coopgo/node_modules/ol/geom/flat/simplify.js

/**
 * @module ol/geom/flat/simplify
 */
// Based on simplify-js https://github.com/mourner/simplify-js
// Copyright (c) 2012, Vladimir Agafonkin
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//    1. Redistributions of source code must retain the above copyright notice,
//       this list of conditions and the following disclaimer.
//
//    2. Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in the
//       documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
import { squaredDistance, squaredSegmentDistance } from '../../math.js';
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {number} end End.
 * @param {number} stride Stride.
 * @param {number} squaredTolerance Squared tolerance.
 * @param {boolean} highQuality Highest quality.
 * @param {Array<number>} [opt_simplifiedFlatCoordinates] Simplified flat
 *     coordinates.
 * @return {Array<number>} Simplified line string.
 */
export function simplifyLineString(flatCoordinates, offset, end, stride, squaredTolerance, highQuality, opt_simplifiedFlatCoordinates) {
    var simplifiedFlatCoordinates = opt_simplifiedFlatCoordinates !== undefined
        ? opt_simplifiedFlatCoordinates
        : [];
    if (!highQuality) {
        end = radialDistance(flatCoordinates, offset, end, stride, squaredTolerance, simplifiedFlatCoordinates, 0);
        flatCoordinates = simplifiedFlatCoordinates;
        offset = 0;
        stride = 2;
    }
    simplifiedFlatCoordinates.length = douglasPeucker(flatCoordinates, offset, end, stride, squaredTolerance, simplifiedFlatCoordinates, 0);
    return simplifiedFlatCoordinates;
}
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {number} end End.
 * @param {number} stride Stride.
 * @param {number} squaredTolerance Squared tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @return {number} Simplified offset.
 */
export function douglasPeucker(flatCoordinates, offset, end, stride, squaredTolerance, simplifiedFlatCoordinates, simplifiedOffset) {
    var n = (end - offset) / stride;
    if (n < 3) {
        for (; offset < end; offset += stride) {
            simplifiedFlatCoordinates[simplifiedOffset++] = flatCoordinates[offset];
            simplifiedFlatCoordinates[simplifiedOffset++] =
                flatCoordinates[offset + 1];
        }
        return simplifiedOffset;
    }
    /** @type {Array<number>} */
    var markers = new Array(n);
    markers[0] = 1;
    markers[n - 1] = 1;
    /** @type {Array<number>} */
    var stack = [offset, end - stride];
    var index = 0;
    while (stack.length > 0) {
        var last = stack.pop();
        var first = stack.pop();
        var maxSquaredDistance = 0;
        var x1 = flatCoordinates[first];
        var y1 = flatCoordinates[first + 1];
        var x2 = flatCoordinates[last];
        var y2 = flatCoordinates[last + 1];
        for (var i = first + stride; i < last; i += stride) {
            var x = flatCoordinates[i];
            var y = flatCoordinates[i + 1];
            var squaredDistance_1 = squaredSegmentDistance(x, y, x1, y1, x2, y2);
            if (squaredDistance_1 > maxSquaredDistance) {
                index = i;
                maxSquaredDistance = squaredDistance_1;
            }
        }
        if (maxSquaredDistance > squaredTolerance) {
            markers[(index - offset) / stride] = 1;
            if (first + stride < index) {
                stack.push(first, index);
            }
            if (index + stride < last) {
                stack.push(index, last);
            }
        }
    }
    for (var i = 0; i < n; ++i) {
        if (markers[i]) {
            simplifiedFlatCoordinates[simplifiedOffset++] =
                flatCoordinates[offset + i * stride];
            simplifiedFlatCoordinates[simplifiedOffset++] =
                flatCoordinates[offset + i * stride + 1];
        }
    }
    return simplifiedOffset;
}
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {Array<number>} ends Ends.
 * @param {number} stride Stride.
 * @param {number} squaredTolerance Squared tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @param {Array<number>} simplifiedEnds Simplified ends.
 * @return {number} Simplified offset.
 */
export function douglasPeuckerArray(flatCoordinates, offset, ends, stride, squaredTolerance, simplifiedFlatCoordinates, simplifiedOffset, simplifiedEnds) {
    for (var i = 0, ii = ends.length; i < ii; ++i) {
        var end = ends[i];
        simplifiedOffset = douglasPeucker(flatCoordinates, offset, end, stride, squaredTolerance, simplifiedFlatCoordinates, simplifiedOffset);
        simplifiedEnds.push(simplifiedOffset);
        offset = end;
    }
    return simplifiedOffset;
}
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {Array<Array<number>>} endss Endss.
