Android: I am unable to have ViewPager WRAP_CONTENT

Question

I have setup a simple ViewPager that has an ImageView with a height of 200dp on each page.

Here is my pager:

pager = new ViewPager(this);
pager.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT));
pager.setBackgroundColor(Color.WHITE);
pager.setOnPageChangeListener(listener);
layout.addView(pager);

Despite the height set as wrap_content, the pager always fills the screen even though the imageview is only 200dp. I tried to replace the height of the pager with "200" but that gives me different results with multiple resolutions. I am unable to add "dp" to that value. How do I add 200dp to the pager's layout?

Answer 1

Overriding onMeasure of your ViewPager as follows will make it get the height of the biggest child it currently has.

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

    int height = 0;
    int childWidthSpec = MeasureSpec.makeMeasureSpec(
        Math.max(0, MeasureSpec.getSize(widthMeasureSpec) -
            getPaddingLeft() - getPaddingRight()),
        MeasureSpec.getMode(widthMeasureSpec)
    );
    for (int i = 0; i < getChildCount(); i++) {
        View child = getChildAt(i);
        child.measure(childWidthSpec, MeasureSpec.UNSPECIFIED);
        int h = child.getMeasuredHeight();
        if (h > height) height = h;
    }
    
    if (height != 0) {
        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
    }

    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

Answer 2

For those who want a solution of ViewPager2 that will have the ViewPager2 have the same height as the max height of all of its pages, sadly I've found only this workaround:

viewPager.doOnPreDraw {
    //workaround to set the viewPagerheight the same as its children
    var height = 0
    for (i in 0 until featuresViewPager.adapter!!.itemCount) {
        val viewHolder = viewPager.adapter!!.createViewHolder(viewPager, 0)
        viewPager.adapter!!.bindViewHolder(viewHolder, i)
        val child: View = viewHolder.itemView
        child.layoutParams.height = ViewGroup.LayoutParams.WRAP_CONTENT
        val widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(viewPager.width, View.MeasureSpec.EXACTLY)
        val heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED)
        child.measure(widthMeasureSpec, heightMeasureSpec)
        val childHeight = child.measuredHeight
        child.layoutParams.height = ViewGroup.LayoutParams.MATCH_PARENT
        if (childHeight > height)
            height = childHeight
    }
    viewPager.layoutParams.height = height
}

I say "sadly" because it goes over all of the pages, creates their views, measures them, and on the way it calls functions that are meant for other purposes.

Should work fine in most cases.

Please let me know if you know of a nicer solution.

Answer 3

Another Kotlin code

class DynamicViewPager @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null
) : ViewPager(context, attrs) {

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        var height = 0
        (0 until childCount).forEach {
            val child = getChildAt(it)
            child.measure(
                widthMeasureSpec,
                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)
            )
            height = max(height, child.measuredHeight)
        }
        if (height > 0) {
            super.onMeasure(
                widthMeasureSpec,
                MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY)
            )
        } else {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        }
    }
}

Answer 4

All answers do not work perfectly. So I created one. Below class would request layout when a new page was selected to make viewPager 's height is the current child view's height.

class WrapContentViewPager : ViewPager {
    constructor(context: Context) : super(context)
    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)

    private var curPos = 0

    init {
        addOnPageChangeListener(object : ViewPager.OnPageChangeListener {
            override fun onPageScrollStateChanged(state: Int) {}

            override fun onPageScrolled(
                position: Int,
                positionOffset: Float,
                positionOffsetPixels: Int
            ) {}

            override fun onPageSelected(position: Int) {
                curPos = position
                requestLayout()
            }
        })
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        if (childCount == 0) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec)
            return
        }
        measureChildren(widthMeasureSpec, heightMeasureSpec)
        setMeasuredDimension(measuredWidth, getChildAt(curPos).measuredHeight)
    }
}

Answer 5

I edit cybergen answer for make viewpager to change height depending on selected item The class is the same of cybergen's, but I added a Vector of integers that is all viewpager's child views heights and we can access it when page change to update height

This is the class:

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.viewpager.widget.ViewPager;

import java.util.Vector;

public class WrapContentHeightViewPager extends ViewPager {
    private Vector<Integer> heights = new Vector<>();

    public WrapContentHeightViewPager(@NonNull Context context) {
        super(context);
    }

    public WrapContentHeightViewPager(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

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

        for(int i=0;i<getChildCount();i++) {
            View view = getChildAt(i);
            if (view != null) {
                view.measure(widthMeasureSpec, heightMeasureSpec);
                heights.add(measureHeight(heightMeasureSpec, view));
            }
        }
        setMeasuredDimension(getMeasuredWidth(), measureHeight(heightMeasureSpec, getChildAt(0)));
    }

    public int getHeightAt(int position){
        return heights.get(position);
    }

    private int measureHeight(int measureSpec, View view) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        } else {
            if (view != null) {
                result = view.getMeasuredHeight();
            }
            if (specMode == MeasureSpec.AT_MOST) {
                result = Math.min(result, specSize);
            }
        }
        return result;
    }
}

