android 毛玻璃模糊效果背景实现

今天我们来简单了解一下Android开发上的几种图片高斯模糊技术的效果实现。

1，首先看实现前效果图（这图别介意，这不是重点）：



2，高斯模糊实现后效果图
：



一，利用 RenderScript接口 

RenderScript 是一种低级的高性能编程语言，用于3D渲染和处理密集型计算，RenderScript
也是3.0 以后才开始引用，所以需要进行一定的兼容性，从代码实现上来说是最简单也相对高效的实现. 在此过程中会遇到问题（比如当模糊半径
(radius)变大后会直接出现计算性能问题. 模糊半径不能大于25，因此,
直接使用ScriptIntrinsicBlur也不能得到模糊程度较高的图片），下面看代码。

1，Activity
文件

public class MainActivity extends Activity {

private ImageView iv_image;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
iv_image = (ImageView) findViewById(R.id.iv_image);
iv_image.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
new MakeBitmapAsyncTask().execute();//建议用AsynTask或者其他机制来处理
}
});
}

@TargetApi(Build.VERSION_CODES.KITKAT)
private Bitmap blur(Bitmap bitmap, View view) {
// 把 bitmap的尺寸缩小到原图的1/8 这时候bitmap在模糊处理过程中先被缩小然再放大
float scaleFactor = 8;
float radius = 3;
Bitmap overlayBmp = Bitmap.createBitmap((int) (view.getMeasuredWidth() / scaleFactor),
(int) (view.getMeasuredHeight() / scaleFactor), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(overlayBmp);
canvas.translate(-view.getLeft() / scaleFactor, -view.getTop() / scaleFactor);
canvas.scale(1 / scaleFactor, 1 / scaleFactor);
Paint paint = new Paint();
// 这里bitmap缩放时 加FILTER_BITMAP_FLAG会更加顺畅
paint.setFlags(Paint.FILTER_BITMAP_FLAG);
canvas.drawBitmap(bitmap, 0, 0, paint);
// 通过 RenderScript 调用底层接口来实现高斯模糊计算
RenderScript rs = RenderScript.create(MainActivity.this);
Allocation overlayAlloc = Allocation.createFromBitmap(rs, overlayBmp);
// 有个缺点那就是 ScriptIntrinsicBlur只支持API17以上
ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(rs, overlayAlloc.getElement());
blur.setInput(overlayAlloc);
blur.setRadius(radius);
blur.forEach(overlayAlloc);
overlayAlloc.copyTo(overlayBmp);
rs.destroy();
return overlayBmp;
}

private class MakeBitmapAsyncTask extends AsyncTask<String, Void, Bitmap> {
@Override
protected Bitmap doInBackground(String... params) {
View view = getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache(true);
Bitmap bitmap = view.getDrawingCache();
return blur(bitmap, view);
}
@Override
protected void onPostExecute(Bitmap result) {
super.onPostExecute(result);
iv_image.setBackground(new BitmapDrawable(getResources(), result));
}
}
}

2，activity_main.xml 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">

<ImageView
android:id="@+id/iv_image"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:background="@drawable/image" />

</RelativeLayout>

二，使用 FashBlur 实现

FastBlur进行模糊操作比Renderscript
要快一些，因为FastBlur在进行bitmap复制操作时还同时进行其他操作，所以说节省了一些时间。

1，Activity
文件

public class MainActivity2 extends Activity {

private ImageView iv_image2;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
iv_image2 = (ImageView) findViewById(R.id.iv_image2);
iv_image2.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {

@Override
public boolean onPreDraw() {
iv_image2.getViewTreeObserver().removeOnPreDrawListener(this);
iv_image2.buildDrawingCache();
Bitmap bmp = iv_image2.getDrawingCache();
blur(bmp, iv_image2);
return true;
}
});
}

private void blur(Bitmap bkg, View view) {
float scaleFactor = 8;
float radius = 3;
Bitmap overlay = Bitmap.createBitmap((int) (view.getMeasuredWidth() / scaleFactor),
(int) (view.getMeasuredHeight() / scaleFactor), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(overlay);
canvas.translate(-view.getLeft() / scaleFactor, -view.getTop() / scaleFactor);
canvas.scale(1 / scaleFactor, 1 / scaleFactor);
Paint paint = new Paint();
paint.setFlags(Paint.FILTER_BITMAP_FLAG);
canvas.drawBitmap(bkg, 0, 0, paint);
//然后通过FastBlur.doBlur() 实现处理
overlay = FastBlur.doBlur(overlay, (int) radius, true);
view.setBackground(new BitmapDrawable(getResources(), overlay));
}
}

2，activity_main2.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent">

<ImageView
android:id="@+id/iv_image2"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
android:background="@drawable/image" />

</RelativeLayout>

3，FastBlur.java 

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++) {
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);
}
}

其实模糊算法在 java层实现对性能有影响，如果你想做到高效率的模糊效果，那就必须用到JNI来实现。

好了，如果有兴趣可以看看这些文章或许对你有帮助： http://blog.csdn.net/grp0916/article/details/50494712 https://github.com/kikoso/android-stackblur https://github.com/harism/android_anndblur https://github.com/500px/500px-android-blur