我正在开发一个在相对布局中使用拖放 View 的项目。我有一个按钮，单击时会生成新的 ImageView 。该 ImageView 创建在屏幕的左上角，相对于父 View 为 (0,0)。然后我可以将 ImageView 拖放到我想要的任何位置。问题是:当我再次单击按钮以创建另一个 ImageView 时，所有 ImageView 都会移动到左上角。我是否应该使用不同的添加方法或某种方法来保持其他 ImageView 就位？所有代码都贴在下面。
代码:
MyFragment.java
package com.example.layouttest;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
public class MyFragment extends Fragment {
public static final String EXTRA_MESSAGE = "EXTRA_MESSAGE";
public String text;
static FragmentManager fragMan;
public static final MyFragment newInstance(String message)
{
MyFragment f = new MyFragment();
f.setRetainInstance(true);
Bundle bdl = new Bundle(1);
bdl.putString(EXTRA_MESSAGE, message);
f.setArguments(bdl);
return f;
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
String message = getArguments().getString(EXTRA_MESSAGE);
View v = inflater.inflate(R.layout.myfragment_layout, container, false);
TextView messageTextView = (TextView)v.findViewById(R.id.textView);
messageTextView.setText(message);
text = message;
return v;
}
}
PageViewActivity.java
package com.example.layouttest;
import java.util.ArrayList;
import java.util.List;
import com.example.layouttest.R;
import android.content.ClipData;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.view.ViewPager;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.DragShadowBuilder;
import android.view.View.OnTouchListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class PageViewActivity extends FragmentActivity {
MyPageAdapter pageAdapter;
FragmentManager fragMan;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_page_view);
fragMan = getSupportFragmentManager();
List<Fragment> fragments = getFragments();
FragmentTransaction fragTrans = fragMan.beginTransaction();
fragTrans.commit();
pageAdapter = new MyPageAdapter(getSupportFragmentManager(), fragments);
ViewPager pager = (ViewPager)findViewById(R.id.viewpager);
pager.setAdapter(pageAdapter);
pager.setPageTransformer(true, new ZoomOutPageTransformer());
pager.setCurrentItem(pageAdapter.cur);
}
public void click(View v){
RelativeLayout layout = (RelativeLayout)v.getParent();
ImageView image = new ImageView(this);
image.setLayoutParams(new LayoutParams(80,80));
image.setImageDrawable(getResources().getDrawable(R.drawable.shape));
image.setOnTouchListener(new MyTouchListener());
layout.setOnDragListener(new MyDragListener(layout));
layout.addView(image);
}
private List<Fragment> getFragments(){
List<Fragment> fList = new ArrayList<Fragment>();
for(int i = 1; i <= 5;i++){
MyFragment f = MyFragment.newInstance("Fragment " + i);
fList.add(f);
}
return fList;
}
private class MyPageAdapter extends FragmentPagerAdapter {
public List<Fragment> fragments;
public int cur;
public MyPageAdapter(FragmentManager fm, List<Fragment> fragments) {
super(fm);
this.fragments = fragments;
cur = fragments.size()/2;
}
@Override
public Fragment getItem(int position) {
return this.fragments.get(position);
}
@Override
public int getCount() {
return this.fragments.size();
}
}
private class MyTouchListener implements OnTouchListener{
@Override
public boolean onTouch(View arg0, MotionEvent arg1) {
if(arg1.getAction() == MotionEvent.ACTION_DOWN){
ClipData data = ClipData.newPlainText("", "");
DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(arg0);
arg0.startDrag(data, shadowBuilder, arg0, 0);
arg0.setVisibility(View.INVISIBLE);
}
return true;
}
}
}
MyDragListener.java
package com.example.layouttest;
import android.util.Log;
import android.view.DragEvent;
import android.view.View;
