QgsScaleCalculator Class Reference
[QGIS core library]

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

#include <qgsscalecalculator.h>

List of all members.

Public Member Functions
	QgsScaleCalculator (double dpi=0, QGis::UnitType mapUnits=QGis::Meters)
	Constructor.
	~QgsScaleCalculator ()
	Destructor.
void	setDpi (double dpi)
	Set the dpi to be used in scale calculations.
double	dpi ()
	Accessor for dpi used in scale calculations.
void	setMapUnits (QGis::UnitType mapUnits)
	Set the map units.
QGis::UnitType	mapUnits () const
	Returns current map units.
double	calculate (const QgsRectangle &mapExtent, int canvasWidth)
	Calculate the scale.
double	calculateGeographicDistance (const QgsRectangle &mapExtent)
	Calculate the distance between two points in geographic coordinates.
Private Attributes
double	mDpi
	dpi member
QGis::UnitType	mMapUnits
	map unit member

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Detailed Description

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

Definition at line 32 of file qgsscalecalculator.h.

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Constructor & Destructor Documentation

QgsScaleCalculator::QgsScaleCalculator	(	double	dpi = 0,
		QGis::UnitType	mapUnits = QGis::Meters
	)

Constructor.

Parameters:

	dpi	Monitor resolution in dots per inch
	mapUnits	Units of the data on the map. Must match a value from the QGis::UnitType enum (Meters, Feet, Degrees)

Definition at line 26 of file qgsscalecalculator.cpp.

QgsScaleCalculator::~QgsScaleCalculator

(

)

Destructor.

Definition at line 30 of file qgsscalecalculator.cpp.

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Member Function Documentation

void QgsScaleCalculator::setDpi

(

double

dpi

)

Set the dpi to be used in scale calculations.

Parameters:

dpi

Dots per inch of monitor resolution

Definition at line 33 of file qgsscalecalculator.cpp.

References mDpi.

Referenced by QgsComposerMap::scale(), and QgsMapRenderer::setOutputSize().

double QgsScaleCalculator::dpi

(

)

Accessor for dpi used in scale calculations.

Returns:

int the dpi used for scale calculations.

Definition at line 37 of file qgsscalecalculator.cpp.

References mDpi.

Referenced by QgsMapRenderer::outputDpi(), and QgsMapRenderer::render().

void QgsScaleCalculator::setMapUnits

(

QGis::UnitType

mapUnits

)

Set the map units.

Parameters:

mapUnits

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

Definition at line 42 of file qgsscalecalculator.cpp.

References mMapUnits, and QgsDebugMsg.

Referenced by QgsComposerMap::scale(), and QgsMapRenderer::setMapUnits().

QGis::UnitType QgsScaleCalculator::mapUnits

(

)

const

Returns current map units.

Definition at line 48 of file qgsscalecalculator.cpp.

References mMapUnits, and QgsDebugMsgLevel.

Referenced by QgsMapRenderer::mapUnits(), and QgsMapRenderer::render().

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

Calculate the scale.

Parameters:

	mapExtent	QgsRectangle containing the current map extent
	canvasWidth	Width of the map canvas in pixel (physical) units

Returns:

scale of current map view

Definition at line 54 of file qgsscalecalculator.cpp.

References calculateGeographicDistance(), QGis::DecimalDegrees, QGis::DegreesDecimalMinutes, QGis::DegreesMinutesSeconds, QGis::Feet, mDpi, QGis::Meters, mMapUnits, QgsDebugMsg, QgsRectangle::xMaximum(), and QgsRectangle::xMinimum().

Referenced by QgsComposerMap::scale(), and QgsMapRenderer::updateScale().

double QgsScaleCalculator::calculateGeographicDistance

(

const QgsRectangle &

mapExtent

)

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 101 of file qgsscalecalculator.cpp.

References QgsDebugMsg, QgsRectangle::xMaximum(), QgsRectangle::xMinimum(), QgsRectangle::yMaximum(), and QgsRectangle::yMinimum().

Referenced by calculate().

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Member Data Documentation

double QgsScaleCalculator::mDpi [private]

dpi member

Definition at line 87 of file qgsscalecalculator.h.

Referenced by calculate(), dpi(), and setDpi().

QGis::UnitType QgsScaleCalculator::mMapUnits [private]

map unit member

Definition at line 90 of file qgsscalecalculator.h.

Referenced by calculate(), mapUnits(), and setMapUnits().

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

• src/core/qgsscalecalculator.h
• src/core/qgsscalecalculator.cpp