Android 模糊ListView项后面的背景

我需要在

列表视图

的项目后面进行模糊效果。预期效果如下所示

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问题是，我需要一个非常快速的解决方案，以便项目可以快速滚动。

看看这篇博客文章，详细介绍了几个不同的选项

还有这里的github项目

这里有有趣的课程

package com.npi.blureffect;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.os.Build.VERSION;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicBlur;
import android.util.Log;

public class Blur {

    private static final String TAG = "Blur";

    @SuppressLint("NewApi")
    public static Bitmap fastblur(Context context, Bitmap sentBitmap, int radius) {

        if (VERSION.SDK_INT > 16) {
            Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);

            final RenderScript rs = RenderScript.create(context);
            final Allocation input = Allocation.createFromBitmap(rs, sentBitmap, Allocation.MipmapControl.MIPMAP_NONE,
                    Allocation.USAGE_SCRIPT);
            final Allocation output = Allocation.createTyped(rs, input.getType());
            final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
            script.setRadius(radius /* e.g. 3.f */);
            script.setInput(input);
            script.forEach(output);
            output.copyTo(bitmap);
            return bitmap;
        }

        // Stack Blur v1.0 from
        // http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
        //
        // Java Author: Mario Klingemann <mario at quasimondo.com>
        // http://incubator.quasimondo.com
        // created Feburary 29, 2004
        // Android port : Yahel Bouaziz <yahel at kayenko.com>
        // http://www.kayenko.com
        // ported april 5th, 2012

        // This is a compromise between Gaussian Blur and Box blur
        // It creates much better looking blurs than Box Blur, but is
        // 7x faster than my Gaussian Blur implementation.
        //
        // I called it Stack Blur because this describes best how this
        // filter works internally: it creates a kind of moving stack
        // of colors whilst scanning through the image. Thereby it
        // just has to add one new block of color to the right side
        // of the stack and remove the leftmost color. The remaining
        // colors on the topmost layer of the stack are either added on
        // or reduced by one, depending on if they are on the right or
        // on the left side of the stack.
        //
        // If you are using this algorithm in your code please add
        // the following line:
        //
        // Stack Blur Algorithm by Mario Klingemann <mario@quasimondo.com>

        Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);

        if (radius < 1) {
            return (null);
        }

        int w = bitmap.getWidth();
        int h = bitmap.getHeight();

        int[] pix = new int[w * h];
        Log.e("pix", w + " " + h + " " + pix.length);
        bitmap.getPixels(pix, 0, w, 0, 0, w, h);

        int wm = w - 1;
        int hm = h - 1;
        int wh = w * h;
        int div = radius + radius + 1;

        int r[] = new int[wh];
        int g[] = new int[wh];
        int b[] = new int[wh];
        int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;
        int vmin[] = new int[Math.max(w, h)];

        int divsum = (div + 1) >> 1;
        divsum *= divsum;
        int dv[] = new int[256 * divsum];
        for (i = 0; i < 256 * divsum; i++) {
            dv[i] = (i / divsum);
        }

        yw = yi = 0;

        int[][] stack = new int[div][3];
        int stackpointer;
        int stackstart;
        int[] sir;
        int rbs;
        int r1 = radius + 1;
        int routsum, goutsum, boutsum;
        int rinsum, ginsum, binsum;

        for (y = 0; y < h; y++) {
            rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
            for (i = -radius; i <= radius; i++) {
                p = pix[yi + Math.min(wm, Math.max(i, 0))];
                sir = stack[i + radius];
                sir[0] = (p & 0xff0000) >> 16;
                sir[1] = (p & 0x00ff00) >> 8;
                sir[2] = (p & 0x0000ff);
                rbs = r1 - Math.abs(i);
                rsum += sir[0] * rbs;
                gsum += sir[1] * rbs;
                bsum += sir[2] * rbs;
                if (i > 0) {
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                } else {
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                }
            }
            stackpointer = radius;

            for (x = 0; x < w; x++) {

                r[yi] = dv[rsum];
                g[yi] = dv[gsum];
                b[yi] = dv[bsum];

                rsum -= routsum;
                gsum -= goutsum;
                bsum -= boutsum;

                stackstart = stackpointer - radius + div;
                sir = stack[stackstart % div];

                routsum -= sir[0];
                goutsum -= sir[1];
                boutsum -= sir[2];

                if (y == 0) {
                    vmin[x] = Math.min(x + radius + 1, wm);
                }
                p = pix[yw + vmin[x]];

                sir[0] = (p & 0xff0000) >> 16;
                sir[1] = (p & 0x00ff00) >> 8;
                sir[2] = (p & 0x0000ff);

                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];

                rsum += rinsum;
                gsum += ginsum;
                bsum += binsum;

                stackpointer = (stackpointer + 1) % div;
                sir = stack[(stackpointer) % div];

