[feature][expression] Add exif() and exif_geotag() functions to the Q…

…GIS expression engine (#44081)
qgis · Jul 8, 2021 · 754328c · 754328c
1 parent 7341492
commit 754328c
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Showing 5 changed files with 97 additions and 22 deletions.
diff --git a/resources/function_help/json/exif b/resources/function_help/json/exif
@@ -0,0 +1,13 @@
+{
+  "name": "exif",
+  "type": "function",
+  "groups": ["Files and Paths"],
+  "description": "Retrieves exif tag values from an image file.",
+  "arguments": [
+    {"arg":"path","description":"An image file path."},
+    {"arg":"tag", "optional": true, "description":"The tag to return. If empty, a map with all exif tag values will be returned."}
+  ],
+  "examples": [
+    { "expression":"exif('/my/photo.jpg','Exif.Image.Orientation')", "returns":"0"}
+  ]
+}
diff --git a/resources/function_help/json/exif_geotag b/resources/function_help/json/exif_geotag
@@ -0,0 +1,12 @@
+{
+  "name": "exif_geotag",
+  "type": "function",
+  "groups": ["GeometryGroup"],
+  "description": "Creates a point geometry from the exif geotags of an image file.",
+  "arguments": [
+    {"arg":"path","description":"An image file path."}
+  ],
+  "examples": [
+    { "expression":"geom_to_wkt(exif_geotag('/my/photo.jpg'))", "returns":"'Point (2 4)'"}
+  ]
+}
diff --git a/src/core/expression/qgsexpressionfunction.cpp b/src/core/expression/qgsexpressionfunction.cpp
@@ -21,6 +21,7 @@
 #include "qgsexpressionfunction.h"
 #include "qgsexpressionutils.h"
 #include "qgsexpressionnodeimpl.h"
+#include "qgsexiftools.h"
 #include "qgsfeaturerequest.h"
 #include "qgsstringutils.h"
 #include "qgsmultipoint.h"
@@ -2358,6 +2359,20 @@ static QVariant fcnDateTimeFromEpoch( const QVariantList &values, const QgsExpre
   return QVariant( QDateTime::fromMSecsSinceEpoch( millisecs_since_epoch ) );
 }
 
+static QVariant fcnExif( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
+{
+  QString filepath = QgsExpressionUtils::getStringValue( values.at( 0 ), parent );
+  QString tag = QgsExpressionUtils::getStringValue( values.at( 1 ), parent );
+  return !tag.isNull() ? QgsExifTools::readTag( filepath, tag ) : QVariant( QgsExifTools::readTags( filepath ) );
+}
+
+static QVariant fcnExifGeoTag( const QVariantList &values, const QgsExpressionContext *, QgsExpression *parent, const QgsExpressionNodeFunction * )
+{
+  QString filepath = QgsExpressionUtils::getStringValue( values.at( 0 ), parent );
+  bool ok;
+  return QVariant::fromValue( QgsGeometry( new QgsPoint( QgsExifTools::getGeoTag( filepath, ok ) ) ) );
+}
+
 #define ENSURE_GEOM_TYPE(f, g, geomtype) \
   if ( !(f).hasGeometry() ) \
     return QVariant(); \
@@ -6672,6 +6687,11 @@ const QList<QgsExpressionFunction *> &QgsExpression::Functions()
         << new QgsStaticExpressionFunction( QStringLiteral( "file_size" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "path" ) ),
                                             fcnFileSize, QStringLiteral( "Files and Paths" ) )
 
+        << new QgsStaticExpressionFunction( QStringLiteral( "exif" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "path" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "tag" ), true ),
+                                            fcnExif, QStringLiteral( "Files and Paths" ) )
+        << new QgsStaticExpressionFunction( QStringLiteral( "exif_geotag" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "path" ) ),
+                                            fcnExifGeoTag, QStringLiteral( "Geometry" ) )
+
         // hash
         << new QgsStaticExpressionFunction( QStringLiteral( "hash" ), QgsExpressionFunction::ParameterList() << QgsExpressionFunction::Parameter( QStringLiteral( "string" ) ) << QgsExpressionFunction::Parameter( QStringLiteral( "method" ) ),
                                             fcnGenericHash, QStringLiteral( "Conversions" ) )

diff --git a/src/core/raster/qgsexiftools.cpp b/src/core/raster/qgsexiftools.cpp
@@ -171,42 +171,62 @@ QString doubleToExifCoordinateString( const double val )
 
 QVariant QgsExifTools::readTag( const QString &imagePath, const QString &key )
 {
-  std::unique_ptr< Exiv2::Image > image( Exiv2::ImageFactory::open( imagePath.toStdString() ) );
-  if ( !image || key.isEmpty() )
+  if ( !QFileInfo::exists( imagePath ) )
     return QVariant();
 
-  image->readMetadata();
-  Exiv2::ExifData &exifData = image->exifData();
-  if ( exifData.empty() )
+  try
+  {
+    std::unique_ptr< Exiv2::Image > image( Exiv2::ImageFactory::open( imagePath.toStdString() ) );
+    if ( !image || key.isEmpty() )
+      return QVariant();
+
+    image->readMetadata();
+    Exiv2::ExifData &exifData = image->exifData();
+    if ( exifData.empty() )
+    {
+      return QVariant();
+    }
+
+    Exiv2::ExifData::const_iterator i = exifData.findKey( Exiv2::ExifKey( key.toUtf8().constData() ) );
+    return i != exifData.end() ? decodeExifData( key, i ) : QVariant();
+  }
+  catch ( ... )
   {
     return QVariant();
   }
-
-  Exiv2::ExifData::const_iterator i = exifData.findKey( Exiv2::ExifKey( key.toUtf8().constData() ) );
-  return i != exifData.end() ? decodeExifData( key, i ) : QVariant();
 }
 
