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Improved Stack Blur algorithm with its optimized version #112

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fc4cf93
Optimized stack blur implementation & fixes for Android S
KaustubhPatange Apr 27, 2021
f7ae952
Missed one replacement
KaustubhPatange Apr 27, 2021
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299 changes: 295 additions & 4 deletions blurry/src/main/java/jp/wasabeef/blurry/Blur.java
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Original file line number Diff line number Diff line change
Expand Up @@ -61,10 +61,15 @@ public static Bitmap of(Context context, Bitmap source, BlurFactor factor) {
paint.setColorFilter(filter);
canvas.drawBitmap(source, 0, 0, paint);

try {
bitmap = Blur.rs(context, bitmap, factor.radius);
} catch (RSRuntimeException e) {
bitmap = Blur.stack(bitmap, factor.radius, true);
if (Build.VERSION.SDK_INT >= 31) {
// Render script is deprecated in Android S
bitmap = Blur.optimizedStack(bitmap, factor.radius, true);
} else {
try {
bitmap = Blur.rs(context, bitmap, factor.radius);
} catch (RSRuntimeException e) {
bitmap = Blur.optimizedStack(bitmap, factor.radius, true);
}
}

if (factor.sampling == BlurFactor.DEFAULT_SAMPLING) {
Expand Down Expand Up @@ -349,4 +354,290 @@ private static Bitmap stack(Bitmap sentBitmap, int radius, boolean canReuseInBit

return (bitmap);
}

public static Bitmap optimizedStack(Bitmap sentBitmap, int radius, boolean canReuseInBitmap) {

/*
* An optimized version of stack blur, 2x faster than the original.
*
* @author Enrique López Mañas <eenriquelopez@gmail.com>
* http://www.neo-tech.es
*
* Author of the original algorithm: Mario Klingemann <mario.quasimondo.com>
*
* Based heavily on http://vitiy.info/Code/stackblur.cpp
* See http://vitiy.info/stackblur-algorithm-multi-threaded-blur-for-cpp/
*
* @copyright: Enrique López Mañas
* @license: Apache License 2.0
*/

Bitmap bitmap;
if (canReuseInBitmap) {
bitmap = sentBitmap;
} else {
bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
}

int w = bitmap.getWidth();
int h = bitmap.getHeight();
int[] src = new int[w * h];
bitmap.getPixels(src, 0, w, 0, 0, w, h);
int cores = EXECUTOR_THREADS;

for(int i = 0; i < cores; i++) {
internal_optimized_stack_iteration(src, w, h, radius, cores, i, 1);
internal_optimized_stack_iteration(src, w, h, radius, cores, i, 2);
}

return Bitmap.createBitmap(src, w, h, Bitmap.Config.ARGB_8888);
}

private static void internal_optimized_stack_iteration(int[] src, int w, int h, int radius, int cores, int core, int step) {
int x, y, xp, yp, i;
int sp;
int stack_start;
int stack_i;

int src_i;
int dst_i;

long sum_r, sum_g, sum_b,
sum_in_r, sum_in_g, sum_in_b,
sum_out_r, sum_out_g, sum_out_b;

int wm = w - 1;
int hm = h - 1;
int div = (radius * 2) + 1;
int mul_sum = stackblur_mul[radius];
byte shr_sum = stackblur_shr[radius];
int[] stack = new int[div];

if (step == 1)
{
int minY = core * h / cores;
int maxY = (core + 1) * h / cores;

for(y = minY; y < maxY; y++)
{
sum_r = sum_g = sum_b =
sum_in_r = sum_in_g = sum_in_b =
sum_out_r = sum_out_g = sum_out_b = 0;

src_i = w * y; // start of line (0,y)

for(i = 0; i <= radius; i++)
{
stack_i = i;
stack[stack_i] = src[src_i];
sum_r += ((src[src_i] >>> 16) & 0xff) * (i + 1);
sum_g += ((src[src_i] >>> 8) & 0xff) * (i + 1);
sum_b += (src[src_i] & 0xff) * (i + 1);
sum_out_r += ((src[src_i] >>> 16) & 0xff);
sum_out_g += ((src[src_i] >>> 8) & 0xff);
sum_out_b += (src[src_i] & 0xff);
}


