizontalWeight;
}
public int getTopVerticalWeight()
{
return _topVerticalWeight;
}
public void setTopVerticalWeight(final int topVerticalWeight)
{
if(topVerticalWeight<0)
throw new IllegalArgumentException("negative weight :"+topVerticalWeight);
_topVerticalWeight=topVerticalWeight;
}
public int getBottomVerticalWeight()
{
return _bottomVerticalWeight;
}
public void setBottomVerticalWeight(final int bottomVerticalWeight)
{
if(bottomVerticalWeight<0)
throw new IllegalArgumentException("negative weight :"+bottomVerticalWeight);
_bottomVerticalWeight=bottomVerticalWeight;
}
public int getViewVerticalWeight()
{
return _viewVerticalWeight;
}
public void setViewVerticalWeight(final int viewVerticalWeight)
{
if(viewVerticalWeight<0)
throw new IllegalArgumentException("negative weight :"+viewVerticalWeight);
_viewVerticalWeight=viewVerticalWeight;
}
}
}

I accepted your challenge and attempted to create the layout you describe in response to my comment. You are right. It is surprisingly difficult to accomplish. Besides that, I do like shooting house flies. So I jumped on board and came up with this solution.
Extend the existing layout classes rather than creating your own from scratch. I went with RelativeLayout to start with but the same approach can be used by all of them. This gives you the ability to use the default behavior for that layout on child views that you don't want to manipulate.
I added four attributes to the layout called top, left, width and height. My intention was to mimic HTML by allowing values such as "10%", "100px", "100dp" etc.. At this time the only value accepted is an integer representing the % of parent. "20" = 20% of the layout.
For better performance I allow the super.onLayout() to execute through all of it's iterations and only manipulate the views with the custom attributes on it's last pass. Since these views will be positioned and scaled independently of the siblings we can move them after everything else has settled.
Here is atts.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="HtmlStyleLayout">
<attr name="top" format="integer"/>
<attr name="left" format="integer"/>
<attr name="height" format="integer"/>
<attr name="width" format="integer"/>
</declare-styleable>
</resources>
Here is my layout class.
package com.example.helpso;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class HtmlStyleLayout extends RelativeLayout{
private int pass =0;
#Override
protected HtmlStyleLayout.LayoutParams generateDefaultLayoutParams()
{
return new HtmlStyleLayout.LayoutParams(RelativeLayout.LayoutParams.WRAP_CONTENT,RelativeLayout.LayoutParams.WRAP_CONTENT);
}
#Override
public HtmlStyleLayout.LayoutParams generateLayoutParams(final AttributeSet attrs)
{
return new HtmlStyleLayout.LayoutParams(getContext(),attrs);
}
#Override
protected RelativeLayout.LayoutParams generateLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
return new HtmlStyleLayout.LayoutParams(p.width,p.height);
}
#Override
protected boolean checkLayoutParams(final android.view.ViewGroup.LayoutParams p)
{
final boolean isCorrectInstance=p instanceof HtmlStyleLayout.LayoutParams;
return isCorrectInstance;
}
public HtmlStyleLayout(Context context, AttributeSet attrs) {
super(context, attrs);
}
public void setScaleType(View v){
try{
((ImageView) v).setScaleType (ImageView.ScaleType.FIT_XY);
}catch (Exception e){
// The view is not an ImageView
}
}
#Override
protected void onLayout(final boolean changed,final int l,final int t,final int r,final int b)
{
super.onLayout(changed, l, t, r, b); //Let the parent layout do it's thing
pass++; // After the last pass of
final int childCount = this.getChildCount(); // the parent layout
if(true){ // we do our thing
for(int i=0;i<childCount;++i)
{
final View v=getChildAt(i);
final HtmlStyleLayout.LayoutParams params = (HtmlStyleLayout.LayoutParams)v.getLayoutParams();
int newTop = v.getTop(); // set the default value
int newLeft = v.getLeft(); // of these to the value
int newBottom = v.getBottom(); // set by super.onLayout()
int newRight= v.getRight();
boolean viewChanged = false;
if(params.getTop() >= 0){
newTop = ( (int) ((b-t) * (params.getTop() * .01)) );
viewChanged = true;
}
if(params.getLeft() >= 0){
newLeft = ( (int) ((r-l) * (params.getLeft() * .01)) );
viewChanged = true;
}
if(params.getHeight() > 0){
newBottom = ( (int) ((int) newTop + ((b-t) * (params.getHeight() * .01))) );
setScaleType(v); // set the scale type to fitxy
viewChanged = true;
}else{
newBottom = (newTop + (v.getBottom() - v.getTop()));
Log.i("heightElse","v.getBottom()=" +
Integer.toString(v.getBottom())
+ " v.getTop=" +
Integer.toString(v.getTop()));
}
if(params.getWidth() > 0){
newRight = ( (int) ((int) newLeft + ((r-l) * (params.getWidth() * .01))) );
setScaleType(v);
viewChanged = true;
}else{
newRight = (newLeft + (v.getRight() - v.getLeft()));
}
// only call layout() if we changed something
if(viewChanged)
Log.i("SizeLocation",
Integer.toString(i) + ": "
+ Integer.toString(newLeft) + ", "
+ Integer.toString(newTop) + ", "
+ Integer.toString(newRight) + ", "
+ Integer.toString(newBottom));
v.layout(newLeft, newTop, newRight, newBottom);
}
pass = 0; // reset the parent pass counter
}
}
public class LayoutParams extends RelativeLayout.LayoutParams
{
private int top, left, width, height;
public LayoutParams(final Context context, final AttributeSet atts) {
super(context, atts);
TypedArray a = context.obtainStyledAttributes(atts, R.styleable.HtmlStyleLayout);
top = a.getInt(R.styleable.HtmlStyleLayout_top , -1);
left = a.getInt(R.styleable.HtmlStyleLayout_left, -1);
width = a.getInt(R.styleable.HtmlStyleLayout_width, -1);
height = a.getInt(R.styleable.HtmlStyleLayout_height, -1);
a.recycle();
}
public LayoutParams(int w, int h) {
super(w,h);
Log.d("lp","2");
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
Log.d("lp","3");
}
public LayoutParams(ViewGroup.MarginLayoutParams source) {
super(source);
Log.d("lp","4");
}
public int getTop(){
return top;
}
public int getLeft(){
return left;
}
public int getWidth(){
return width;
}
public int getHeight(){
return height;
}
}
}
Here is an example activity xml
<com.example.helpso.HtmlStyleLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:html="http://schemas.android.com/apk/res/com.example.helpso"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="#+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:scaleType="fitXY"
android:src="#drawable/bg" />
<ImageView
android:id="#+id/imageView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="#drawable/overlay"
html:height="10"
html:left="13"
html:top="18"
html:width="23" />
</com.example.helpso.HtmlStyleLayout>
Here are the images I used for testing.
If you do not set a value for a particular attribute it's default will be used. So if you set width but not height the image will scale in width and wrap_content for height.
Zipped project folder.
apk
I found the source of the bug. The problem is that I was using the layout's child count as in indicator of how many calls to onLayout it will make. This doesn't seem to hold true in older versions of android. I noticed in 2.1 onLayout is only called once. So I changed
if(pass == childCount){
to
if(true){
and it started working as expected.
I still thinks it's beneficial to adjust the layout only after the super is done. Just need to find a better way to know when that is.
EDIT
I didn't realize that your intention was to patch together images with pixel by pixel precision. I achieved the precision you are looking for by using double float precision variables instead of integers. However, you will not be able accomplish this while allowing your images to scale. When an images is scaled up pixels are added at some interval between the existing pixels. The color of the new pixels are some weighted average of the surrounding pixels. When you scale the images independently of each other they don't share any information. The result is that you will always have some artifact at the seam. Add to that the result of rounding since you can't have a partial pixel and you will always have a +/-1 pixel tolerance.
To verify this you can attempt the same task in your premium photo editing software. I use PhotoShop. Using the same images as in my apk, I placed them in seperate files. I scaled them both by 168% vertically and 127% horizontally. I then placed them in a file together and attempted to align them. The result was exactly the same as is seen in my apk.
To demonstrate the accuracy of the layout, I added a second activity to my apk. On this activity I did not scale the background image. Everything else is exactly the same. The result is seamless.
I also added a button to show/hide the overlay image and one to switch between the activities.
I updated both the apk and the zipped project folder on my google drive. You can get them by the links above.