                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];

                rinsum -= sir[0];
                ginsum -= sir[1];
                binsum -= sir[2];

                yi++;
            }
            yw += w;
        }
        for (x = 0; x < w; x++) {
            rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
            yp = -radius * w;
            for (i = -radius; i <= radius; i++) {
                yi = Math.max(0, yp) + x;

                sir = stack[i + radius];

                sir[0] = r[yi];
                sir[1] = g[yi];
                sir[2] = b[yi];

                rbs = r1 - Math.abs(i);

                rsum += r[yi] * rbs;
                gsum += g[yi] * rbs;
                bsum += b[yi] * rbs;

                if (i > 0) {
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                } else {
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                }

                if (i < hm) {
                    yp += w;
                }
            }
            yi = x;
            stackpointer = radius;
            for (y = 0; y < h; y++) {
                // Preserve alpha channel: ( 0xff000000 & pix[yi] )
                pix[yi] = (0xff000000 & pix[yi]) | (dv[rsum] << 16) | (dv[gsum] << 8) | dv[bsum];

                rsum -= routsum;
                gsum -= goutsum;
                bsum -= boutsum;

                stackstart = stackpointer - radius + div;
                sir = stack[stackstart % div];

                routsum -= sir[0];
                goutsum -= sir[1];
                boutsum -= sir[2];

                if (x == 0) {
                    vmin[y] = Math.min(y + r1, hm) * w;
                }
                p = x + vmin[y];

                sir[0] = r[p];
                sir[1] = g[p];
                sir[2] = b[p];

                rinsum += sir[0];
                ginsum += sir[1];
                binsum += sir[2];

                rsum += rinsum;
                gsum += ginsum;
                bsum += binsum;

                stackpointer = (stackpointer + 1) % div;
                sir = stack[stackpointer];

                routsum += sir[0];
                goutsum += sir[1];
                boutsum += sir[2];

                rinsum -= sir[0];
                ginsum -= sir[1];
                binsum -= sir[2];

                yi += w;
            }
        }

        Log.e("pix", w + " " + h + " " + pix.length);
        bitmap.setPixels(pix, 0, w, 0, 0, w, h);
        return (bitmap);
    }

}

package com.npi.fulleffect；
导入android.annotation.SuppressLint；
导入android.content.Context；
导入android.graphics.Bitmap；
导入android.os.Build.VERSION；
导入android.renderscript.Allocation；
导入android.renderscript.Element；
导入android.renderscript.renderscript；
导入android.renderscript.ScriptIntrinsicBlur；
导入android.util.Log；
公共类模糊{
私有静态最终字符串TAG=“Blur”；
@SuppressLint（“新API”）
公共静态位图fastblur（上下文上下文、位图sentBitmap、整数半径）{
如果（VERSION.SDK_INT>16）{
位图Bitmap=sentBitmap.copy（sentBitmap.getConfig（），true）；
final RenderScript rs=RenderScript.create（上下文）；
最终分配输入=Allocation.createFromBitmap（rs，sentBitmap，Allocation.MipmapControl.MIPMAP\u无，
分配、使用（U脚本）；
最终分配输出=Allocation.createTyped（rs，input.getType（））；
final ScriptIntrinsicBlur script=ScriptIntrinsicBlur.create（rs，Element.U8_4（rs））；
脚本.setRadius（radius/*例如3.f*/）；
script.setInput（输入）；
script.forEach（输出）；
输出.copyTo（位图）；
返回位图；
}
//堆栈模糊v1.0从
// http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
//
//Java作者：Mario Klingemann
// http://incubator.quasimondo.com
//创建于2004年2月29日
//Android端口：Yahel Bouaziz
// http://www.kayenko.com
//2012年4月5日移植
//这是高斯模糊和盒模糊之间的折衷
//它创建的模糊比长方体模糊好看得多，但是
//比我的高斯模糊实现快7倍。
//
//我称之为堆栈模糊，因为这最能描述
//过滤器在内部工作：它创建一种移动堆栈
//扫描图像时的颜色。因此
//只需在右侧添加一块新的颜色
//并移除最左边的颜色。剩余的
//堆栈最顶层的颜色可以添加到
//或减少1，取决于它们是否在右侧或右侧
//在堆栈的左侧。
//
//如果您在代码中使用此算法，请添加
//以下一行：
//
//Mario Klingemann的堆栈模糊算法
位图Bitmap=sentBitmap.copy（sentBitmap.getConfig（），true）；
如果（半径<1）{
返回（空）；
}
int w=bitmap.getWidth（）；
int h=bitmap.getHeight（）；
int[]pix=新int[w*h]；
Log.e（“pix”，w+“”+h+“”+pix.length）；
获取像素（像素，0，w，0，0，w，h）；
int-wm=w-1；
int hm=h-1；
int-wh=w*h；
int div=半径+半径+1；
int r[]=新的int[wh]；
int g[]=新的int[wh]；
int b[]=新int[wh]；
整数rsum，gsum，bsum，x，y，i，p，yp，yi，yw；
int vmin[]=新的int[Math.max（w，h）]；
int divsum=（div+1）>>1；
divsum*=divsum；
int dv[]=新的int[256*divsum]；
对于（i=0；i<256*divsum；i++）{
dv[i]=（i/divsum）；
}
yw=yi=0；
int[][]堆栈=新int[div][3]；
int堆栈指针；
int stackstart；
国际[]先生；
国际苏格兰皇家银行；
int r1=半径+1；
国际路苏姆、古松、布松；
内特林松、金松、宾松；
对于（y=0；y16；
sir[1]=（p&0x00ff00）>>8；
sir[2]=（p&0x0000ff）；
rbs=r1——数学绝对值（i）；
rsum+=sir[0]*rbs；
gsum+=sir[1]*rbs；
bsum+=sir[2]*rbs；
如果（i>0）{
rinsum+=sir[0]；
ginsum+=sir[1]；
binsum+=sir[2]；
}否则{
routsum+=sir[0]；
痛风+=爵士[1]；
boutsum+=sir[2]；
}
}
堆栈指针=半径；
对于（x=0；x>16；
sir[1]=（p&0x00ff00）>>8；
sir[2]=（p&0x0000ff）；
rinsum+=sir[0]；
ginsum+=sir[1]；
binsum+=sir[2]；
rsum+=rinsum；
gsum+=人参；
bsum+=binsum；
stackpointer=（stackpointer+1）%div；
sir=堆栈[（堆栈指针）%div]；
routsum+=sir[0]；
痛风+=爵士[1]；
boutsum+=sir[2]；
rinsum-=sir[0]；
人参属-
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Rect;
import android.os.AsyncTask;
import android.os.Build;
import android.support.v8.renderscript.Allocation;
import android.support.v8.renderscript.Element;
import android.support.v8.renderscript.RenderScript;
import android.support.v8.renderscript.ScriptIntrinsicBlur;
import android.view.View;

