Question

我已经设置了一个简单的ViewPager，每页都有一个高度为200dp的ImageView。

这是我的寻呼机：

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

尽管将高度设置为wrap_content，但即使imageview仅为200dp，寻呼机也会填充屏幕。我试图用“200”替换寻呼机的高度，但这给了我多种分辨率的不同结果。我无法将“dp”添加到该值。如何将200dp添加到寻呼机的布局？

Answer 1

按照以下方式覆盖ViewPager的{Me}将使其达到目前最大孩子的身高。

@Override
protected void onMeasure(int widthMeasureSpec, int 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;
    }

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

    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

Answer 2

另一个更通用的解决方案是让wrap_content正常工作。

我已延长ViewPager以覆盖onMeasure()。高度围绕第一个子视图。如果子视图的高度不完全相同，这可能会导致意外结果。为此，可以轻松扩展该类，让其说动画为当前视图/页面的大小。但我并不需要那样。

您可以像原始ViewPager一样在您的XML布局中使用此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"/>

优点：此方法允许在包括RelativeLayout在内的任何布局中使用ViewPager来覆盖其他ui元素。

还有一个缺点：如果要使用边距，则必须创建两个嵌套布局，并为内部布局提供所需的边距。

以下是代码：

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 3

我的回答是关于DanielLópezLacalle和这篇文章http://www.henning.ms/2013/09/09/viewpager-that-simply-dont-measure-up/。 Daniel的答案的问题在于，在某些情况下，我的孩子的身高为零。不幸的是，解决方案是两次测量。

@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);
}

如果你想要或只是wrap_content，这也允许你在ViewPager上设置一个高度。

Answer 4

我刚刚回答了一个非常相似的问题，并且在寻找支持我的索赔的链接时碰巧找到了这个，很幸运你:)

我的另一个答案：
ViewPager不支持wrap_content，因为它（通常）不会同时加载所有子项，因此无法获得适当的大小（选项是每次有一个更改大小的寻呼机切换页面。）

但是，您可以设置精确尺寸（例如150dp）和match_parent 您还可以通过更改height中的LayoutParams - 属性，从代码中动态修改维度。

根据您的需要您可以在自己的xml文件中创建ViewPager，并将layout_height设置为200dp，然后在您的代码中，而不是从头开始创建新的ViewPager，您可以膨胀那个xml文件：

LayoutInflater inflater = context.getLayoutInflater();
inflater.inflate(R.layout.viewpagerxml, layout, true);

Answer 5

我已经在几个项目中遇到过这个问题，但从未有过完整的解决方案。所以我创建了一个WrapContentViewPager github项目作为ViewPager的就地替代。

https://github.com/rnevet/WCViewPager

这个解决方案受到了一些答案的启发，但改进了：

根据当前视图动态更改ViewPager高度，包括滚动时。
考虑到装饰的高度＆＃34;像PagerTabStrip这样的观点。
考虑所有Padding。

针对支持库版本24进行了更新，该版本打破了之前的实施。

Answer 6

我刚刚碰到了同样的问题。我有一个ViewPager，我想在它的按钮上显示一个广告。我找到的解决方案是将寻呼机放入RelativeView并将其layout_above设置为我想在其下方看到的视图ID。这对我有用。

这是我的布局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 7

使用Daniel López Localle的答案，我在Kotlin中创建了此类。希望它为您节省更多时间

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 8

我也遇到了这个问题，但在我的情况下，我有一个FragmentPagerAdapter正在为ViewPager提供其页面。我遇到的问题是onMeasure()的{{1}}在创建任何ViewPager之前被调用（因此无法正确调整大小）。

经过一些试验和错误后，我发现Fragments初始化finishUpdate()之后调用了FragmentPagerAdapter的Fragments方法（来自instantiateItem() FragmentPagerAdapter ），以及页面滚动后/期间。我做了一个小界面：

public interface AdapterFinishUpdateCallbacks
{
    void onFinishUpdate();
}

我将其传入FragmentPagerAdapter并致电：

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

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

反过来允许我在setVariableHeight()实施中致电CustomViewPager：

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;
    }
}

我不确定这是最好的方法，如果你认为好/坏/邪恶会喜欢评论，但它在我的实现中似乎运作良好：）

希望这有助于那里的人！

编辑：我在调用requestLayout()后忘记添加super.measure()（否则它不会重新绘制视图）。

我也忘了将父级填充添加到最终高度。

我还保留了原始宽度/高度MeasureSpecs，有利于根据需要创建一个新的。已相应更新了代码。

我遇到的另一个问题是它在ScrollView中无法正确调整自己的大小，并发现罪魁祸首是用MeasureSpec.EXACTLY代替MeasureSpec.UNSPECIFIED来衡量孩子。更新以反映这一点。

