最近在做一款叫叽叽的App（男银懂的），其中有一个功能需要对图片处理实现毛玻璃的特效

进过一番预研，找到了3中实现方案，其中各有优缺点：

1、如果系统的api在16以上，可以使用系统提供的方法直接处理图片

复制代码 代码如下:

if (VERSION.SDK_INT > 16) {

Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);

final RenderScript rs = RenderScript.create(context);

final Allocation input = Allocation.createFromBitmap(rs, sentBitmap, Allocation.MipmapControl.MIPMAP_NONE,

Allocation.USAGE_SCRIPT);

final Allocation output = Allocation.createTyped(rs, input.getType());

final ScriptIntrinsicBlur script = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));

script.setRadius(radius /* e.g. 3.f */);

script.setInput(input);

script.forEach(output);

output.copyTo(bitmap);

return bitmap;

}

2、 如果Api条件不满足，可以使用如下方法

复制代码 代码如下:

@SuppressLint("NewApi")

public static Bitmap fastblur(Context context, Bitmap sentBitmap, int radius) {

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 temp = 256 * divsum;

int dv[] = new int[temp];

for (i = 0; i < temp; 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);

}

3、以上方法都存在一个问题，性能较低，下面提供一个C实现

复制代码 代码如下:

static int* StackBlur(int* pix, int w, int h, int radius) {

int wm = w - 1;

int hm = h - 1;

int wh = w * h;

int div = radius + radius + 1;

int *r = (int *)malloc(wh * sizeof(int));

int *g = (int *)malloc(wh * sizeof(int));

int *b = (int *)malloc(wh * sizeof(int));

int rsum, gsum, bsum, x, y, i, p, yp, yi, yw;

int *vmin = (int *)malloc(MAX(w,h) * sizeof(int));

int divsum = (div + 1) >> 1;

divsum *= divsum;

int *dv = (int *)malloc(256 * divsum * sizeof(int));

for (i = 0; i < 256 * divsum; i++) {

dv[i] = (i / divsum);

}

yw = yi = 0;

int(*stack)[3] = (int(*)[3])malloc(div * 3 * sizeof(int));

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 + (MIN(wm, MAX(i, 0)))];

sir = stack[i + radius];

sir[0] = (p & 0xff0000) >> 16;

sir[1] = (p & 0x00ff00) >> 8;

sir[2] = (p & 0x0000ff);

rbs = r1 - 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] = 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 = MAX(0, yp) + x;

sir = stack[i + radius];

sir[0] = r[yi];

sir[1] = g[yi];

sir[2] = b[yi];

rbs = r1 - 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] = 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;

}

}

free(r);

free(g);

free(b);

free(vmin);

free(dv);

free(stack);

return(pix);

}