After trying your code, I just find the reason of the problems you mentioned, and it is because in your customed layout, you only layout the child properly, however you forgot to measure your child properly, which will directly affect the drawing hierarchy, so simply add the below code, and it works for me.
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthSize = MeasureSpec.getSize(widthMeasureSpec)-this.getPaddingRight()-this.getPaddingRight();
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec)-this.getPaddingTop()-this.getPaddingBottom();
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if(heightMode == MeasureSpec.UNSPECIFIED || widthMode == MeasureSpec.UNSPECIFIED)
throw new IllegalArgumentException("the layout must have a exact size");
for (int i = 0; i < this.getChildCount(); ++i) {
View child = this.getChildAt(i);
LayoutParams lp = (LayoutParams)child.getLayoutParams();
int width = lp._viewHorizontalWeight * widthSize/(lp._leftHorizontalWeight+lp._rightHorizontalWeight+lp._viewHorizontalWeight);
int height = lp._viewVerticalWeight * heightSize/(lp._topVerticalWeight+lp._bottomVerticalWeight+lp._viewVerticalWeight);
child.measure(width | MeasureSpec.EXACTLY, height | MeasureSpec.EXACTLY);
}
this.setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.getSize(heightMeasureSpec));
}

Now there is a nicer solution than the custom layout I've made:
PercentRelativeLayout
Tutorial can be found here and a repo can be found here.
Example code:
<android.support.percent.PercentRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
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/>
or:
<android.support.percent.PercentFrameLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
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/>
I wonder though if it can handle the issues I've shown here.

I propose to use following optimizations:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:gravity="center">
<TextView android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="#string/hello_world"
android:background="#ffff0000" android:gravity="center"
android:textSize="20dp" android:textColor="#ff000000" />
</FrameLayout>
or use http://developer.android.com/reference/android/widget/LinearLayout.html#attr_android:weightSum
or use TableLayout with layout_weight for rows and columns
or use GridLayout.