qgsfieldexpressionwidget.h

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/***************************************************************************
   qgsfieldexpressionwidget.h
    --------------------------------------
   Date                 : 01.04.2014
   Copyright            : (C) 2014 Denis Rouzaud
   Email                : [email protected]
***************************************************************************
*                                                                         *
*   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 QGSFIELDEXPRESSIONWIDGET_H
#define QGSFIELDEXPRESSIONWIDGET_H

#include <QColor>
#include <QComboBox>
#include <QToolButton>
#include <QWidget>
#include <memory>

#include "qgis_gui.h"
#include "qgis.h"
#include "qgsdistancearea.h"
#include "qgsexpressioncontextgenerator.h"
#include "qgsexpressioncontext.h"
#include "qgsfieldproxymodel.h"


class QgsMapLayer;
class QgsVectorLayer;


class GUI_EXPORT QgsFieldExpressionWidget : public QWidget
{
    Q_OBJECT
    Q_PROPERTY( QString expressionDialogTitle READ expressionDialogTitle WRITE setExpressionDialogTitle )
    Q_PROPERTY( QgsFieldProxyModel::Filters filters READ filters WRITE setFilters )
    Q_PROPERTY( bool allowEmptyFieldName READ allowEmptyFieldName WRITE setAllowEmptyFieldName )
    Q_PROPERTY( bool allowEvalErrors READ allowEvalErrors WRITE setAllowEvalErrors NOTIFY allowEvalErrorsChanged )

  public:

    explicit QgsFieldExpressionWidget( QWidget *parent SIP_TRANSFERTHIS = nullptr );

    void setExpressionDialogTitle( const QString &title );

    void appendScope( QgsExpressionContextScope *scope SIP_TRANSFER );

    const QString expressionDialogTitle() { return mExpressionDialogTitle; }

    void setFilters( QgsFieldProxyModel::Filters filters );

    void setAllowEmptyFieldName( bool allowEmpty );

    bool allowEmptyFieldName() const;

    void setLeftHandButtonStyle( bool isLeft );

    QgsFieldProxyModel::Filters filters() const { return mFieldProxyModel->filters(); }

    void setGeomCalculator( const QgsDistanceArea &da );

    QString currentField( bool *isExpression = nullptr, bool *isValid = nullptr ) const;

    bool isValidExpression( QString *expressionError = nullptr ) const;

    bool isExpression() const;

    QString currentText() const;

    QString asExpression() const;

    QString expression() const;

    QgsVectorLayer *layer() const;

    void registerExpressionContextGenerator( const QgsExpressionContextGenerator *generator );

    bool allowEvalErrors() const;

    void setAllowEvalErrors( bool allowEvalErrors );

  signals:
    void fieldChanged( const QString &fieldName );

    void fieldChanged( const QString &fieldName, bool isValid );

    void allowEvalErrorsChanged();

  public slots:

    void setLayer( QgsMapLayer *layer );

    void setRow( int row ) { mCombo->setCurrentIndex( row ); }

    void setField( const QString &fieldName );

    void setExpression( const QString &expression );

  protected slots:
    void editExpression();

    void expressionEdited( const QString &expression );

    void expressionEditingFinished();

    void currentFieldChanged();

    void updateLineEditStyle( const QString &expression = QString() );

    bool isExpressionValid( const QString &expressionStr );

  protected:
    void changeEvent( QEvent *event ) override;

    bool eventFilter( QObject *watched, QEvent *event ) override;

  private slots:
    void reloadLayer();

    void beforeResetModel();
    void afterResetModel();

  private:
    QComboBox *mCombo = nullptr;
    QToolButton *mButton = nullptr;
    QgsFieldProxyModel *mFieldProxyModel = nullptr;
    QString mExpressionDialogTitle;
    std::shared_ptr<const QgsDistanceArea> mDa;
    QgsExpressionContext mExpressionContext;
    const QgsExpressionContextGenerator *mExpressionContextGenerator = nullptr;
    QString mBackupExpression;
    bool mAllowEvalErrors = false;

    friend class TestQgsFieldExpressionWidget;
};

#endif // QGSFIELDEXPRESSIONWIDGET_H