import org.pademobile.application.ApplicationLoader;

import java.util.concurrent.ExecutionException;


public class BlurService {

    public static BlurService instance;


    public static BlurService getInstance(){
        if(instance == null){
            instance = new BlurService();
        }
        return instance;
    }


    public Bitmap blurRenderScript(Bitmap smallBitmap)
    {
        Bitmap output = Bitmap.createBitmap(smallBitmap.getWidth(), smallBitmap.getHeight(), smallBitmap.getConfig());
        RenderScript rs = RenderScript.create(ApplicationLoader.mainContext);
        ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        Allocation inAlloc = Allocation.createFromBitmap(rs, smallBitmap, Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_GRAPHICS_TEXTURE);
        Allocation outAlloc = Allocation.createFromBitmap(rs, output);
        script.setRadius(25);
        script.setInput(inAlloc);
        script.forEach(outAlloc);
        outAlloc.copyTo(output);
        rs.destroy();
        return output;
    }

    public Bitmap blurRenderScript(Bitmap smallBitmap, int radius)
    {
        Bitmap output = Bitmap.createBitmap(smallBitmap.getWidth(), smallBitmap.getHeight(), smallBitmap.getConfig());
        RenderScript rs = RenderScript.create(ApplicationLoader.mainContext);
        ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        Allocation inAlloc = Allocation.createFromBitmap(rs, smallBitmap, Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_GRAPHICS_TEXTURE);
        Allocation outAlloc = Allocation.createFromBitmap(rs, output);
        script.setRadius(radius > 25 ? 25 : radius);
        script.setInput(inAlloc);
        script.forEach(outAlloc);
        outAlloc.copyTo(output);
        rs.destroy();
        return output;
    }
public Bitmap performRequestBlurByImage(Bitmap bitmap)
{
    DoAsyncBlur doAsyncBlur = new DoAsyncBlur();
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        doAsyncBlur.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, bitmap);
    } else {
        doAsyncBlur.execute(bitmap);
    }
    try {
        return doAsyncBlur.get();
    } catch (InterruptedException e) {
        return bitmap;
    } catch (ExecutionException e) {
        return bitmap;
    }
}

public Bitmap performRequestBlurByImageWithRadius(Bitmap bitmap, int radius)
{
    DoAsyncBlurWithRadius doAsyncBlur = new DoAsyncBlurWithRadius();
    doAsyncBlur.setRadius(radius);
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
        doAsyncBlur.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, bitmap);
    } else {
        doAsyncBlur.execute(bitmap);
    }
    try {
        return doAsyncBlur.get();
    } catch (InterruptedException e) {
        return bitmap;
    } catch (ExecutionException e) {
        return bitmap;
    }
}

private class DoAsyncBlur extends AsyncTask<Bitmap, Void, Bitmap> {

    @Override
    protected Bitmap doInBackground(Bitmap... bitmaps) {
        return blurRenderScript(bitmaps[0]);
    }
}

private class DoAsyncBlurWithRadius extends AsyncTask<Bitmap, Void, Bitmap> {
    private int radius;

    public void setRadius(int radius) {
        this.radius = radius;
    }

    @Override
    protected Bitmap doInBackground(Bitmap... bitmaps) {
        return blurRenderScript(bitmaps[0], radius);
    }
}