for(i = 1; i <= radius; i++)
{
if (i <= wm) src_i += 1;
stack_i = i + radius;
stack[stack_i] = src[src_i];
sum_r += ((src[src_i] >>> 16) & 0xff) * (radius + 1 - i);
sum_g += ((src[src_i] >>> 8) & 0xff) * (radius + 1 - i);
sum_b += (src[src_i] & 0xff) * (radius + 1 - i);
sum_in_r += ((src[src_i] >>> 16) & 0xff);
sum_in_g += ((src[src_i] >>> 8) & 0xff);
sum_in_b += (src[src_i] & 0xff);
}


sp = radius;
xp = radius;
if (xp > wm) xp = wm;
src_i = xp + y * w; // img.pix_ptr(xp, y);
dst_i = y * w; // img.pix_ptr(0, y);
for(x = 0; x < w; x++)
{
src[dst_i] = (int)
((src[dst_i] & 0xff000000) |
((((sum_r * mul_sum) >>> shr_sum) & 0xff) << 16) |
((((sum_g * mul_sum) >>> shr_sum) & 0xff) << 8) |
((((sum_b * mul_sum) >>> shr_sum) & 0xff)));
dst_i += 1;

sum_r -= sum_out_r;
sum_g -= sum_out_g;
sum_b -= sum_out_b;

stack_start = sp + div - radius;
if (stack_start >= div) stack_start -= div;
stack_i = stack_start;

sum_out_r -= ((stack[stack_i] >>> 16) & 0xff);
sum_out_g -= ((stack[stack_i] >>> 8) & 0xff);
sum_out_b -= (stack[stack_i] & 0xff);

if(xp < wm)
{
src_i += 1;
++xp;
}

stack[stack_i] = src[src_i];

sum_in_r += ((src[src_i] >>> 16) & 0xff);
sum_in_g += ((src[src_i] >>> 8) & 0xff);
sum_in_b += (src[src_i] & 0xff);
sum_r += sum_in_r;
sum_g += sum_in_g;
sum_b += sum_in_b;

++sp;
if (sp >= div) sp = 0;
stack_i = sp;

sum_out_r += ((stack[stack_i] >>> 16) & 0xff);
sum_out_g += ((stack[stack_i] >>> 8) & 0xff);
sum_out_b += (stack[stack_i] & 0xff);
sum_in_r -= ((stack[stack_i] >>> 16) & 0xff);
sum_in_g -= ((stack[stack_i] >>> 8) & 0xff);
sum_in_b -= (stack[stack_i] & 0xff);
}

}
}
// step 2
else if (step == 2)
{
int minX = core * w / cores;
int maxX = (core + 1) * w / cores;

for(x = minX; x < maxX; x++)
{
sum_r = sum_g = sum_b =
sum_in_r = sum_in_g = sum_in_b =
sum_out_r = sum_out_g = sum_out_b = 0;

src_i = x; // x,0
for(i = 0; i <= radius; i++)
{
stack_i = i;
stack[stack_i] = src[src_i];
sum_r += ((src[src_i] >>> 16) & 0xff) * (i + 1);
sum_g += ((src[src_i] >>> 8) & 0xff) * (i + 1);
sum_b += (src[src_i] & 0xff) * (i + 1);
sum_out_r += ((src[src_i] >>> 16) & 0xff);
sum_out_g += ((src[src_i] >>> 8) & 0xff);
sum_out_b += (src[src_i] & 0xff);
}
for(i = 1; i <= radius; i++)
{
if(i <= hm) src_i += w; // +stride

stack_i = i + radius;
stack[stack_i] = src[src_i];
sum_r += ((src[src_i] >>> 16) & 0xff) * (radius + 1 - i);
sum_g += ((src[src_i] >>> 8) & 0xff) * (radius + 1 - i);
sum_b += (src[src_i] & 0xff) * (radius + 1 - i);
sum_in_r += ((src[src_i] >>> 16) & 0xff);
sum_in_g += ((src[src_i] >>> 8) & 0xff);
sum_in_b += (src[src_i] & 0xff);
}

