滑动 图片设置为高斯模糊效果

//效果前

//效果后

//在Bulid里面加入这两句话
defaultConfig {
        renderscriptTargetApi 18
        renderscriptSupportModeEnabled true

    }

//布局
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <ImageView
            android:id="@+id/iv"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

        <ImageView
            android:id="@+id/iv_cover"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:src="@drawable/m"/>

    </FrameLayout>

    <SeekBar
        android:id="@+id/sb"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:max="255"/>

</LinearLayout>

//.java

package com.example.gaosimohu;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Build;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicBlur;
import android.support.annotation.RequiresApi;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.SeekBar;

public class MainActivity extends AppCompatActivity implements SeekBar.OnSeekBarChangeListener {
    private ImageView mImageView;
    private ImageView mImageViewCover;
    private Bitmap sampleImg;
    private Bitmap gaussianBlurImg;
    private SeekBar mSeekBar;

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mImageView = (ImageView) findViewById(R.id.iv);
        mSeekBar = (SeekBar) findViewById(R.id.sb);
        mImageViewCover = (ImageView) findViewById(R.id.iv_cover);
        sampleImg = BitmapFactory.decodeResource(getResources(), R.drawable.m); // 获取原图
        gaussianBlurImg = blur(sampleImg, 25f);
        mImageView.setImageBitmap(gaussianBlurImg);
        mSeekBar.setOnSeekBarChangeListener(this);
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR1)
    private Bitmap blur(Bitmap bitmap, float radius) {
        Bitmap output = Bitmap.createBitmap(bitmap); // 创建输出图片
        RenderScript rs = RenderScript.create(this); // 构建一个RenderScript对象
        ScriptIntrinsicBlur gaussianBlue = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs)); //
        // 创建高斯模糊脚本
        Allocation allIn = Allocation.createFromBitmap(rs, bitmap); // 开辟输入内存
        Allocation allOut = Allocation.createFromBitmap(rs, output); // 开辟输出内存
        gaussianBlue.setRadius(radius); // 设置模糊半径，范围0f<radius<=25f
        gaussianBlue.setInput(allIn); // 设置输入内存
        gaussianBlue.forEach(allOut); // 模糊编码，并将内存填入输出内存
        allOut.copyTo(output); // 将输出内存编码为Bitmap，图片大小必须注意
        rs.destroy(); // 关闭RenderScript对象，API>=23则使用rs.releaseAllContexts()
        return output;
    }

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
        int alpha = 255 - progress;
        mImageViewCover.setImageAlpha(alpha);
    }

    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {

    }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {

    }
}