 * @param {number} stride Stride.
 * @param {number} squaredTolerance Squared tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @param {Array<Array<number>>} simplifiedEndss Simplified endss.
 * @return {number} Simplified offset.
 */
export function douglasPeuckerMultiArray(flatCoordinates, offset, endss, stride, squaredTolerance, simplifiedFlatCoordinates, simplifiedOffset, simplifiedEndss) {
    for (var i = 0, ii = endss.length; i < ii; ++i) {
        var ends = endss[i];
        var simplifiedEnds = [];
        simplifiedOffset = douglasPeuckerArray(flatCoordinates, offset, ends, stride, squaredTolerance, simplifiedFlatCoordinates, simplifiedOffset, simplifiedEnds);
        simplifiedEndss.push(simplifiedEnds);
        offset = ends[ends.length - 1];
    }
    return simplifiedOffset;
}
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {number} end End.
 * @param {number} stride Stride.
 * @param {number} squaredTolerance Squared tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @return {number} Simplified offset.
 */
export function radialDistance(flatCoordinates, offset, end, stride, squaredTolerance, simplifiedFlatCoordinates, simplifiedOffset) {
    if (end <= offset + stride) {
        // zero or one point, no simplification possible, so copy and return
        for (; offset < end; offset += stride) {
            simplifiedFlatCoordinates[simplifiedOffset++] = flatCoordinates[offset];
            simplifiedFlatCoordinates[simplifiedOffset++] =
                flatCoordinates[offset + 1];
        }
        return simplifiedOffset;
    }
    var x1 = flatCoordinates[offset];
    var y1 = flatCoordinates[offset + 1];
    // copy first point
    simplifiedFlatCoordinates[simplifiedOffset++] = x1;
    simplifiedFlatCoordinates[simplifiedOffset++] = y1;
    var x2 = x1;
    var y2 = y1;
    for (offset += stride; offset < end; offset += stride) {
        x2 = flatCoordinates[offset];
        y2 = flatCoordinates[offset + 1];
        if (squaredDistance(x1, y1, x2, y2) > squaredTolerance) {
            // copy point at offset
            simplifiedFlatCoordinates[simplifiedOffset++] = x2;
            simplifiedFlatCoordinates[simplifiedOffset++] = y2;
            x1 = x2;
            y1 = y2;
        }
    }
    if (x2 != x1 || y2 != y1) {
        // copy last point
        simplifiedFlatCoordinates[simplifiedOffset++] = x2;
        simplifiedFlatCoordinates[simplifiedOffset++] = y2;
    }
    return simplifiedOffset;
}
/**
 * @param {number} value Value.
 * @param {number} tolerance Tolerance.
 * @return {number} Rounded value.
 */
export function snap(value, tolerance) {
    return tolerance * Math.round(value / tolerance);
}
/**
 * Simplifies a line string using an algorithm designed by Tim Schaub.
 * Coordinates are snapped to the nearest value in a virtual grid and
 * consecutive duplicate coordinates are discarded.  This effectively preserves
 * topology as the simplification of any subsection of a line string is
 * independent of the rest of the line string.  This means that, for examples,
 * the common edge between two polygons will be simplified to the same line
 * string independently in both polygons.  This implementation uses a single
 * pass over the coordinates and eliminates intermediate collinear points.
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {number} end End.
 * @param {number} stride Stride.
 * @param {number} tolerance Tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @return {number} Simplified offset.
 */
export function quantize(flatCoordinates, offset, end, stride, tolerance, simplifiedFlatCoordinates, simplifiedOffset) {
    // do nothing if the line is empty
    if (offset == end) {
        return simplifiedOffset;
    }
    // snap the first coordinate (P1)
    var x1 = snap(flatCoordinates[offset], tolerance);
    var y1 = snap(flatCoordinates[offset + 1], tolerance);
    offset += stride;
    // add the first coordinate to the output
    simplifiedFlatCoordinates[simplifiedOffset++] = x1;
    simplifiedFlatCoordinates[simplifiedOffset++] = y1;
    // find the next coordinate that does not snap to the same value as the first
    // coordinate (P2)
    var x2, y2;
    do {
        x2 = snap(flatCoordinates[offset], tolerance);
        y2 = snap(flatCoordinates[offset + 1], tolerance);
        offset += stride;
        if (offset == end) {
            // all coordinates snap to the same value, the line collapses to a point
            // push the last snapped value anyway to ensure that the output contains
            // at least two points
            // FIXME should we really return at least two points anyway?