sp = radius;
yp = radius;
if (yp > hm) yp = hm;
src_i = x + yp * w; // img.pix_ptr(x, yp);
dst_i = x; // img.pix_ptr(x, 0);
for(y = 0; y < h; y++)
{
src[dst_i] = (int)
((src[dst_i] & 0xff000000) |
((((sum_r * mul_sum) >>> shr_sum) & 0xff) << 16) |
((((sum_g * mul_sum) >>> shr_sum) & 0xff) << 8) |
((((sum_b * mul_sum) >>> shr_sum) & 0xff)));
dst_i += w;

sum_r -= sum_out_r;
sum_g -= sum_out_g;
sum_b -= sum_out_b;

stack_start = sp + div - radius;
if(stack_start >= div) stack_start -= div;
stack_i = stack_start;

sum_out_r -= ((stack[stack_i] >>> 16) & 0xff);
sum_out_g -= ((stack[stack_i] >>> 8) & 0xff);
sum_out_b -= (stack[stack_i] & 0xff);

if(yp < hm)
{
src_i += w; // stride
++yp;
}

stack[stack_i] = src[src_i];

sum_in_r += ((src[src_i] >>> 16) & 0xff);
sum_in_g += ((src[src_i] >>> 8) & 0xff);
sum_in_b += (src[src_i] & 0xff);
sum_r += sum_in_r;
sum_g += sum_in_g;
sum_b += sum_in_b;

++sp;
if (sp >= div) sp = 0;
stack_i = sp;

sum_out_r += ((stack[stack_i] >>> 16) & 0xff);
sum_out_g += ((stack[stack_i] >>> 8) & 0xff);
sum_out_b += (stack[stack_i] & 0xff);
sum_in_r -= ((stack[stack_i] >>> 16) & 0xff);
sum_in_g -= ((stack[stack_i] >>> 8) & 0xff);
sum_in_b -= (stack[stack_i] & 0xff);
}
}
}
}

private static final int EXECUTOR_THREADS = Runtime.getRuntime().availableProcessors();
private static final short[] stackblur_mul = {
512, 512, 456, 512, 328, 456, 335, 512, 405, 328, 271, 456, 388, 335, 292, 512,
454, 405, 364, 328, 298, 271, 496, 456, 420, 388, 360, 335, 312, 292, 273, 512,
482, 454, 428, 405, 383, 364, 345, 328, 312, 298, 284, 271, 259, 496, 475, 456,
437, 420, 404, 388, 374, 360, 347, 335, 323, 312, 302, 292, 282, 273, 265, 512,
497, 482, 468, 454, 441, 428, 417, 405, 394, 383, 373, 364, 354, 345, 337, 328,
320, 312, 305, 298, 291, 284, 278, 271, 265, 259, 507, 496, 485, 475, 465, 456,
446, 437, 428, 420, 412, 404, 396, 388, 381, 374, 367, 360, 354, 347, 341, 335,
329, 323, 318, 312, 307, 302, 297, 292, 287, 282, 278, 273, 269, 265, 261, 512,
505, 497, 489, 482, 475, 468, 461, 454, 447, 441, 435, 428, 422, 417, 411, 405,
399, 394, 389, 383, 378, 373, 368, 364, 359, 354, 350, 345, 341, 337, 332, 328,
324, 320, 316, 312, 309, 305, 301, 298, 294, 291, 287, 284, 281, 278, 274, 271,
268, 265, 262, 259, 257, 507, 501, 496, 491, 485, 480, 475, 470, 465, 460, 456,
451, 446, 442, 437, 433, 428, 424, 420, 416, 412, 408, 404, 400, 396, 392, 388,
385, 381, 377, 374, 370, 367, 363, 360, 357, 354, 350, 347, 344, 341, 338, 335,
332, 329, 326, 323, 320, 318, 315, 312, 310, 307, 304, 302, 299, 297, 294, 292,
289, 287, 285, 282, 280, 278, 275, 273, 271, 269, 267, 265, 263, 261, 259
};

private static final byte[] stackblur_shr = {
9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,
17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19,
19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24
};
}