Multiple pages

WORK IN PROGRES. A book has multiple pages, so has PDF. We will extend the rpnPDFdevice to support multiple pages. PostScript already provides multi page support through the showpage operator. Each time showpage renders the page, initatiates the graphics and starts a new page. However, our main loop must tell all the devices to clean up when we are at the end of the code. But this should happen only on the main loop, not when rpn is called inside the context. rpn will delegate this to context so it does not have to know about the devices.

Javascript Editor

operators.initgraphics = function(context) {
    context.initgraphics();
    return context
};

operators.showpage = function(context) {
    for (let n of context.nodes) context = n.showpage(context);
    context.initgraphics();
    return context;
};

rpn = function(s, context = null ) {  
    var outerContext = false;
    if (!context) {
        context = new rpnContext();
        outerContext = true;
    }
    const list = s.concat(" ").split("");
    var state = "start";
    var current = "";
    var depth = 0;
    for (let elem of list) {
        if (context.lasterror) {
           return context;
        }
        context.currentcode += elem;
        switch (state) {
            case "start":
                if (/[0-9-.]/.test(elem)) {
                    state = "number";
                    current = elem;
                } else if (/[a-zA-Z]/.test(elem)) {
                    state = "operator";
                    current = elem;
                }  else if (elem == "/") {
                    state = "namestart";
                }  else if (elem == "{") {
                    state = "procedure";
                }  else if (elem == "(") {
                    state = "string";
                }  else if (elem == "[") {
                    context.stack.push(new rpnMark()); //mark
                }  else if (elem == "]") {
                    context.popArray();
                }  else if (elem == "%") {
                    state = "comment";
                }  else if (elem.trim() === '') {
                    // ignore whitespace
                }  else  {
                    context.error("syntaxerror");
                } 
                break;
            case "number":
                if (/[0-9]/.test(elem)) {
                    current += elem;
                } else if (elem == ".") {
                    state = "fraction";
                    current += elem;
                } else if (/[a-zA-Z-]/.test(elem)) {
                    context.error("syntaxerror");
                }  else if (elem.trim() === "") {
                    context.stack.push(new rpnNumber(parseFloat(current)));
                    state = "start";
                    current = "";
                } else if (elem == "]") {
                    context.stack.push(new rpnNumber(parseFloat(current)));
                    state = "start";
                    current = "";
                    context.popArray();
                } else if (elem == "/") {
                    context.stack.push(new rpnNumber(parseFloat(current)));
                    state = "name";
                    current = "";
                }  else {
                    context.error("syntaxerror");
                }
                break;
            case "fraction":
                if (/[0-9]/.test(elem)) {
                    current += elem;
                } else if (elem.trim() === "") {
                    context.stack.push(new rpnNumber(parseFloat(current)));
                    state = "start";
                    current = "";
               } else if (elem == "]") {
                    context.stack.push(new rpnNumber(parseFloat(current)));
                    state = "start";
                    current = "";
                    context.popArray();
                } else if (elem == "/") {
                    context.stack.push(new rpnNumber(parseFloat(current)));
                    state = "name";
                    current = "";
               } else {
                    context.error("syntaxerror");
               }
               break;
            case "operator":
                if (/[a-zA-Z0-9]/.test(elem)) {
                    current += elem;
                } else if (elem.trim() !== "" && elem != "]"){
                    context.error("syntaxerror");
                } else {
                    var data = context.dict[current];
                    if (!data) {
                        for (let i = context.dictstack.length - 1; i >= 0; i--) {
                            data = context.dictstack[i][current];
                            if (data) {
                                i = 0; // break
                            }
                        }
                    }
                    const op = operators[current];
                    if (data) {
                       if (data.type == "procedure") {
                          context = rpn(data.value, context);
                       } else if (data.type == "array"){
                            data.reference.inc();
                            context.stack.push(data);
                       } else if (data.type == "string"){
                            data.reference.inc();
                            context.stack.push(data);
                       } else {
                            context.stack.push(data);
                       }
                    } else if (op) {
                       context = op(context);
                    } else {
                    context.error("syntaxerror");
                    }
                    state = "start";
                    current = "";
                    if (elem == "]") {
                       context.popArray();
                    }