            simplifiedFlatCoordinates[simplifiedOffset++] = x2;
            simplifiedFlatCoordinates[simplifiedOffset++] = y2;
            return simplifiedOffset;
        }
    } while (x2 == x1 && y2 == y1);
    while (offset < end) {
        // snap the next coordinate (P3)
        var x3 = snap(flatCoordinates[offset], tolerance);
        var y3 = snap(flatCoordinates[offset + 1], tolerance);
        offset += stride;
        // skip P3 if it is equal to P2
        if (x3 == x2 && y3 == y2) {
            continue;
        }
        // calculate the delta between P1 and P2
        var dx1 = x2 - x1;
        var dy1 = y2 - y1;
        // calculate the delta between P3 and P1
        var dx2 = x3 - x1;
        var dy2 = y3 - y1;
        // if P1, P2, and P3 are colinear and P3 is further from P1 than P2 is from
        // P1 in the same direction then P2 is on the straight line between P1 and
        // P3
        if (dx1 * dy2 == dy1 * dx2 &&
            ((dx1 < 0 && dx2 < dx1) || dx1 == dx2 || (dx1 > 0 && dx2 > dx1)) &&
            ((dy1 < 0 && dy2 < dy1) || dy1 == dy2 || (dy1 > 0 && dy2 > dy1))) {
            // discard P2 and set P2 = P3
            x2 = x3;
            y2 = y3;
            continue;
        }
        // either P1, P2, and P3 are not colinear, or they are colinear but P3 is
        // between P3 and P1 or on the opposite half of the line to P2.  add P2,
        // and continue with P1 = P2 and P2 = P3
        simplifiedFlatCoordinates[simplifiedOffset++] = x2;
        simplifiedFlatCoordinates[simplifiedOffset++] = y2;
        x1 = x2;
        y1 = y2;
        x2 = x3;
        y2 = y3;
    }
    // add the last point (P2)
    simplifiedFlatCoordinates[simplifiedOffset++] = x2;
    simplifiedFlatCoordinates[simplifiedOffset++] = y2;
    return simplifiedOffset;
}
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {Array<number>} ends Ends.
 * @param {number} stride Stride.
 * @param {number} tolerance Tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @param {Array<number>} simplifiedEnds Simplified ends.
 * @return {number} Simplified offset.
 */
export function quantizeArray(flatCoordinates, offset, ends, stride, tolerance, simplifiedFlatCoordinates, simplifiedOffset, simplifiedEnds) {
    for (var i = 0, ii = ends.length; i < ii; ++i) {
        var end = ends[i];
        simplifiedOffset = quantize(flatCoordinates, offset, end, stride, tolerance, simplifiedFlatCoordinates, simplifiedOffset);
        simplifiedEnds.push(simplifiedOffset);
        offset = end;
    }
    return simplifiedOffset;
}
/**
 * @param {Array<number>} flatCoordinates Flat coordinates.
 * @param {number} offset Offset.
 * @param {Array<Array<number>>} endss Endss.
 * @param {number} stride Stride.
 * @param {number} tolerance Tolerance.
 * @param {Array<number>} simplifiedFlatCoordinates Simplified flat
 *     coordinates.
 * @param {number} simplifiedOffset Simplified offset.
 * @param {Array<Array<number>>} simplifiedEndss Simplified endss.
 * @return {number} Simplified offset.
 */
export function quantizeMultiArray(flatCoordinates, offset, endss, stride, tolerance, simplifiedFlatCoordinates, simplifiedOffset, simplifiedEndss) {
    for (var i = 0, ii = endss.length; i < ii; ++i) {
        var ends = endss[i];
        var simplifiedEnds = [];
        simplifiedOffset = quantizeArray(flatCoordinates, offset, ends, stride, tolerance, simplifiedFlatCoordinates, simplifiedOffset, simplifiedEnds);
        simplifiedEndss.push(simplifiedEnds);
        offset = ends[ends.length - 1];
    }
    return simplifiedOffset;
}
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