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404 lines
11 KiB
JavaScript
404 lines
11 KiB
JavaScript
var CHAR_TILDE = 126;
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var CODE_FNC1 = 102;
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var SET_STARTA = 103;
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var SET_STARTB = 104;
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var SET_STARTC = 105;
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var SET_SHIFT = 98;
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var SET_CODEA = 101;
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var SET_CODEB = 100;
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var SET_STOP = 106;
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var REPLACE_CODES = {
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CHAR_TILDE: CODE_FNC1 //~ corresponds to FNC1 in GS1-128 standard
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}
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var CODESET = {
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ANY: 1,
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AB: 2,
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A: 3,
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B: 4,
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C: 5
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};
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function getBytes(str) {
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var bytes = [];
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for (var i = 0; i < str.length; i++) {
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bytes.push(str.charCodeAt(i));
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}
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return bytes;
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}
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exports.code128 = function (ctx, text, width, height) {
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width = parseInt(width);
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height = parseInt(height);
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var codes = stringToCode128(text);
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console.debug('codes', codes)
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var g = new Graphics(ctx, width, height);
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var barWeight = g.area.width / ((codes.length - 3) * 11 + 35);
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var x = g.area.left;
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var y = g.area.top;
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for (var i = 0; i < codes.length; i++) {
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var c = codes[i];
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//two bars at a time: 1 black and 1 white
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for (var bar = 0; bar < 8; bar += 2) {
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var barW = PATTERNS[c][bar] * barWeight;
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// var barH = height - y - this.border;
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var barH = height - y;
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var spcW = PATTERNS[c][bar + 1] * barWeight;
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//no need to draw if 0 width
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if (barW > 0) {
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g.fillFgRect(x, y, barW, barH);
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}
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x += barW + spcW;
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}
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}
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ctx.draw();
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}
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function stringToCode128(text) {
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var barc = {
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currcs: CODESET.C
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};
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var bytes = getBytes(text);
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//decide starting codeset
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var index = bytes[0] == CHAR_TILDE ? 1 : 0;
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var csa1 = bytes.length > 0 ? codeSetAllowedFor(bytes[index++]) : CODESET.AB;
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var csa2 = bytes.length > 0 ? codeSetAllowedFor(bytes[index++]) : CODESET.AB;
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barc.currcs = getBestStartSet(csa1, csa2);
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barc.currcs = perhapsCodeC(bytes, barc.currcs);
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//if no codeset changes this will end up with bytes.length+3
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//start, checksum and stop
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var codes = new Array();
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switch (barc.currcs) {
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case CODESET.A:
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codes.push(SET_STARTA);
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break;
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case CODESET.B:
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codes.push(SET_STARTB);
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break;
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default:
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codes.push(SET_STARTC);
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break;
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}
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for (var i = 0; i < bytes.length; i++) {
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var b1 = bytes[i]; //get the first of a pair
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//should we translate/replace
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if (b1 in REPLACE_CODES) {
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codes.push(REPLACE_CODES[b1]);
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i++ //jump to next
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b1 = bytes[i];
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}
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//get the next in the pair if possible
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var b2 = bytes.length > (i + 1) ? bytes[i + 1] : -1;
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codes = codes.concat(codesForChar(b1, b2, barc.currcs));
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//code C takes 2 chars each time
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if (barc.currcs == CODESET.C) i++;
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}
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//calculate checksum according to Code 128 standards
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var checksum = codes[0];
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for (var weight = 1; weight < codes.length; weight++) {
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checksum += (weight * codes[weight]);
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}
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codes.push(checksum % 103);
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codes.push(SET_STOP);
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//encoding should now be complete
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return codes;
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function getBestStartSet(csa1, csa2) {
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//tries to figure out the best codeset
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//to start with to get the most compact code
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var vote = 0;
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vote += csa1 == CODESET.A ? 1 : 0;
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vote += csa1 == CODESET.B ? -1 : 0;
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vote += csa2 == CODESET.A ? 1 : 0;
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vote += csa2 == CODESET.B ? -1 : 0;
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//tie goes to B due to my own predudices
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return vote > 0 ? CODESET.A : CODESET.B;
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}
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function perhapsCodeC(bytes, codeset) {
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for (var i = 0; i < bytes.length; i++) {
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var b = bytes[i]
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if ((b < 48 || b > 57) && b != CHAR_TILDE)
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return codeset;
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}
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if (bytes.length % 2 == 0)
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return CODESET.C;
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else
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return CODESET.A;
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}
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//chr1 is current byte
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//chr2 is the next byte to process. looks ahead.