}
                break;
           case "namestart":
                if (/[a-zA-Z.]/.test(elem)) {
                    state = "name";
                    current = elem;
                } else {
                    context.error("syntaxerror");
                }
                break;
            case "name":
                if (/[a-zA-Z0-9-.]/.test(elem)) {
                    current += elem;
                } else if (elem.trim() === "") {
                    context.stack.push(new rpnName(current));
                    state = "start";
                    current = "";
               } else if (elem == "]") {
                    context.stack.push(new rpnName(current));
                    state = "start";
                    current = "";
                    context.popArray();
               } else  {
                    context.error("syntaxerror");
               }
                break;
            case "procedure":
               if (elem == "}") {
                   if (depth) {
                      depth--;
                      current += elem;
                   } else {
                        context.stack.push(new rpnProcedure(current));
                        state = "start";
                        current = "";
                   }
               } else if (elem == "{") {
                  depth++;
                  current += elem;
               } else {
                   current += elem;
               }
               break;
           case "string":
               if (elem == ")") {
                   if (depth) {
                      depth--;
                      current += elem;
                   } else {
                        const s = new rpnString(current, context.heap);
                        s.reference.inc();
                        context.stack.push(s);
                        state = "start";
                        current = "";
                   }
               } else if (elem == "(") {
                  depth++;
                  current += elem;
               } else {
                   current += elem;
               }
               break;
           case "comment":
             if (elem == endofline ) {
                state = "start";
             }
        } // switch state
    } // for
    if (state !== "start") {
       context.error("syntaxerror");
    }
    if (outerContext) context.finalize();
    return context;
};

rpnContext = class {
    constructor() { 
        this.stack = [];
        this.heap = [];
        this.lasterror = "";
        this.currentcode = "";
        this.width = 600;
        this.height = 800;
        this.dictstack = [];
        this.dictstack.push({});
        this.nodes = [];
        this.fontdict = {};
        this.device = { canvas: 0, canvasurl: 0, console: 1, oversampling: 1, pdf: 0, pdfurl: 0, raw: 1, rawurl : 0, svg: 0, svgurl: 0, textmode: 0,  transparent: 0  };
        this.initgraphics();
    }
    get dict() {
        return this.dictstack[this.dictstack.length - 1];
    }
    get graphics() {
        return this.graphicsstack[this.graphicsstack.length - 1];
    }
    error(s) {
        this.lasterror = s;
        this.stack.push(new rpnError(s));
        return this;
    }
    finalize() { 
        for (let n of this.nodes) n.finalize();
    }
    initgraphics () {
        this.graphicsstack = [];
        this.graphicsstack.push({ path: [], clip: [], current: [], color: [0, 0, 0, 255], linewidth: 1, matrix : [1, 0, 0, 1, 0, 0] , font: "", size: 12, cachedevice : [0, 0, 0, 0, 0, 0] });
    }
    itransform(x,y) {
       const m = this.graphics.matrix; 
       const det = m[0]*m[3] - m[1]*m[2];
       return [ (x*m[3] - y*m[2] +m[2]*m[5] - m[4]*m[3])/det, 
(-x*m[1] + y*m[0] + m[4]*m[1] - m[0]*m[5])/det ]; 
    }
    pop(...parameters) {
        if (this.stack.length < parameters.length) {
            this.error("stackunderflow");
            return [];
        }
        const result = [];
        for (let p of parameters) {
            const data = this.stack.pop(); 
            if (p == "any") {
                result.push(data);
            } else if (p.includes(data.type)) {
                result.push(data);   
            } else {
                console.log(data.type+p);
                this.error("typeerror");
                return [];
            }
         }
         return result;
    }
    popArray() {
        var found = false;
        var arr = [];
        while (this.stack.length && ! found) {
            const value = this.stack.pop();
            if (value.type == "mark") {
                found = true;
            } else {
                arr.push(value);
            }   
        }
        if (! found) {
            return this.error("stackunderflow");
        }
        arr.reverse();
        const a = new rpnArray(arr, this.heap);
        a.reference.inc();
        this.stack.push(a); 
    }
    transform(x,y) {
       const m = this.graphics.matrix; 
       return [ x * m[0] + y * m[2] + m[4],
x * m[1] + y * m[3] + m[5] ];
    }
};

