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DEFINITIONS
This source file includes following definitions.
- ibbox_new
- ibbox_destroy
- get_bitmap_bboxes_simple
- head_new
- head_delete
- link_to
- ibbox_does_overlap
- ibbox_expand
- merge
- annotate
- overlap_bboxes
- compare_circle_coord
- search_vicinity
- fix_small_boxes
- display
- get_bitmap_bboxes
- main
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <math.h>
#include <assert.h>
#include "../types.h"
#include "../mem.h"
typedef struct _ibbox {
int xmin,ymin,xmax,ymax;
struct _ibbox*next;
} ibbox_t;
ibbox_t* ibbox_new(int x1, int y1, int x2, int y2)
{
ibbox_t*b = (ibbox_t*)rfx_calloc(sizeof(ibbox_t));
b->xmin = x1;
b->ymin = y1;
b->xmax = x2;
b->ymax = y2;
return b;
}
void ibbox_destroy(ibbox_t*b)
{
while(b) {
ibbox_t*next = b->next;
free(b);
b = next;
}
}
ibbox_t*get_bitmap_bboxes_simple(unsigned char*alpha, int width, int height)
{
int ymin = -1;
int ymax = -1;
int xmin = width;
int xmax = 0;
int x,y;
for(y=0;y<height;y++) {
unsigned char*a = &alpha[y*width];
for(x=0;x<width;x++) {
if(a[x]) break;
}
int left = x; //first occupied pixel from left
int right = x+1; //last non-occupied pixel from right
for(;x<width;x++) {
if(a[x]) right=x+1;
}
if(left!=width) {
if(ymin<0)
ymin=y;
ymax=y+1;
if(left<xmin) xmin = left;
if(right>xmax) xmax = right;
}
}
ibbox_t* bbox = 0;
if(xmin<xmax || ymin<ymax) {
bbox = ibbox_new(xmin, ymin, xmax, ymax);
}
return bbox;
}
typedef struct _head {
ptroff_t magic;
ibbox_t bbox;
int nr;
int pos;
int rank;
int x,y;
char seen;
struct _head*next;
struct _head*prev;
} head_t;
typedef struct _context {
void**group;
unsigned char*alpha;
int width;
int height;
head_t*heads;
int count;
} context_t;
#define HEAD_MAGIC ((ptroff_t)-1)
static head_t*head_new(context_t*context, int x, int y)
{
int pos = context->width*y+x;
head_t*h = rfx_calloc(sizeof(head_t));
h->magic = HEAD_MAGIC;
h->nr = context->count++;
h->pos = pos;
h->x = x;
h->y = y;
h->bbox.xmin = h->bbox.xmax = x;
h->bbox.ymin = h->bbox.ymax = y;
h->next = context->heads;
context->heads = h;
if(h->next) {
h->next->prev = h;
}
return h;
}
static void head_delete(context_t*context, head_t*h)
{
if(h->prev) {
h->prev->next = h->next;
}
if(h->next) {
h->next->prev = h->prev;
}
if(h==context->heads) {
assert(!h->prev);
context->heads = h->next;
}
free(h);
}
#define POINTS_TO_HEAD(ptr) (((head_t*)(ptr))->magic==HEAD_MAGIC)
static inline void link_to(context_t*context, int from, int to)
{
// path compression
void**data = context->group;
int head = to;
assert(data[head]);
while(!POINTS_TO_HEAD(data[head])) {
assert(data[head]!=(void*)&data[head]); // check that we're not in an infinite loop
head=(void**)data[head]-(void**)data;
}
head_t*h = (head_t*)data[head];
int x = from%context->width;
int y = from/context->width;
if(x < h->bbox.xmin) h->bbox.xmin = x;
if(y < h->bbox.ymin) h->bbox.ymin = y;
if(x > h->bbox.xmax) h->bbox.xmax = x;
if(y > h->bbox.ymax) h->bbox.ymax = y;
data[from] = (void*)&data[head];
}
static char ibbox_does_overlap(ibbox_t*b1, ibbox_t*b2)
{
if(b1->xmax < b2->xmin) return 0;
if(b2->xmax < b1->xmin) return 0;
