package com.mixpanel.android.util;
import android.graphics.Bitmap;
/**
* <p>StackBlur v1.0 for Android</p>
*
* <p>Author: Enrique López Mañas <eenriquelopez@gmail.com></p>
* <p>http://www.neo-tech.es</p>
*
* <p>Author of the original algorithm: Mario Klingemann <mario.quasimondo.com></p>
*
* <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>
* <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>
*
* <p>Copyright: Enrique López Mañas</p>
* <p>License: Apache License 2.0</p>
*
* <p>This file has been modified from its original version by Mixpanel, Inc
* The original was retrieved from
* https://github.com/kikoso/android-stackblur on October 23rd, 2013</p>
*/
public class StackBlurManager {
public static void process(Bitmap source, int radius) {
if (radius < 1) {
return; // No work to do
}
final int width = source.getWidth();
final int height = source.getHeight();
final int[] currentPixels = new int[width * height];
source.getPixels(currentPixels, 0, width, 0, 0, width, height);
final int wm = width-1;
final int hm = height-1;
final int wh = width * height;
final int div = radius + radius + 1;
final int r[] = new int[wh];
final int g[] = new int[wh];
final int b[] = new int[wh];
int rsum, gsum, bsum, x, y, i, p, yp;
final int vmin[] = new int[Math.max(width, height)];
int divsum = (div+1)>>1;
divsum *= divsum;
final int dv[] = new int[256*divsum];
for (i = 0; i < 256 * divsum;i++){
dv[i] = i / divsum;
}
int yw = 0;
int yi = 0;
final int[][] stack = new int[div][3];
int stackpointer;
int stackstart;
int[] sir;
int rbs;
final int r1=radius+1;
int routsum,goutsum,boutsum;
int rinsum,ginsum,binsum;
for (y=0; y < height; y++){
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
for(i = -radius; i <= radius; i++){
p = currentPixels[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 < width; 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 = currentPixels[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 += width;
}
for (x=0; x < width; x++){
rinsum = ginsum = binsum = routsum = goutsum = boutsum = rsum = gsum = bsum = 0;
yp = -radius * width;
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 += width;
}
}
yi=x;
stackpointer=radius;
for (y = 0; y < height; y++){
currentPixels[yi] = 0xff000000 | (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) * width;
}
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 += width;
}
}
source.setPixels(currentPixels, 0, width, 0, 0, width, height);
}// process()
}