Then in your activity add an OnPageChangeListener

WrapContentHeightViewPager viewPager = findViewById(R.id.my_viewpager);
viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
     @Override
     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {}
     @Override
     public void onPageSelected(int position) {
         LinearLayout.LayoutParams params = (LinearLayout.LayoutParams) viewPager.getLayoutParams();
         params.height = viewPager.getHeightAt(position);
         viewPager.setLayoutParams(params);
     }
     @Override
     public void onPageScrollStateChanged(int state) {}
});

And here is xml:

<com.example.example.WrapContentHeightViewPager
    android:id="@+id/my_viewpager"
    android:fillViewport="true"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

Please correct my English if necessary

Answer 6

Give parent layout of ViewPager as NestedScrollView

   <androidx.core.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="5dp"
    android:paddingRight="5dp"
    android:fillViewport="true">
        <androidx.viewpager.widget.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
        </androidx.viewpager.widget.ViewPager>
    </androidx.core.widget.NestedScrollView>

Don't forget to set android:fillViewport="true"

This will stretch scrollview and its child's content to fill the viewport.

https://developer.android.com/reference/android/widget/ScrollView.html#attr_android:fillViewport

Answer 7

Improved Daniel López Lacalle answer, rewritten in Kotlin:

class MyViewPager(context: Context, attrs: AttributeSet): ViewPager(context, attrs) {
    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        val zeroHeight = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)

        val maxHeight = children
            .map { it.measure(widthMeasureSpec, zeroHeight); it.measuredHeight }
            .max() ?: 0

        if (maxHeight > 0) {
            val maxHeightSpec = MeasureSpec.makeMeasureSpec(maxHeight, MeasureSpec.EXACTLY)
            super.onMeasure(widthMeasureSpec, maxHeightSpec)
            return
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
    }
}

Answer 8

Measure the height of ViewPager:

public class WrapViewPager extends ViewPager {
    View primaryView;

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

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (primaryView != null) {
            int height = 0;
            for (int i = 0; i < getChildCount(); i++) {
                if (primaryView == getChildAt(i)) {
                    int childHeightSpec = MeasureSpec.makeMeasureSpec(0x1 << 30 - 1, MeasureSpec.AT_MOST);
                    getChildAt(i).measure(widthMeasureSpec, childHeightSpec);
                    height = getChildAt(i).getMeasuredHeight();
                }

            }

            setMeasuredDimension(widthMeasureSpec, MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
        }
    }

    public void setPrimaryView(View view) {
        primaryView = view;
    }

}

call setPrimaryView(View) ：

public class ZGAdapter extends PagerAdapter {

    @Override
    public void setPrimaryItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        super.setPrimaryItem(container, position, object);
        ((WrapViewPager)container).setPrimaryView((View)object);
    }

}

Answer 9

This ViewPager only resizes to the current visible children (not the biggest of its actual children)

The idea from https://stackoverflow.com/a/56325869/4718406

public class DynamicHeightViewPager extends ViewPager {

public DynamicHeightViewPager (Context context) {
    super(context);
    initPageChangeListener();
}

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



private void initPageChangeListener() {
    addOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            requestLayout();
        }
    });
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    //View child = getChildAt(getCurrentItem());
    View child = getCurrentView(this);
    if (child != null) {
        child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, 
         MeasureSpec.UNSPECIFIED));
        int h = child.getMeasuredHeight();

        heightMeasureSpec = MeasureSpec.makeMeasureSpec(h, MeasureSpec.EXACTLY);
    }
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}


View getCurrentView(ViewPager viewPager) {
    try {
        final int currentItem = viewPager.getCurrentItem();
        for (int i = 0; i < viewPager.getChildCount(); i++) {
            final View child = viewPager.getChildAt(i);
            final ViewPager.LayoutParams layoutParams = (ViewPager.LayoutParams) 
             child.getLayoutParams();

            Field f = layoutParams.getClass().getDeclaredField("position"); 
            //NoSuchFieldException
            f.setAccessible(true);
            int position = (Integer) f.get(layoutParams); //IllegalAccessException

            if (!layoutParams.isDecor && currentItem == position) {
                return child;
            }
        }
    } catch (NoSuchFieldException e) {
        e.fillInStackTrace();
    } catch (IllegalArgumentException e) {
        e.fillInStackTrace();
    } catch (IllegalAccessException e) {
        e.fillInStackTrace();
    }
    return null;
}

}

Answer 10

The below code is the only thing worked for me

1. Use this class to declare a HeightWrappingViewPager:

 public class HeightWrappingViewPager extends ViewPager {

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

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

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            int mode = MeasureSpec.getMode(heightMeasureSpec);
            // Unspecified means that the ViewPager is in a ScrollView WRAP_CONTENT.
            // At Most means that the ViewPager is not in a ScrollView WRAP_CONTENT.
            if (mode == MeasureSpec.UNSPECIFIED || mode == MeasureSpec.AT_MOST) {
                // super has to be called in the beginning so the child views can be initialized.
                super.onMeasure(widthMeasureSpec, heightMeasureSpec);
                int height = 0;
                for (int i = 0; i < getChildCount(); i++) {
                    View child = getChildAt(i);
                    child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                    int h = child.getMeasuredHeight();
                    if (h > height) height = h;
                }
                heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
            }
            // super has to be called again so the new specs are treated as exact measurements
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }

2. Insert the height wrapping view pager to your xml file:

<com.project.test.HeightWrappingViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</com.project.test.HeightWrappingViewPager>

