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

我也遇到了同样的问题。我有一个ViewPager,我想在它的按钮上显示一个广告。我发现的解决方案是让寻呼机进入一个RelativeView,并设置它的layout_above的视图id,我想看到它下面。这对我很管用。

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>

其他回答

我的答案基于Daniel López Lacalle和这篇文章http://www.henning.ms/2013/09/09/viewpager-that-simply-dont-measure-up/。丹尼尔回答的问题是,在某些情况下,我的孩子的身高为零。不幸的是,解决办法是测量两次。

@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);
}

这也允许你在ViewPager上设置一个高度,如果你想要的话,或者只是wrap_content。

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)
        }
    }
}

我遇到了同样的问题,当用户在页面之间滚动时,我还必须让ViewPager环绕其内容。使用cybergen上面的答案,我定义onMeasure方法如下:

@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。

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!

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);
    }
}