Allow value fetching and histogram calculation to be canceled

qgis · Feb 22, 2017 · 0faf7c3 · 0faf7c3
1 parent cc9b5a4
commit 0faf7c3
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Showing 6 changed files with 24 additions and 34 deletions.
diff --git a/python/core/qgshistogram.sip b/python/core/qgshistogram.sip
@@ -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.

diff --git a/python/core/qgsvectorlayer.sip b/python/core/qgsvectorlayer.sip
@@ -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 );

diff --git a/src/core/qgshistogram.cpp b/src/core/qgshistogram.cpp
@@ -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;
 

diff --git a/src/core/qgshistogram.h b/src/core/qgshistogram.h
@@ -21,6 +21,7 @@
 #include <QList>
 
 #include "qgis_core.h"
+#include "qgsfeedback.h"
 
 class QgsVectorLayer;
 
@@ -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.

diff --git a/src/core/qgsvectorlayer.cpp b/src/core/qgsvectorlayer.cpp
@@ -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;
 
@@ -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;
 
@@ -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;

diff --git a/src/core/qgsvectorlayer.h b/src/core/qgsvectorlayer.h
@@ -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 );