QString QgsCoordinateUtils::formatCoordinateForProject( const QgsPoint& point, const QgsCoordinateReferenceSystem& destCrs, int precision )
{
QString format = QgsProject::instance()->readEntry( "PositionPrecision", "/DegreeFormat", "MU" );
QgsPoint geo = point;
if ( format == "DM" || format == "DMS" || format == "D" )
{
// degrees
if ( destCrs.isValid() && !destCrs.geographicFlag() )
{
// need to transform to geographic coordinates
QgsCoordinateTransform ct( destCrs, QgsCoordinateReferenceSystem( GEOSRID ) );
try
{
geo = ct.transform( point );
}
catch ( QgsCsException& )
{
return QString();
}
}
if ( format == "DM" )
return geo.toDegreesMinutes( precision, true, true );
else if ( format == "DMS" )
return geo.toDegreesMinutesSeconds( precision, true, true );
else
return geo.toString( precision );
}
else
{
// coordinates in map units
return point.toString( precision );
}
}
int QgsCoordinateUtils::calculateCoordinatePrecision( double mapUnitsPerPixel, const QgsCoordinateReferenceSystem& mapCrs )
{
// Get the display precision from the project settings
bool automatic = QgsProject::instance()->readBoolEntry( "PositionPrecision", "/Automatic" );
int dp = 0;
if ( automatic )
{
QString format = QgsProject::instance()->readEntry( "PositionPrecision", "/DegreeFormat", "MU" );
bool formatGeographic = ( format == "DM" || format == "DMS" || format == "D" );
// we can only calculate an automatic precision if both map CRS and format are geographic or both not geographic
if ( mapCrs.geographicFlag() == formatGeographic )
{
// Work out a suitable number of decimal places for the coordinates with the aim of always
// having enough decimal places to show the difference in position between adjacent pixels.
// Also avoid taking the log of 0.
if ( !qgsDoubleNear( mapUnitsPerPixel, 0.0 ) )
dp = static_cast<int>( ceil( -1.0 * log10( mapUnitsPerPixel ) ) );
}
else
{
dp = format == "D" ? 4 : 2; //guess sensible fallback
}
}
else
dp = QgsProject::instance()->readNumEntry( "PositionPrecision", "/DecimalPlaces" );
// Keep dp sensible
if ( dp < 0 )
dp = 0;
return dp;
}
bool QgsNorthArrowPlugin::calculateNorthDirection()
{
QgsMapCanvas& mapCanvas = *( qGisInterface->mapCanvas() );
bool goodDirn = false;
if ( mapCanvas.layerCount() > 0 )
{
QgsCoordinateReferenceSystem outputCRS = mapCanvas.mapRenderer()->destinationCrs();
if ( outputCRS.isValid() && !outputCRS.geographicFlag() )
{
// Use a geographic CRS to get lat/long to work out direction
QgsCoordinateReferenceSystem ourCRS;
ourCRS.createFromOgcWmsCrs( GEO_EPSG_CRS_AUTHID );
assert( ourCRS.isValid() );
QgsCoordinateTransform transform( outputCRS, ourCRS );
QgsRectangle extent = mapCanvas.extent();
QgsPoint p1( extent.center() );
// A point a bit above p1. XXX assumes that y increases up!!
// May need to involve the maptopixel transform if this proves
// to be a problem.
QgsPoint p2( p1.x(), p1.y() + extent.height() * 0.25 );
// project p1 and p2 to geographic coords
try
{
p1 = transform.transform( p1 );
p2 = transform.transform( p2 );
}
catch ( QgsCsException &e )
{
Q_UNUSED( e );
// just give up
QgsDebugMsg( "North Arrow: Transformation error, quitting" );
return false;
}
// Work out the value of the initial heading one takes to go
// from point p1 to point p2. The north direction is then that
// many degrees anti-clockwise or vertical.
