Android:我无法拥有ViewPager WRAP_CONTENT

我已经设置了一个简单的ViewPager，它在每个页面上都有一个高度为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);

尽管高度设置为wrap_content，但即使imageview只有200dp，分页器也总是充满屏幕。我尝试用“200”替换寻呼机的高度，但在不同分辨率下会得到不同的结果。我无法将“dp”添加到该值。如何将200dp添加到寻呼机的布局?

当前回答

给ViewPager的父布局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内容以填充视口。

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

2019-10-09 10:45:04

其他回答

如果你正在使用的ViewPager是一个ScrollView的子视图，并且有一个PagerTitleStrip子视图，你将需要对已经提供的答案进行轻微修改。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>

在你的onMeasure中，你必须添加PagerTitleStrip的measuredHeight，如果找到一个。否则，即使它占用了额外的空间，它的高度也不会被认为是所有子结点的最大高度。

希望这能帮助到其他人。很抱歉，这有点黑…

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);
    }
}

2015-09-01 00:41:22

下面的代码是唯一对我有用的东西

1. 使用这个类来声明一个hightwrappingviewpager:

 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. 在xml文件中插入高度包装视图分页器:

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

3.声明您的视图分页:

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);

2019-09-03 14:28:31

从爆米花时间安卓应用程序的源代码，我发现这个解决方案，动态调整大小的viewpager与漂亮的动画取决于当前的孩子的大小。

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);
    }
}

2015-09-09 20:25:10

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!

2018-01-03 17:44:47