Question

以下android代码会创建一个带有实心圆圈背景的TextView。单击它时，会在其周围创建一个圆圈。如果再次单击，则圆圈消失。这在API 19中工作正常，但在API 8或10中没有。在那些较旧的API中，单击时不会绘制圆形边界。什么事在这里？

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="#ffffff" >
 <TextView
    android:id="@+id/col1"
    android:layout_width="50dp"
    android:layout_height="50dp"
    android:background="@drawable/circle_notapped"
   android:layout_gravity="center"
   android:layout_marginTop="50dp"/>
</LinearLayout>

MainActivity.java

package com.kitr.sview;

import android.app.Activity;
import android.graphics.Color;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.LayerDrawable;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity  {

private int select1;
private TextView col1;


@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);


    setContentView(R.layout.activity_main);

    col1 = (TextView) findViewById(R.id.col1);

    col1.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(select1==0)
            {
                select1=1;
                selectIt(v);
            }
            else
            {
                select1=0;
                deselectIt(v);
            }
        }
    });

    initializeActivity();   
}

private void initializeActivity()
{
    LayerDrawable bgDrawable = (LayerDrawable)col1.getBackground();
    GradientDrawable shape = (GradientDrawable)         bgDrawable.findDrawableByLayerId(R.id.pat3);
    shape.setColor(0xFFF04646);
    select1=0;
}




private void selectIt(View v)
{
    if(v.getId()==col1.getId())
    {
        LayerDrawable bgDrawable = (LayerDrawable)col1.getBackground();
        GradientDrawable shape = (GradientDrawable)   bgDrawable.findDrawableByLayerId(R.id.pat1);
        shape.setColor(0xFFF04646);     

    }

}

private void deselectIt(View v)
{
    if(v.getId()==col1.getId())
    {
        LayerDrawable bgDrawable = (LayerDrawable)col1.getBackground();
        GradientDrawable shape = (GradientDrawable)   bgDrawable.findDrawableByLayerId(R.id.pat1);

        shape.setColor(Color.WHITE);        
    }

}

}

circle_notapped.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/pat1" android:top="0dp" android:left="0dp" android:right="0dp" android:bottom="0dp">
<shape android:shape="oval">
    <solid android:color="#FFFFFFFF" />
</shape>
</item>
<item android:id="@+id/pat2" android:top="3dp" android:left="3dp" android:right="3dp" android:bottom="3dp">
<shape android:shape="oval">
    <solid android:color="#FFFFFFFF" />
</shape>
</item>
<item android:id="@+id/pat3" android:top="6dp" android:left="6dp" android:right="6dp" android:bottom="6dp">
<shape android:shape="oval">
    <solid android:color="#FF27AE60" />
</shape>
</item>
</layer-list>

Answer 1

必须在较旧的API中使用View.Invalidate()。这可能是一个黑客，但这很好。

无法在旧API中以编程方式修改图层列表元素

1 个答案: