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
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);
}
}
其他回答
重写你的ViewPager的onMeasure如下将使它获得它目前拥有的最大子节点的高度。
@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);
}
我编辑cybergen答案使viewpager改变高度取决于选定的项目 类是cybergen的相同，但我添加了一个整数向量，这是所有viewpager的子视图高度，我们可以在页面更改为更新高度时访问它
这是这个类:
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;
}
}
然后在你的活动中添加一个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) {}
});
这里是xml:
<com.example.example.WrapContentHeightViewPager
android:id="@+id/my_viewpager"
android:fillViewport="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
如有必要请纠正我的英语
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
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);
我已经在几个项目中遇到过这个问题，从来没有一个完整的解决方案。所以我创建了一个WrapContentViewPager github项目作为ViewPager的替代。
https://github.com/rnevet/WCViewPager
解决方案的灵感来自这里的一些答案，但改进了:
根据当前视图(包括滚动时)动态更改ViewPager高度。 考虑像PagerTabStrip这样的“装饰”视图的高度。 考虑所有填充。
更新到支持库版本24，打破了以前的实现。
