android中radio button居中对齐的问题

Question

我使用以下代码动态的生成了 RadioButtons：

RadioButton radioButton=new RadioButton(context);  
LayoutParams layoutParams=new LayoutParams(radioWidth,radioHeight);
layoutParams.gravity=Gravity.CENTER;
radioButton.setLayoutParams(layoutParams);
radioButton.setGravity(Gravity.CENTER);
BitmapDrawable bitmap = ((BitmapDrawable)drawableResource);
bitmap.setGravity(Gravity.CENTER);
radioButton.setBackgroundDrawable(getResources().getDrawable(R.drawable.itabs_radio));
radioButton.setButtonDrawable(bitmap);

由以上代码看出我一直在设置按钮的位置，想把它们放在布局的中间。但是不知道什么原因，按钮可以排列在中间，但是左对齐。以下是android中radio button的默认格式：

<style name="Widget.CompoundButton">
<item name="android:focusable">true</item> 
<item name="android:clickable">true</item>
<item name="android:textAppearance">?android:attr/textAppearance</item> 
<item name="android:textColor">?android:attr/textColorPrimaryDisableOnly</item> 
<item name="android:gravity">center_vertical|left</item> 
</style>
 <style name="Widget.CompoundButton.RadioButton">
<item name="android:background">@android:drawable/btn_radio_label_background</item> 
<item name="android:button">@android:drawable/btn_radio</item> 
</style>

我用什么方法可以把所有的按钮按竖排排列，并都居中对齐呢？

Answer 1

1.首先先创建一个布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<org.test.TestProj.RadioButtonCenter
    android:id="@+id/myview"
    android:layout_width="fill_parent" 
    android:layout_height="100dp" 
    android:layout_centerInParent="true"
    android:text="Button test"
    />
</RelativeLayout>

2.然后再添加自定义的RadioButtonCenter

import android.util.AttributeSet;
import android.view.Gravity;
import android.widget.RadioButton;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;

public class RadioButtonCenter extends RadioButton {

    public RadioButtonCenter(Context context, AttributeSet attrs) {
        super(context, attrs);
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CompoundButton, 0, 0);
        buttonDrawable = a.getDrawable(1);
        setButtonDrawable(android.R.id.empty);
    }
    Drawable buttonDrawable;


     @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);

            if (buttonDrawable != null) {
                buttonDrawable.setState(getDrawableState());
                final int verticalGravity = getGravity() & Gravity.VERTICAL_GRAVITY_MASK;
                final int height = buttonDrawable.getIntrinsicHeight();

                int y = 0;

                switch (verticalGravity) {
                    case Gravity.BOTTOM:
                        y = getHeight() - height;
                        break;
                    case Gravity.CENTER_VERTICAL:
                        y = (getHeight() - height) / 2;
                        break;
                }

            int buttonWidth = buttonDrawable.getIntrinsicWidth();
            int buttonLeft = (getWidth() - buttonWidth) / 2;
            buttonDrawable.setBounds(buttonLeft, y, buttonLeft+buttonWidth, y + height);
                buttonDrawable.draw(canvas);
            }
        }   
}

3.最后，你应该在res/values中添加 attrs.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<resources>    
     <declare-styleable name="CompoundButton">
        <attr name="android:button" />
    </declare-styleable>
</resources>