Android 图片渐变切换效果

原文：https://blog.csdn.net/uyy203/article/details/53992666

package com.example.xyz.colorchange;
 
 
import android.graphics.drawable.Drawable;
import android.graphics.drawable.TransitionDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.LinearLayout;
 
 
public class MainActivity extends AppCompatActivity {
 
 
    private Drawable oldBackground = null;
 
 
    private Drawable bg_a;
    private Drawable bg_b;
    LinearLayout up;
    int isWhat=1;
 
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
 
        up =(LinearLayout) findViewById(R.id.up);
 
 
        up.setBackgroundResource(R.mipmap.a);
 
 
        bg_a = getResources().getDrawable(R.mipmap.a);
        bg_b =getResources().getDrawable(R.mipmap.b);
 

 
        up.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                if(isWhat==1)
                    aTob();
                else if(isWhat==2)
                    bToa();
            }
        });
    }
 
 

 
    private void aTob() {
        up.setBackgroundResource(R.mipmap.a);
        //渐变切换
        TransitionDrawable td = new TransitionDrawable(new Drawable[]{bg_a, bg_b});
        up.setBackgroundDrawable(td);
        td.startTransition(1000);
        isWhat=2;
    }
 
 
 
 
    private void bToa() {
        up.setBackgroundResource(R.mipmap.b);
        //渐变切换
        TransitionDrawable td = new TransitionDrawable(new Drawable[]{bg_b, bg_a});
        up.setBackgroundDrawable(td);
        td.startTransition(1000);
        isWhat=1;
    }
}

假如需要 从透明渐变切换到特定背景的话 可以这样写

td = new TransitionDrawable(new Drawable[]{getResources().getDrawable(android.R.color.transparent),bg_on});

反之，把transitionDrawable数组中元素反过来即可.

github : https://github.com/Cedric-Xuan/colorChange