// Take some care to not divide by zero, etc, and ensure that we
// get sensible results for all possible values for p1 and p2.
goodDirn = true;
double angle = 0.0;
// convert to radians for the equations below
p1.multiply( PI / 180.0 );
p2.multiply( PI / 180.0 );
double y = sin( p2.x() - p1.x() ) * cos( p2.y() );
double x = cos( p1.y() ) * sin( p2.y() ) -
sin( p1.y() ) * cos( p2.y() ) * cos( p2.x() - p1.x() );
if ( y > 0.0 )
{
if ( x > TOL )
angle = atan( y / x );
else if ( x < -TOL )
angle = PI - atan( -y / x );
else
angle = 0.5 * PI;
}
else if ( y < 0.0 )
{
if ( x > TOL )
angle = -atan( -y / x );
else if ( x < -TOL )
angle = atan( y / x ) - PI;
else
angle = 1.5 * PI;
}
else
{
if ( x > TOL )
angle = 0.0;
else if ( x < -TOL )
angle = PI;
else
{
angle = 0.0; // p1 = p2
goodDirn = false;
}
}
// And set the angle of the north arrow. Perhaps do something
// different if goodDirn = false.
mRotationInt = static_cast<int>( round( fmod( 360.0 - angle * 180.0 / PI, 360.0 ) ) );
}
else
{
// For geographic CRS and for when there are no layers, set the
// direction back to the default
mRotationInt = 0;
}
}
return goodDirn;
}
bool QgsDecorationNorthArrow::calculateNorthDirection()
{
QgsMapCanvas* mapCanvas = QgisApp::instance()->mapCanvas();
bool goodDirn = false;
// Get the shown extent...
QgsRectangle canvasExtent = mapCanvas->extent();
// ... and all layers extent, ...
QgsRectangle fullExtent = mapCanvas->fullExtent();
// ... and combine
QgsRectangle extent = canvasExtent.intersect( & fullExtent );
// If no layers are added or shown, we can't get any direction
if ( mapCanvas->layerCount() > 0 && ! extent.isEmpty() )
{
QgsCoordinateReferenceSystem outputCRS = mapCanvas->mapRenderer()->destinationCrs();
if ( outputCRS.isValid() && !outputCRS.geographicFlag() )
{
// Use a geographic CRS to get lat/long to work out direction
QgsCoordinateReferenceSystem ourCRS;
ourCRS.createFromOgcWmsCrs( GEO_EPSG_CRS_AUTHID );
assert( ourCRS.isValid() );
QgsCoordinateTransform transform( outputCRS, ourCRS );
QgsPoint p1( extent.center() );
// A point a bit above p1. XXX assumes that y increases up!!
// May need to involve the maptopixel transform if this proves
// to be a problem.
QgsPoint p2( p1.x(), p1.y() + extent.height() * 0.25 );
// project p1 and p2 to geographic coords
try
{
p1 = transform.transform( p1 );
p2 = transform.transform( p2 );
}
catch ( QgsCsException &e )
{
Q_UNUSED( e );
// just give up
QgsDebugMsg( "North Arrow: Transformation error, quitting" );
return false;
}
// Work out the value of the initial heading one takes to go
// from point p1 to point p2. The north direction is then that
// many degrees anti-clockwise or vertical.
// Take some care to not divide by zero, etc, and ensure that we
// get sensible results for all possible values for p1 and p2.
goodDirn = true;
double angle = 0.0;
// convert to radians for the equations below
p1.multiply( PI / 180.0 );
p2.multiply( PI / 180.0 );
double y = sin( p2.x() - p1.x() ) * cos( p2.y() );
double x = cos( p1.y() ) * sin( p2.y() ) -
sin( p1.y() ) * cos( p2.y() ) * cos( p2.x() - p1.x() );
// Use TOL to decide if the quotient is big enough.
// Both x and y can be very small, if heavily zoomed
// For small y/x, we set directly angle 0. Not sure
// if this is needed.
if ( y > 0.0 )
{
if ( x > 0.0 && ( y / x ) > TOL )
angle = atan( y / x );
else if ( x < 0.0 && ( y / x ) < -TOL )
angle = PI - atan( -y / x );
else
angle = 0.5 * PI;
}
else if ( y < 0.0 )
{
if ( x > 0.0 && ( y / x ) < -TOL )
angle = -atan( -y / x );
else if ( x < 0.0 && ( y / x ) > TOL )
angle = atan( y / x ) - PI;
else
angle = 1.5 * PI;
}
else
{
if ( x > TOL )
angle = 0.0;
else if ( x < -TOL )
angle = PI;
else
{
angle = 0.0; // p1 = p2
goodDirn = false;
}
}
// And set the angle of the north arrow. Perhaps do something
// different if goodDirn = false.
mRotationInt = qRound( fmod( 360.0 - angle * 180.0 / PI, 360.0 ) );
}
else
{
// For geographic CRS and for when there are no layers, set the
// direction back to the default
mRotationInt = 0;
}
}
return goodDirn;
}
