ElevationTilePyramid.h

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/****************************************************************************
 *
 * (c) 2009-2024 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
 *
 * QGroundControl is licensed according to the terms in the file
 * COPYING.md in the root of the source code directory.
 *
 ****************************************************************************/
 
#pragma once
 
#include <QtCore/QHash>
#include <QtCore/QList>
#include <QtCore/QRectF>
#include <QtCore/QSet>
 
#include <utility>
 
#include "TileMath.h"
 
class ElevationTilePyramid
{
public:
    static constexpr int kMaxTiles = 128;
 
    struct Grid
    {
        int width = 0;         
        int height = 0;        
        QList<float> heights;  
 
        bool isValid() const { return (width > 0) && (height > 0) && (heights.size() == qsizetype(width) * height); }
    };
 
    struct View
    {
        const Grid* grid = nullptr;  
        TileMath::TileKey key;       
        QRectF subWindow;
 
        bool isValid() const { return grid != nullptr; }
    };
 
    bool insertTile(const TileMath::TileKey& key, Grid grid, TileMath::TileKey* evictedKey = nullptr);
 
    bool hasTile(const TileMath::TileKey& key) const { return _tiles.contains(key); }
 
    View bestTileFor(const TileMath::TileKey& key) const;
 
    int tileCount() const { return static_cast<int>(_tiles.count()); }
 
    void setPinnedKeys(QSet<TileMath::TileKey> keys) { _pinnedKeys = std::move(keys); }
 
    bool hasDescendant(const TileMath::TileKey& key) const { return _descendantCounts.value(key, 0) > 0; }
 
    qint64 lookupCountForTest() const { return _lookupCount; }
 
private:
    TileMath::TileKey _evictLeastRecentlyUsed();
 
    QHash<TileMath::TileKey, Grid> _tiles;
    QHash<TileMath::TileKey, int> _descendantCounts;  
    QSet<TileMath::TileKey> _pinnedKeys;
    mutable QHash<TileMath::TileKey, qint64> _lastUsed;
    mutable qint64 _useTick = 0;
    mutable qint64 _lookupCount = 0;
};