[转]永久告别Android的背景选择器Selector！无需切很多图了！

package com.zoke.custom.autobg;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.LightingColorFilter;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.LayerDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.Button;

import com.zoke.custom.R;

/**
 * Android按钮显示不同状态无需多张图片的自定义控件
 *
 * @author Jack 2014-2-8
 *
 *
 */
public class AutoBgButton extends Button {

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

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

        public AutoBgButton(Context context, AttributeSet attrs, int defStyle) {
                super(context, attrs, defStyle);
        }
        @Override
        public void setBackgroundDrawable(Drawable d) {
                // 替换背景图
                AutoBgButtonBackgroundDrawable layer = new AutoBgButtonBackgroundDrawable(
                                d);
                super.setBackgroundDrawable(layer);
        }

        /**
         * 按钮所使用的状态图
         */
        protected class AutoBgButtonBackgroundDrawable extends LayerDrawable {

                // 按钮按下时所使用的颜色过滤器
                protected ColorFilter _pressedFilter = new LightingColorFilter(
                                getContext().getResources().getColor(R.color.pressColor), 1);
                // 按钮被禁用时的alpha值
                protected int _disabledAlpha = 100;

                public AutoBgButtonBackgroundDrawable(Drawable d) {
                        super(new Drawable[] { d });
                }

                @Override
                protected boolean onStateChange(int[] states) {
                        boolean enabled = false;
                        boolean pressed = false;

                        for (int state : states) {
                                if (state == android.R.attr.state_enabled)
                                        enabled = true;
                                else if (state == android.R.attr.state_pressed)
                                        pressed = true;
                        }

                        mutate();
                        if (enabled && pressed) {
                                setColorFilter(_pressedFilter);
                        } else if (!enabled) {
                                setColorFilter(null);
                                setAlpha(_disabledAlpha);
                        } else {
                                setColorFilter(null);
                        }

                        invalidateSelf();

                        return super.onStateChange(states);
                }

                @Override
                public boolean isStateful() {
                        return true;
                }
        }

}

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