android RadioButton按钮可绘制重力

Question

我正在使用

动态生成 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);

如您所见，我拼命尝试将可绘制按钮的重力设置为居中，但没有理由它始终居中和左对齐，这就是原因 - android 单选按钮的默认样式:

<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>

有什么方法可以让可绘制的按钮居中对齐吗？

Answer 1

根据CompoundButton.onDraw() source code它总是左对齐的。

(注意buttonDrawable.setBounds(0, y, buttonDrawable.getIntrinsicWidth(), y + height);)

您必须从 RadioButton 派生一个新类并覆盖 onDraw()。

稍后添加的示例:

好的，这就是你要做的。首先，这是一个布局:

<?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>

其次是自定义绘图 RadioButtonCenter:

package org.test.TestProj;

import android.content.Context;
import android.content.res.TypedArray;
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.color.transparent);
    }
    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);
            }
        }   
}

最后，您需要将一个 attrs.xml 文件放入 res/values 中，以便代码可以获取平台定义的属性。

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