Zhang-Suen thinning algorithm: Difference between revisions

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# ############
### ### </pre>
 
=={{header|JavaScript}}==
{{trans|Java}}
<lang javascript>function Point(x, y) {
this.x = x;
this.y = y;
}
var ZhangSuen = (function () {
function ZhangSuen() {
}
ZhangSuen.image =
[" ",
" ################# ############# ",
" ################## ################ ",
" ################### ################## ",
" ######## ####### ################### ",
" ###### ####### ####### ###### ",
" ###### ####### ####### ",
" ################# ####### ",
" ################ ####### ",
" ################# ####### ",
" ###### ####### ####### ",
" ###### ####### ####### ",
" ###### ####### ####### ###### ",
" ######## ####### ################### ",
" ######## ####### ###### ################## ###### ",
" ######## ####### ###### ################ ###### ",
" ######## ####### ###### ############# ###### ",
" "];
 
ZhangSuen.nbrs = [[0, -1], [1, -1], [1, 0], [1, 1], [0, 1], [-1, 1], [-1, 0], [-1, -1], [0, -1]];
 
ZhangSuen.nbrGroups = [[[0, 2, 4], [2, 4, 6]], [[0, 2, 6], [0, 4, 6]]];
 
ZhangSuen.toWhite = new Array();
;
ZhangSuen.main = function (args) {
ZhangSuen.grid = new Array(ZhangSuen.image.length);
for (var r = 0; r < ZhangSuen.image.length; r++)
ZhangSuen.grid[r] = (ZhangSuen.image[r]).split('');
ZhangSuen.thinImage();
};
ZhangSuen.thinImage = function () {
var firstStep = false;
var hasChanged;
do {
hasChanged = false;
firstStep = !firstStep;
for (var r = 1; r < ZhangSuen.grid.length - 1; r++) {
for (var c = 1; c < ZhangSuen.grid[0].length - 1; c++) {
if (ZhangSuen.grid[r][c] !== '#')
continue;
var nn = ZhangSuen.numNeighbors(r, c);
if (nn < 2 || nn > 6)
continue;
if (ZhangSuen.numTransitions(r, c) !== 1)
continue;
if (!ZhangSuen.atLeastOneIsWhite(r, c, firstStep ? 0 : 1))
continue;
ZhangSuen.toWhite.push(new Point(c, r));
hasChanged = true;
}
}
for (let i = 0; i < ZhangSuen.toWhite.length; i++) {
var p = ZhangSuen.toWhite[i];
ZhangSuen.grid[p.y][p.x] = ' ';
}
ZhangSuen.toWhite = new Array();
} while ((firstStep || hasChanged));
ZhangSuen.printResult();
};
ZhangSuen.numNeighbors = function (r, c) {
var count = 0;
for (var i = 0; i < ZhangSuen.nbrs.length - 1; i++)
if (ZhangSuen.grid[r + ZhangSuen.nbrs[i][1]][c + ZhangSuen.nbrs[i][0]] === '#')
count++;
return count;
};
ZhangSuen.numTransitions = function (r, c) {
var count = 0;
for (var i = 0; i < ZhangSuen.nbrs.length - 1; i++)
if (ZhangSuen.grid[r + ZhangSuen.nbrs[i][1]][c + ZhangSuen.nbrs[i][0]] === ' ') {
if (ZhangSuen.grid[r + ZhangSuen.nbrs[i + 1][1]][c + ZhangSuen.nbrs[i + 1][0]] === '#')
count++;
}
return count;
};
ZhangSuen.atLeastOneIsWhite = function (r, c, step) {
var count = 0;
var group = ZhangSuen.nbrGroups[step];
for (var i = 0; i < 2; i++)
for (var j = 0; j < group[i].length; j++) {
var nbr = ZhangSuen.nbrs[group[i][j]];
if (ZhangSuen.grid[r + nbr[1]][c + nbr[0]] === ' ') {
count++;
break;
}
}
return count > 1;
};
ZhangSuen.printResult = function () {
for (var i = 0; i < ZhangSuen.grid.length; i++) {
var row = ZhangSuen.grid[i];
console.log(row.join(''));
}
};
return ZhangSuen;
}());
ZhangSuen.main(null);</lang>
 
Output:
 
<pre>
# ########## #######
## # #### #
# # ##
# # #
# # #
# # #
############ #
# # #
# # #
# # #
# # #
# ##
# ############
### ### </pre>
 
=={{header|Lua}}==
1

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