qgsfieldvalueslineedit.h

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/***************************************************************************
    qgsfieldvalueslineedit.h
     -----------------------
    Date                 : 20-08-2016
    Copyright            : (C) 2016 by Nyall Dawson
    Email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
#ifndef QGSFIELDVALUESLINEEDIT_H
#define QGSFIELDVALUESLINEEDIT_H

#include "qgsfilterlineedit.h"
#include "qgis.h"
#include "qgsfeedback.h"
#include "qgsvectorlayer.h"
#include <QStringListModel>
#include <QTreeView>
#include <QFocusEvent>
#include <QHeaderView>
#include <QTimer>
#include <QThread>
#include "qgis_gui.h"

class QgsFloatingWidget;


#ifndef SIP_RUN

// just internal guff - definitely not for exposing to public API!

class QgsFieldValuesLineEditValuesGatherer: public QThread
{
    Q_OBJECT

  public:
    QgsFieldValuesLineEditValuesGatherer( QgsVectorLayer *layer, int attributeIndex )
      : mLayer( layer )
      , mAttributeIndex( attributeIndex )
      , mWasCanceled( false )
    {}

    void setSubstring( const QString &string ) { mSubstring = string; }

    void run() override
    {
      mWasCanceled = false;
      if ( mSubstring.isEmpty() )
      {
        emit collectedValues( QStringList() );
        return;
      }

      // allow responsive cancelation
      mFeedback = new QgsFeedback();
      // just get 100 values... maybe less/more would be useful?
      mValues = mLayer->uniqueStringsMatching( mAttributeIndex, mSubstring, 100, mFeedback );

      // be overly cautious - it's *possible* stop() might be called between deleting mFeedback and nulling it
      mFeedbackMutex.lock();
      delete mFeedback;
      mFeedback = nullptr;
      mFeedbackMutex.unlock();

      emit collectedValues( mValues );
    }

    void stop()
    {
      // be cautious, in case gatherer stops naturally just as we are canceling it and mFeedback gets deleted
      mFeedbackMutex.lock();
      if ( mFeedback )
        mFeedback->cancel();
      mFeedbackMutex.unlock();

      mWasCanceled = true;
    }

    bool wasCanceled() const { return mWasCanceled; }

  signals:

    void collectedValues( const QStringList &values );

  private:

    QgsVectorLayer *mLayer = nullptr;
    int mAttributeIndex;
    QString mSubstring;
    QStringList mValues;
    QgsFeedback *mFeedback = nullptr;
    QMutex mFeedbackMutex;
    bool mWasCanceled;
};


#endif

class GUI_EXPORT QgsFieldValuesLineEdit: public QgsFilterLineEdit
{
    Q_OBJECT

    Q_PROPERTY( QgsVectorLayer *layer READ layer WRITE setLayer NOTIFY layerChanged )
    Q_PROPERTY( int attributeIndex READ attributeIndex WRITE setAttributeIndex NOTIFY attributeIndexChanged )

  public:

    QgsFieldValuesLineEdit( QWidget *parent SIP_TRANSFERTHIS = nullptr );

    ~QgsFieldValuesLineEdit() override;

    void setLayer( QgsVectorLayer *layer );

    QgsVectorLayer *layer() const { return mLayer; }

    void setAttributeIndex( int index );

    int attributeIndex() const { return mAttributeIndex; }

  signals:

    void layerChanged( QgsVectorLayer *layer );

    void attributeIndexChanged( int index );

  private slots:

    void requestCompleterUpdate();

    void triggerCompleterUpdate();

    void updateCompleter( const QStringList &values );

    void gathererThreadFinished();

  private:

    QgsVectorLayer *mLayer = nullptr;
    int mAttributeIndex = -1;

    bool mUpdateRequested = false;

    QTimer mShowPopupTimer;

    QgsFieldValuesLineEditValuesGatherer *mGatherer = nullptr;

    QString mRequestedCompletionText;

    void updateCompletionList( const QString &substring );

};


#endif //QGSFIELDVALUESLINEEDIT_H