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Measure tool fixes:

- Make unit selection more robust (doesn't rely on translations)
- Make calculation of lengths in degrees use a cartesian
calculation when project CRS is in degrees
- Fix display of calculation details, was misleading and
inaccurate for many CRS/unit combinations
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nyalldawson committed Feb 7, 2016
1 parent 33c37d0 commit b712f3cf4b52364b0e3cf4e5594e2c20a98bc1b6
Showing with 98 additions and 43 deletions.
  1. +96 −37 src/app/qgsmeasuredialog.cpp
  2. +2 −2 src/app/qgsmeasuredialog.h
  3. +0 −4 src/app/qgsmeasuretool.cpp
@@ -50,18 +50,17 @@ QgsMeasureDialog::QgsMeasureDialog( QgsMeasureTool* tool, Qt::WindowFlags f )
mMeasureArea = tool->measureArea();
mTotal = 0.;

mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::Meters ) );
mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::Feet ) );
mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::Degrees ) );
mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::NauticalMiles ) );

mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::Meters ), QGis::Meters );
mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::Feet ), QGis::Feet );
mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::Degrees ), QGis::Degrees );
mUnitsCombo->addItem( QgsUnitTypes::toString( QGis::NauticalMiles ), QGis::NauticalMiles );
QSettings settings;
QString units = settings.value( "/qgis/measure/displayunits", QgsUnitTypes::encodeUnit( QGis::Meters ) ).toString();
mUnitsCombo->setCurrentIndex( mUnitsCombo->findText( QgsUnitTypes::toString( QgsUnitTypes::decodeDistanceUnit( units ) ), Qt::MatchFixedString ) );
mUnitsCombo->setCurrentIndex( mUnitsCombo->findData( QgsUnitTypes::decodeDistanceUnit( units ) ) );

updateSettings();

connect( mUnitsCombo, SIGNAL( currentIndexChanged( const QString & ) ), this, SLOT( unitsChanged( const QString & ) ) );
connect( mUnitsCombo, SIGNAL( currentIndexChanged( int ) ), this, SLOT( unitsChanged( int ) ) );
connect( buttonBox, SIGNAL( rejected() ), this, SLOT( reject() ) );

groupBox->setCollapsed( true );
@@ -79,7 +78,7 @@ void QgsMeasureDialog::updateSettings()
mDecimalPlaces = settings.value( "/qgis/measure/decimalplaces", "3" ).toInt();
mCanvasUnits = mTool->canvas()->mapUnits();
// Configure QgsDistanceArea
mDisplayUnits = QgsUnitTypes::stringToDistanceUnit( mUnitsCombo->currentText() );
mDisplayUnits = static_cast< QGis::UnitType >( mUnitsCombo->itemData( mUnitsCombo->currentIndex() ).toInt() );
mDa.setSourceCrs( mTool->canvas()->mapSettings().destinationCrs().srsid() );
mDa.setEllipsoid( QgsProject::instance()->readEntry( "Measure", "/Ellipsoid", GEO_NONE ) );
// Only use ellipsoidal calculation when project wide transformation is enabled.
@@ -103,9 +102,9 @@ void QgsMeasureDialog::updateSettings()
updateUi();
}

void QgsMeasureDialog::unitsChanged( const QString &units )
void QgsMeasureDialog::unitsChanged( int index )
{
mDisplayUnits = QgsUnitTypes::stringToDistanceUnit( units );
mDisplayUnits = static_cast< QGis::UnitType >( mUnitsCombo->itemData( index ).toInt() );
mTable->clear();
mTotal = 0.;
updateUi();
@@ -243,12 +242,13 @@ void QgsMeasureDialog::saveWindowLocation()
settings.setValue( key, height() );
}

QString QgsMeasureDialog::formatDistance( double distance )
QString QgsMeasureDialog::formatDistance( double distance, bool convertUnits )
{
QSettings settings;
bool baseUnit = settings.value( "/qgis/measure/keepbaseunit", false ).toBool();

distance = convertLength( distance, mDisplayUnits );
if ( convertUnits )
distance = convertLength( distance, mDisplayUnits );
return QgsDistanceArea::textUnit( distance, mDecimalPlaces, mDisplayUnits, false, baseUnit );
}

@@ -266,41 +266,88 @@ void QgsMeasureDialog::updateUi()
{
// Set tooltip to indicate how we calculate measurments
QString toolTip = tr( "The calculations are based on:" );
if ( ! mTool->canvas()->hasCrsTransformEnabled() )

bool forceCartesian = false;
bool convertToDisplayUnits = true;

if ( mTool->canvas()->mapSettings().destinationCrs().mapUnits() == QGis::Degrees
&& mDisplayUnits == QGis::Degrees )
{
toolTip += "<br> * " + tr( "Project CRS transformation is turned off." ) + ' ';
toolTip += tr( "Canvas units setting is taken from project properties setting (%1)." ).arg( QgsUnitTypes::toString( mCanvasUnits ) );
toolTip += "<br> * " + tr( "Ellipsoidal calculation is not possible, as project CRS is undefined." );
setWindowTitle( tr( "Measure (OTF off)" ) );
//both source and destination units are degrees
toolTip += "<br> * " + tr( "Both project CRS (%1) and measured length are in degrees, so measurement is calculated using cartesian calculations in degrees." ).arg(
mTool->canvas()->mapSettings().destinationCrs().description() );
forceCartesian = true;
convertToDisplayUnits = false; //not required since we will be measuring in degrees
}
else
{
if ( mDa.ellipsoidalEnabled() )
QGis::UnitType resultUnit = QGis::UnknownUnit;
if ( ! mTool->canvas()->hasCrsTransformEnabled() )
{
toolTip += "<br> * " + tr( "Project CRS transformation is turned on and ellipsoidal calculation is selected." ) + ' ';
toolTip += "<br> * " + tr( "The coordinates are transformed to the chosen ellipsoid (%1), and the result is in meters" ).arg( mDa.ellipsoid() );
resultUnit = mTool->canvas()->mapSettings().destinationCrs().mapUnits();
toolTip += "<br> * " + tr( "Project CRS transformation is turned off." ) + ' ';
toolTip += tr( "Distance is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
mTool->canvas()->mapSettings().destinationCrs().description() );
toolTip += "<br> * " + tr( "Ellipsoidal calculation is not possible with CRS transformation disabled." );
setWindowTitle( tr( "Measure (OTF off)" ) );
}
else
{
toolTip += "<br> * " + tr( "Project CRS transformation is turned on but ellipsoidal calculation is not selected." );
toolTip += "<br> * " + tr( "The canvas units setting is taken from the project CRS (%1)." ).arg( QgsUnitTypes::toString( mCanvasUnits ) );
if ( mDa.willUseEllipsoid() )
{
resultUnit = QGis::Meters;
toolTip += "<br> * " + tr( "Project CRS transformation is turned on and ellipsoidal calculation is selected." ) + ' ';
toolTip += "<br> * " + tr( "The coordinates are transformed to the chosen ellipsoid (%1), and the measurement is calculated in %2." ).arg( mDa.ellipsoid(),
QgsUnitTypes::toString( resultUnit ) );
}
else
{
resultUnit = mTool->canvas()->mapSettings().destinationCrs().mapUnits();
toolTip += "<br> * " + tr( "Project CRS transformation is turned on but ellipsoidal calculation is not selected." ) + ' ';
toolTip += tr( "Distance is calculated in %1, based on project CRS (%2)." ).arg( QgsUnitTypes::toString( resultUnit ),
mTool->canvas()->mapSettings().destinationCrs().description() );
}
setWindowTitle( tr( "Measure (OTF on)" ) );
}
setWindowTitle( tr( "Measure (OTF on)" ) );
}

if (( mCanvasUnits == QGis::Meters && mDisplayUnits == QGis::Feet ) || ( mCanvasUnits == QGis::Feet && mDisplayUnits == QGis::Meters ) )
{
toolTip += "<br> * " + tr( "Finally, the value is converted from %1 to %2." ).arg( QgsUnitTypes::toString( mCanvasUnits ), QgsUnitTypes::toString( mDisplayUnits ) );
if ( QgsUnitTypes::unitType( resultUnit ) == QgsUnitTypes::Geographic &&
QgsUnitTypes::unitType( mDisplayUnits ) == QgsUnitTypes::Standard )
{
toolTip += "<br> * Distance is roughly converted to meters by using scale at equator (1 degree = 111319.49 meters).";
resultUnit = QGis::Meters;
}
else if ( QgsUnitTypes::unitType( resultUnit ) == QgsUnitTypes::Standard &&
QgsUnitTypes::unitType( mDisplayUnits ) == QgsUnitTypes::Geographic )
{
toolTip += "<br> * Distance is roughly converted to degrees by using scale at equator (1 degree = 111319.49 meters).";
resultUnit = QGis::Degrees;
}

