Java 将占位符返回到其';空的';setContentId()之后的状态
应用placeholder.setContentID(ImageViewID)后,我有一个ImageView,可以在屏幕上移动到占位符 我的问题是如何将ImageView重置为其原始位置?理想情况下,这应该将占位符“重置”为空状态 我试过placeholder.setVisibility(View.GONE)和placeholder.setVisibility(View.INVISIBLE),但没有反应。我还尝试了clearAnimation(),但没有成功 这里是MainActivity.javaJava 将占位符返回到其';空的';setContentId()之后的状态,java,android,android-studio,imageview,placeholder,Java,Android,Android Studio,Imageview,Placeholder,应用placeholder.setContentID(ImageViewID)后,我有一个ImageView,可以在屏幕上移动到占位符 我的问题是如何将ImageView重置为其原始位置?理想情况下,这应该将占位符“重置”为空状态 我试过placeholder.setVisibility(View.GONE)和placeholder.setVisibility(View.INVISIBLE),但没有反应。我还尝试了clearAnimation(),但没有成功 这里是MainActivity.ja
package com.example.stefan.placeholderexperiment;
import android.support.constraint.ConstraintLayout;
import android.support.constraint.Placeholder;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.transition.TransitionManager;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
private Placeholder placeholder;
private ConstraintLayout layout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
placeholder = findViewById(R.id.placeholder);
layout = findViewById(R.id.layout);
}
public void transform(View v){
TransitionManager.beginDelayedTransition(layout);
placeholder.setContentId(v.getId());
}
}
和activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/layout"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:id="@+id/image"
android:onClick="transform"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:src="@drawable/ic_android_black_24dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<android.support.constraint.Placeholder
android:id="@+id/placeholder"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.967" />
</android.support.constraint.ConstraintLayout>
不幸的是,无法将ImageView重置为其原始位置,因为当您调用
占位符.setContentID(ImageViewID)
方法时,它会更改ImageView的布局参数
,并且不会存储以前状态的任何副本
因此,我只能建议您使用两个不同的占位符,并依次更改内容,如下所示:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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/layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:id="@+id/image"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="16dp"
android:onClick="transform"
android:src="@drawable/unnamed"/>
<android.support.constraint.Placeholder
android:id="@+id/placeholder_top"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginStart="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<android.support.constraint.Placeholder
android:id="@+id/placeholder_bottom"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_marginStart="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.967"/>
</android.support.constraint.ConstraintLayout>
public class MainActivity extends AppCompatActivity {
private Placeholder placeholderTop;
private Placeholder placeholderBottom;
private ConstraintLayout layout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
placeholderTop = (Placeholder) findViewById(R.id.placeholder_top);
placeholderBottom = (Placeholder) findViewById(R.id.placeholder_bottom);
layout = (ConstraintLayout) findViewById(R.id.layout);
placeholderTop.setContentId(R.id.image);
}
public void transform(View v) {
if (placeholderTop.getContent() == null) {
TransitionManager.beginDelayedTransition(layout);
placeholderTop.setContentId(v.getId());
placeholderBottom.setContentId(-1);
} else if (placeholderBottom.getContent() == null) {
TransitionManager.beginDelayedTransition(layout);
placeholderBottom.setContentId(v.getId());
placeholderTop.setContentId(-1);
}
}
}
公共类MainActivity扩展了AppCompatActivity{
私人占位符占位符顶部;
私有占位符占位符底部;
私人住宅布局;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
占位符top=(占位符)findViewById(R.id.Placeholder\u top);
占位符底部=(占位符)findViewById(R.id.Placeholder\u底部);
布局=(ConstraintLayout)findViewById(R.id.layout);
占位符top.setContentId(R.id.image);
}
公共空间变换(视图v){
if(占位符top.getContent()==null){
TransitionManager.beginDelayedTransition(布局);
占位符top.setContentId(v.getId());
placeholderBottom.setContentId(-1);
}else if(占位符bottom.getContent()==null){
TransitionManager.beginDelayedTransition(布局);
placeholderBottom.setContentId(v.getId());
占位符top.setContentId(-1);
}
}
}
这项功能非常有效!非常感谢。我很惊讶占位符top.setContentId(-1);不会引起任何问题…一种更好的编写方法是View.NO\u ID
。这有意义吗?