if(b1->ymax < b2->ymin) return 0;
if(b2->ymax < b1->ymin) return 0;
return 1;
}
static void ibbox_expand(ibbox_t*src, ibbox_t*add)
{
if(add->xmin < src->xmin)
src->xmin = add->xmin;
if(add->ymin < src->ymin)
src->ymin = add->ymin;
if(add->xmax > src->xmax)
src->xmax = add->xmax;
if(add->ymax > src->ymax)
src->ymax = add->ymax;
}
static inline void merge(context_t*context, int set1, int set2)
{
void**data = context->group;
assert(data[set1]);
assert(data[set2]);
int head1 = set1;
int head2 = set2;
while(!POINTS_TO_HEAD(data[head1])) {
head1=(void**)data[head1]-(void**)data;
}
while(!POINTS_TO_HEAD(data[head2])) {
head2=(void**)data[head2]-(void**)data;
}
head_t*h1 = (head_t*)data[head1];
head_t*h2 = (head_t*)data[head2];
if(h1==h2)
return;
if(h1->rank>h2->rank) {
h1->rank++;
ibbox_expand(&h1->bbox,&h2->bbox);
data[head2] = (void*)&data[head1];
head_delete(context, h2);
} else {
h2->rank++;
ibbox_expand(&h2->bbox,&h1->bbox);
data[head1] = (void*)&data[head2];
head_delete(context, h1);
}
}
static void** annotate(context_t*context)
{
unsigned char*alpha = context->alpha;
int width = context->width;
int height = context->height;
void** group = rfx_calloc(width*height*sizeof(void*));
context->group = group;
int x,y;
for(x=1;x<width;x++) {
if(alpha[x]) {
if(group[x-1])
link_to(context,x,x-1);
else
group[x]=head_new(context,x,0);
}
}
int pos = 0;
for(y=1;y<height;y++) {
pos += width;
if(alpha[pos]) {
if(group[pos-width])
link_to(context,pos,pos-width);
else
group[pos]=head_new(context,0,y);
}
for(x=1;x<width;x++) {
/* once this code is stable we should copy&paste it
out of the loop, change the loop end to width-1 and
add the pos-width+1 case */
if(alpha[pos+x]) {
if(group[pos+x-width]) {
link_to(context,pos+x,pos+x-width);
if(group[pos+x-1])
merge(context,pos+x,pos+x-1);
} else if(group[pos+x-1]) {
link_to(context,pos+x,pos+x-1);
} else if(group[pos+x-width-1]) {
link_to(context,pos+x,pos+x-width-1);
} else {
group[pos+x]=head_new(context,x,y);
}
}
}
}
return group;
}
static void overlap_bboxes(context_t*context)
{
char changed;
do {
head_t*h1 = context->heads;
changed = 0;
while(h1) {
head_t*next = h1->next;
head_t*h2 = context->heads;
while(h2) {
if(h1!=h2) {
if(ibbox_does_overlap(&h1->bbox, &h2->bbox)) {
merge(context, h1->pos, h2->pos);
changed = 1;
break;
}
}
h2 = h2->next;
}
h1 = next;
}
} while(changed);
}
typedef struct _circle_coord {
S16 x,y;
} circle_coord_t;
static int compare_circle_coord(const void *_v1, const void *_v2)
{
circle_coord_t*v1=(circle_coord_t*)_v1;
circle_coord_t*v2=(circle_coord_t*)_v2;
return (v1->x*v1->x + v1->y*v1->y) - (v2->x*v2->x + v2->y*v2->y);
}
static head_t* search_vicinity(context_t*context, head_t*h, int max_radius, double*cos, double*sin)
{
static circle_coord_t*circle_order = 0;
static int circle_order_size = 0;
if(!circle_order) {
circle_order_size = (max_radius*(max_radius+1))/2;
circle_order = malloc(sizeof(circle_coord_t)*circle_order_size);
int x,y;
int i = 0;
for(y=0;y<max_radius;y++) {
for(x=0;x<=y;x++) {
circle_order[i].x=x;
circle_order[i].y=y;
i++;
}
}
assert(i==circle_order_size);