We add empty functions to the devices to test if it works

Javascript Editor

rpnRawDevice = class {
    constructor(node, urlnode) { 
        this.node = node; 
        if (!node) document.createElement("CANVAS");
        this.urlnode = urlnode;
        if (node) this.initgraphics(node.width, node.height, 1); 
    }
    finalize() {}
    initgraphics(width, height, oversampling, transparent) {
        this.data = new Uint8ClampedArray(width * height * 4 * oversampling * oversampling);
        if (!transparent) {
            for (let i = 0; i < this.data.length; i++) this.data[i] = 255;
        }
        this.clipdata = new Uint8ClampedArray(width * height * 4 * oversampling * oversampling);
        this.clippath = "";
        for (let i = 0; i < this.clipdata.length; i++) this.clipdata[i] = 255;
        this.node.width = width;
        this.node.height = height;
        const ctx = this.node.getContext("2d");
        ctx.fillStyle = "white";
        ctx.fillRect(0, 0, width, height);
    }
    getFlatPath(path) {
        const flatpath = [];
        for (let subpath of path) {
            for (let line of subpath) {
                if (line[0] == "C") {
                    const lines = bezier(line,-1);
                    for (let elem of lines) {
                        flatpath.push(elem);
                    }
                } else {
                    flatpath.push(line);
                }
            }
        }
        return flatpath;
    }
    clip(context) {
        const test = JSON.stringify(context.graphics.clip);
        if (this.clippath == test) return context;
        
        this.clipdata = new Uint8ClampedArray(this.data.length);
        for (let i = 0; i < this.clipdata.length; i++) this.clipdata[i] = 255;
        
        for (let clip of context.graphics.clip) {
            const flatpath = this.getFlatPath(clip);
            const newclip = new Uint8ClampedArray(this.data.length);         
            this.clipdata = scanFill(flatpath, context.width, context.height, [255,255,255,255], true, newclip, this.clipdata);
        }
        this.clippath = test;
        return context;
    }  
    eofill(context) {
        return this.fill(context, false);
    }
    fill(context, zerowind = true) {
        if (context.device.raw + context.device.rawurl < 1) return context;
        const flatpath = this.getFlatPath(context.graphics.path);
        context = this.clip(context);        
        this.data = scanFill(flatpath, context.width, context.height, context.graphics.color, zerowind, this.data, this.clipdata);
        return context;
    }
    stroke(context) {
        if (context.device.raw + context.device.rawurl < 1) return context;
        const w = context.graphics.linewidth / 2;
        const ad = Math.PI / 2;
        if (!w) return context;
        for (let subpath of context.graphics.path) {
            const subflatpath = this.getFlatPath([subpath]);
            var olda = [];
            var oldb = [];
            const fillpath = [];
            if (!subflatpath.length) continue;
            if (subflatpath[0][1] == subflatpath[subflatpath.length-1][3] && subflatpath[0][2] == subflatpath[subflatpath.length-1][4])
                subflatpath.push(subflatpath[0]);
            for (let line of subflatpath) {
                const [type, x0, y0, x1, y1] = line;
                const a = Math.atan2(y1 - y0, x1 - x0);
                const x0a = x0 + Math.cos(a - ad) * w;
                const y0a = y0 + Math.sin(a - ad) * w;
                const x1a = x1 + Math.cos(a - ad) * w;
                const y1a = y1 + Math.sin(a - ad) * w;
                const x0b = x0 + Math.cos(a + ad) * w;
                const y0b = y0 + Math.sin(a + ad) * w;
                const x1b = x1 + Math.cos(a + ad) * w;
                const y1b = y1 + Math.sin(a + ad) * w;
                fillpath.push(["L", x0a, y0a, x1a, y1a]);
                fillpath.push(["L", x1a, y1a, x1b, y1b]);
                fillpath.push(["L", x1b, y1b, x0b, y0b]);
                fillpath.push(["L", x0b, y0b, x0a, y0a]);