import android.view.View.OnDragListener;
import android.widget.RelativeLayout;
public class MyDragListener implements OnDragListener{
int x;
int y;
RelativeLayout layout;
public MyDragListener(RelativeLayout l){
layout = l;
}
@Override
public boolean onDrag(View v, DragEvent event) {
int action = event.getAction();
View view = (View) event.getLocalState();
RelativeLayout l = (RelativeLayout)view.getParent();
if(!l.equals(layout))
return false;
if(action == DragEvent.ACTION_DRAG_LOCATION){
x = (int)event.getX();
y = (int)event.getY();
Log.d("DRAG", x + "," + y);
}
if(action == DragEvent.ACTION_DRAG_ENDED){
Log.d("DRAG", "Dropped at " + x + "," + y);
view.layout(x-(view.getWidth()/2), y-(view.getHeight()/2), x+(view.getWidth()/2), y+(view.getHeight()/2));
view.setVisibility(View.VISIBLE);
}
return true;
}
}
ZoomOutPageTransformer.java
package com.example.layouttest;
import android.support.v4.view.ViewPager.PageTransformer;
import android.view.View;
public class ZoomOutPageTransformer implements PageTransformer {
private static float MIN_SCALE = 0.85f;
private static float MIN_ALPHA = 0.5f;
public void transformPage(View view, float position) {
int pageWidth = view.getWidth();
int pageHeight = view.getHeight();
if (position < -1) { // [-Infinity,-1)
// This page is way off-screen to the left.
view.setAlpha(0);
} else if (position <= 1) { // [-1,1]
// Modify the default slide transition to shrink the page as well
float scaleFactor = Math.max(MIN_SCALE, 1 - Math.abs(position));
float vertMargin = pageHeight * (1 - scaleFactor) / 2;
float horzMargin = pageWidth * (1 - scaleFactor) / 2;
if (position < 0) {
view.setTranslationX(horzMargin - vertMargin / 2);
} else {
view.setTranslationX(-horzMargin + vertMargin / 2);
}
// Scale the page down (between MIN_SCALE and 1)
view.setScaleX(scaleFactor);
view.setScaleY(scaleFactor);
// Fade the page relative to its size.
view.setAlpha(MIN_ALPHA +
(scaleFactor - MIN_SCALE) /
(1 - MIN_SCALE) * (1 - MIN_ALPHA));
} else { // (1,+Infinity]
// This page is way off-screen to the right.
view.setAlpha(0);
}
}
}
myfragment_layout.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:id="@+id/layout"
android:background="#00308F" >
<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView"
android:layout_centerHorizontal="true"
android:layout_marginTop="20dp"
android:onClick="click"
android:text="@string/hello_world" />
</RelativeLayout>
shape.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<stroke
android:width="2dp"
android:color="#FFFFFF" />
<gradient
android:angle="225"
android:endColor="#FFFFFF"
android:startColor="#000000" />
<corners
android:bottomLeftRadius="7dp"
android:bottomRightRadius="7dp"
android:topLeftRadius="7dp"
android:topRightRadius="7dp" />
</shape>
activity_page_view.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v4.view.ViewPager
android:id="@+id/viewpager"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</RelativeLayout>
如果有人能找到我的代码中的缺陷或让我知道如何在添加新图像时保持图像就位，我将不胜感激。
如果有人想亲眼目睹该问题，这里有一个 .apk 链接:LayoutTest.apk
最佳答案
问题已解决。
我去过的地方
view.layout(x-(view.getWidth()/2), y-(view.getHeight()/2), x+(view.getWidth()/2), y+(view.getHeight()/2));
我需要有
view.setX(x-(view.getWidth()/2));
view.setY(y-(view.getHeight()/2));
显然，.layout()是依赖于 View 层次结构的相对定位，而.setX()和.setY() > 是独立于层次结构的绝对定位。当新 View 添加到布局中时，层次结构会发生变化，受影响的任何内容都会返回到其默认起始位置。对于 xml 添加的 View ，定义了默认位置，但对于以编程方式添加的 View ，默认位置为 (0,0)。
要解决这个问题，我所要做的就是用两条新线替换该线，一切正常!
关于android - 拖放持久位置，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16990247/