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6d1d213973
The qgssizescalewidget as been modified to handle line symbols as well as markers. The scale expression has been enhanced to support general exponentials (i.e. eponents different from Flanery .57 and Area .5a) The assistant as been modified to disply the exponent when Exponential scaling is required.
95 lines
2.7 KiB
Plaintext
95 lines
2.7 KiB
Plaintext
/** \ingroup core
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* \class QgsScaleExpression
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* \brief Class storing parameters of a scale expression, which is a subclass of
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* QgsExpression for expressions which return a size or width.
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* \note Added in version 2.9
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*/
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class QgsScaleExpression : QgsExpression
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{
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%TypeHeaderCode
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#include <qgsscaleexpression.h>
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%End
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public:
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enum Type
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{
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Linear,
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Area,
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Flannery,
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Unknown
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};
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/** Constructor for QgsScaleExpression which parses an expression string
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* to determine whether it's a scale expression
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* @param expression expression string
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*/
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QgsScaleExpression( const QString &expression );
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/** Constructor for QgsScaleExpression which creates an expression from
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* specified parameters
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* @param type scale method
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* @param baseExpression expression (or field) used for value
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* @param minValue minimum value, corresponds to specified minimum size
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* @param maxValue maximum value, corresponds to specified maximum size
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* @param minSize minimum size
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* @param maxSize maximum size
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* @param nullSize size in case expression evaluates to NULL
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* @param exponent to use in case of Exponential type
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*/
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QgsScaleExpression( Type type, const QString& baseExpression, double minValue, double maxValue, double minSize, double maxSize, double nullSize = 0, double exponent = 1 );
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operator bool() const;
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/** Calculates the size corresponding to a specific value.
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* @param value
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* @returns calculated size using expression's parameters and type
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*/
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double size( double value ) const;
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/** Returns the minimum size calculated by the expression
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* @see maxSize
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*/
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double minSize() const;
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/** Returns the maximum size calculated by the expression
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* @see minSize
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*/
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double maxSize() const;
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/** Returns the minimum value expected by the expression. The minimum
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* value corresponds to the expression's minimum size.
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* @see maxValue
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*/
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double minValue() const;
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/** Returns the maximum value expected by the expression. The maximum
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* value corresponds to the expression's maximum size.
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* @see minValue
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*/
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double maxValue() const;
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/** Returns the size value when expression evaluates to NULL.
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* @see nullSize
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*/
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double nullSize() const;
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/** Returns the exponent of the exponential expression.
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* @see exponent
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*/
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double exponent() const;
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/** Returns the base expression string (or field reference) used for
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* calculating the values to be mapped to a size.
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*/
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QString baseExpression() const;
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/** Returns the scale expression's type (method used to calculate
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* the size from a value).
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*/
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Type type() const;
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};
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