ViewPager wrap_content不起作用

您可以自定义ViewPager以ViewPager在页面滑动时调整其当前页面大小.

您可以使用以下代码.

 public class WrapContentViewPager extends ViewPager {

        private int mCurrentPagePosition = 0;

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

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

        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        try {
             boolean wrapHeight = MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.AT_MOST;
             if (wrapHeight) {
                 View child = getChildAt(mCurrentPagePosition);
                 if (child != null) {
                 child.measure(widthMeasureSpec, MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
                 int h = child.getMeasuredHeight();

                 heightMeasureSpec = MeasureSpec.makeMeasureSpec(h, MeasureSpec.EXACTLY);
                }
            }
    } catch (Exception e) {
        e.printStackTrace();
    }
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

        public void reMeasureCurrentPage(int position) {
            mCurrentPagePosition = position;
            requestLayout();
        }
    }

在xml中声明它:

在reMeasureCurrentpage页面滑动后调用该功能.

    final WrapContentViewPager wrapContentViewPager = (WrapContentViewPager) findViewById(R.id.view_pager);

    wrapContentViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                @Override
                public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

                }

                @Override
                public void onPageSelected(int position) {
                    wrapContentViewPager.reMeasureCurrentPage(wrapContentViewPager.getCurrentItem());
                }

                @Override
                public void onPageScrollStateChanged(int state) {

                }
            });

我真的很喜欢@ abhishek-v的答案,但做了一些升级:

addPageChangeListener(...)在我们内部ViewPager调用(不需要reMeasureCurrentPage(...)在页面滑动外手动调用)

不需要存储mCurrentPagePosition,因为我们可以使用getCurrentItem()

删除废物try/catch块

ViewPager现在看起来像:

public class WrapContentViewPager extends ViewPager {

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

    public WrapContentViewPager(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());
        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);
    }

}

终于找到了更好的WrapContentViewPager解决方案!

另一个解决方案包含一些难以解决的错误,但我认为这个解决方案可以简单地应用在我们的代码中

我在这个网站上找到了它https://github.com/akhahaha/burn-android/blob/master/app/src/main/java/com/ucla/burn/android/WrapContentViewPager.java

这是代码

public class WrapContentViewPager extends ViewPager {
        public WrapContentViewPager(Context context) {
            super(context);
        }

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

        @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;
            }

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

            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        }
    }