Android高斯模糊、高斯平滑（Gaussian Blur）【2】
Android上的高斯模糊效果实现，策略不唯一，在github上有一个开源的实现算法：
/paveldudka/blurring
性能上对附录参考文章【1】进行了改进和提升。
Java代码：
package zhangphil.blur;import android.widget.ImageView;import android.widget.TextView;import android.annotation.TargetApi;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.drawable.BitmapDrawable;import android.os.Build;import android.os.Bundle;import android.view.View;import android.view.ViewTreeObserver;public class MainActivity extends Activity {private ImageView image;private TextView text;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);image = (ImageView) findViewById(R.id.image);text = (TextView) findViewById(R.id.text);image.setImageResource(R.drawable.pic);applyBlur();}private void applyBlur() {image.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {@Overridepublic boolean onPreDraw() {image.getViewTreeObserver().removeOnPreDrawListener(this);image.buildDrawingCache();Bitmap bmp = image.getDrawingCache();blur(bmp, text);return true;}});}//为一个view增加一个以Bitmap bkg为底的高斯模糊图@TargetApi(Build.VERSION_CODES.JELLY_BEAN)private void blur(Bitmap bkg, View view) {float scaleFactor = 1;float radius = 20;//性能优先。如果换成这组数据,则速度明显提高//scaleFactor = 8;//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));}}
布局文件：
<?xml version="1.0" encoding="utf-8"?><FrameLayout xmlns:android="/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent" ><ImageViewandroid:id="@+id/image"android:layout_width="match_parent"android:layout_height="match_parent"android:src="@drawable/pic" /><TextViewandroid:id="@+id/text"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_gravity="center"android:gravity="center"android:padding="5dip"android:text="Zhang Phil @ CSDN"android:textColor="@android:color/white"android:textSize="25sp"android:textStyle="bold" /></FrameLayout>
FastBlur.java工具类：
package zhangphil.blur;import android.graphics.Bitmap;import android.util.Log;public class FastBlur {public Bitmap fastblur(Bitmap sentBitmap, int radius) {// Stack Blur v1.0 from// /StackBlurForCanvas/StackBlurDemo.html//// Java Author: Mario Klingemann <mario at >// // created Feburary 29, // Android port : Yahel Bouaziz <yahel at >// // ported april 5th, // 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@>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);}public static Bitmap doBlur(Bitmap sentBitmap, int radius,boolean canReuseInBitmap) {// Stack Blur v1.0 from// /StackBlurForCanvas/StackBlurDemo.html//// Java Author: Mario Klingemann <mario at >// // created Feburary 29, // Android port : Yahel Bouaziz <yahel at >// // ported april 5th, // 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@>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);}}
处理前的图片pic.png：
代码运行结果：
附录参考文章：
【文章1】《Android高斯模糊、高斯平滑（Gaussian Blur）【1】》链接地址：/zhangphil/article/details/49981499