这些更改都已添加到代码中。如果需要，您可以查看历史记录以查看旧版本（不正确）。

Answer 9

另一种解决方案是根据ViewPager中的当前页面高度更新PagerAdapter高度。假设您以这种方式创建ViewPager页：

@Override
public Object instantiateItem(ViewGroup container, int position) {
  PageInfo item = mPages.get(position);
  item.mImageView = new CustomImageView(container.getContext());
  item.mImageView.setImageDrawable(item.mDrawable);
  container.addView(item.mImageView, 0);
  return item;
}

其中mPages是动态添加到PageInfo和PagerAdapter的{{1}}结构的内部列表，只有常规CustomImageView并且覆盖ImageView方法根据指定的宽度设置高度并保持图像宽高比。

您可以onMeasure()方法强制ViewPager身高：

setPrimaryItem()

请注意@Override public void setPrimaryItem(ViewGroup container, int position, Object object) { super.setPrimaryItem(container, position, object); PageInfo item = (PageInfo) object; ViewPager pager = (ViewPager) container; int width = item.mImageView.getMeasuredWidth(); int height = item.mImageView.getMeasuredHeight(); pager.setLayoutParams(new FrameLayout.LayoutParams(width, Math.max(height, 1))); }。这修复了Math.max(height, 1)未更新显示页面（显示为空白）的烦人错误，当前一页面具有零高度（即ViewPager中的空值可绘制）时，每个奇数在两页之间来回滑动。

Answer 10

在viewpager中使用静态内容并且您希望没有花哨的动画时，您可以使用以下视图分页器

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 11

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 12

我遇到了同样的问题，当用户在页面之间滚动时，我还必须使ViewPager包围其内容。使用cybergen的上述答案，我将onMeasure方法定义如下：

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

    if (getCurrentItem() < getChildCount()) {
        View child = getChildAt(getCurrentItem());
        if (child.getVisibility() != GONE) {
            heightMeasureSpec = MeasureSpec.makeMeasureSpec(MeasureSpec.getSize(heightMeasureSpec),
                    MeasureSpec.UNSPECIFIED);
            child.measure(widthMeasureSpec, heightMeasureSpec);
        }

        setMeasuredDimension(getMeasuredWidth(), measureHeight(heightMeasureSpec, getChildAt(getCurrentItem())));            
    }
}

这样，onMeasure方法设置ViewPager显示的当前页面的高度。

Answer 13

如果您需要的ViewPager能够调整每个孩子的大小，而不仅仅是最大的孩子，我已经编写了一段代码来做到这一点。请注意，更改后没有动画（在我的情况下不是必需的）

android：minHeight 标志也受支持。

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 14

上面没有任何建议对我有用。我的用例是在ScrollView中有4个自定义ViewPagers。其中最重要的是基于宽高比来衡量，其余的只有layout_height=wrap_content。我尝试了cybergen，Daniel López Lacalle解决方案。他们都没有为我完全工作。

我猜为什么 cybergen 在页面＆gt;上无效1是因为它根据第1页计算寻呼机的高度，如果你进一步滚动则会隐藏它。

cybergen 和DanielLópezLacalle建议在我的情况下都有奇怪的行为：3个中的2个加载正常，1个随机高度为0.显示{{1}在孩子们居住之前就被召唤了。所以我想出了这两个答案的混合物+我自己的修复：

onMeasure

想法是让@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; } } }计算子项的维度，并在ViewPager的布局参数中保存第一页的计算高度。不要忘记将片段的布局高度设置为ViewPager，否则你可以得到height = 0。我用过这个：

wrap_content

请注意，如果您的所有网页都具有相同的高度，此解决方案效果很好。否则，您需要根据当前活动的子项重新计算<?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">  </LinearLayout>高度。我不需要它，但如果你建议解决方案，我很乐意更新答案。

Answer 15

我修改了Cybergen答案，以使Viewpager根据所选项目更改高度该类与Cybergen的类相同，但是我添加了一个整数向量，它是viewpager的所有子视图高度，我们可以在页面更改以更新高度时访问它

这是课程：

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;
    }
}

然后在您的活动中添加一个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) {}
});

这是xml：

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

请根据需要更正我的英语

Answer 16

下面的代码是唯一对我有用的

1。使用此类来声明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。将高度环绕视图分页器插入到您的xml文件中：

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

3。声明您的视图传呼机：

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 17

改进的Daniel López Lacalle答案，用科特林重写：

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 18

对于有这个问题并在C＃中编写Xamarin Android编码的人来说，这也可能是一个快速的解决方案：

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

如果您的孩子视图具有相同的高度，这将非常有用。否则，您将需要为您检查的所有子项存储某种“minimumHeight”值，即使这样，您可能也不希望在较小的子视图下方显示空白空间。

解决方案本身对我来说还不够，但这是因为我的子项是listViews，而且它们的MeasuredHeight计算不正确，似乎。

Answer 19

如果您使用的ViewPager是ScrollView 的孩子且有PagerTitleStrip孩子，则您需要稍加修改已经提供了很好的答案。作为参考，我的XML看起来像这样：

<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>

在您的onMeasure中，您必须添加 PagerTitleStrip的测量高度（如果找到）。否则，它的高度将不会被视为所有孩子的最大高度，即使它占用额外的空间。

希望这有助于其他人。对不起，这有点像黑客......