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function codesForChar(chr1, chr2, currcs) {
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var result = [];
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var shifter = -1;
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if (charCompatible(chr1, currcs)) {
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if (currcs == CODESET.C) {
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if (chr2 == -1) {
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shifter = SET_CODEB;
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currcs = CODESET.B;
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}
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else if ((chr2 != -1) && !charCompatible(chr2, currcs)) {
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//need to check ahead as well
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if (charCompatible(chr2, CODESET.A)) {
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shifter = SET_CODEA;
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currcs = CODESET.A;
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}
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else {
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shifter = SET_CODEB;
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currcs = CODESET.B;
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}
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}
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}
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}
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else {
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//if there is a next char AND that next char is also not compatible
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if ((chr2 != -1) && !charCompatible(chr2, currcs)) {
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//need to switch code sets
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switch (currcs) {
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case CODESET.A:
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shifter = SET_CODEB;
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currcs = CODESET.B;
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break;
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case CODESET.B:
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shifter = SET_CODEA;
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currcs = CODESET.A;
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break;
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}
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}
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else {
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//no need to shift code sets, a temporary SHIFT will suffice
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shifter = SET_SHIFT;
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}
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}
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//ok some type of shift is nessecary
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if (shifter != -1) {
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result.push(shifter);
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result.push(codeValue(chr2));
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}
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else {
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if (currcs == CODESET.C) {
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//include next as well
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result.push(codeValue(chr1, chr2));
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}
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else {
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result.push(codeValue(chr1));
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}
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}
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barc.currcs = currcs;
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return result;
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}
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}
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//reduce the ascii code to fit into the Code128 char table
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function codeValue(chr1, chr2) {
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if (typeof chr2 == "undefined") {
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return chr1 >= 32 ? chr1 - 32 : chr1 + 64;
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}
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else {
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return parseInt(String.fromCharCode(chr1) + String.fromCharCode(chr2));
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}
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}
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function charCompatible(chr, codeset) {
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var csa = codeSetAllowedFor(chr);
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if (csa == CODESET.ANY) return true;
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//if we need to change from current
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if (csa == CODESET.AB) return true;
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if (csa == CODESET.A && codeset == CODESET.A) return true;
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if (csa == CODESET.B && codeset == CODESET.B) return true;
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return false;
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}
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function codeSetAllowedFor(chr) {
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if (chr >= 48 && chr <= 57) {
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//0-9
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return CODESET.ANY;
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}