3. Declare your view pager:

HeightWrappingViewPager mViewPager;
mViewPager = (HeightWrappingViewPager) itemView.findViewById(R.id.pager);
CustomAdapter adapter = new CustomAdapter(context);
mViewPager.setAdapter(adapter);
mViewPager.measure(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);

Answer 11

In my case, I needed a viewpager with a wrap_content for the currently selected element and animation when applying the size. Below you can see my implementation. Can someone come in handy.

package one.xcorp.widget

import android.animation.ValueAnimator
import android.content.Context
import android.util.AttributeSet
import android.view.View
import android.view.ViewGroup.LayoutParams.MATCH_PARENT
import android.view.ViewGroup.LayoutParams.WRAP_CONTENT
import one.xcorp.widget.R
import kotlin.properties.Delegates.observable

class ViewPager : android.support.v4.view.ViewPager {

    var enableAnimation by observable(false) { _, _, enable ->
        if (enable) {
            addOnPageChangeListener(onPageChangeListener)
        } else {
            removeOnPageChangeListener(onPageChangeListener)
        }
    }

    private var animationDuration = 0L
    private var animator: ValueAnimator? = null

    constructor (context: Context) : super(context) {
        init(context, null)
    }

    constructor (context: Context, attrs: AttributeSet?) : super(context, attrs) {
        init(context, attrs)
    }

    private fun init(context: Context, attrs: AttributeSet?) {
        context.theme.obtainStyledAttributes(
            attrs,
            R.styleable.ViewPager,
            0,
            0
        ).apply {
            try {
                enableAnimation = getBoolean(
                    R.styleable.ViewPager_enableAnimation,
                    enableAnimation
                )
                animationDuration = getInteger(
                    R.styleable.ViewPager_animationDuration,
                    resources.getInteger(android.R.integer.config_shortAnimTime)
                ).toLong()
            } finally {
                recycle()
            }
        }
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        val heightMode = MeasureSpec.getMode(heightMeasureSpec)

        val measuredHeight = if (heightMode == MeasureSpec.EXACTLY) {
            MeasureSpec.getSize(heightMeasureSpec)
        } else {
            val currentViewHeight = findViewByPosition(currentItem)?.also {
                measureView(it)
            }?.measuredHeight ?: 0

            if (heightMode != MeasureSpec.AT_MOST) {
                currentViewHeight
            } else {
                Math.min(
                    currentViewHeight,
                    MeasureSpec.getSize(heightMeasureSpec)
                )
            }
        }

        super.onMeasure(
            widthMeasureSpec,
            MeasureSpec.makeMeasureSpec(measuredHeight, MeasureSpec.EXACTLY)
        )
    }

    private fun measureView(view: View) = with(view) {
        val horizontalMode: Int
        val horizontalSize: Int
        when (layoutParams.width) {
            MATCH_PARENT -> {
                horizontalMode = MeasureSpec.EXACTLY
                horizontalSize = this@ViewPager.measuredWidth
            }
            WRAP_CONTENT -> {
                horizontalMode = MeasureSpec.UNSPECIFIED
                horizontalSize = 0
            }
            else -> {
                horizontalMode = MeasureSpec.EXACTLY
                horizontalSize = layoutParams.width
            }
        }

        val verticalMode: Int
        val verticalSize: Int
        when (layoutParams.height) {
            MATCH_PARENT -> {
                verticalMode = MeasureSpec.EXACTLY
                verticalSize = this@ViewPager.measuredHeight
            }
            WRAP_CONTENT -> {
                verticalMode = MeasureSpec.UNSPECIFIED
                verticalSize = 0
            }
            else -> {
                verticalMode = MeasureSpec.EXACTLY
                verticalSize = layoutParams.height
            }
        }

        val horizontalMeasureSpec = MeasureSpec.makeMeasureSpec(horizontalSize, horizontalMode)
        val verticalMeasureSpec = MeasureSpec.makeMeasureSpec(verticalSize, verticalMode)

        measure(horizontalMeasureSpec, verticalMeasureSpec)
    }

    private fun findViewByPosition(position: Int): View? {
        for (i in 0 until childCount) {
            val childView = getChildAt(i)
            val childLayoutParams = childView.layoutParams as LayoutParams

            val childPosition by lazy {
                val field = childLayoutParams.javaClass.getDeclaredField("position")
                field.isAccessible = true
                field.get(childLayoutParams) as Int
            }

            if (!childLayoutParams.isDecor && position == childPosition) {
                return childView
            }
        }

        return null
    }

    private fun animateContentHeight(childView: View, fromHeight: Int, toHeight: Int) {
        animator?.cancel()

        if (fromHeight == toHeight) {
            return
        }

        animator = ValueAnimator.ofInt(fromHeight, toHeight).apply {
            addUpdateListener {
                measureView(childView)
                if (childView.measuredHeight != toHeight) {
                    animateContentHeight(childView, height, childView.measuredHeight)
                } else {
                    layoutParams.height = animatedValue as Int
                    requestLayout()
                }
            }
            duration = animationDuration
            start()
        }
    }

    private val onPageChangeListener = object : OnPageChangeListener {

        override fun onPageScrollStateChanged(state: Int) {
            /* do nothing */
        }

        override fun onPageScrolled(
            position: Int,
            positionOffset: Float,
            positionOffsetPixels: Int
        ) {
            /* do nothing */
        }

        override fun onPageSelected(position: Int) {
            if (!isAttachedToWindow) {
                return
            }

            findViewByPosition(position)?.let { childView ->
                measureView(childView)
                animateContentHeight(childView, height, childView.measuredHeight)
            }
        }
    }
}

