Hướng dẫn blur một ảnh bitmap

Hôm nay mình chia sẽ 1 đoạn code blur ảnh , làm cho ảnh avatar thêm sinh động .

http://upques.com/questions/huong-dan-blur-mot-anh-bitmap-56dc38fb70eb730b5091f182

@SuppressLint("NewApi")
    public static Bitmap blurRenderScript(Context context, Bitmap smallBitmap, int radius) {
        //http://stackoverflow.com/questions/32786838/android-renderscript-support-library-error-loading-rs-jni-library?rq=1
        //https://code.google.com/p/android/issues/detail?id=68520
        final String architecture = System.getProperty("os.arch");
        Log.d("architecture", architecture);
        if ("armeabi-v7a".equalsIgnoreCase(architecture)) {
            try {
                RenderScript renderScript = RenderScript.create(context);

                smallBitmap = RGB565toARGB888(smallBitmap);

                Bitmap bitmap = Bitmap.createBitmap(
                        smallBitmap.getWidth(), smallBitmap.getHeight(),
                        Bitmap.Config.ARGB_8888);

                Allocation blurInput = Allocation.createFromBitmap(renderScript, smallBitmap);
                Allocation blurOutput = Allocation.createFromBitmap(renderScript, bitmap);

                ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(renderScript,
                        Element.U8_4(renderScript));
                blur.setInput(blurInput);
                blur.setRadius(radius); // radius must be 0 < r <= 25
                blur.forEach(blurOutput);

                blurOutput.copyTo(bitmap);
                renderScript.destroy();

                return bitmap;
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        // This devices architecture not supported blur image.
//        // I just used flag filter=true in bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true); for blur.
//        return Bitmap.createScaledBitmap(smallBitmap, smallBitmap.getWidth(), smallBitmap.getHeight(), true);
        //http://stackoverflow.com/questions/2067955/fast-bitmap-blur-for-android-sdk
        return fastblur(smallBitmap, 1, radius);
    }

    /**
     * Stack Blur v1.0 from
     * http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
     * Java Author: Mario Klingemann <mario at quasimondo.com>
     * http://incubator.quasimondo.com
     * <p/>
     * created Feburary 29, 2004
     * Android port : Yahel Bouaziz <yahel at kayenko.com>
     * http://www.kayenko.com
     * ported april 5th, 2012
     * <p/>
     * 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.
     * <p/>
     * 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.
     * <p/>
     * If you are using this algorithm in your code please add
     * the following line:
     * Stack Blur Algorithm by Mario Klingemann <mario@quasimondo.com>
     */

    public static Bitmap fastblur(Bitmap sentBitmap, float scale, int radius) {

        int width = Math.round(sentBitmap.getWidth() * scale);
        int height = Math.round(sentBitmap.getHeight() * scale);
        sentBitmap = Bitmap.createScaledBitmap(sentBitmap, width, height, false);

        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 RGB565toARGB888(Bitmap img) throws Exception {
        int numPixels = img.getWidth() * img.getHeight();
        int[] pixels = new int[numPixels];

        //Get JPEG pixels.  Each int is the color values for one pixel.
        img.getPixels(pixels, 0, img.getWidth(), 0, 0, img.getWidth(), img.getHeight());

        //Create a Bitmap of the appropriate format.
        Bitmap result = Bitmap.createBitmap(img.getWidth(), img.getHeight(), Bitmap.Config.ARGB_8888);

        //Set RGB pixels.
        result.setPixels(pixels, 0, result.getWidth(), 0, 0, result.getWidth(), result.getHeight());
        return result;
    }