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Allow value fetching and histogram calculation to be canceled
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nyalldawson committed Feb 22, 2017
1 parent cc9b5a4 commit 0faf7c3
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Showing 6 changed files with 24 additions and 34 deletions.
8 changes: 1 addition & 7 deletions python/core/qgshistogram.sip
Original file line number Diff line number Diff line change
Expand Up @@ -22,13 +22,7 @@ class QgsHistogram
*/
void setValues( const QList<double>& values );

/** Assigns numeric source values for the histogram from a vector layer's field or as the
* result of an expression.
* @param layer vector layer
* @param fieldOrExpression field name or expression to be evaluated
* @returns true if values were successfully set
*/
bool setValues( QgsVectorLayer* layer, const QString& fieldOrExpression );
bool setValues( QgsVectorLayer* layer, const QString& fieldOrExpression, QgsFeedback* feedback = 0 );

/** Calculates the optimal bin width using the Freedman-Diaconis rule. Bins widths are
* determined by the inter-quartile range of values and the number of values.
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22 changes: 2 additions & 20 deletions python/core/qgsvectorlayer.sip
Original file line number Diff line number Diff line change
Expand Up @@ -1352,27 +1352,9 @@ class QgsVectorLayer : QgsMapLayer, QgsExpressionContextGenerator
QgsExpressionContext* context = nullptr,
bool* ok = nullptr ) const;

/** Fetches all values from a specified field name or expression.
* @param fieldOrExpression field name or an expression string
* @param ok will be set to false if field or expression is invalid, otherwise true
* @param selectedOnly set to true to get values from selected features only
* @returns list of fetched values
* @note added in QGIS 2.9
* @see getDoubleValues
*/
QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false ) const;
QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, QgsFeedback* feedback = 0 ) const;

/** Fetches all double values from a specified field name or expression. Null values or
* invalid expression results are skipped.
* @param fieldOrExpression field name or an expression string evaluating to a double value
* @param ok will be set to false if field or expression is invalid, otherwise true
* @param selectedOnly set to true to get values from selected features only
* @param nullCount optional pointer to integer to store number of null values encountered in
* @returns list of fetched values
* @note added in QGIS 2.9
* @see getValues
*/
QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, int* nullCount = 0 ) const;
QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, int* nullCount = 0, QgsFeedback* feedback = 0 ) const;

/** Set the blending mode used for rendering each feature */
void setFeatureBlendMode( QPainter::CompositionMode blendMode );
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4 changes: 2 additions & 2 deletions src/core/qgshistogram.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -47,14 +47,14 @@ void QgsHistogram::setValues( const QList<double> &values )
prepareValues();
}

bool QgsHistogram::setValues( QgsVectorLayer *layer, const QString &fieldOrExpression )
bool QgsHistogram::setValues( QgsVectorLayer *layer, const QString &fieldOrExpression, QgsFeedback* feedback )
{
mValues.clear();
if ( !layer )
return false;

bool ok;
mValues = layer->getDoubleValues( fieldOrExpression, ok );
mValues = layer->getDoubleValues( fieldOrExpression, ok, false, nullptr, feedback );
if ( !ok )
return false;

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4 changes: 3 additions & 1 deletion src/core/qgshistogram.h
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
#include <QList>

#include "qgis_core.h"
#include "qgsfeedback.h"

class QgsVectorLayer;

Expand Down Expand Up @@ -49,9 +50,10 @@ class CORE_EXPORT QgsHistogram
* result of an expression.
* @param layer vector layer
* @param fieldOrExpression field name or expression to be evaluated
* @param feedback optional feedback object to allow cancelation of calculation
* @returns true if values were successfully set
*/
bool setValues( QgsVectorLayer* layer, const QString& fieldOrExpression );
bool setValues( QgsVectorLayer* layer, const QString& fieldOrExpression, QgsFeedback* feedback = nullptr );

/** Calculates the optimal bin width using the Freedman-Diaconis rule. Bins widths are
* determined by the inter-quartile range of values and the number of values.
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14 changes: 12 additions & 2 deletions src/core/qgsvectorlayer.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -3565,7 +3565,7 @@ QVariant QgsVectorLayer::aggregate( QgsAggregateCalculator::Aggregate aggregate,
return c.calculate( aggregate, fieldOrExpression, context, ok );
}

QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly ) const
QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly, QgsFeedback* feedback ) const
{
QList<QVariant> values;

Expand Down Expand Up @@ -3623,12 +3623,17 @@ QList<QVariant> QgsVectorLayer::getValues( const QString &fieldOrExpression, boo
{
values << f.attribute( attrNum );
}
if ( feedback && feedback->isCanceled() )
{
ok = false;
return values;
}
}
ok = true;
return values;
}

QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly, int* nullCount ) const
QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression, bool& ok, bool selectedOnly, int* nullCount, QgsFeedback* feedback ) const
{
QList<double> values;

Expand All @@ -3650,6 +3655,11 @@ QList<double> QgsVectorLayer::getDoubleValues( const QString &fieldOrExpression,
if ( nullCount )
*nullCount += 1;
}
if ( feedback && feedback->isCanceled() )
{
ok = false;
return values;
}
}
ok = true;
return values;
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6 changes: 4 additions & 2 deletions src/core/qgsvectorlayer.h
Original file line number Diff line number Diff line change
Expand Up @@ -1497,23 +1497,25 @@ class CORE_EXPORT QgsVectorLayer : public QgsMapLayer, public QgsExpressionConte
* @param fieldOrExpression field name or an expression string
* @param ok will be set to false if field or expression is invalid, otherwise true
* @param selectedOnly set to true to get values from selected features only
* @param feedback optional feedback object to allow cancelation
* @returns list of fetched values
* @note added in QGIS 2.9
* @see getDoubleValues
*/
QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false ) const;
QList< QVariant > getValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, QgsFeedback* feedback = nullptr ) const;

/** Fetches all double values from a specified field name or expression. Null values or
* invalid expression results are skipped.
* @param fieldOrExpression field name or an expression string evaluating to a double value
* @param ok will be set to false if field or expression is invalid, otherwise true
* @param selectedOnly set to true to get values from selected features only
* @param nullCount optional pointer to integer to store number of null values encountered in
* @param feedback optional feedback object to allow cancelation
* @returns list of fetched values
* @note added in QGIS 2.9
* @see getValues
*/
QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, int* nullCount = nullptr ) const;
QList< double > getDoubleValues( const QString &fieldOrExpression, bool &ok, bool selectedOnly = false, int* nullCount = nullptr, QgsFeedback* feedback = nullptr ) const;

//! Set the blending mode used for rendering each feature
void setFeatureBlendMode( QPainter::CompositionMode blendMode );
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