Add attrs.xml in project:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="ViewPager">
        <attr name="enableAnimation" format="boolean" />
        <attr name="animationDuration" format="integer" />
    </declare-styleable>
</resources>

And use:

<one.xcorp.widget.ViewPager
    android:id="@+id/wt_content"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:enableAnimation="true" />

Answer 12

Most of the solutions I see here seem to be doing a double measurement: first measuring the child views, and then calling the super.onMeasure()

I have come up with a custom WrapContentViewPager that is more efficient, works well with RecyclerView and Fragment

You can check the demo here:

github/ssynhtn/WrapContentViewPager

and the code of the class here: WrapContentViewPager.java

Answer 13

I've found a solution that is a bit like merging of some of the solutions mentioned here.

The idea is to measure the current view of the ViewPager.

Here's the full code:

MainActivity.kt

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        viewPager.adapter = WrapHeightViewPager.CustomPagerAdapter(this)
    }
}

activity_main.xml

<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"
        tools:context=".MainActivity">

    <com.android.myapplication.WrapHeightViewPager
            android:layout_width="match_parent" android:id="@+id/viewPager"
            android:background="#33ff0000"
            android:layout_height="wrap_content"/>

</FrameLayout>

view_pager_page.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical" android:gravity="center"
              android:layout_width="match_parent"
              android:layout_height="wrap_content">

    <ImageView android:layout_width="wrap_content" android:layout_height="wrap_content"
               android:src="@android:drawable/sym_def_app_icon"/>


    <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:id="@+id/textView"/>
</LinearLayout>

WrapHeightViewPager.kt

class WrapHeightViewPager : ViewPager {
    constructor(context: Context) : super(context) {}

    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {}

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        val adapter = adapter as CustomPagerAdapter?
        val currentView = adapter?.currentView
        if (currentView != null) {
            currentView.measure(widthMeasureSpec, heightMeasureSpec)
            super.onMeasure(
                widthMeasureSpec,
                View.MeasureSpec.makeMeasureSpec(currentView.measuredHeight, View.MeasureSpec.EXACTLY)
            )
            return
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
    }

    class CustomPagerAdapter(private val context: Context) : PagerAdapter() {
        var currentView: View? = null

        override fun instantiateItem(parent: ViewGroup, position: Int): Any {
            val inflater = LayoutInflater.from(context)
            val view = inflater.inflate(R.layout.view_pager_page, parent, false)
            view.textView.text = "item$position"
            parent.addView(view)
            return view
        }

        override fun setPrimaryItem(container: ViewGroup, position: Int, obj: Any) {
            super.setPrimaryItem(container, position, obj)
            currentView = obj as View
        }

        override fun destroyItem(collection: ViewGroup, position: Int, view: Any) = collection.removeView(view as View)

        override fun getCount(): Int = 3

        override fun isViewFromObject(view: View, obj: Any) = view === obj

        override fun getPageTitle(position: Int): CharSequence? = "item $position"

    }
}

If you use RecyclerPagerAdapter library, the way to get the "currentView" is by getting it from the pager-view-holder that you've set:

    val item = obj as PagerViewHolder
    currentView = item.itemView

Answer 14

I my case adding android:fillViewport="true" solved the issue

Answer 15

In case you need ViewPager that adjust its size to every child, not just to biggest one, I have wrote a piece of code that does it. Note that there is no animation upon that change (not neccessary in my case)

android:minHeight flag is also supported.

public class ChildWrappingAdjustableViewPager extends ViewPager {
    List<Integer> childHeights = new ArrayList<>(getChildCount());
    int minHeight = 0;
    int currentPos = 0;

    public ChildWrappingAdjustableViewPager(@NonNull Context context) {
        super(context);
        setOnPageChangeListener();
    }

    public ChildWrappingAdjustableViewPager(@NonNull Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        obtainMinHeightAttribute(context, attrs);
        setOnPageChangeListener();
    }

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

        //calculate child views
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
            int h = child.getMeasuredHeight();
            if (h < minHeight) {
                h = minHeight;
            }
            childHeights.add(i, h);
        }

        if (childHeights.size() - 1 >= currentPos) {
            heightMeasureSpec = MeasureSpec.makeMeasureSpec(childHeights.get(currentPos), MeasureSpec.EXACTLY);
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    private void obtainMinHeightAttribute(@NonNull Context context, @Nullable AttributeSet attrs) {
        int[] heightAttr = new int[]{android.R.attr.minHeight};
        TypedArray typedArray = context.obtainStyledAttributes(attrs, heightAttr);
        minHeight = typedArray.getDimensionPixelOffset(0, -666);
        typedArray.recycle();
    }

    private void setOnPageChangeListener() {
        this.addOnPageChangeListener(new SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                currentPos = position;

                ViewGroup.LayoutParams layoutParams = ChildWrappingAdjustableViewPager.this.getLayoutParams();
                layoutParams.height = childHeights.get(position);
                ChildWrappingAdjustableViewPager.this.setLayoutParams(layoutParams);
                ChildWrappingAdjustableViewPager.this.invalidate();
            }
        });
    }
}

Answer 16

Using Daniel López Localle answer, I created this class in Kotlin. Hope it save you more time

class DynamicHeightViewPager @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null) : ViewPager(context, attrs) {

override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
    var heightMeasureSpec = heightMeasureSpec

    var height = 0
    for (i in 0 until childCount) {
        val child = getChildAt(i)
        child.measure(widthMeasureSpec, View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED))
        val h = child.measuredHeight
        if (h > height) height = h
    }

    if (height != 0) {
        heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(height, View.MeasureSpec.EXACTLY)
    }

    super.onMeasure(widthMeasureSpec, heightMeasureSpec)
}}

Answer 17

in my case adding clipToPadding solved the problem.

<android.support.v4.view.ViewPager
    ...
    android:clipToPadding="false"
    ...
    />

Cheers!

Answer 18

Another more generic solution is to get wrap_content to just work.

I've extended ViewPager to override onMeasure(). The height is wraped around the first child view. This could lead to unexpected results if the child views are not exactly the same height. For that the class can be easily extended to let's say animate to the size of the current view/page. But I didn't need that.

You can use this ViewPager in yout XML layouts just like the original ViewPager:

<view
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    class="de.cybergen.ui.layout.WrapContentHeightViewPager"
    android:id="@+id/wrapContentHeightViewPager"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"/>

Advantage: This approach allows using the ViewPager in any layout including RelativeLayout to overlay other ui elements.

One drawback remains: If you want to use margins, you have to create two nested layouts and give the inner one the desired margins.

Here's the code:

public class WrapContentHeightViewPager extends ViewPager {

    /**
     * Constructor
     *
     * @param context the context
     */
    public WrapContentHeightViewPager(Context context) {
        super(context);
    }

    /**
     * Constructor
     *
     * @param context the context
     * @param attrs the attribute set
     */
    public WrapContentHeightViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

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

        // find the first child view
        View view = getChildAt(0);
        if (view != null) {
            // measure the first child view with the specified measure spec
            view.measure(widthMeasureSpec, heightMeasureSpec);
        }

        setMeasuredDimension(getMeasuredWidth(), measureHeight(heightMeasureSpec, view));
    }

    /**
     * Determines the height of this view
     *
     * @param measureSpec A measureSpec packed into an int
     * @param view the base view with already measured height
     *
     * @return The height of the view, honoring constraints from measureSpec
     */
    private int measureHeight(int measureSpec, View view) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY) {
            result = specSize;
        } else {
            // set the height from the base view if available
            if (view != null) {
                result = view.getMeasuredHeight();
            }
            if (specMode == MeasureSpec.AT_MOST) {
                result = Math.min(result, specSize);
            }
        }
        return result;
    }

}

Answer 19

I have a similar (but more complex scenario). I have a dialog, which contains a ViewPager.
One of the child pages is short, with a static height.
Another child page should always be as tall as possible.
Another child page contains a ScrollView, and the page (and thus the entire dialog) should WRAP_CONTENT if the ScrollView contents don't need the full height available to the dialog.

None of the existing answers worked completely for this specific scenario. Hold on- it's a bumpy ride.

void setupView() {
    final ViewPager.SimpleOnPageChangeListener pageChangeListener = new ViewPager.SimpleOnPageChangeListener() {
        @Override
        public void onPageSelected(int position) {
            currentPagePosition = position;

            // Update the viewPager height for the current view

            /*
            Borrowed from https://github.com/rnevet/WCViewPager/blob/master/wcviewpager/src/main/java/nevet/me/wcviewpager/WrapContentViewPager.java
            Gather the height of the "decor" views, since this height isn't included
            when measuring each page's view height.
             */
            int decorHeight = 0;
            for (int i = 0; i < viewPager.getChildCount(); i++) {
                View child = viewPager.getChildAt(i);
                ViewPager.LayoutParams lp = (ViewPager.LayoutParams) child.getLayoutParams();
                if (lp != null && lp.isDecor) {
                    int vgrav = lp.gravity & Gravity.VERTICAL_GRAVITY_MASK;
                    boolean consumeVertical = vgrav == Gravity.TOP || vgrav == Gravity.BOTTOM;
                    if (consumeVertical) {
                        decorHeight += child.getMeasuredHeight();
                    }
                }
            }

            int newHeight = decorHeight;

            switch (position) {
                case PAGE_WITH_SHORT_AND_STATIC_CONTENT:
                    newHeight += measureViewHeight(thePageView1);
                    break;
                case PAGE_TO_FILL_PARENT:
                    newHeight = ViewGroup.LayoutParams.MATCH_PARENT;
                    break;
                case PAGE_TO_WRAP_CONTENT:
//                  newHeight = ViewGroup.LayoutParams.WRAP_CONTENT; // Works same as MATCH_PARENT because...reasons...
//                  newHeight += measureViewHeight(thePageView2); // Doesn't allow scrolling when sideways and height is clipped

