Android 背景模糊

1.在一些社交app中每每看到以下图片：

最近工作中有用到，研究了以下，希望能够对大家起到一个抛砖引玉的作用。
首先：在网络上找了一个模糊图片的工具类

package com.sinocloud;import android.graphics.Bitmap;/*** Created by paveld on 3/6/14.*/
public class FastBlur {public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {// Stack Blur v1.0 from// http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html//// Java Author: Mario Klingemann // http://incubator.quasimondo.com// created Feburary 29, 2004// Android port : Yahel Bouaziz // 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 Bitmap bitmap;if (canReuseInBitmap) {bitmap = sentBitmap;} else {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];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;}}bitmap.setPixels(pix, 0, w, 0, 0, w, h);return (bitmap);}
}

至于里面是怎么模糊的我也搞不清楚。
2.在需要进行模糊的页面，写一个线程，进行图片的模糊（在主线程完成这样耗时的操作不好）
ps:据美工将，仅仅图片模糊还不行，有些图片颜色太淡了，需要添加一个透明度为40%的黑色

private Bitmap blur(Bitmap bkg) {bkg = ThumbnailUtils.extractThumbnail(bkg, scaleImageSize,scaleImageSize);int radius = 10;Bitmap overlay = Bitmap.createBitmap(scaleImageSize, scaleImageSize,Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(overlay);Paint paint = new Paint();paint.setFlags(Paint.FILTER_BITMAP_FLAG);canvas.drawBitmap(bkg, 0, 0, paint);overlay = FastBlur.doBlur(overlay, (int) radius, true);canvas.save();canvas.drawARGB(102, 0, 0, 0);canvas.restore();return overlay;}

注意：255*40%=102；radius如果写的太小就没有效果，写的太大影响模糊效率。至于多少，还请大家根据项目需要来定啊。
3.在线程完成之后，给handler发送消息，进行页面刷新（PS：在非主线程中刷新页面会报错），为了防止内存泄露，最近学了一种比较好的handler的方法：

static class BlurHandler extends Handler {private final WeakReference weakReference;public BlurHandler(ScrubActivity scrub) {weakReference = new WeakReference(scrub);}@SuppressWarnings("deprecation")@Overridepublic void handleMessage(Message msg) {ScrubActivity scrub = weakReference.get();if (scrub != null) {if (android.os.Build.VERSION.SDK_INT >= 16) {scrub.mLinearTwo.setBackground(new BitmapDrawable(scrub.getResources(), scrub.destBitmap));} else {scrub.mLinearTwo.setBackgroundDrawable(new BitmapDrawable(scrub.getResources(), scrub.destBitmap));}}}}

至此结束了：下面贴上调用页面的完整代码：

/* Cking Inc. (C) 2014. All rights reserved.** ScrubActivity.java* classes : com.sinocloud.ScrubActivity* @author "zwl"* V 1.0.0* Create at 2014年7月28日 上午10:23:11*/
package com.sinocloud;import java.lang.ref.WeakReference;import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.drawable.BitmapDrawable;
import android.media.ThumbnailUtils;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.widget.LinearLayout;/*** com.sinocloud.ScrubActivity* */
public class ScrubActivity extends Activity {private LinearLayout mLinearTwo;Bitmap srcBitmap;Bitmap destBitmap;final int scaleImageSize = 100;BlurHandler mBlurHandler;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_scrub);mBlurHandler = new BlurHandler(this);mLinearTwo = (LinearLayout) findViewById(R.id.linear_two);srcBitmap = ((BitmapDrawable) getResources().getDrawable(R.drawable.test_light)).getBitmap();// blur(bmp, mLinearTwo);new BlurThread().start();}class BlurThread extends Thread {@Overridepublic void run() {super.run();destBitmap = blur(srcBitmap);mBlurHandler.sendEmptyMessage(0);}}static class BlurHandler extends Handler {private final WeakReference weakReference;public BlurHandler(ScrubActivity scrub) {weakReference = new WeakReference(scrub);}@SuppressWarnings("deprecation")@Overridepublic void handleMessage(Message msg) {ScrubActivity scrub = weakReference.get();if (scrub != null) {if (android.os.Build.VERSION.SDK_INT >= 16) {scrub.mLinearTwo.setBackground(new BitmapDrawable(scrub.getResources(), scrub.destBitmap));} else {scrub.mLinearTwo.setBackgroundDrawable(new BitmapDrawable(scrub.getResources(), scrub.destBitmap));}}}}private Bitmap blur(Bitmap bkg) {bkg = ThumbnailUtils.extractThumbnail(bkg, scaleImageSize,scaleImageSize);int radius = 10;Bitmap overlay = Bitmap.createBitmap(scaleImageSize, scaleImageSize,Bitmap.Config.ARGB_8888);Canvas canvas = new Canvas(overlay);Paint paint = new Paint();paint.setFlags(Paint.FILTER_BITMAP_FLAG);canvas.drawBitmap(bkg, 0, 0, paint);overlay = FastBlur.doBlur(overlay, (int) radius, true);canvas.save();canvas.drawARGB(102, 0, 0, 0);canvas.restore();return overlay;}}

另附Demo方便大家品鉴，http://download.csdn.net/detail/guchuanhang/9040883

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