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Filename : rasterizer.js
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import Tracer from './tracer';

/**
 * http://www.codeproject.com/Tips/407172/Connected-Component-Labeling-and-Vectorization
 */
var Rasterizer = {
    createContour2D: function() {
        return {
            dir: null,
            index: null,
            firstVertex: null,
            insideContours: null,
            nextpeer: null,
            prevpeer: null
        };
    },
    CONTOUR_DIR: {
        CW_DIR: 0,
        CCW_DIR: 1,
        UNKNOWN_DIR: 2
    },
    DIR: {
        OUTSIDE_EDGE: -32767,
        INSIDE_EDGE: -32766
    },
    create: function(imageWrapper, labelWrapper) {
        var imageData = imageWrapper.data,
            labelData = labelWrapper.data,
            width = imageWrapper.size.x,
            height = imageWrapper.size.y,
            tracer = Tracer.create(imageWrapper, labelWrapper);

        return {
            rasterize: function(depthlabel) {
                var color,
                    bc,
                    lc,
                    labelindex,
                    cx,
                    cy,
                    colorMap = [],
                    vertex,
                    p,
                    cc,
                    sc,
                    pos,
                    connectedCount = 0,
                    i;

                for ( i = 0; i < 400; i++) {
                    colorMap[i] = 0;
                }

                colorMap[0] = imageData[0];
                cc = null;
                for ( cy = 1; cy < height - 1; cy++) {
                    labelindex = 0;
                    bc = colorMap[0];
                    for ( cx = 1; cx < width - 1; cx++) {
                        pos = cy * width + cx;
                        if (labelData[pos] === 0) {
                            color = imageData[pos];
                            if (color !== bc) {
                                if (labelindex === 0) {
                                    lc = connectedCount + 1;
                                    colorMap[lc] = color;
                                    bc = color;
                                    vertex = tracer.contourTracing(cy, cx, lc, color, Rasterizer.DIR.OUTSIDE_EDGE);
                                    if (vertex !== null) {
                                        connectedCount++;
                                        labelindex = lc;
                                        p = Rasterizer.createContour2D();
                                        p.dir = Rasterizer.CONTOUR_DIR.CW_DIR;
                                        p.index = labelindex;
                                        p.firstVertex = vertex;
                                        p.nextpeer = cc;
                                        p.insideContours = null;
                                        if (cc !== null) {
                                            cc.prevpeer = p;
                                        }
                                        cc = p;
                                    }
                                } else {
                                    vertex = tracer
                                        .contourTracing(cy, cx, Rasterizer.DIR.INSIDE_EDGE, color, labelindex);
                                    if (vertex !== null) {
                                        p = Rasterizer.createContour2D();
                                        p.firstVertex = vertex;
                                        p.insideContours = null;
                                        if (depthlabel === 0) {
                                            p.dir = Rasterizer.CONTOUR_DIR.CCW_DIR;
                                        } else {
                                            p.dir = Rasterizer.CONTOUR_DIR.CW_DIR;
                                        }
                                        p.index = depthlabel;
                                        sc = cc;
                                        while ((sc !== null) && sc.index !== labelindex) {
                                            sc = sc.nextpeer;
                                        }
                                        if (sc !== null) {
                                            p.nextpeer = sc.insideContours;
                                            if (sc.insideContours !== null) {
                                                sc.insideContours.prevpeer = p;
                                            }
                                            sc.insideContours = p;
                                        }
                                    }
                                }
                            } else {
                                labelData[pos] = labelindex;
                            }
                        } else if (labelData[pos] === Rasterizer.DIR.OUTSIDE_EDGE
                                || labelData[pos] === Rasterizer.DIR.INSIDE_EDGE) {
                            labelindex = 0;
                            if (labelData[pos] === Rasterizer.DIR.INSIDE_EDGE) {
                                bc = imageData[pos];
                            } else {
                                bc = colorMap[0];
                            }
                        } else {
                            labelindex = labelData[pos];
                            bc = colorMap[labelindex];
                        }
                    }
                }
                sc = cc;
                while (sc !== null) {
                    sc.index = depthlabel;
                    sc = sc.nextpeer;
                }
                return {
                    cc: cc,
                    count: connectedCount
                };
            },
            debug: {
                drawContour: function(canvas, firstContour) {
                    var ctx = canvas.getContext("2d"),
                        pq = firstContour,
                        iq,
                        q,
                        p;

                    ctx.strokeStyle = "red";
                    ctx.fillStyle = "red";
                    ctx.lineWidth = 1;

                    if (pq !== null) {
                        iq = pq.insideContours;
                    } else {
                        iq = null;
                    }

                    while (pq !== null) {
                        if (iq !== null) {
                            q = iq;
                            iq = iq.nextpeer;
                        } else {
                            q = pq;
                            pq = pq.nextpeer;
                            if (pq !== null) {
                                iq = pq.insideContours;
                            } else {
                                iq = null;
                            }
                        }

                        switch (q.dir) {
                        case Rasterizer.CONTOUR_DIR.CW_DIR:
                            ctx.strokeStyle = "red";
                            break;
                        case Rasterizer.CONTOUR_DIR.CCW_DIR:
                            ctx.strokeStyle = "blue";
                            break;
                        case Rasterizer.CONTOUR_DIR.UNKNOWN_DIR:
                            ctx.strokeStyle = "green";
                            break;
                        }

                        p = q.firstVertex;
                        ctx.beginPath();
                        ctx.moveTo(p.x, p.y);
                        do {
                            p = p.next;
                            ctx.lineTo(p.x, p.y);
                        } while (p !== q.firstVertex);
                        ctx.stroke();
                    }
                }
            }
        };
    }
};

export default Rasterizer;