                    /*
                    Only option that allows the ScrollView content to scroll fully.
                    Just doing this might be way too tall, especially on tablets.
                    (Will shrink it down below)
                     */
                    newHeight = ViewGroup.LayoutParams.MATCH_PARENT;
                    break;
            }

            // Update the height
            ViewGroup.LayoutParams layoutParams = viewPager.getLayoutParams();
            layoutParams.height = newHeight;
            viewPager.setLayoutParams(layoutParams);

            if (position == PAGE_TO_WRAP_CONTENT) {
                // This page should wrap content

                // Measure height of the scrollview child
                View scrollViewChild = ...; // (generally this is a LinearLayout)
                int scrollViewChildHeight = scrollViewChild.getHeight(); // full height (even portion which can't be shown)
                // ^ doesn't need measureViewHeight() because... reasons...

                if (viewPager.getHeight() > scrollViewChildHeight) { // View pager too tall?
                    // Wrap view pager height down to child height
                    newHeight = scrollViewChildHeight + decorHeight;

                    ViewGroup.LayoutParams layoutParams2 = viewPager.getLayoutParams();
                    layoutParams2.height = newHeight;
                    viewPager.setLayoutParams(layoutParams2);
                }
            }

            // Bonus goodies :)
            // Show or hide the keyboard as appropriate. (Some pages have EditTexts, some don't)
            switch (position) {
                // This case takes a little bit more aggressive code than usual

                if (position needs keyboard shown){
                    showKeyboardForEditText();
                } else if {
                    hideKeyboard();
                }
            }
        }
    };

    viewPager.addOnPageChangeListener(pageChangeListener);

    viewPager.getViewTreeObserver().addOnGlobalLayoutListener(
            new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    // http://stackoverflow.com/a/4406090/4176104
                    // Do things which require the views to have their height populated here
                    pageChangeListener.onPageSelected(currentPagePosition); // fix the height of the first page

                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                        viewPager.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    } else {
                        viewPager.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    }

                }
            }
    );
}


...

private void showKeyboardForEditText() {
    // Make the keyboard appear.
    getDialog().getWindow().clearFlags(WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM);
    getDialog().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE | WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);

    inputViewToFocus.requestFocus();

    // http://stackoverflow.com/a/5617130/4176104
    InputMethodManager inputMethodManager =
            (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
    inputMethodManager.toggleSoftInputFromWindow(
            inputViewToFocus.getApplicationWindowToken(),
            InputMethodManager.SHOW_IMPLICIT, 0);
}

...

/**
 * Hide the keyboard - http://stackoverflow.com/a/8785471
 */
private void hideKeyboard() {
    InputMethodManager inputManager = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);

    inputManager.hideSoftInputFromWindow(inputBibleBookStart.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
}

...

//https://github.com/rnevet/WCViewPager/blob/master/wcviewpager/src/main/java/nevet/me/wcviewpager/WrapContentViewPager.java
private int measureViewHeight(View view) {
    view.measure(ViewGroup.getChildMeasureSpec(-1, -1, view.getLayoutParams().width), View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
    return view.getMeasuredHeight();
}

Much thanks to @Raanan for the code to measure views and measure the decor height. I ran into problems with his library- the animation stuttered, and I think my ScrollView wouldn't scroll when the height of the dialog was short enough to require it.

Answer 20

I have faced this issue in several project already and never had a complete solution. So I created a WrapContentViewPager github project as a in-place replacement for ViewPager.

https://github.com/rnevet/WCViewPager

The solution was inspired by some of the answers here, but improves on:

• Dynamically changes the ViewPager height according to current View including while scrolling.
• Takes into consideration the height of "decor" views like PagerTabStrip.
• Takes into consideration all Padding.

Updated for support library version 24 which broke previous implementation.

Answer 21

I have an version of WrapContentHeightViewPager that was working correctly before API 23 that will resize the parent view's height base on the current child view selected.

After upgrading to API 23, it stopped working. It turns out the old solution was using getChildAt(getCurrentItem()) to get the current child view to measure which is not working. See solution here: https://stackoverflow.com/a/16512217/1265583

Below works with API 23:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int height = 0;
    ViewPagerAdapter adapter = (ViewPagerAdapter)getAdapter();
    View child = adapter.getItem(getCurrentItem()).getView();
    if(child != null) {
        child.measure(widthMeasureSpec,  MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
        height = child.getMeasuredHeight();
    }
    heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);

    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

Answer 22

When using static content inside the viewpager and you wish no fancy animation you may use the following view pager

public class HeightWrappingViewPager extends ViewPager {

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

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

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)   {
      super.onMeasure(widthMeasureSpec, heightMeasureSpec);
      View firstChild = getChildAt(0);
      firstChild.measure(widthMeasureSpec, heightMeasureSpec);
      super.onMeasure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(firstChild.getMeasuredHeight(), MeasureSpec.EXACTLY));
  }
}

Answer 23

For people having this problem and coding for Xamarin Android in C#, this might also be a quick solution:

pager.ChildViewAdded += (sender, e) => {
    e.Child.Measure ((int)MeasureSpecMode.Unspecified, (int)MeasureSpecMode.Unspecified);
    e.Parent.LayoutParameters.Height = e.Child.MeasuredHeight;
};

This is mainly useful if your child views are of the same height. Otherwise, you would be required to store some kind of "minimumHeight" value over all children that you check against, and even then you might not want to have empty spaces visible beneath your smaller child views.

