Class: QgsScaleCalculator¶

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

Methods

`calculate`	Calculate the scale denominator.
`calculateGeographicDistance`	Calculate the distance between two points in geographic coordinates.
`calculateImageSize`	Calculate the image size in pixel (physical) units.
`dpi`	Returns the DPI (dots per inch) used in scale calculations.
`mapUnits`	Returns current map units.
`setDpi`	Sets the dpi (dots per inch) for the output resolution, to be used in scale calculations.
`setMapUnits`	Set the map units.

class qgis.core.QgsScaleCalculator[source]¶

Bases: object

__init__(dpi: float = 0, mapUnits: Qgis.DistanceUnit = Qgis.DistanceUnit.Meters)

Constructor

Parameters:

dpi (float = 0) – Monitor resolution in dots per inch
mapUnits (Qgis.DistanceUnit = Qgis.DistanceUnit.Meters) – Units of the data on the map

calculate(self, mapExtent: QgsRectangle, canvasWidth: float) → float[source]¶

Calculate the scale denominator.

Parameters:

mapExtent (QgsRectangle) – QgsRectangle containing the current map extent. Units are specified by mapUnits().
canvasWidth (float) – Width of the map canvas in pixel (physical) units

Return type:

float

Returns:

scale denominator of current map view, e.g. 1000.0 for a 1:1000 map.

calculateGeographicDistance(self, mapExtent: QgsRectangle) → float[source]¶

Calculate the distance between two points in geographic coordinates. Used to calculate scale for map views with geographic (decimal degree) data.

Parameters:: mapExtent (QgsRectangle) – QgsRectangle containing the current map extent
Return type:: float

calculateImageSize(self, mapExtent: QgsRectangle, scale: float) → QSizeF[source]¶

Calculate the image size in pixel (physical) units.

Parameters:

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

Return type: