/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.java2d.pisces;

import sun.awt.geom.PathConsumer2D;

final class Renderer implements PathConsumer2D {

    private class ScanlineIterator {

        private int[] crossings;

        // crossing bounds. The bounds are not necessarily tight (the scan line

        // at minY, for example, might have no crossings). The x bounds will

        // be accumulated as crossings are computed.

        private final int maxY;

        private int nextY;

        // indices into the segment pointer lists. They indicate the "active"

        // sublist in the segment lists (the portion of the list that contains

        // all the segments that cross the next scan line).

        private int edgeCount;

        private int[] edgePtrs;

        private static final int INIT_CROSSINGS_SIZE = 10;

        // Preconditions: Only subpixel scanlines in the range

        // (start <= subpixel_y <= end) will be evaluated. No

        // edge may have a valid (i.e. inside the supplied clip)

        // crossing that would be generated outside that range.

        private ScanlineIterator(int start, int end) {

            crossings = new int[INIT_CROSSINGS_SIZE];

            edgePtrs = new int[INIT_CROSSINGS_SIZE];

            nextY = start;

            maxY = end;

            edgeCount = 0;

        }

        private int next() {

            int cury = nextY++;

            int bucket = cury - boundsMinY;

            int count = this.edgeCount;

            int ptrs[] = this.edgePtrs;

            int bucketcount = edgeBucketCounts[bucket];

            if ((bucketcount & 0x1) != 0) {

                int newCount = 0;

                for (int i = 0; i < count; i++) {

                    int ecur = ptrs[i];

                    if (edges[ecur+YMAX] > cury) {

                        ptrs[newCount++] = ecur;

                    }

                }

                count = newCount;

            }

            ptrs = Helpers.widenArray(ptrs, count, bucketcount >> 1);

            for (int ecur = edgeBuckets[bucket]; ecur != NULL; ecur = (int)edges[ecur+NEXT]) {

                ptrs[count++] = ecur;

                // REMIND: Adjust start Y if necessary

            }

            this.edgePtrs = ptrs;

            this.edgeCount = count;

//            if ((count & 0x1) != 0) {

//                System.out.println("ODD NUMBER OF EDGES!!!!");

//            }

            int xings[] = this.crossings;

            if (xings.length < count) {

                this.crossings = xings = new int[ptrs.length];

            }

            for (int i = 0; i < count; i++) {

                int ecur = ptrs[i];

                float curx = edges[ecur+CURX];

                int cross = ((int) curx) << 1;

                edges[ecur+CURX] = curx + edges[ecur+SLOPE];

                if (edges[ecur+OR] > 0) {

                    cross |= 1;

                }

                int j = i;

                while (--j >= 0) {

                    int jcross = xings[j];

                    if (jcross <= cross) {

                        break;

                    }

                    xings[j+1] = jcross;

                    ptrs[j+1] = ptrs[j];

                }

                xings[j+1] = cross;

                ptrs[j+1] = ecur;

            }

            return count;

        }

        private boolean hasNext() {

            return nextY < maxY;

        }

        private int curY() {

            return nextY - 1;

        }

    }

//////////////////////////////////////////////////////////////////////////////

//  EDGE LIST

//////////////////////////////////////////////////////////////////////////////

// TODO(maybe): very tempting to use fixed point here. A lot of opportunities

// for shifts and just removing certain operations altogether.

    // common to all types of input path segments.

    private static final int YMAX = 0;

    private static final int CURX = 1;

    // NEXT and OR are meant to be indices into "int" fields, but arrays must

    // be homogenous, so every field is a float. However floats can represent

    // exactly up to 26 bit ints, so we're ok.

    private static final int OR   = 2;

    private static final int SLOPE = 3;

    private static final int NEXT = 4;

    private float edgeMinY = Float.POSITIVE_INFINITY;

    private float edgeMaxY = Float.NEGATIVE_INFINITY;

    private float edgeMinX = Float.POSITIVE_INFINITY;

    private float edgeMaxX = Float.NEGATIVE_INFINITY;

    private static final int SIZEOF_EDGE = 5;

    // don't just set NULL to -1, because we want NULL+NEXT to be negative.

    private static final int NULL = -SIZEOF_EDGE;

    private float[] edges = null;

    private static final int INIT_NUM_EDGES = 8;

    private int[] edgeBuckets = null;

    private int[] edgeBucketCounts = null; // 2*newedges + (1 if pruning needed)

    private int numEdges;

    private static final float DEC_BND = 20f;

    private static final float INC_BND = 8f;

    // each bucket is a linked list. this method adds eptr to the

    // start of the "bucket"th linked list.

    private void addEdgeToBucket(final int eptr, final int bucket) {

        edges[eptr+NEXT] = edgeBuckets[bucket];

        edgeBuckets[bucket] = eptr;

        edgeBucketCounts[bucket] += 2;

    }

    // Flattens using adaptive forward differencing. This only carries out

    // one iteration of the AFD loop. All it does is update AFD variables (i.e.

    // X0, Y0, D*[X|Y], COUNT; not variables used for computing scanline crossings).

    private void quadBreakIntoLinesAndAdd(float x0, float y0,

                                          final Curve c,

                                          final float x2, final float y2)

    {

        final float QUAD_DEC_BND = 32;

        final int countlg = 4;

        int count = 1 << countlg;

        int countsq = count * count;

        float maxDD = Math.max(c.dbx / countsq, c.dby / countsq);

        while (maxDD > QUAD_DEC_BND) {

            maxDD /= 4;

            count <<= 1;

        }

        countsq = count * count;

        final float ddx = c.dbx / countsq;

        final float ddy = c.dby / countsq;

        float dx = c.bx / countsq + c.cx / count;

        float dy = c.by / countsq + c.cy / count;

        while (count-- > 1) {

            float x1 = x0 + dx;

            dx += ddx;

            float y1 = y0 + dy;

            dy += ddy;

            addLine(x0, y0, x1, y1);

            x0 = x1;

            y0 = y1;

        }

        addLine(x0, y0, x2, y2);

    }

    // x0, y0 and x3,y3 are the endpoints of the curve. We could compute these

    // using c.xat(0),c.yat(0) and c.xat(1),c.yat(1), but this might introduce

    // numerical errors, and our callers already have the exact values.

    // Another alternative would be to pass all the control points, and call c.set

    // here, but then too many numbers are passed around.

    private void curveBreakIntoLinesAndAdd(float x0, float y0,

                                           final Curve c,

                                           final float x3, final float y3)

    {

        final int countlg = 3;

        int count = 1 << countlg;

        // the dx and dy refer to forward differencing variables, not the last

        // coefficients of the "points" polynomial

        float dddx, dddy, ddx, ddy, dx, dy;

        dddx = 2f * c.dax / (1 << (3 * countlg));

        dddy = 2f * c.day / (1 << (3 * countlg));

        ddx = dddx + c.dbx / (1 << (2 * countlg));

        ddy = dddy + c.dby / (1 << (2 * countlg));

        dx = c.ax / (1 << (3 * countlg)) + c.bx / (1 << (2 * countlg)) + c.cx / (1 << countlg);

        dy = c.ay / (1 << (3 * countlg)) + c.by / (1 << (2 * countlg)) + c.cy / (1 << countlg);

        // we use x0, y0 to walk the line

        float x1 = x0, y1 = y0;

        while (count > 0) {

            while (Math.abs(ddx) > DEC_BND || Math.abs(ddy) > DEC_BND) {

                dddx /= 8;

                dddy /= 8;

                ddx = ddx/4 - dddx;

                ddy = ddy/4 - dddy;

                dx = (dx - ddx) / 2;

                dy = (dy - ddy) / 2;

                count <<= 1;

            }

            // can only do this on even "count" values, because we must divide count by 2

            while (count % 2 == 0 && Math.abs(dx) <= INC_BND && Math.abs(dy) <= INC_BND) {

                dx = 2 * dx + ddx;

                dy = 2 * dy + ddy;

                ddx = 4 * (ddx + dddx);

                ddy = 4 * (ddy + dddy);

                dddx = 8 * dddx;

                dddy = 8 * dddy;

                count >>= 1;

            }

            count--;

            if (count > 0) {

                x1 += dx;

                dx += ddx;

                ddx += dddx;

                y1 += dy;

                dy += ddy;

                ddy += dddy;

            } else {

                x1 = x3;

                y1 = y3;

            }

            addLine(x0, y0, x1, y1);

            x0 = x1;

            y0 = y1;

        }

    }

    private void addLine(float x1, float y1, float x2, float y2) {

        float or = 1; // orientation of the line. 1 if y increases, 0 otherwise.

        if (y2 < y1) {

            or = y2; // no need to declare a temp variable. We have or.

            y2 = y1;

            y1 = or;

            or = x2;

            x2 = x1;

            x1 = or;

            or = 0;

        }

        final int firstCrossing = Math.max((int)Math.ceil(y1), boundsMinY);

        final int lastCrossing = Math.min((int)Math.ceil(y2), boundsMaxY);

        if (firstCrossing >= lastCrossing) {

            return;