 QVariantMap QgsExifTools::readTags( const QString &imagePath )
 {
-  std::unique_ptr< Exiv2::Image > image( Exiv2::ImageFactory::open( imagePath.toStdString() ) );
-  if ( !image )
+  if ( !QFileInfo::exists( imagePath ) )
     return QVariantMap();
 
-  image->readMetadata();
-  Exiv2::ExifData &exifData = image->exifData();
-  if ( exifData.empty() )
+  try
   {
-    return QVariantMap();
-  }
+    std::unique_ptr< Exiv2::Image > image( Exiv2::ImageFactory::open( imagePath.toStdString() ) );
+    if ( !image )
+      return QVariantMap();
+
+    image->readMetadata();
+    Exiv2::ExifData &exifData = image->exifData();
+    if ( exifData.empty() )
+    {
+      return QVariantMap();
+    }
 
-  QVariantMap res;
-  Exiv2::ExifData::const_iterator end = exifData.end();
-  for ( Exiv2::ExifData::const_iterator i = exifData.begin(); i != end; ++i )
+    QVariantMap res;
+    Exiv2::ExifData::const_iterator end = exifData.end();
+    for ( Exiv2::ExifData::const_iterator i = exifData.begin(); i != end; ++i )
+    {
+      const QString key = QString::fromStdString( i->key() );
+      res.insert( key, decodeExifData( key, i ) );
+    }
+    return res;
+  }
+  catch ( ... )
   {
-    const QString key = QString::fromStdString( i->key() );
-    res.insert( key, decodeExifData( key, i ) );
+    return QVariantMap();
   }
-  return res;
 }
 
 bool QgsExifTools::hasGeoTag( const QString &imagePath )

diff --git a/tests/src/core/testqgsexpression.cpp b/tests/src/core/testqgsexpression.cpp
@@ -1806,8 +1806,18 @@ class TestQgsExpression: public QObject
       QTest::newRow( "uuid('WithoutBraces')" ) << QStringLiteral( "regexp_match( uuid('WithoutBraces'), '([a-zA-Z\\\\d]{8}\\\\-[a-zA-Z\\\\d]{4}\\\\-[a-zA-Z\\\\d]{4}\\\\-[a-zA-Z\\\\d]{4}\\\\-[a-zA-Z\\\\d]{12})')" ) << false << QVariant( 1 );
       QTest::newRow( "uuid('Id128')" ) << QStringLiteral( "regexp_match( uuid('Id128'), '([a-zA-Z\\\\d]{32})')" ) << false << QVariant( 1 );
       QTest::newRow( "uuid('invalid-format')" ) << QStringLiteral( "regexp_match( uuid('invalid-format'), '({[a-zA-Z\\\\d]{8}\\\\-[a-zA-Z\\\\d]{4}\\\\-[a-zA-Z\\\\d]{4}\\\\-[a-zA-Z\\\\d]{4}\\\\-[a-zA-Z\\\\d]{12}})')" ) << false << QVariant( 1 );
-    }
 
+      //exif functions
+      QString testDataDir = QStringLiteral( TEST_DATA_DIR ) + '/';
+      QTest::newRow( "exif number" ) << QStringLiteral( "exif('%1photos/0997.JPG','Exif.GPSInfo.GPSAltitude')" ).arg( testDataDir ) << false << QVariant( 422.19101123595505 );
+      QTest::newRow( "exif number from map" ) << QStringLiteral( "exif('%1photos/0997.JPG')['Exif.GPSInfo.GPSAltitude']" ).arg( testDataDir ) << false << QVariant( 422.19101123595505 );
+      QTest::newRow( "exif date" ) << QStringLiteral( "exif('%1photos/0997.JPG','Exif.Image.DateTime')" ).arg( testDataDir ) << false << QVariant( QDateTime( QDate( 2018, 3, 16 ), QTime( 12, 19, 19 ) ) );
+      QTest::newRow( "exif date from map" ) << QStringLiteral( "exif('%1photos/0997.JPG')['Exif.Image.DateTime']" ).arg( testDataDir ) << false << QVariant( QDateTime( QDate( 2018, 3, 16 ), QTime( 12, 19, 19 ) ) );
+      QTest::newRow( "exif bad tag" ) << QStringLiteral( "exif('%1photos/0997.JPG','bad tag')" ).arg( testDataDir ) << false << QVariant();
+      QTest::newRow( "exif bad file path" ) << QStringLiteral( "exif('bad path','Exif.Image.DateTime')" ) << false << QVariant();
+      QTest::newRow( "exif_geotag" ) << QStringLiteral( "geom_to_wkt(exif_geotag('%1photos/0997.JPG'))" ).arg( testDataDir ) << false << QVariant( "PointZ (149.27516667 -37.2305 422.19101124)" );
+      QTest::newRow( "exif_geotag bad file path" ) << QStringLiteral( "geom_to_wkt(exif_geotag('bad path'))" ).arg( testDataDir ) << false << QVariant( "Point EMPTY" );
+    }
 
     void run_evaluation_test( QgsExpression &exp, bool evalError, QVariant &expected )
     {