Class: QgsScaleWidget

A combobox which lets the user select map scale from predefined list and highlights nearest to current scale value

Class Hierarchy

Base classes

QWidget
QObject
QPaintDevice

Methods

allowNull	Returns True if the widget can be set to a NULL value.
isNull	Returns True if the widget is currently set to a "null" value.
minScale	Returns the minimum scale, or 0 if no minimum scale set.
scale	Returns the selected scale as a double.
scaleString	Returns the selected scale as a string, e.g. "1:150".
setAllowNull	Sets whether the scale widget can be set to a NULL value.
setMapCanvas	Set the map canvas associated to the current button.
setMinScale	Set the minimum allowed scale.
setNull	Sets the widget to the null value.
setPredefinedScales	Sets the list of predefined scales to show in the widget.
setScale	Set the selected scale from a double.
setScaleFromCanvas	Assigns the current scale from the map canvas, if set.
setScaleString	Set the selected scale from a string, e.g. "1:150".
setShowCurrentScaleButton	Sets whether to show a button to set the scale to the current scale of the map canvas next to the combobox.
showCurrentScaleButton	Returns whether a button to set the scale from map canvas is shown or not.
updateScales	Sets the list of predefined scales to show in the widget.

Static Methods

toDouble	Helper function to convert a scale string to double.
toString	Helper function to convert a scale double to scale string.

Signals

scaleChanged

Emitted when user has finished editing/selecting a new scale.

class qgis.gui.QgsScaleWidget

Bases: QWidget

__init__(parent: QWidget | None = None)

QgsScaleWidget creates a combobox which lets the user select map scale from predefined list and highlights nearest to current scale value

Parameters:

parent (Optional[QWidget] = None)

allowNull(self) → bool

Returns True if the widget can be set to a NULL value.

See also

setAllowNull()

See also

isNull()

See also

setNull()

Added in version 3.8.

Return type:

bool

isNull(self) → bool

Returns True if the widget is currently set to a “null” value.

See also

setAllowNull()

See also

setNull()

Added in version 3.8.

Return type:

bool

minScale(self) → float

Returns the minimum scale, or 0 if no minimum scale set. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. Any scale lower than the minimum scale will automatically be converted to the minimum scale. Except for 0 which is always allowed.

Return type:

float

scale(self) → float

Returns the selected scale as a double. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.

See also

setScale()

Return type:

float

signal scaleChanged(scale: float)

Emitted when user has finished editing/selecting a new scale. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.

Parameters:

scale (float)

scaleString(self) → str

Returns the selected scale as a string, e.g. “1:150”.

See also

setScaleString()

Return type:

str

setAllowNull(self, allowNull: bool)

Sets whether the scale widget can be set to a NULL value.

See also

allowNull()

See also

isNull()

See also

setNull()

Added in version 3.8.

Parameters:

allowNull (bool)

setMapCanvas(self, canvas: QgsMapCanvas | None)

Set the map canvas associated to the current button.

Parameters:

canvas (Optional[QgsMapCanvas])

setMinScale(self, scale: float)

Set the minimum allowed scale. Set to 0 to disable the minimum scale. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. Any scale lower than the minimum scale will automatically be converted to the minimum scale. Except for 0 which is always allowed.

Parameters:

scale (float)

setNull(self)

Sets the widget to the null value.

This only has an effect if allowNull() is True.

See also

allowNull()

See also

isNull()

Added in version 3.8.

setPredefinedScales(self, scales: Iterable[float])

Sets the list of predefined scales to show in the widget. List elements are expected to be scale denominators, e.g. 1000.0 for a 1:1000 map.

If scales is empty then the default user scale options will be used instead.

Added in version 3.38.

Parameters:

scales (Iterable[float])

setScale(self, scale: float)

Set the selected scale from a double. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.

See also

scale()

Parameters:

scale (float)

setScaleFromCanvas(self)

Assigns the current scale from the map canvas, if set.

See also

setMapCanvas()

setScaleString(self, string: str | None) → bool

Set the selected scale from a string, e.g. “1:150”.

See also

scaleString()

Parameters:

string (Optional[str])

Return type:

bool

setShowCurrentScaleButton(self, showCurrentScaleButton: bool)

Sets whether to show a button to set the scale to the current scale of the map canvas next to the combobox.

Note

the map canvas must be defined to show the button

See also

showCurrentScaleButton()

See also

setMapCanvas()

Parameters:

showCurrentScaleButton (bool)

showCurrentScaleButton(self) → bool

Returns whether a button to set the scale from map canvas is shown or not.

See also

setShowCurrentScaleButton()

Return type:

bool

static toDouble(scaleString: str | None)

Helper function to convert a scale string to double. The returned value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map. If specified, ok will be set to True if the string was successfully interpreted as a scale.

See also

toString()

Parameters:

scaleString (Optional[str]) -> (float)

static toString(scale: float) → str

Helper function to convert a scale double to scale string. The scale value indicates the scale denominator, e.g. 1000.0 for a 1:1000 map.

The returned string will be rounded (e.g. 1:1000, not 1:1000.345).

See also

toDouble()

Parameters:

scale (float)

Return type:

str

updateScales(self, scales: Iterable[str | None] = [])

Sets the list of predefined scales to show in the widget. List elements are expected to be valid scale strings, such as “1:1000000”.

Parameters:

scales (Iterable[Optional[str]] = [])