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else if (chr >= 32 && chr <= 95) {
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//0-9 A-Z
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return CODESET.AB;
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}
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else {
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//if non printable
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return chr < 32 ? CODESET.A : CODESET.B;
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}
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}
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var Graphics = function (ctx, width, height) {
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this.width = width;
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this.height = height;
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this.quiet = Math.round(this.width / 40);
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this.border_size = 0;
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this.padding_width = 0;
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this.area = {
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width: width - this.padding_width * 2 - this.quiet * 2,
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height: height - this.border_size * 2,
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top: this.border_size - 4,
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left: this.padding_width + this.quiet
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};
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this.ctx = ctx;
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this.fg = "#000000";
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this.bg = "#ffffff";
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// fill background
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this.fillBgRect(0, 0, width, height);
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// fill center to create border
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this.fillBgRect(0, this.border_size, width, height - this.border_size * 2);
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}
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//use native color
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Graphics.prototype._fillRect = function (x, y, width, height, color) {
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this.ctx.setFillStyle(color)
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this.ctx.fillRect(x, y, width, height)
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}
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Graphics.prototype.fillFgRect = function (x, y, width, height) {
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this._fillRect(x, y, width, height, this.fg);
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}
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Graphics.prototype.fillBgRect = function (x, y, width, height) {
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this._fillRect(x, y, width, height, this.bg);
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}
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var PATTERNS = [
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[2, 1, 2, 2, 2, 2, 0, 0], // 0
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[2, 2, 2, 1, 2, 2, 0, 0], // 1
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[2, 2, 2, 2, 2, 1, 0, 0], // 2
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[1, 2, 1, 2, 2, 3, 0, 0], // 3
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[1, 2, 1, 3, 2, 2, 0, 0], // 4
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[1, 3, 1, 2, 2, 2, 0, 0], // 5
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[1, 2, 2, 2, 1, 3, 0, 0], // 6
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[1, 2, 2, 3, 1, 2, 0, 0], // 7
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[1, 3, 2, 2, 1, 2, 0, 0], // 8
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[2, 2, 1, 2, 1, 3, 0, 0], // 9
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[2, 2, 1, 3, 1, 2, 0, 0], // 10
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[2, 3, 1, 2, 1, 2, 0, 0], // 11
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[1, 1, 2, 2, 3, 2, 0, 0], // 12
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[1, 2, 2, 1, 3, 2, 0, 0], // 13
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[1, 2, 2, 2, 3, 1, 0, 0], // 14
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[1, 1, 3, 2, 2, 2, 0, 0], // 15
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[1, 2, 3, 1, 2, 2, 0, 0], // 16
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[1, 2, 3, 2, 2, 1, 0, 0], // 17
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[2, 2, 3, 2, 1, 1, 0, 0], // 18
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[2, 2, 1, 1, 3, 2, 0, 0], // 19
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[2, 2, 1, 2, 3, 1, 0, 0], // 20
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[2, 1, 3, 2, 1, 2, 0, 0], // 21
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[2, 2, 3, 1, 1, 2, 0, 0], // 22
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[3, 1, 2, 1, 3, 1, 0, 0], // 23
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[3, 1, 1, 2, 2, 2, 0, 0], // 24
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[3, 2, 1, 1, 2, 2, 0, 0], // 25
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[3, 2, 1, 2, 2, 1, 0, 0], // 26
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[3, 1, 2, 2, 1, 2, 0, 0], // 27
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[3, 2, 2, 1, 1, 2, 0, 0], // 28
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[3, 2, 2, 2, 1, 1, 0, 0], // 29
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[2, 1, 2, 1, 2, 3, 0, 0], // 30
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[2, 1, 2, 3, 2, 1, 0, 0], // 31
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[2, 3, 2, 1, 2, 1, 0, 0], // 32
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[1, 1, 1, 3, 2, 3, 0, 0], // 33
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[1, 3, 1, 1, 2, 3, 0, 0], // 34
