QgsScaleCalculator Class Reference

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

#include <qgsscalecalculator.h>

Public Member Functions
	QgsScaleCalculator (double dpi=0, Qgis::DistanceUnit mapUnits=Qgis::DistanceUnit::Meters)
	Constructor.
double	calculate (const QgsRectangle &mapExtent, double canvasWidth) const
	Calculate the scale denominator.
double	calculateGeographicDistance (const QgsRectangle &mapExtent) const
	Calculate the distance between two points in geographic coordinates.
QSizeF	calculateImageSize (const QgsRectangle &mapExtent, double scale) const
	Calculate the image size in pixel (physical) units.
double	dpi () const
	Returns the DPI (dots per inch) used in scale calculations.
Qgis::DistanceUnit	mapUnits () const
	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 (Qgis::DistanceUnit mapUnits)
	Set the map units.

Detailed Description

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

Definition at line 34 of file qgsscalecalculator.h.

Constructor & Destructor Documentation

QgsScaleCalculator()

QgsScaleCalculator::QgsScaleCalculator	(	double	dpi = 0,
		Qgis::DistanceUnit	mapUnits = Qgis::DistanceUnit::Meters
	)

Constructor.

Parameters

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

Definition at line 26 of file qgsscalecalculator.cpp.

Member Function Documentation

calculate()

double QgsScaleCalculator::calculate	(	const QgsRectangle &	mapExtent,
		double	canvasWidth
	)		const

Calculate the scale denominator.

Parameters

mapExtent	QgsRectangle containing the current map extent. Units are specified by mapUnits().
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.

Definition at line 52 of file qgsscalecalculator.cpp.

calculateGeographicDistance()

double QgsScaleCalculator::calculateGeographicDistance

(

const QgsRectangle &

mapExtent

)

const

Calculate the distance between two points in geographic coordinates.

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

Parameters

mapExtent

QgsRectangle containing the current map extent

Definition at line 163 of file qgsscalecalculator.cpp.

calculateImageSize()

QSizeF QgsScaleCalculator::calculateImageSize	(	const QgsRectangle &	mapExtent,
		double	scale
	)		const

Calculate the image size in pixel (physical) units.

Parameters

mapExtent	QgsRectangle containing the current map extent. Units are specified by mapUnits()
scale	Scale denominator, e.g. 1000.0 for a 1:1000 map

Returns

image size

Since

QGIS 3.24

Definition at line 69 of file qgsscalecalculator.cpp.

dpi()

double QgsScaleCalculator::dpi

(

)

const

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

See also

setDpi()

Definition at line 35 of file qgsscalecalculator.cpp.

mapUnits()

Qgis::DistanceUnit QgsScaleCalculator::mapUnits

(

)

const

Returns current map units.

See also

setMapUnits()

Definition at line 46 of file qgsscalecalculator.cpp.

setDpi()

void QgsScaleCalculator::setDpi

(

double

dpi

)

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

See also

dpi()

Definition at line 31 of file qgsscalecalculator.cpp.

setMapUnits()

void QgsScaleCalculator::setMapUnits

(

Qgis::DistanceUnit

mapUnits

)

Set the map units.

See also

mapUnits()

Definition at line 40 of file qgsscalecalculator.cpp.

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The documentation for this class was generated from the following files:

• /build/qgis-3.41.0+git20241225+af5edcb665c+99sid/src/core/qgsscalecalculator.h
• /build/qgis-3.41.0+git20241225+af5edcb665c+99sid/src/core/qgsscalecalculator.cpp