if (olda.length) {
                    const [xa, ya] = lineIntersection(olda[1],olda[2],olda[3],olda[4],x0a, y0a, x1a, y1a);
                    const [xb, yb] = lineIntersection(oldb[1],oldb[2],oldb[3],oldb[4],x0b, y0b, x1b, y1b);
                    if (xa !== null && xb !== null) {
                        fillpath.push(["L", olda[3],olda[4], xa, ya]);
                        fillpath.push(["L", xa, ya, x0a, y0a]);
                        fillpath.push(["L", x0a, y0a, x0b, y0b]);
                        fillpath.push(["L", x0b, y0b, xb, yb]);
                        fillpath.push(["L", xb, yb, oldb[3], oldb[4]]);
                        fillpath.push(["L", oldb[3], oldb[4], olda[3], olda[4]]);
                    }
                }
                olda = ["L", x0a, y0a, x1a, y1a];
                oldb = ["L", x0b, y0b, x1b, y1b];
            }
            context = this.clip(context);
            this.data = scanFill(fillpath, context.width, context.height, context.graphics.color, true, this.data, this.clipdata);
        }
        return context;     
    }
    showpage(context) {
        if (context.device.raw + context.device.rawurl < 1) {
            this.node.style.display = "none";
            if (this.urlnode) this.urlnode.style.display = "none";
            return context;
        }
        this.node.style.display = (context.device.raw) ? "block" : "none";
        const image = new ImageData(this.data, context.width * context.device.oversampling);
        const canvas = (this.node) ? this.node : document.createElement("CANVAS");        
        const ctx = canvas.getContext("2d");
        if (context.device.oversampling > 1) { 
            var nodebig = document.createElement("CANVAS");
     nodebig.width = context.width * context.device.oversampling; 
            nodebig.height = context.height * context.device.oversampling; 
            nodebig.getContext("2d").putImageData(image, 0,0);
            ctx.save();
            ctx.scale(1/context.device.oversampling, 1/context.device.oversampling);
            ctx.imageSmoothingEnabled = true;
            ctx.imageSmoothingQuality = "high";
            ctx.drawImage(nodebig,0,0);
            ctx.restore();
        } else {
            ctx.putImageData(image, 0,0);
        }
        if (this.urlnode && context.device.rawurl) {
            this.urlnode.style.display = "block";
            const url = canvas.toDataURL();
            this.urlnode.href = url; 
            this.urlnode.setAttribute("download", "PS.png"); 
        } else {
            if (this.urlnode)  this.urlnode.style.display = "none";
        }
        return context;
    }

};

rpnCanvasDevice = class {
    constructor(node, urlnode) { 
        this.node = node;
        if (!node) document.createElement("CANVAS");
        this.urlnode = urlnode;
        this.clippath = "";
        this.initgraphics(this.node.width, this.node.height, 1);
    }
    finalize() {}
    initgraphics(width, height, oversampling, transparent) {
        this.node.width = width;
        this.node.height = height;
        const ctx = this.node.getContext("2d");
        if (!transparent) {
            ctx.fillStyle = "white";
            ctx.fillRect(0, 0, width, height);
        }
    }
    applyPath(path) {
        const ctx = this.node.getContext("2d");
        ctx.beginPath();
        for (let subpath of path) {
           if (!subpath.length) continue;
           ctx.moveTo(subpath[0][1], this.node.height - subpath[0][2]);
           for (let line of subpath) {
               if (line[0] == "C") {
                   ctx.bezierCurveTo(line[3],  this.node.height - line[4], line[5],  this.node.height - line[6], line[7],  this.node.height - line[8]);
               } else {
                  ctx.lineTo(line[3],  this.node.height - line[4]);
                  if (line[0] == "Z") ctx.closePath();                   
               }
           }
        } 
    }
    clip(context) {
        const ctx = this.node.getContext("2d");        
        for (let clip of context.graphics.clip) {
            this.applyPath(clip); 
            ctx.clip();
        }
        return context;
    }
    eofill(context) {
        return this.fill(context, false);
    }
    fill(context, zerowind = true) {
        if (context.device.canvas + context.device.canvasurl < 1) return context;
        if (context.device.canvas) this.node.style.display = "block";
        const ctx = this.node.getContext("2d");
        ctx.save();
        context = this.clip(context);
        this.applyPath(context.graphics.path);
        ctx.fillStyle = "rgb("+Math.round(context.graphics.color[0])+" "+Math.round(context.graphics.color[1])+" "+ Math.round(context.graphics.color[2])+")";
        ctx.globalAlpha = context.graphics.color[3]/255.0;
        if (zerowind) {
            ctx.fill("nonzero");
        } else {
            ctx.fill("evenodd");
        }
        ctx.restore();
        return context;
    }
    stroke(context) {
        if (context.device.canvas + context.device.canvasurl < 1) return context;
        const ctx = this.node.getContext("2d");
        ctx.save();
        context = this.clip(context);
        this.applyPath(context.graphics.path);
        ctx.strokeStyle = "rgb("+Math.round(context.graphics.color[0])+" "+Math.round(context.graphics.color[1])+" "+ Math.round(context.graphics.color[2])+")";
        ctx.globalAlpha = context.graphics.color[3]/255.0;
        ctx.lineWidth = context.graphics.linewidth;
        ctx.stroke();
        ctx.restore();
        return context;
    }
    showpage(context) { 
        if (context.device.canvas + context.device.canvasurl < 1) {
            this.node.style.display = "none";
            if (this.urlnode) this.urlnode.style.display = "none";
            return context;
        }
        this.node.style.display = (context.device.canvas) ? "block" : "none";
        if (context.device.canvasurl) {
            this.urlnode.style.display = "block";
            const url = this.node.toDataURL();
            this.urlnode.href = url; 
            this.urlnode.setAttribute("download", "PS.png"); 
        } else {
            if (this.urlnode) this.urlnode.style.display = "none";
        }
       