qsort(circle_order, circle_order_size, sizeof(circle_coord_t), compare_circle_coord);
}
int t;
void**data = context->group;
int signx[4] = {-1,1,-1,1};
int signy[4] = {-1,-1,1,1};
for(t=1;t<circle_order_size;t++) {
int xx = circle_order[t].x;
int yy = circle_order[t].y;
int s;
for(s=0;s<4;s++) {
int x=h->x+xx*signx[s];
int y=h->y+yy*signy[s];
if(x>=0 && y>=0 && x<context->width && y<context->height) {
int pos = y*context->width+x;
if(data[pos]) {
while(!POINTS_TO_HEAD(data[pos])) {
pos=(void**)data[pos]-(void**)data;
}
head_t*new_head = (head_t*)data[pos];
if(new_head != h) {
return new_head;
}
}
}
}
}
return 0;
}
static void fix_small_boxes(context_t*context)
{
double sintab[256];
double costab[256];
int t;
for(t=0;t<256;t++) {
sintab[t] = sin(t*M_PI/128);
costab[t] = cos(t*M_PI/128);
}
head_t*h = context->heads;
while(h) {
h->seen = 0;
h = h->next;
}
char changed;
do {
changed = 0;
head_t*h = context->heads;
while(h) {
head_t*next = h->next;
if(!h->seen) {
if(h->bbox.xmax - h->bbox.xmin < 32
|| h->bbox.ymax - h->bbox.ymin < 32) {
head_t*other = search_vicinity(context, h, 64, costab, sintab);
if(other) {
merge(context, h->pos, other->pos);
changed = 1;
break;
} else {
//printf("nothing in the vicinity of %d,%d,%d,%d\n", h->bbox);
h->seen = 1;
}
} /*else {
printf("area %d,%d,%d,%d is large enough (%dx%d)\n",
h->bbox.xmin,
h->bbox.ymin,
h->bbox.xmax,
h->bbox.ymax,
h->bbox.xmax - h->bbox.xmin,
h->bbox.ymax - h->bbox.ymin);
} */
}
h = next;
}
} while(changed);
}
static void display(context_t*context)
{
int width = context->width;
int height = context->height;
void**group = context->group;
int x,y;
for(y=0;y<height;y++) {
for(x=0;x<width;x++) {
if(!group[y*width+x]) {
printf(" -- ");
} else if(POINTS_TO_HEAD(group[y*width+x])) {
printf("g%02d ", ((head_t*)group[y*width+x])->nr);
} else {
printf("x%02d ", (void**)group[y*width+x]-(void**)group);
}
}
printf("\n");
}
head_t*h = context->heads;
while(h) {
printf("head: %d\n", h->nr);
printf(" pos: %d/%d\n", h->pos%width, h->pos/width);
printf(" bbox: [%d/%d,%d/%d]\n", h->bbox.xmin, h->bbox.ymin, h->bbox.xmax, h->bbox.ymax);
h = h->next;
}
}
ibbox_t*get_bitmap_bboxes(unsigned char*alpha, int width, int height)
{
int size = width*height;
if(width<=1 || height<=1)
return get_bitmap_bboxes_simple(alpha, width, height);
context_t context;
context.alpha = alpha;
context.width = width;
context.height = height;
context.heads = 0;
context.count = 1;
void**group = annotate(&context);
fix_small_boxes(&context);
overlap_bboxes(&context);
#ifdef MAIN
display(&context);
#endif
ibbox_t*bboxes = 0;
head_t*h = context.heads;
while(h) {
head_t*next = h->next;
ibbox_t*bbox = malloc(sizeof(ibbox_t));
memcpy(bbox, &h->bbox, sizeof(ibbox_t));
/* ibbox_t defines the open upper bound */
bbox->xmax++;
bbox->ymax++;
bbox->next = bboxes;
bboxes = bbox;
free(h);
h = next;
}
free(context.group);
return bboxes;
}
#ifdef MAIN
int main(int argn, char*argv[])
{
unsigned char alpha[8*8]=
"\0\0\1\0\0\0\0\0"
"\1\0\0\1\0\1\0\0"
"\0\0\0\0\0\0\1\0"
"\0\0\1\0\1\0\0\0"
"\1\0\1\0\1\0\0\0"
"\1\0\1\1\1\0\0\1"
"\1\0\0\0\0\0\1\0"
"\1\1\1\0\0\0\0\0";
get_bitmap_bboxes(alpha, 8,8);
}
#endif