if ( resultUnit != mDisplayUnits )
{
if ( QgsUnitTypes::unitType( resultUnit ) == QgsUnitTypes::Standard &&
QgsUnitTypes::unitType( mDisplayUnits ) == QgsUnitTypes::Standard )
{
// only shown if both conditions are true:
// - the display unit is a standard distance measurement (eg feet)
// - either the canvas units is also a standard distance OR we are using an ellipsoid (in which case the
// value will be in meters)
toolTip += "<br> * " + tr( "The value is converted from %1 to %2." ).arg( QgsUnitTypes::toString( resultUnit ),
QgsUnitTypes::toString( mDisplayUnits ) );
}
else
{
//should not be possible!
}
}
}

editTotal->setToolTip( toolTip );
mTable->setToolTip( toolTip );
mNotesLabel->setText( toolTip );

QGis::UnitType newDisplayUnits;
double dummy = 1.0;
convertMeasurement( dummy, newDisplayUnits, true );
mTable->setHeaderLabels( QStringList( tr( "Segments [%1]" ).arg( QgsUnitTypes::toString( newDisplayUnits ) ) ) );
mUnitsCombo->setCurrentIndex( mUnitsCombo->findData( mDisplayUnits ) );
mTable->setHeaderLabels( QStringList( tr( "Segments [%1]" ).arg( QgsUnitTypes::toString( mDisplayUnits ) ) ) );

if ( mMeasureArea )
{
@@ -318,14 +365,24 @@ void QgsMeasureDialog::updateUi()
bool b = true; // first point

QgsPoint p1, p2;

mTotal = 0;
for ( it = mTool->points().constBegin(); it != mTool->points().constEnd(); ++it )
{
p2 = *it;
if ( !b )
{
double d = mDa.measureLine( p1, p2 );
d = convertLength( d, mDisplayUnits );
double d = -1;
if ( forceCartesian )
{
//cartesian calculation forced
d = sqrt( p2.sqrDist( p1 ) );
mTotal += d;
}
else
{
d = mDa.measureLine( p1, p2 );
d = convertLength( d, mDisplayUnits );
}

QTreeWidgetItem *item = new QTreeWidgetItem( QStringList( QLocale::system().toString( d, 'f', mDecimalPlaces ) ) );
item->setTextAlignment( 0, Qt::AlignRight );
@@ -335,15 +392,17 @@ void QgsMeasureDialog::updateUi()
p1 = p2;
b = false;
}
mTotal = mDa.measureLine( mTool->points() );

if ( !forceCartesian )
mTotal = mDa.measureLine( mTool->points() );
mTable->show(); // Show the table with items
editTotal->setText( formatDistance( mTotal ) );
editTotal->setText( formatDistance( mTotal, convertToDisplayUnits ) );
}
}

void QgsMeasureDialog::convertMeasurement( double &measure, QGis::UnitType &u, bool isArea )
{
// Helper for converting between meters and feet
// Helper for converting between units
// The parameter &u is out only...

// Get the canvas units
@@ -66,15 +66,15 @@ class APP_EXPORT QgsMeasureDialog : public QDialog, private Ui::QgsMeasureBase
void updateSettings();

private slots:
void unitsChanged( const QString &units );
void unitsChanged( int index );

//! Open configuration tab
void openConfigTab();

private:

//! formats distance to most appropriate units
QString formatDistance( double distance );
QString formatDistance( double distance, bool convertUnits = true );

//! formats area to most appropriate units
QString formatArea( double area );
@@ -108,12 +108,8 @@ void QgsMeasureTool::restart()
mRubberBand->reset( mMeasureArea ? QGis::Polygon : QGis::Line );
mRubberBandPoints->reset( QGis::Point );

// re-read settings
updateSettings();

mDone = true;
mWrongProjectProjection = false;

}

void QgsMeasureTool::updateSettings()

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