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 20

我有一个版本的WrapContentHeightViewPager，它在API 23之前正常工作，它将调整父视图在所选当前子视图上的高度基础。

升级到API 23后，它停止工作。事实证明，旧的解决方案是使用getChildAt(getCurrentItem())来获取当前子视图以测量哪些不起作用。请在此处查看解决方案：https://stackoverflow.com/a/16512217/1265583

以下适用于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 21

另一个Kotlin代码

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 22

我在这里看到的大多数解决方案似乎都在进行双重测量：首先测量子视图，然后调用super.onMeasure()

我想出了一个自定义WrapContentViewPager，它效率更高，可以与RecyclerView和Fragment一起很好地工作

您可以在此处查看演示：

github/ssynhtn/WrapContentViewPager

以及该类的代码： WrapContentViewPager.java

Answer 23

对于那些希望ViewPager2解决方案具有ViewPager2与其所有页面的最大高度相同的高度的人，可悲的是，我只找到了以下解决方法：

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
}

我之所以说“不好意思”，是因为它遍历了所有页面，创建了它们的视图，对其进行了度量，并以它调用用于其他目的的功能的方式进行了

在大多数情况下应该可以正常工作。

如果您知道更好的解决方案，请告诉我。

Answer 24

并非所有答案都完美。所以我创建了一个。下面类将要求布局当一个新的页面被选择以使viewPager的高度是当前子视图的高度。

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 25

您可以切换到ViewPager2。它是ViewPager的更新版本。它执行与ViewPager相同的操作，但以一种更智能，更有效的方式。 ViewPager2带有各种新功能。当然，“换行内容”问题已由ViewPager2解决。

来自Android文档：“ ViewPager2取代了ViewPager，解决了其前任的大部分难题，包括从右到左的布局支持，垂直方向，可修改的Fragment集合等。”

我向初学者推荐这篇文章：

https://medium.com/google-developer-experts/exploring-the-view-pager-2-86dbce06ff71

Answer 26

将ViewPager的父级布局设置为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>

别忘了设置android:fillViewport="true"

这将拉伸滚动视图及其子元素的内容以填充视口。

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

Answer 27

测量ViewPager的高度：

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;
    }

}

调用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 28

此ViewPager仅调整为当前可见子级的大小（不是其实际子级中最大的子项）

https://stackoverflow.com/a/56325869/4718406的想法

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 29

就我而言，在应用尺寸时，我需要一个带有wrap_content的viewpager用于当前选择的元素和动画。在下面您可以看到我的实现。有人可以派上用场吗。

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)
            }
        }
    }
}

在项目中添加attrs.xml：

<?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>

并使用：

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

Answer 30

我添加android：fillViewport =“ true”的案例解决了该问题

Answer 31

在我的情况下，添加clipToPadding解决了这个问题。

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

干杯！

Answer 32

我有类似的（但更复杂的情况）。我有一个包含ViewPager的对话框其中一个子页面很短，具有静态高度另一个子页面应该尽可能高。
另一个子页面包含ScrollView，如果ScrollView内容不需要对话框可用的完整高度，则页面（以及整个对话框）应为WRAP_CONTENT。

现有的答案都没有完全适用于这种特定情况。坚持下去 - 这是一个颠簸的旅程。

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();
}

非常感谢@Raanan测量视图和测量装饰高度的代码。我遇到了他的图书馆的问题 - 动画结结巴巴，我认为当对话框的高度足够短以至于需要它时，我的ScrollView不会滚动。

Answer 33

我找到了一个解决方案，有点像合并这里提到的一些解决方案。

想法是测量ViewPager的当前视图。

这是完整的代码：

<强> MainActivity.kt

class MainActivity : AppCompatActivity() {

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

<强> activity_main.xml中

<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>

<强> 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>

<强> 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"

    }
}

如果您使用RecyclerPagerAdapter library，获取“currentView”的方法是从您设置的寻呼机视图持有者处获取它：

    val item = obj as PagerViewHolder
    currentView = item.itemView

Android：我无法拥有ViewPager WRAP_CONTENT

33 个答案: