android自定义view属性-优快云博客

本文介绍了一种在Android中使用自定义属性创建圆形视图的方法。通过两种方式展示了如何定义视图属性并在布局文件中应用这些属性来改变视图外观。

第一种

/MainActivity/res/values/attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyCircle">
        <attr name="radius" format="integer"/>
        <attr name="mycolor" format="reference|color"/>
    </declare-styleable>
</resources>

/MainActivity/src/com/ch/myviews/MyCircle.java

package com.ch.myviews;

import com.ch.myviewattr.R;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyCircle extends View {
    private Paint paint;
    private int radius;
   
    public MyCircle(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        //获得自定义的属性，即获得自定义的半径
        TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.MyCircle);
        radius = ta.getInt(R.styleable.MyCircle_radius, 0);
        
      
    }
    //绘制的方法
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        paint = new Paint();
        paint.setColor(Color.RED);
        
//        canvas.drawColor(Color.BLACK);
        canvas.drawCircle(getMeasuredWidth()/2, getMeasuredHeight()/2, radius, paint);
        super.onDraw(canvas);
    }
    
    

}

/MainActivity/res/layout/activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:myattr="http://schemas.android.com/apk/res/com.ch.myviewattr"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <com.ch.myviews.MyCircle
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        myattr:radius="200"
        />

</RelativeLayout>

第二种

/MainActivity/res/values/attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="MyCircle">
        <attr name="radius" format="integer"/>
        <attr name="mycolor" format="reference|color"/>
    </declare-styleable>
</resources>

/MainActivity/src/com/ch/myviews/MyCircle.java

package com.ch.myviews;

import com.ch.myviewattr.R;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class MyCircle extends View {
    private Paint paint;
    private int radius;
    private final static String NAMESPACE = "aaa1407a";
    public MyCircle(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
        //获得自定义的属性，即获得自定义的半径
    
        radius = attrs.getAttributeIntValue(NAMESPACE, "radius", 0);
    }
    //绘制的方法
    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        paint = new Paint();
        paint.setColor(Color.RED);
        
//        canvas.drawColor(Color.BLACK);
        canvas.drawCircle(getMeasuredWidth()/2, getMeasuredHeight()/2, radius, paint);
        super.onDraw(canvas);
    }
    
    

}

/MainActivity/res/layout/activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:myattr="aaa1407a"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <com.ch.myviews.MyCircle
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        myattr:radius="200"
        />

</RelativeLayout>