        return context;
    }

};

rpnPDFDevice = class {
    constructor(node, urlnode) { 
        this.node = node;
        if (!this.node) this.node = document.createElement("IMG");
        this.urlnode = urlnode;
        this.initgraphics(this.node.width, this.node.height, 1);
        this.canshow = true;
        this.catalog = {};
        this.pages = {};
        this.elements = [];
        this.usedfonts = {};
        this.currentfont = {};
    }
    finalize() {} 
    initgraphics(width, height, oversampling, transparent) { 
        if (Number.isFinite(width)) this.width = width;         
        if (Number.isFinite(height)) this.height = height;  
        this.node.style.backgroundColor = (transparent) ? "transparent" : "white";             
    }
    numberFormat(z) {
        return Intl.NumberFormat('en-IN', { minimumFractionDigits: 3, maximumFractionDigits: 3 }).format(z);
    }
    asciiHexEncode(buffer) {
       const data = new Array(buffer.length);
       for (let i=0; i < buffer.length; i++) {
           data[i] = ("0" + (buffer.codePointAt(i).toString(16))).substr(0,2);
       }
       return data.join(" ")+endtag;
    }
    objectDict(obj) {
       const elements = [];
       for (let k in obj) {
           const v = obj[k];
           if (typeof v == "object") {
               elements.push("/" + k + " " + this.objectDict(v));
           } else {
               elements.push("/" + k + " " + v);
           } 
       }
       return "<< " + elements.join(" ") + " >> ";
    }
    getPath(path, close = true) { 
       const p = [];
       for (let subpath of path) {
           if (!subpath.length) continue;
           p.push(this.numberFormat(subpath[0][1]) + " " + this.numberFormat(subpath[0][2]) + " m");
           for (let line of subpath) {
               if (line[0] == "C") {
                   p.push(this.numberFormat(line[3]) + " " + this.numberFormat(line[4]) + " " + this.numberFormat(line[5]) + " " + this.numberFormat(line[6]) + " " + this.numberFormat(line[7]) + " " + line[8] + " c");
               } else {
                   p.push(this.numberFormat(line[3]) + " " + this.numberFormat(line[4]) + " l");
                  if (line[0] == "Z") p.push("h");
               }
           }
        } 
        if (close) p.push("h");
        return p.join(" "); 
    }
    clip(context) {
        this.elements.push("q");
        for (let clip of context.graphics.clip) {
            this.elements.push(this.getPath(clip));
            this.elements.push("W n");
        }
        return context;     
    }
    eofill (context) {
        return this.fill(context, false);
    }
    fill(context, zerowind = true) { 
        if (context.device.pdf + context.device.pdfurl < 1) return context;
        if (context.device.textmode * context.showmode) return context;
        if (context.graphics.clip.length) context = this.clip(context);
        this.elements.push(this.getPath(context.graphics.path));
        this.setcolor(context);
        this.setalpha(context);
        if (zerowind) {
            this.elements.push("f");
        } else {
            this.elements.push("f*");
        }
        if (context.graphics.clip.length) this.elements.push("Q");
        return context;     
    }
    setcolor(context) {
        const rs = this.numberFormat(context.graphics.color[0]/255);
 const gs = this.numberFormat(context.graphics.color[1]/255);
 const bs = this.numberFormat(context.graphics.color[2]/255);
        this.elements.push(rs+' '+gs+' '+bs+' rg');
        this.elements.push(rs+' '+gs+' '+bs+' RG');   
    }
    setalpha(context)
    {
        const gs = Math.round(context.graphics.color[3]/16)
        this.elements.push("/GS"+gs+" gs");
    }
    setfont(context) {
        const f = {};
        f.Type = "/Font";
        f.Subtype = "/Type1";
        f.Encoding = "/MacRomanEncoding";
        f.BaseFont = "/" + context.graphics.font;
 
 const key = f.BaseFont;
 var k;
  
 if (this.usedfonts.hasOwnProperty(key)) {
     k = this.usedfonts[key].key;
        } else {
     k = Object.keys(this.usedfonts).length + 1;
     f.key = k;
     this.usedfonts[key] = f;
        }
 if (f != this.currentfont) {
     this.currentfont = f;
     this.elements.push("BT /F" + k + "  " + this.numberFormat(context.graphics.size) + " Tf ET"); 
 }

}
    show(s, context, targetwidth = 0, extraspace = 0) {
        if (context.device.pdf + context.device.pdfurl < 1) return context;
        if (context.graphics.clip.length) context = this.clip(context);
        this.setfont(context);
        this.setcolor(context);
        this.setalpha(context);
        const matrix = context.graphics.matrix.slice();
        const decomposed = decompose_2d_matrix(matrix);
        const s2 = macRomanEncoding(s);
        if (decomposed.rotation) {
             const tmatrix = [ 1, 0, 0, 1, this.numberFormat(context.graphics.current[0]), this.numberFormat (context.graphics.current[1])];
             const rmatrix = [ this.numberFormat (Math.cos(decomposed.rotation)), this.numberFormat (Math.sin(decomposed.rotation)), this.numberFormat(-Math.sin(decomposed.rotation)), this.numberFormat(Math.cos(decomposed.rotation)), 0, 0];
             this.elements.push("q " + tmatrix.join(" ") + " cm " + rmatrix.join(" ") + " cm"); 
             this.elements.push("BT 0 0 Td " + extraspace + " Tw (" + s2 + ") Tj ET");
             this.elements.push ("Q");
             
        } else {
            this.elements.push("BT " + this.numberFormat(context.graphics.current[0]) + " " + this.numberFormat(context.graphics.current[1]) + " Td " + extraspace + " Tw (" + s2 + ") Tj ET");
        }
        if (context.graphics.clip.length) this.elements.push("Q");
        return context;
    }
    showpage(context) { 
        if (context.device.pdf + context.device.pdfurl < 1) return context; 
        const objects = [];
        this.catalog.Type = "/Catalog";
        this.catalog.Pages = "2 0 R"; 
        objects.push([this.catalog]);

this.pages.Type = "/Pages";
        this.pages.Kids = "[ 3 0 R ]";
        this.pages.Count = "1";
        this.pages.MediaBox = "[0 0 " + this.width + " " + this.height + "]"; 
        objects.push([this.pages]);

const streamdict = {};
        const stream = this.elements.join(endofline);
        streamdict.Length = stream.length;
        objects.push([streamdict, stream]);

for (let i = 0; i < 17; i++ ) {
            alphadict["GS"+i] = (5+i) + " 0 R";
            const ad = {};
            ad.type = "/ExtGState"; 
            ad.ca = i / 16.0;
            ad.CA = i / 16.0;
            objects.push([ad])
        }

const xrefoffset = [];
        var file = "%PDF-1.1" + endofline; // signature
        file +=  "%¥±ë rpn" + endofline; // random binary characters 
        
        for (let k in objects) {    
     const o = objects[k];
            xrefoffset.push(file.length);
            file += xrefoffset.length + " 0 obj" + endofline;
            file += this.objectDict(o[0]) + endofline;
            if (o.length == 2) {
                file += "stream" + endofline;
                file += o[1] + endofline;
                file += "endstream" + endofline;
            }
            file += "endobj" + endofline + endofline;
        }
        
        
        const startxref = file.length;

file += "xref" + endofline;
        file += "0 6" + endofline;
        file += "0000000000 65535 f" + endofline; 
        for (let i in xrefoffset) {
            const x = new Intl.NumberFormat('en-IN', { minimumIntegerDigits: 10 , useGrouping: false}).format(xrefoffset[i]);
            file += x + ' 00000 n ' + endofline;
        }

// trailer
        const trailderdict = {};
        trailderdict.Root = "1 0 R";
        trailderdict.Size = 5;
        file += "trailer " + this.objectDict(trailderdict) + endofline;
        file += 'startxref'+ endofline;
        file += startxref + endofline;
        file +='%%EOF' + endofline;
        const url = "data:application/pdf;base64," + btoa(file);
        this.urlnode.style.display = (context.device.pdfurl) ? "block" : "none";
        this.node.style.display = (context.device.pdf) ? "block" : "none";

if (context.device.pdfurl) {
            this.urlnode.href = url; 
            this.urlnode.setAttribute("download", "PS.pdf"); 
        }
        if (context.device.pdf) {
            this.node.src = url;
            this.node.style.display = "block";
            this.node.width = this.width;
            this.node.height = this.height;
        }
        
        return context; 
    }
    stroke(context) { 
        if (context.device.pdf + context.device.pdfurl < 1) return context;
        if (context.graphics.clip.length) context = this.clip(context);
        this.elements.push(this.getPath(context.graphics.path, false));
        this.setcolor(context);
        this.setalpha(context);
        const ws = this.numberFormat(context.graphics.linewidth);
 this.elements.push(ws+' w'); 
        this.elements.push("S");
        if (context.graphics.clip.length) this.elements.push("Q");
        return context;     
    }
};

rpnSVGDevice = class {
    constructor(node, urlnode) { 
        this.node = node;
        this.canshow = true;
        this.fonts = {};
        if (!node) this.node = document.createElement("SVG");
        this.node.setAttribute("xmlns","http://www.w3.org/2000/svg");
        this.urlnode = urlnode;
        this.initgraphics( 590, 330, 1);
    }
    finalize() {}
    initgraphics(width, height, oversampling, transparent) {
        if (Number.isFinite(width)) { 
            this.node.setAttribute("width",width+"px");
            this.width = width;
        } 
        if (Number.isFinite(height)) {
            this.node.setAttribute("height",height+"px"); 
            this.height = height;
        }
        if (Number.isFinite(width) && Number.isFinite(height))         
        this.node.setAttribute("viewbox", "0 0 " + width+" " + height);
        this.node.style.backgroundColor = (transparent) ? "transparent" : "white";
        this.node.style.display = (context.device.svg) ? "block" : "none";
        this.clippath = "";
        this.clippathsource = "";
        this.node.innerHTML = "";
        
    }
    getPath(path, close = true) {
       const p = [];
       if (!path.length) return "";
       for (let subpath of path) {
           if (!subpath.length) continue;
           p.push("M " + (subpath[0][1]) + " " + (this.height - subpath[0][2]));
           for (let line of subpath) {
               if (line[0] == "C") {
                   p.push("C " +(line[3]) + " " + (this.height - line[4]) + " " + (line[5]) + " " + (this.height - line[6]) + " " +(line[7]) + " " + (this.height - line[8]));
               } else {
                   p.push("L "+(line[3]) + " " + (this.height - line[4]));
                   if (line[0] == "Z") p.push("Z");             
}
           }
        } 
        if (close) p.push("Z");
        return p.join(" ");
    }
    clip(context) {
        const test = JSON.stringify(context.graphics.clip);
        if (this.clippathsource == test) return context;
        this.clippath = "";
        this.clippathsource == test;
        for (let clip of context.graphics.clip) {
            const node = document.createElement("CLIPPATH");
            if (this.clippath) node.setAttribute("clip-path", "url(#"+this.clippath+")"); 
            this.clippath = "clippath"+this.node.childElementCount;
            node.setAttribute("id", this.clippath);
            const node2 = document.createElement("PATH");
            node2.setAttribute("d", this.getPath(clip));
            node.appendChild(node2);
            this.node.appendChild(node);
        }
       