The solution itself is not sufficient for me though, but that is because my child items are listViews and their MeasuredHeight is not calculated correctly, it seems.

Answer 24

From Popcorn time android app's source code I found this solution which dynamically adjusts size of viewpager with nice animation depending on the size of current child.

https://git.popcorntime.io/popcorntime/android/blob/5934f8d0c8fed39af213af4512272d12d2efb6a6/mobile/src/main/java/pct/droid/widget/WrappingViewPager.java

public class WrappingViewPager extends ViewPager {

    private Boolean mAnimStarted = false;

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

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

    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);

        if(!mAnimStarted && null != getAdapter()) {
            int height = 0;
            View child = ((FragmentPagerAdapter) getAdapter()).getItem(getCurrentItem()).getView();
            if (child != null) {
                child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                height = child.getMeasuredHeight();
                if (VersionUtils.isJellyBean() && height < getMinimumHeight()) {
                    height = getMinimumHeight();
                }
            }

            // Not the best place to put this animation, but it works pretty good.
            int newHeight = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
            if (getLayoutParams().height != 0 && heightMeasureSpec != newHeight) {
                    final int targetHeight = height;
                    final int currentHeight = getLayoutParams().height;
                    final int heightChange = targetHeight - currentHeight;

                    Animation a = new Animation() {
                        @Override
                        protected void applyTransformation(float interpolatedTime, Transformation t) {
                            if (interpolatedTime >= 1) {
                                getLayoutParams().height = targetHeight;
                            } else {
                                int stepHeight = (int) (heightChange * interpolatedTime);
                                getLayoutParams().height = currentHeight + stepHeight;
                            }
                            requestLayout();
                        }

                        @Override
                        public boolean willChangeBounds() {
                            return true;
                        }
                    };

                    a.setAnimationListener(new Animation.AnimationListener() {
                        @Override
                        public void onAnimationStart(Animation animation) {
                            mAnimStarted = true;
                        }

                        @Override
                        public void onAnimationEnd(Animation animation) {
                            mAnimStarted = false;
                        }

                        @Override
                        public void onAnimationRepeat(Animation animation) {
                        }
                    });

                    a.setDuration(1000);
                    startAnimation(a);
                    mAnimStarted = true;
            } else {
                heightMeasureSpec = newHeight;
            }
        }

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

Answer 25

If the ViewPager you're using is a child of a ScrollView AND has a PagerTitleStrip child you'll need to use a slight modification of the great answers already provided. For reference my XML looks like this:

<ScrollView
    android:id="@+id/match_scroll_view"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/white">

    <LinearLayout
        android:id="@+id/match_and_graphs_wrapper"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <view
            android:id="@+id/pager"
            class="com.printandpixel.lolhistory.util.WrapContentHeightViewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v4.view.PagerTitleStrip
                android:id="@+id/pager_title_strip"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_gravity="top"
                android:background="#33b5e5"
                android:paddingBottom="4dp"
                android:paddingTop="4dp"
                android:textColor="#fff" />
        </view>
    </LinearLayout>
</ScrollView>

In your onMeasure you have to ADD the measuredHeight of the PagerTitleStrip if one is found. Otherwise its height won't be considered into the largest height of all the children even though it takes up additional space.

Hope this helps someone else. Sorry that it's a bit of a hack...

public class WrapContentHeightViewPager extends ViewPager {

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

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

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int pagerTitleStripHeight = 0;
        int height = 0;
        for(int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
            int h = child.getMeasuredHeight();
            if (h > height) {
                // get the measuredHeight of the tallest fragment
                height = h;
            }
            if (child.getClass() == PagerTitleStrip.class) {
                // store the measured height of the pagerTitleStrip if one is found. This will only
                // happen if you have a android.support.v4.view.PagerTitleStrip as a direct child
                // of this class in your XML.
                pagerTitleStripHeight = h;
            }
        }

        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height+pagerTitleStripHeight, MeasureSpec.EXACTLY);

        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }
}

Answer 26

I just bumped into the same issue. I had a ViewPager and I wanted to display an ad at the button of it. The solution I found was to get the pager into a RelativeView and set it's layout_above to the view id i want to see below it. that worked for me.

here is my layout XML:

  <RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <LinearLayout
        android:id="@+id/AdLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="vertical" >
    </LinearLayout>

    <android.support.v4.view.ViewPager
        android:id="@+id/mainpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/AdLayout" >
    </android.support.v4.view.ViewPager>
</RelativeLayout>

Answer 27

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

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

int getMeasureExactly(View child, int widthMeasureSpec) {
    child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
    int height = child.getMeasuredHeight();
    return MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
}

@Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    boolean wrapHeight = MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.AT_MOST;

    final View tab = getChildAt(0);
    if (tab == null) {
        return;
    }

    int width = getMeasuredWidth();
    if (wrapHeight) {
        // Keep the current measured width.
        widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY);
    }
    Fragment fragment = ((Fragment) getAdapter().instantiateItem(this, getCurrentItem()));
    heightMeasureSpec = getMeasureExactly(fragment.getView(), widthMeasureSpec);

    //Log.i(Constants.TAG, "item :" + getCurrentItem() + "|height" + heightMeasureSpec);
    // super has to be called again so the new specs are treated as
    // exact measurements.
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

Answer 28

Nothing of suggested above worked for me. My use case is having 4 custom ViewPagers in ScrollView. Top of them is measured based on aspect ratio and the rest just has layout_height=wrap_content. I've tried cybergen , Daniel López Lacalle solutions. None of them work fully for me.

