![](/img/trans.png)
[英]Custom views added to horizontal scrollview do not appear when scrollview is larger than screen
[英]Android multiple views show when scrollview is added but only first shows if scrollview removed and custom scrolling implemented
我已將片段添加到線性布局中,其中每個子片段視圖都占據整個屏幕。 現在我必須實現滾動功能,以便我可以瀏覽它們。 我試圖添加一個滾動視圖(水平),它顯示了所有的孩子,但由於一些問題,我無法使用滾動視圖。 因此,要滾動,我使用了以下代碼可以很好地滾動但並未顯示所有子項,即使滾動后也只有第一個可見:
/**
* A function to scroll towards the left.
*/
public void scrollLeft(){
LinearLayout layout = findViewById(R.id.viewList);
int x = getResources().getDisplayMetrics().widthPixels;
layout.scrollBy(-x, 0); // scroll by the amount of the screen's width
}
/**
* A function to scroll towards the right.
*/
public void scrollRight(){
LinearLayout layout = findViewById(R.id.viewList);
int x = getResources().getDisplayMetrics().widthPixels;
layout.scrollBy(x, 0); // scroll by the amount of the screen's width
}
我什至嘗試滾動 ConstraintLayout(基本布局),但這也給出了相同的結果。 這是我的activity_test.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/TestRoot"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".TestActivity">
<LinearLayout
android:id="@+id/viewList"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:baselineAligned="false"
android:orientation="horizontal"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"></LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
這是我用來向 LinearLayout 添加片段的代碼,它僅在 onCreate 方法中調用:
FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
for (int i = 0; i < results.length; i++) {
ResultFragment result = new ResultFragment();
// configuring the fragment
// ....
LinearLayout l = new LinearLayout(this);
l.setId(View.generateViewId());
transaction.add(l.getId(), result, "result-"+i);
((LinearLayout)findViewById(R.id.viewList)).addView(l,i);
findViewById(R.id.viewList).invalidate();
}
transaction.commit();
沒有響應但沒有問題,我自己找到了解決方案。 所以我做的很簡單。 我創建了一個自定義的 ScrollView,它覆蓋了onTouchEvent
函數,實現了我自己的滾動機制並將我的線性布局放置在這個 scrollView 和 kaboom! 有效。 新的 ScrollView 如下所示:
package com.nalin.test;
import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.HorizontalScrollView;
public class LockedHScrollView extends HorizontalScrollView {
/** The variables used to detect left-right swipes*/
float x1, x2;
/** variable to check whether the swipes made were valid (distance was large enough) */
final float distance = 200;
public LockedHScrollView(Context context){super(context);}
public LockedHScrollView(Context context, AttributeSet attrs){super(context, attrs);}
public LockedHScrollView(Context context, AttributeSet attrs, int defStyleAttr){super(context, attrs, defStyleAttr);}
/**
* A function to scroll towards the left.
*/
public void scrollLeft(){
int x = getResources().getDisplayMetrics().widthPixels;
scrollBy(-x, 0); // scroll by the amount of the screen's width
}
/**
* A function to scroll towards the right.
*/
public void scrollRight(){
int x = getResources().getDisplayMetrics().widthPixels;
scrollBy(x, 0); // scroll by the amount of the screen's width
}
/**
* A function to check swipes for scrolling between multiple result fragments.
*/
@Override
public boolean onTouchEvent(MotionEvent event) {
if (event.getAction()==MotionEvent.ACTION_DOWN){
x1 = event.getX();
}else if (event.getAction() == MotionEvent.ACTION_UP){
x2 = event.getX();
if ((x2-x1)>0){ //Right swipe
if (x2-x1 >= distance){ // Validate that the swipe was long enough
scrollLeft();
}
}else if((x1-x2)>0){ // Left swipe
if ((x1-x2)>=distance){ // Validate that the swipe was long enough
scrollRight();
}
}
}
return true;
}
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.