Add ToT WebGL conformance tests : part 10

conformance/resources/pnglib.js

+/**
+* A handy class to calculate color values.
+*
+* @version 1.0
+* @author Robert Eisele <robert@xarg.org>
+* @copyright Copyright (c) 2010, Robert Eisele
+* @link http://www.xarg.org/2010/03/generate-client-side-png-files-using-javascript/
+* @license http://www.opensource.org/licenses/bsd-license.php BSD License
+*
+*/
+
+(function() {
+
+    // helper functions for that ctx
+    function write(buffer, offs) {
+        for (var i = 2; i < arguments.length; i++) {
+            for (var j = 0; j < arguments[i].length; j++) {
+                buffer[offs++] = arguments[i].charAt(j);
+            }
+        }
+    }
+
+    function byte2(w) {
+        return String.fromCharCode((w >> 8) & 255, w & 255);
+    }
+
+    function byte4(w) {
+        return String.fromCharCode((w >> 24) & 255, (w >> 16) & 255, (w >> 8) & 255, w & 255);
+    }
+
+    function byte2lsb(w) {
+        return String.fromCharCode(w & 255, (w >> 8) & 255);
+    }
+
+    window.PNGlib = function(width,height,depth) {
+
+        this.width   = width;
+        this.height  = height;
+        this.depth   = depth;
+
+        // pixel data and row filter identifier size
+        this.pix_size = height * (width + 1);
+
+        // deflate header, pix_size, block headers, adler32 checksum
+        this.data_size = 2 + this.pix_size + 5 * Math.floor((0xfffe + this.pix_size) / 0xffff) + 4;
+
+        // offsets and sizes of Png chunks
+        this.ihdr_offs = 0;                                    // IHDR offset and size
+        this.ihdr_size = 4 + 4 + 13 + 4;
+        this.plte_offs = this.ihdr_offs + this.ihdr_size;    // PLTE offset and size
+        this.plte_size = 4 + 4 + 3 * depth + 4;
+        this.trns_offs = this.plte_offs + this.plte_size;    // tRNS offset and size
+        this.trns_size = 4 + 4 + depth + 4;
+        this.idat_offs = this.trns_offs + this.trns_size;    // IDAT offset and size
+        this.idat_size = 4 + 4 + this.data_size + 4;
+        this.iend_offs = this.idat_offs + this.idat_size;    // IEND offset and size
+        this.iend_size = 4 + 4 + 4;
+        this.buffer_size  = this.iend_offs + this.iend_size;    // total PNG size
+
+        this.buffer  = new Array();
+        this.palette = new Object();
+        this.pindex  = 0;
+
+        var _crc32 = new Array();
+
+        // initialize buffer with zero bytes
+        for (var i = 0; i < this.buffer_size; i++) {
+            this.buffer[i] = "\x00";
+        }
+
+        // initialize non-zero elements
+        write(this.buffer, this.ihdr_offs, byte4(this.ihdr_size - 12), 'IHDR', byte4(width), byte4(height), "\x08\x03");
+        write(this.buffer, this.plte_offs, byte4(this.plte_size - 12), 'PLTE');
+        write(this.buffer, this.trns_offs, byte4(this.trns_size - 12), 'tRNS');
+        write(this.buffer, this.idat_offs, byte4(this.idat_size - 12), 'IDAT');
+        write(this.buffer, this.iend_offs, byte4(this.iend_size - 12), 'IEND');
+
+        // initialize deflate header
+        var header = ((8 + (7 << 4)) << 8) | (3 << 6);
+        header+= 31 - (header % 31);
+
+        write(this.buffer, this.idat_offs + 8, byte2(header));
+
+        // initialize deflate block headers
+        for (var i = 0; (i << 16) - 1 < this.pix_size; i++) {
+            var size, bits;
+            if (i + 0xffff < this.pix_size) {
+                size = 0xffff;
+                bits = "\x00";
+            } else {
+                size = this.pix_size - (i << 16) - i;
+                bits = "\x01";
+            }
+            write(this.buffer, this.idat_offs + 8 + 2 + (i << 16) + (i << 2), bits, byte2lsb(size), byte2lsb(~size));
+        }
+
+        /* Create crc32 lookup table */
+        for (var i = 0; i < 256; i++) {
+            var c = i;
+            for (var j = 0; j < 8; j++) {
+                if (c & 1) {
+                    c = -306674912 ^ ((c >> 1) & 0x7fffffff);
+                } else {
+                    c = (c >> 1) & 0x7fffffff;
+                }
+            }
+            _crc32[i] = c;
+        }
+
+        // compute the index into a png for a given pixel
+        this.index = function(x,y) {
+            var i = y * (this.width + 1) + x + 1;
+            var j = this.idat_offs + 8 + 2 + 5 * Math.floor((i / 0xffff) + 1) + i;
+            return j;
+        }
+
+        // convert a color and build up the palette
+        this.color = function(red, green, blue, alpha) {
+
+            alpha = alpha >= 0 ? alpha : 255;
+            var color = (((((alpha << 8) | red) << 8) | green) << 8) | blue;
+
+            if (typeof this.palette[color] == "undefined") {
+                if (this.pindex == this.depth) return "\x00";
+
+                var ndx = this.plte_offs + 8 + 3 * this.pindex;
+
+                this.buffer[ndx + 0] = String.fromCharCode(red);
+                this.buffer[ndx + 1] = String.fromCharCode(green);
+                this.buffer[ndx + 2] = String.fromCharCode(blue);
+                this.buffer[this.trns_offs+8+this.pindex] = String.fromCharCode(alpha);
+
+                this.palette[color] = String.fromCharCode(this.pindex++);
+            }
+            return this.palette[color];
+        }
+
+        // output a PNG string, Base64 encoded
+        this.getBase64 = function() {
+
+            var s = this.getDump();
+
+            var ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
+            var c1, c2, c3, e1, e2, e3, e4;
+            var l = s.length;
+            var i = 0;
+            var r = "";
+
+            do {
+                c1 = s.charCodeAt(i);
+                e1 = c1 >> 2;
+                c2 = s.charCodeAt(i+1);
+                e2 = ((c1 & 3) << 4) | (c2 >> 4);
+                c3 = s.charCodeAt(i+2);
+                if (l < i+2) { e3 = 64; } else { e3 = ((c2 & 0xf) << 2) | (c3 >> 6); }
+                if (l < i+3) { e4 = 64; } else { e4 = c3 & 0x3f; }
+                r+= ch.charAt(e1) + ch.charAt(e2) + ch.charAt(e3) + ch.charAt(e4);
+            } while ((i+= 3) < l);
+            return r;
+        }
+
+        // output a PNG string
+        this.getDump = function() {
+
+            // compute adler32 of output pixels + row filter bytes
+            var BASE = 65521; /* largest prime smaller than 65536 */
+            var NMAX = 5552;  /* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
+            var s1 = 1;
+            var s2 = 0;
+            var n = NMAX;
+
+            for (var y = 0; y < this.height; y++) {
+                for (var x = -1; x < this.width; x++) {
+                    s1+= this.buffer[this.index(x, y)].charCodeAt(0);
+                    s2+= s1;
+                    if ((n-= 1) == 0) {
+                        s1%= BASE;
+                        s2%= BASE;
+                        n = NMAX;
+                    }
+                }
+            }
+            s1%= BASE;
+            s2%= BASE;
+            write(this.buffer, this.idat_offs + this.idat_size - 8, byte4((s2 << 16) | s1));
+
+            // compute crc32 of the PNG chunks
+            function crc32(png, offs, size) {
+                var crc = -1;
+                for (var i = 4; i < size-4; i += 1) {
+                    crc = _crc32[(crc ^ png[offs+i].charCodeAt(0)) & 0xff] ^ ((crc >> 8) & 0x00ffffff);
+                }
+                write(png, offs+size-4, byte4(crc ^ -1));
+            }
+
+            crc32(this.buffer, this.ihdr_offs, this.ihdr_size);
+            crc32(this.buffer, this.plte_offs, this.plte_size);
+            crc32(this.buffer, this.trns_offs, this.trns_size);
+            crc32(this.buffer, this.idat_offs, this.idat_size);
+            crc32(this.buffer, this.iend_offs, this.iend_size);
+
+            // convert PNG to string
+            return "\211PNG\r\n\032\n"+this.buffer.join('');
+        }
+    }
+
+})();