My guess why cybergen doesn't work on page > 1 is because it calculates height of pager based on page 1, that is hidden if you scroll further.

Both cybergen and Daniel López Lacalle suggestions have weird behavior in my case: 2 of 3 are loaded ok and 1 randomly height is 0. Appears that onMeasure was called before children were populated. So I came up with a mixture of these 2 answers + my own fixes:

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    if (getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
        // find the first child view
        View view = getChildAt(0);
        if (view != null) {
            // measure the first child view with the specified measure spec
            view.measure(widthMeasureSpec, heightMeasureSpec);
            int h = view.getMeasuredHeight();
            setMeasuredDimension(getMeasuredWidth(), h);
            //do not recalculate height anymore
            getLayoutParams().height = h;
        }
    }
}

Idea is to let ViewPager calculate children's dimensions and save calculated height of first page in layout params of the ViewPager. Don't forget to set fragment's layout height to wrap_content otherwise you can get height=0. I've used this one:

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="wrap_content">
        <!-- Childs are populated in fragment -->
</LinearLayout>

Please note that this solution works great if all of your pages have same height. Otherwise you need to recalculate ViewPager height based on current child active. I don't need it, but if you suggest the solution I would be happy to update the answer.

Answer 29

I based my answer on Daniel López Lacalle and this post http://www.henning.ms/2013/09/09/viewpager-that-simply-dont-measure-up/. The problem with Daniel's answer is that in some cases my children had a height of zero. The solution was to unfortunately measure twice.

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int mode = MeasureSpec.getMode(heightMeasureSpec);
    // Unspecified means that the ViewPager is in a ScrollView WRAP_CONTENT.
    // At Most means that the ViewPager is not in a ScrollView WRAP_CONTENT.
    if (mode == MeasureSpec.UNSPECIFIED || mode == MeasureSpec.AT_MOST) {
        // super has to be called in the beginning so the child views can be initialized.
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int height = 0;
        for (int i = 0; i < getChildCount(); i++) {
            View child = getChildAt(i);
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
            int h = child.getMeasuredHeight();
            if (h > height) height = h;
        }
        heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);
    }
    // super has to be called again so the new specs are treated as exact measurements
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

This also lets you set a height on the ViewPager if you so want to or just wrap_content.

Answer 30

I also ran into this problem, but in my case I had a FragmentPagerAdapter that was supplying the ViewPager with its pages. The problem I had was that onMeasure() of the ViewPager was called before any of the Fragments had been created (and therefore could not size itself correctly).

After a bit of trial and error, I found that the finishUpdate() method of the FragmentPagerAdapter is called after the Fragments have been initialized (from instantiateItem() in the FragmentPagerAdapter), and also after/during the page scrolling. I made a small interface:

public interface AdapterFinishUpdateCallbacks
{
    void onFinishUpdate();
}

which I pass into my FragmentPagerAdapter and call:

@Override
public void finishUpdate(ViewGroup container)
{
    super.finishUpdate(container);

    if (this.listener != null)
    {
        this.listener.onFinishUpdate();
    }
}

which in turn allows me to call setVariableHeight() on my CustomViewPager implementation:

public void setVariableHeight()
{
    // super.measure() calls finishUpdate() in adapter, so need this to stop infinite loop
    if (!this.isSettingHeight)
    {
        this.isSettingHeight = true;

        int maxChildHeight = 0;
        int widthMeasureSpec = MeasureSpec.makeMeasureSpec(getMeasuredWidth(), MeasureSpec.EXACTLY);
        for (int i = 0; i < getChildCount(); i++)
        {
            View child = getChildAt(i);
            child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(ViewGroup.LayoutParams.WRAP_CONTENT, MeasureSpec.UNSPECIFIED));
            maxChildHeight = child.getMeasuredHeight() > maxChildHeight ? child.getMeasuredHeight() : maxChildHeight;
        }

        int height = maxChildHeight + getPaddingTop() + getPaddingBottom();
        int heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY);

        super.measure(widthMeasureSpec, heightMeasureSpec);
        requestLayout();

        this.isSettingHeight = false;
    }
}

I am not sure it is the best approach, would love comments if you think it is good/bad/evil, but it seems to be working pretty well in my implementation :)

Hope this helps someone out there!

EDIT: I forgot to add a requestLayout() after calling super.measure() (otherwise it doesn't redraw the view).

I also forgot to add the parent's padding to the final height.

I also dropped keeping the original width/height MeasureSpecs in favor of creating a new one as required. Have updated the code accordingly.

Another problem I had was that it wouldn't size itself correctly in a ScrollView and found the culprit was measuring the child with MeasureSpec.EXACTLY instead of MeasureSpec.UNSPECIFIED. Updated to reflect this.

These changes have all been added to the code. You can check the history to see the old (incorrect) versions if you want.