QgsScaleCalculator class

Calculates scale for a given combination of canvas size, map extent, and monitor dpi.

Constructors, destructors, conversion operators

QgsScaleCalculator(double dpi = 0, QgsUnitTypes::DistanceUnit mapUnits = QgsUnitTypes::DistanceMeters): Constructor.

auto calculate(const QgsRectangle& mapExtent, double canvasWidth) -> double: Calculate the scale denominator.
auto calculateGeographicDistance(const QgsRectangle& mapExtent) -> double: Calculate the distance between two points in geographic coordinates.
auto dpi() -> double: Returns the DPI (dots per inch) used in scale calculations.
auto mapUnits() const -> QgsUnitTypes::DistanceUnit: Returns current map units.
void setDpi(double dpi): Sets the dpi (dots per inch) for the output resolution, to be used in scale calculations.
void setMapUnits(QgsUnitTypes::DistanceUnit mapUnits): Set the map units.

Constructor.

Parameters
dpi	Monitor resolution in dots per inch
mapUnits	Units of the data on the map

Calculate the scale denominator.

Parameters
mapExtent	QgsRectangle containing the current map extent
canvasWidth	Width of the map canvas in pixel (physical) units
Returns	scale denominator of current map view, e.g. 1000.0 for a 1:1000 map.

Calculate the distance between two points in geographic coordinates.

Parameters
mapExtent	QgsRectangle containing the current map extent

Used to calculate scale for map views with geographic (decimal degree) data.

Returns the DPI (dots per inch) used in scale calculations.

Sets the dpi (dots per inch) for the output resolution, to be used in scale calculations.

Set the map units.

Parameters
mapUnits	Units of the data on the map. Must match a value from the