[locator] add clearPreviousResults virtual method (#7256)

* [locator] add clearPreviousResults virtual method

* also clear previous results when triggering result

Author: 3nids

python/core/auto_generated/locator/qgslocator.sip.in

@@ -123,6 +123,13 @@ take some time to cancel after calling this.
     bool isRunning() const;
 %Docstring
 Returns true if a query is currently being executed by the locator.
+%End
+
+    void clearPreviousResults();
+%Docstring
+Will call clearPreviousResults on all filters
+
+.. versionadded:: 3.2
 %End
 
   signals:

python/core/auto_generated/locator/qgslocatorfilter.sip.in

@@ -172,6 +172,17 @@ by a user. The filter subclass must implement logic here
 to perform the desired operation for the search result.
 E.g. a file search filter would open file associated with the triggered
 result.
+%End
+
+    virtual void clearPreviousResults();
+%Docstring
+This method will be called on main thread on the original filter (not a clone)
+before fetching results or before triggering a result to clear any change made
+by a former call to triggerResult.
+For instance, this can be used to remove any on-canvas rubber bands which have been created
+when a previous search result was triggered.
+
+.. versionadded:: 3.2
 %End
 
     bool useWithoutPrefix() const;

src/core/locator/qgslocator.cpp

@@ -172,6 +172,7 @@ void QgsLocator::fetchResults( const QString &string, const QgsLocatorContext &c
   QList< QgsLocatorFilter *> threadedFilters;
   for ( QgsLocatorFilter *filter : qgis::as_const( activeFilters ) )
   {
+    filter->clearPreviousResults();
     std::unique_ptr< QgsLocatorFilter > clone( filter->clone() );
     connect( clone.get(), &QgsLocatorFilter::resultFetched, clone.get(), [this, filter]( QgsLocatorResult result )
     {
@@ -236,6 +237,17 @@ bool QgsLocator::isRunning() const
   return !mActiveThreads.empty();
 }
 
+void QgsLocator::clearPreviousResults()
+{
+  for ( QgsLocatorFilter *filter : qgis::as_const( mFilters ) )
+  {
+    if ( filter->enabled() )
+    {
+      filter->clearPreviousResults();
+    }
+  }
+}
+
 void QgsLocator::filterSentResult( QgsLocatorResult result )
 {
   // if query has been canceled then discard any results we receive

src/core/locator/qgslocator.h

@@ -139,6 +139,12 @@ class CORE_EXPORT QgsLocator : public QObject
      */
     bool isRunning() const;
 
+    /**
+     * Will call clearPreviousResults on all filters
+     * \since QGIS 3.2
+     */
+    void clearPreviousResults();
+
   signals:
 
     /**

src/core/locator/qgslocatorfilter.h

@@ -207,6 +207,16 @@ class CORE_EXPORT QgsLocatorFilter : public QObject
      */
     virtual void triggerResult( const QgsLocatorResult &result ) = 0;
 
+    /**
+     * This method will be called on main thread on the original filter (not a clone)
+     * before fetching results or before triggering a result to clear any change made
+     * by a former call to triggerResult.
+     * For instance, this can be used to remove any on-canvas rubber bands which have been created
+     * when a previous search result was triggered.
+     * \since QGIS 3.2
+     */
+    virtual void clearPreviousResults() {}
+
     /**
      * Returns true if the filter should be used when no prefix
      * is entered.

src/gui/locator/qgslocatorwidget.cpp

@@ -339,6 +339,7 @@ void QgsLocatorWidget::acceptCurrentEntry()
     QgsLocatorResult result = mProxyModel->data( index, QgsLocatorModel::ResultDataRole ).value< QgsLocatorResult >();
     mResultsContainer->hide();
     mLineEdit->clearFocus();
+    mLocator->clearPreviousResults();
     result.filter->triggerResult( result );
   }
 }