做项目时遇到要做图片模糊的需求，和微信语音通话的背景效果一样。网上有很多不错的博客，记录一下使用的两种方式。
1. 先来看看第一种，博客原文
首先创建一个工具类
/**
* 快速模糊化工具
*/
public class FastBlur {
public static Bitmap doBlur(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {
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);
}
}
然后在需要图片模糊的地方调用即可
private int scaleRatio = 5;
private int blurRadius = 10;
Bitmap mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.header1);
Bitmap scaledBitmap = Bitmap.createScaledBitmap(mBitmap,
mBitmap.getWidth() / scaleRatio,
mBitmap.getHeight() / scaleRatio,
false);
Bitmap blurBitmap = FastBlur.doBlur(scaledBitmap, blurRadius, true);
imgBg.setImageBitmap(blurBitmap);
这个大家可以去看看原博主的文章，就不赘述了。
2. 接下来看第二种方式。利用Glide 和 Glide Transformations实现高斯模糊
Gilde功能十分强大，它可以实现图片处理、图片本地加载、图片网络加载、位图加载、图片内存缓存、图片磁盘缓存、Gif图片加载。
Glide中的Transformations用于在图片显示前对图片进行处理。glide-transformations 这个库为Glide提供了多种多样的 Transformations实现。
// 图片资源加载库
implementation 'com.github.bumptech.glide:glide:4.13.0'
annotationProcessor 'com.github.bumptech.glide:compiler:4.13.0'
implementation 'jp.wasabeef:glide-transformations:4.3.0'
通过这两个库的结合使用，就可以使用其中的BlurTransformation实现图片的高斯模糊
/**
* new BlurTransformation() 模糊图片,参数为模糊度
*
* 注意： RequestOptions options5 = new RequestOptions();
* options5.bitmapTransform(new BlurTransformation()); 设置无效,可能作废
*/
MultiTransformation mation4 = new MultiTransformation(new BlurTransformation(90));
// 设置网络图片资源
Glide.with(this)
.load("https://t7.baidu.com/it/u=1285847167,3193778276&fm=193&f=GIF")
.apply(RequestOptions.bitmapTransform(mation4))
.into(imgBg);
// 设置本地图片资源
Glide.with(this)
.load(getDrawable(R.drawable.header1))
.apply(RequestOptions.bitmapTransform(mation4))
.into(imgBg);
第二种方式对我来说比较友好，不仅可以设置本地图片模糊，也可以网络图片模糊。