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[1, 3, 1, 3, 2, 1, 0, 0], // 35
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[1, 1, 2, 3, 1, 3, 0, 0], // 36
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[1, 3, 2, 1, 1, 3, 0, 0], // 37
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[1, 3, 2, 3, 1, 1, 0, 0], // 38
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[2, 1, 1, 3, 1, 3, 0, 0], // 39
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[2, 3, 1, 1, 1, 3, 0, 0], // 40
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[2, 3, 1, 3, 1, 1, 0, 0], // 41
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[1, 1, 2, 1, 3, 3, 0, 0], // 42
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[1, 1, 2, 3, 3, 1, 0, 0], // 43
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[1, 3, 2, 1, 3, 1, 0, 0], // 44
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[1, 1, 3, 1, 2, 3, 0, 0], // 45
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[1, 1, 3, 3, 2, 1, 0, 0], // 46
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[1, 3, 3, 1, 2, 1, 0, 0], // 47
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[3, 1, 3, 1, 2, 1, 0, 0], // 48
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[2, 1, 1, 3, 3, 1, 0, 0], // 49
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[2, 3, 1, 1, 3, 1, 0, 0], // 50
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[2, 1, 3, 1, 1, 3, 0, 0], // 51
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[2, 1, 3, 3, 1, 1, 0, 0], // 52
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[2, 1, 3, 1, 3, 1, 0, 0], // 53
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[3, 1, 1, 1, 2, 3, 0, 0], // 54
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[3, 1, 1, 3, 2, 1, 0, 0], // 55
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[3, 3, 1, 1, 2, 1, 0, 0], // 56
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[3, 1, 2, 1, 1, 3, 0, 0], // 57
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[3, 1, 2, 3, 1, 1, 0, 0], // 58
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[3, 3, 2, 1, 1, 1, 0, 0], // 59
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[3, 1, 4, 1, 1, 1, 0, 0], // 60
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[2, 2, 1, 4, 1, 1, 0, 0], // 61
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[4, 3, 1, 1, 1, 1, 0, 0], // 62
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[1, 1, 1, 2, 2, 4, 0, 0], // 63
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[1, 1, 1, 4, 2, 2, 0, 0], // 64
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[1, 2, 1, 1, 2, 4, 0, 0], // 65
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[1, 2, 1, 4, 2, 1, 0, 0], // 66
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[1, 4, 1, 1, 2, 2, 0, 0], // 67
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[1, 4, 1, 2, 2, 1, 0, 0], // 68
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[1, 1, 2, 2, 1, 4, 0, 0], // 69
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[1, 1, 2, 4, 1, 2, 0, 0], // 70
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[1, 2, 2, 1, 1, 4, 0, 0], // 71
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[1, 2, 2, 4, 1, 1, 0, 0], // 72
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[1, 4, 2, 1, 1, 2, 0, 0], // 73
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[1, 4, 2, 2, 1, 1, 0, 0], // 74
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[2, 4, 1, 2, 1, 1, 0, 0], // 75
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[2, 2, 1, 1, 1, 4, 0, 0], // 76
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[4, 1, 3, 1, 1, 1, 0, 0], // 77
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[2, 4, 1, 1, 1, 2, 0, 0], // 78
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[1, 3, 4, 1, 1, 1, 0, 0], // 79
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[1, 1, 1, 2, 4, 2, 0, 0], // 80
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[1, 2, 1, 1, 4, 2, 0, 0], // 81
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[1, 2, 1, 2, 4, 1, 0, 0], // 82
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[1, 1, 4, 2, 1, 2, 0, 0], // 83
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[1, 2, 4, 1, 1, 2, 0, 0], // 84
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[1, 2, 4, 2, 1, 1, 0, 0], // 85
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[4, 1, 1, 2, 1, 2, 0, 0], // 86
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[4, 2, 1, 1, 1, 2, 0, 0], // 87
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[4, 2, 1, 2, 1, 1, 0, 0], // 88
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[2, 1, 2, 1, 4, 1, 0, 0], // 89
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[2, 1, 4, 1, 2, 1, 0, 0], // 90
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[4, 1, 2, 1, 2, 1, 0, 0], // 91
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[1, 1, 1, 1, 4, 3, 0, 0], // 92
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[1, 1, 1, 3, 4, 1, 0, 0], // 93
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[1, 3, 1, 1, 4, 1, 0, 0], // 94
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[1, 1, 4, 1, 1, 3, 0, 0], // 95
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[1, 1, 4, 3, 1, 1, 0, 0], // 96
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[4, 1, 1, 1, 1, 3, 0, 0], // 97
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[4, 1, 1, 3, 1, 1, 0, 0], // 98
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[1, 1, 3, 1, 4, 1, 0, 0], // 99
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[1, 1, 4, 1, 3, 1, 0, 0], // 100
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[3, 1, 1, 1, 4, 1, 0, 0], // 101
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[4, 1, 1, 1, 3, 1, 0, 0], // 102
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[2, 1, 1, 4, 1, 2, 0, 0], // 103
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[2, 1, 1, 2, 1, 4, 0, 0], // 104
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[2, 1, 1, 2, 3, 2, 0, 0], // 105
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[2, 3, 3, 1, 1, 1, 2, 0] // 106
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] |