TextView、Button的drawableLeft和drawableRight与文本一起居中显示

public class DrawableCenterButton extends TextView {

    public DrawableCenterButton(Context context, AttributeSet attrs,
                                int defStyle) {
        super(context, attrs, defStyle);
    }

    public DrawableCenterButton(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public DrawableCenterButton(Context context) {
        super(context);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        Drawable[] drawables = getCompoundDrawables();
        if (drawables != null) {
            Drawable drawableLeft = drawables[0];
            if (drawableLeft != null) {
                float textWidth = getPaint().measureText(getText().toString());
                int drawablePadding = getCompoundDrawablePadding();
                int drawableWidth = 0;
                drawableWidth = drawableLeft.getIntrinsicWidth();
                float bodyWidth = textWidth + drawableWidth + drawablePadding;
                canvas.translate((getWidth() - bodyWidth) / 11 * 5, 0);
            }
        }
        super.onDraw(canvas);
    }
}

use

        <com.justwayward.reader.view.DrawableCenterButton
            android:id="@+id/btnToAdd"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:background="@drawable/shape_common_green_bg"
            android:clickable="true"
            android:drawableLeft="@drawable/book_detail_info_add_img"
            android:drawablePadding="5dp"
            android:padding="10dp"
            android:text="@string/to_add"
            android:textColor="@color/white"/>

public class DrawableCenterButton extends Button {  

    public DrawableCenterButton(Context context) {  
        super(context);  
        // TODO Auto-generated constructor stub  
    }  

    public DrawableCenterButton(Context context, AttributeSet attrs,  
    int defStyle) {  
        super(context, attrs, defStyle);  
    }  

    public DrawableCenterButton(Context context, AttributeSet attrs) {  
        super(context, attrs);  
    }  


    @Override  
    protected void onDraw(Canvas canvas) {  
        Drawable[] drawables = getCompoundDrawables();  
        if (drawables != null) {  
            Drawable drawableLeft = drawables[2];  
                if (drawableLeft != null) {  

                float textWidth = getPaint().measureText(getText().toString());  
                int drawablePadding = getCompoundDrawablePadding();  
                int drawableWidth = 0;  
                drawableWidth = drawableLeft.getIntrinsicWidth();  
                float bodyWidth = textWidth + drawableWidth + drawablePadding;  
                setPadding(0, 0, (int)(getWidth() - bodyWidth), 0);  
                canvas.translate((getWidth() - bodyWidth) / 2, 0);  
            }  
        }  
        super.onDraw(canvas);  
    }  
}