        return context;     
    }
    eofill (context) {
        return this.fill(context, false);
    }
    fill(context, zerowind = true) { 
        if (context.device.svg + context.device.svgurl < 1) return context;
        if (context.device.textmode * context.showmode) return context;
        if (context.device.svg) this.node.style.display = "block";
        context = this.clip(context);
        const node = document.createElement("PATH");
        node.setAttribute("id","fill"+this.node.childElementCount); 
        node.setAttribute("d", this.getPath(context.graphics.path));
        node.setAttribute("stroke","none");
        node.setAttribute("fill", "rgb(" + Math.round(context.graphics.color[0]) + ", " + Math.round(context.graphics.color[1]) + ", " + Math.round(context.graphics.color[2]) + ")"); 
        node.setAttribute("fill-opacity", context.graphics.color[3]/255.0); 
        if (this.clippath) node.setAttribute("clip-path", "url(#"+this.clippath+")"); 
        if (zerowind) {
            node.setAttribute("fill-rule", "nonzero");
        } else {
            node.setAttribute("fill-rule", "evenodd");
        } 
        this.node.appendChild(node);
        return context;     
    }
    stroke(context) { 
        if (context.device.svg + context.device.svgurl < 1) return context;
        if (context.device.svg) this.node.style.display = "block";
        context = this.clip(context);
        const node = document.createElement("PATH");
        node.setAttribute("id","stroke" + this.node.childElementCount); 
        node.setAttribute("d", this.getPath(context.graphics.path, false));
        node.setAttribute("fill","none");
        node.setAttribute("stroke-width",context.graphics.linewidth);
        node.setAttribute("stroke", "rgb(" + Math.round(context.graphics.color[0]) + ", " + Math.round(context.graphics.color[1]) + ", " + Math.round(context.graphics.color[2]) + ")");
        node.setAttribute("stroke-opacity", context.graphics.color[3]/255.0); 
         if (this.clippath) node.setAttribute("clip-path", "url(#"+this.clippath+")"); 
        this.node.appendChild(node);
        return context;         
    }
    show(s, context, targetwidth = 0) {
        if (context.device.svg + context.device.svgurl < 1) return context;
        if (context.device.svg) this.node.style.display = "block";
        if (!this.fonts.hasOwnProperty(context.graphics.font)) {
            this.fonts[context.graphics.font] = context.graphics.font;
        }
        context = this.clip(context);
        const node = document.createElement("TEXT");
        node.setAttribute("x", "0");
        node.setAttribute("y", "0");
        node.setAttribute("font-family", context.graphics.font);
        node.setAttribute("font-size", context.graphics.size);
        node.setAttribute("fill", "rgb(" + Math.round(context.graphics.color[0]) + ", " + Math.round(context.graphics.color[1]) + ", " + Math.round(context.graphics.color[2]) + ")" ); 
        node.setAttribute("fill-opacity", context.graphics.color[3]/255.0); 
        if (this.clippath) node.setAttribute("clip-path", "url(#"+this.clippath+")"); 
        const matrix = context.graphics.matrix.slice();
        const decomposed = decompose_2d_matrix(matrix);
        const x = context.graphics.current[0];
        const y = context.height - context.graphics.current[1];
        node.setAttribute("text-anchor","start");
        node.setAttribute("transform", "translate(" + x + " " + y  +") rotate(" +  -decomposed.rotation*180/Math.PI + ")" ); 
        if (targetwidth) {
            node.setAttribute("textLength", targetwidth);
            node.setAttribute("lengthAdjust", "spacing");
        }
        node.innerHTML = htmlspecialchars(s); // clean XML
        this.node.appendChild(node);
        return context;
    }
    showpage(context) { 
        if (context.device.svg + context.device.svgurl < 1) {
            this.node.style.display = "none";
            if (this.urlnode) this.urlnode.style.display = "none";
            return context;
        }
        const node = document.createElement("DEFS");
        this.node.insertBefore(node, this.node.firstChild);
        for (const font in this.fonts) {
            const style = document.createElement("STYLE");
            const src = readSyncDataURL(fontbasepath + font + ".ttf", "font/ttf");
            style.innerHTML = "@font-face { font-family: '" + font + "'; font-weight: normal; src:  url('" + src + "') format('truetype')} }";
            node.appendChild(style);
        }
        this.node.outerHTML = this.node.outerHTML; // force refresh
        if (context.device.svgurl) {
            const file = starttag + "?xml version='1.0' encoding='UTF-8'?" + endtag + this.node.outerHTML;
            const url = "data:image/svg+xml;base64," + btoa(file);
            this.urlnode.href = url; 
            this.urlnode.setAttribute("download", "PS.svg"); 
        } 
        this.node.style.display = (context.device.svg) ? "block" : "none";
        if (this.urlnode) 
         this.urlnode.style.display = (context.device.svgurl) ? "block" : "none";
        return context;
    }

};

And we add now a code for 3 pages and look what happens

Javascript Editor

My Journey to PostScript