        }

        if (y1 < edgeMinY) { edgeMinY = y1; }

        if (y2 > edgeMaxY) { edgeMaxY = y2; }

        final float slope = (x2 - x1) / (y2 - y1);

        if (slope > 0) { // <==> x1 < x2

            if (x1 < edgeMinX) { edgeMinX = x1; }

            if (x2 > edgeMaxX) { edgeMaxX = x2; }

        } else {

            if (x2 < edgeMinX) { edgeMinX = x2; }

            if (x1 > edgeMaxX) { edgeMaxX = x1; }

        }

        final int ptr = numEdges * SIZEOF_EDGE;

        edges = Helpers.widenArray(edges, ptr, SIZEOF_EDGE);

        numEdges++;

        edges[ptr+OR] = or;

        edges[ptr+CURX] = x1 + (firstCrossing - y1) * slope;

        edges[ptr+SLOPE] = slope;

        edges[ptr+YMAX] = lastCrossing;

        final int bucketIdx = firstCrossing - boundsMinY;

        addEdgeToBucket(ptr, bucketIdx);

        edgeBucketCounts[lastCrossing - boundsMinY] |= 1;

    }

// END EDGE LIST

//////////////////////////////////////////////////////////////////////////////

    public static final int WIND_EVEN_ODD = 0;

    public static final int WIND_NON_ZERO = 1;

    // Antialiasing

    final private int SUBPIXEL_LG_POSITIONS_X;

    final private int SUBPIXEL_LG_POSITIONS_Y;

    final private int SUBPIXEL_POSITIONS_X;

    final private int SUBPIXEL_POSITIONS_Y;

    final private int SUBPIXEL_MASK_X;

    final private int SUBPIXEL_MASK_Y;

    final int MAX_AA_ALPHA;

    // Cache to store RLE-encoded coverage mask of the current primitive

    PiscesCache cache;

    // Bounds of the drawing region, at subpixel precision.

    private final int boundsMinX, boundsMinY, boundsMaxX, boundsMaxY;

    // Current winding rule

    private final int windingRule;

    // Current drawing position, i.e., final point of last segment

    private float x0, y0;

    // Position of most recent 'moveTo' command

    private float pix_sx0, pix_sy0;

    public Renderer(int subpixelLgPositionsX, int subpixelLgPositionsY,

                    int pix_boundsX, int pix_boundsY,

                    int pix_boundsWidth, int pix_boundsHeight,

                    int windingRule)

    {

        this.SUBPIXEL_LG_POSITIONS_X = subpixelLgPositionsX;

        this.SUBPIXEL_LG_POSITIONS_Y = subpixelLgPositionsY;

        this.SUBPIXEL_MASK_X = (1 << (SUBPIXEL_LG_POSITIONS_X)) - 1;

        this.SUBPIXEL_MASK_Y = (1 << (SUBPIXEL_LG_POSITIONS_Y)) - 1;

        this.SUBPIXEL_POSITIONS_X = 1 << (SUBPIXEL_LG_POSITIONS_X);

        this.SUBPIXEL_POSITIONS_Y = 1 << (SUBPIXEL_LG_POSITIONS_Y);

        this.MAX_AA_ALPHA = (SUBPIXEL_POSITIONS_X * SUBPIXEL_POSITIONS_Y);

        this.windingRule = windingRule;

        this.boundsMinX = pix_boundsX * SUBPIXEL_POSITIONS_X;

        this.boundsMinY = pix_boundsY * SUBPIXEL_POSITIONS_Y;

        this.boundsMaxX = (pix_boundsX + pix_boundsWidth) * SUBPIXEL_POSITIONS_X;

        this.boundsMaxY = (pix_boundsY + pix_boundsHeight) * SUBPIXEL_POSITIONS_Y;

        edges = new float[INIT_NUM_EDGES * SIZEOF_EDGE];

        numEdges = 0;

        edgeBuckets = new int[boundsMaxY - boundsMinY];

        java.util.Arrays.fill(edgeBuckets, NULL);

        edgeBucketCounts = new int[edgeBuckets.length + 1];

    }

    private float tosubpixx(float pix_x) {

        return pix_x * SUBPIXEL_POSITIONS_X;

    }

    private float tosubpixy(float pix_y) {

        return pix_y * SUBPIXEL_POSITIONS_Y;

    }

    public void moveTo(float pix_x0, float pix_y0) {

        closePath();

        this.pix_sx0 = pix_x0;

        this.pix_sy0 = pix_y0;

        this.y0 = tosubpixy(pix_y0);

        this.x0 = tosubpixx(pix_x0);

    }

    public void lineTo(float pix_x1, float pix_y1) {

        float x1 = tosubpixx(pix_x1);

        float y1 = tosubpixy(pix_y1);

        addLine(x0, y0, x1, y1);

        x0 = x1;

        y0 = y1;

