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Added support for ZIPed DEM files

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This commit is contained in:
Martin Tůma 2020-12-31 14:03:30 +01:00
parent 7e39a34d0e
commit c3f345c7f9
2 changed files with 43 additions and 12 deletions
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52
src/data/dem.cpp
View File

@ -1,7 +1,21 @@
/*
WARNING: This code uses internal Qt API - the QZipReader class for reading
ZIP files - and things may break if Qt changes the API. For Qt5 this is not
a problem as we can "see the future" now and there are no changes in all
the supported Qt5 versions up to the last one (5.15). In Qt6 the class
might change or even disappear in the future, but this is very unlikely
as there were no changes for several years and The Qt Company's policy
is: "do not invest any resources into any desktop related stuff unless
absolutely necessary". There is an issue (QTBUG-3897) since the year 2009 to
include the ZIP reader into the public API, which aptly illustrates the
effort The Qt Company is willing to make about anything desktop related...
*/
#include <QtEndian>
#include <QtMath>
#include <QDir>
#include <QFile>
#include <private/qzipreader_p.h>
#include "common/coordinates.h"
#include "dem.h"
@ -55,15 +69,19 @@ static qreal height(const Coordinates &c, const QByteArray *data)
QString DEM::_dir;
QCache<DEM::Key, QByteArray> DEM::_data;
QString DEM::fileName(const Key &key)
QString DEM::baseName(const Key &key)
{
const char ns = (key.lat() >= 0) ? 'N' : 'S';
const char ew = (key.lon() >= 0) ? 'E' : 'W';
QString basename = QString("%1%2%3%4.hgt").arg(ns)
return QString("%1%2%3%4.hgt").arg(ns)
.arg(qAbs(key.lat()), 2, 10, QChar('0')).arg(ew)
.arg(qAbs(key.lon()), 3, 10, QChar('0'));
return QDir(_dir).absoluteFilePath(basename);
}
QString DEM::fileName(const QString &baseName)
{
return QDir(_dir).absoluteFilePath(baseName);
}
void DEM::setDir(const QString &path)
@ -80,17 +98,29 @@ qreal DEM::elevation(const Coordinates &c)
QByteArray *ba = _data[k];
if (!ba) {
QFile file(fileName(k));
if (!file.open(QIODevice::ReadOnly)) {
qWarning("%s: %s", qPrintable(file.fileName()),
qPrintable(file.errorString()));
_data.insert(k, new QByteArray());
return NAN;
} else {
ba = new QByteArray(file.readAll());
QString bn(baseName(k));
QString fn(fileName(bn));
QString zn(fn + ".zip");
if (QFileInfo::exists(zn)) {
QZipReader zip(zn, QIODevice::ReadOnly);
ba = new QByteArray(zip.fileData(bn));
qreal ele = height(c, ba);
_data.insert(k, ba);
return ele;
} else {
QFile file(fn);
if (!file.open(QIODevice::ReadOnly)) {
qWarning("%s: %s", qPrintable(file.fileName()),
qPrintable(file.errorString()));
_data.insert(k, new QByteArray());
return NAN;
} else {
ba = new QByteArray(file.readAll());
qreal ele = height(c, ba);
_data.insert(k, ba);
return ele;
}
}
} else
return height(c, ba);

3
src/data/dem.h
View File

@ -27,7 +27,8 @@ private:
int _lon, _lat;
};
static QString fileName(const Key &key);
static QString baseName(const Key &key);
static QString fileName(const QString &baseName);
static QString _dir;
static QCache<Key, QByteArray> _data;