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82 lines
1.9 KiB
C++
82 lines
1.9 KiB
C++
#include <cmath>
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#include <QLineF>
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#include "map.h"
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#define SAMPLES 100
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#define DELTA 1e-6
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static void growLeft(const Coordinates &c, RectC &rect)
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{
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if (c.lon() < rect.left())
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rect.setLeft(c.lon());
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}
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static void growRight(const Coordinates &c, RectC &rect)
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{
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if (c.lon() > rect.right())
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rect.setRight(c.lon());
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}
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static void growTop(const Coordinates &c, RectC &rect)
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{
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if (c.lat() > rect.top())
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rect.setTop(c.lat());
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}
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static void growBottom(const Coordinates &c, RectC &rect)
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{
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if (c.lat() < rect.bottom())
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rect.setBottom(c.lat());
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}
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RectC Map::llBounds()
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{
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QRectF b(bounds());
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double dx = b.width() / SAMPLES;
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double dy = b.height() / SAMPLES;
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Coordinates tl(xy2ll(b.topLeft()));
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Coordinates br(xy2ll(b.bottomRight()));
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RectC rect(tl, br);
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for (int i = 0; i <= SAMPLES; i++) {
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double x = b.left() + i * dx;
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growBottom(xy2ll(QPointF(x, b.bottom())), rect);
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growTop(xy2ll(QPointF(x, b.top())), rect);
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}
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for (int i = 0; i <= SAMPLES; i++) {
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double y = b.top() + i * dy;
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growLeft(xy2ll(QPointF(b.left(), y)), rect);
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growRight(xy2ll(QPointF(b.right(), y)), rect);
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}
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if (rect.right() <= -180.0 + DELTA)
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rect.setRight(180.0);
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if (rect.left() >= 180.0 - DELTA)
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rect.setLeft(-180.0);
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return rect;
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}
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qreal Map::resolution(const QRectF &rect)
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{
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/* The haversine formula used in Coordinates::distanceTo() only gives
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"half world" distances and shorter so we have to use only the center
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"half rectangle" in case e.g. world map bounds are on the input */
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QRectF halfRect(QPointF(rect.left() + (rect.width() / 4.0),
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rect.top() + (rect.height() / 4.0)),
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QPointF(rect.right() - (rect.width() / 4.0),
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rect.bottom() - (rect.height() / 4.0)));
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qreal cy = halfRect.center().y();
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QPointF cl(halfRect.left(), cy);
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QPointF cr(halfRect.right(), cy);
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qreal ds = xy2ll(cl).distanceTo(xy2ll(cr));
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qreal ps = QLineF(cl, cr).length();
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return ds/ps;
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}
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