    }

    private Curve c = new Curve();

    @Override public void curveTo(float x1, float y1,

                                  float x2, float y2,

                                  float x3, float y3)

    {

        final float xe = tosubpixx(x3);

        final float ye = tosubpixy(y3);

        c.set(x0, y0, tosubpixx(x1), tosubpixy(y1), tosubpixx(x2), tosubpixy(y2), xe, ye);

        curveBreakIntoLinesAndAdd(x0, y0, c, xe, ye);

        x0 = xe;

        y0 = ye;

    }

    @Override public void quadTo(float x1, float y1, float x2, float y2) {

        final float xe = tosubpixx(x2);

        final float ye = tosubpixy(y2);

        c.set(x0, y0, tosubpixx(x1), tosubpixy(y1), xe, ye);

        quadBreakIntoLinesAndAdd(x0, y0, c, xe, ye);

        x0 = xe;

        y0 = ye;

    }

    public void closePath() {

        // lineTo expects its input in pixel coordinates.

        lineTo(pix_sx0, pix_sy0);

    }

    public void pathDone() {

        closePath();

    }

    @Override

    public long getNativeConsumer() {

        throw new InternalError("Renderer does not use a native consumer.");

    }

    private void _endRendering(final int pix_bboxx0, final int pix_bboxx1,

                               int ymin, int ymax)

    {

        // Mask to determine the relevant bit of the crossing sum

        // 0x1 if EVEN_ODD, all bits if NON_ZERO

        int mask = (windingRule == WIND_EVEN_ODD) ? 0x1 : ~0x0;

        // add 2 to better deal with the last pixel in a pixel row.

        int width = pix_bboxx1 - pix_bboxx0;

        int[] alpha = new int[width+2];

        int bboxx0 = pix_bboxx0 << SUBPIXEL_LG_POSITIONS_X;

        int bboxx1 = pix_bboxx1 << SUBPIXEL_LG_POSITIONS_X;

        // Now we iterate through the scanlines. We must tell emitRow the coord

        // of the first non-transparent pixel, so we must keep accumulators for

        // the first and last pixels of the section of the current pixel row

        // that we will emit.

        // We also need to accumulate pix_bbox*, but the iterator does it

        // for us. We will just get the values from it once this loop is done

        int pix_maxX = Integer.MIN_VALUE;

        int pix_minX = Integer.MAX_VALUE;

        int y = boundsMinY; // needs to be declared here so we emit the last row properly.

        ScanlineIterator it = this.new ScanlineIterator(ymin, ymax);

        for ( ; it.hasNext(); ) {

            int numCrossings = it.next();

            int[] crossings = it.crossings;

            y = it.curY();

            if (numCrossings > 0) {

                int lowx = crossings[0] >> 1;

                int highx = crossings[numCrossings - 1] >> 1;

                int x0 = Math.max(lowx, bboxx0);

                int x1 = Math.min(highx, bboxx1);

                pix_minX = Math.min(pix_minX, x0 >> SUBPIXEL_LG_POSITIONS_X);

                pix_maxX = Math.max(pix_maxX, x1 >> SUBPIXEL_LG_POSITIONS_X);

            }

            int sum = 0;

            int prev = bboxx0;

            for (int i = 0; i < numCrossings; i++) {

                int curxo = crossings[i];

                int curx = curxo >> 1;

                // to turn {0, 1} into {-1, 1}, multiply by 2 and subtract 1.

                int crorientation = ((curxo & 0x1) << 1) - 1;

                if ((sum & mask) != 0) {

                    int x0 = Math.max(prev, bboxx0);

                    int x1 = Math.min(curx, bboxx1);

                    if (x0 < x1) {

                        x0 -= bboxx0; // turn x0, x1 from coords to indeces

                        x1 -= bboxx0; // in the alpha array.

                        int pix_x = x0 >> SUBPIXEL_LG_POSITIONS_X;

                        int pix_xmaxm1 = (x1 - 1) >> SUBPIXEL_LG_POSITIONS_X;

                        if (pix_x == pix_xmaxm1) {

                            // Start and end in same pixel

                            alpha[pix_x] += (x1 - x0);

                            alpha[pix_x+1] -= (x1 - x0);

                        } else {

                            int pix_xmax = x1 >> SUBPIXEL_LG_POSITIONS_X;

                            alpha[pix_x] += SUBPIXEL_POSITIONS_X - (x0 & SUBPIXEL_MASK_X);

                            alpha[pix_x+1] += (x0 & SUBPIXEL_MASK_X);

                            alpha[pix_xmax] -= SUBPIXEL_POSITIONS_X - (x1 & SUBPIXEL_MASK_X);