Android 图片虚化，虚化图片，模糊图片

Blur

自从iOS系统引入了Blur效果，也就是所谓的毛玻璃、模糊化效果，磨砂效果，各大系统就开始竞相模仿，这是一个怎样的效果呢，我们现来看一些图：

这些就是典型的Blur效果，在iOS和MIUI中还有很多，这里就不再贴图了。

有兴趣的朋友可以去看看。

使用

下面我们来看看如何在Android中来使用Blur，当然，我们需要使用上面提到的FastBlur

packagecom.xys.blur; importandroid.graphics.Bitmap; /** * Created by paveld on 3/6/14. */public class FastBlur {     publicstatic Bitmap doBlur(Bitmap sentBitmap, intradius, booleancanReuseInBitmap) {         // 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 <[e-mail]>         Bitmap bitmap;        if(canReuseInBitmap) {            bitmap = sentBitmap;        }else{            bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);        }         if(radius < 1) {            return(null);        }         intw = bitmap.getWidth();        inth = bitmap.getHeight();         int[] pix = newint[w * h];        bitmap.getPixels(pix,0, w, 0,0, w, h);         intwm = w - 1;        inthm = h - 1;        intwh = w * h;        intdiv = radius + radius + 1;         intr[] = newint[wh];        intg[] = newint[wh];        intb[] = newint[wh];        intrsum, gsum, bsum, x, y, i, p, yp, yi, yw;        intvmin[] = newint[Math.max(w, h)];         intdivsum = (div + 1) >> 1;        divsum *= divsum;        intdv[] = newint[256* divsum];        for(i = 0; i < 256* divsum; i++) {            dv[i] = (i / divsum);        }         yw = yi = 0;         int[][] stack = newint[div][3];        intstackpointer;        intstackstart;        int[] sir;        intrbs;        intr1 = radius + 1;        introutsum, goutsum, boutsum;        intrinsum, 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);    }}

算法就是这样了，不要问我懂不懂，你懂的。

使用

如何在程序中使用呢，也很简单：

package com.xys.blur; import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.view.View;import android.view.ViewTreeObserver.OnPreDrawListener;import android.widget.ImageView; public class Test extends Activity {     @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        final ImageView imageView = (ImageView) findViewById(R.id.image1);         final Bitmap bitmap = BitmapFactory.decodeResource(getResources(),                R.drawable.blur);         imageView.getViewTreeObserver().addOnPreDrawListener(                new OnPreDrawListener() {                     @Override                    public boolean onPreDraw() {                        blur(bitmap, imageView);                        return true;                    }                });    }     private void blur(Bitmap bkg, View view) {        long startMs = System.currentTimeMillis();        float scaleFactor = 8;        float radius = 2;         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);         overlay = FastBlur.doBlur(overlay, (int) radius, true);        view.setBackground(new BitmapDrawable(getResources(), overlay));        System.out.println(System.currentTimeMillis() - startMs + "ms");    }}

为什么我们要在addOnPreDrawListener中来调用blur方法呢，看我前面的文章的朋友应该会知道，这样做是为了能够在onCreate中获取控件尺寸，通过scaleFactor和radius两个参数，我们来控制Blur的程度。

代码中还有几点需要解释下：

1、我们为什么要通过scaleFactor来缩小图片：由于在做Blur的时候，图片精度本来就要降低，那么我们为什么不先降低精度再去处理呢，这样的效果就是巨大的缩小了生成时间

2、我们给Paint提供了FILTER_BITMAP_FLAG标示，这样的话在处理bitmap缩放的时候，就可以达到双缓冲的效果，模糊处理的过程就更加顺畅了

3、如果我们要做某一部分的Blur效果，一般是将这部分图片裁减下来，然后Blur后设给某个控件的背景

最终效果如下：

效果已经出来了，Demo很简单，只是为了演示使用方法。

以上。