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       1                 :            : /***************************************************************************
       2                 :            :     qgsabstractvaliditycheck.h
       3                 :            :     --------------------------
       4                 :            :     begin                : November 2018
       5                 :            :     copyright            : (C) 2018 by Nyall Dawson
       6                 :            :     email                : nyall dot dawson at gmail dot com
       7                 :            :  ***************************************************************************
       8                 :            :  *                                                                         *
       9                 :            :  *   This program is free software; you can redistribute it and/or modify  *
      10                 :            :  *   it under the terms of the GNU General Public License as published by  *
      11                 :            :  *   the Free Software Foundation; either version 2 of the License, or     *
      12                 :            :  *   (at your option) any later version.                                   *
      13                 :            :  *                                                                         *
      14                 :            :  ***************************************************************************/
      15                 :            : #ifndef QGSABSTRACTVALIDITYCHECK_H
      16                 :            : #define QGSABSTRACTVALIDITYCHECK_H
      17                 :            : 
      18                 :            : #include "qgis_core.h"
      19                 :            : #include "qgis_sip.h"
      20                 :            : #include <QString>
      21                 :            : #include <QObject>
      22                 :            : 
      23                 :            : class QgsValidityCheckContext;
      24                 :            : class QgsFeedback;
      25                 :            : 
      26                 :            : /**
      27                 :            :  * \class QgsValidityCheckResult
      28                 :            :  * \ingroup core
      29                 :            :  * \brief Represents an individual result from a validity check run by a QgsAbstractValidityCheck subclass.
      30                 :            :  *
      31                 :            :  * Results can either be warnings or critical errors, as dictated by the type member. Critical error
      32                 :            :  * are errors which are serious enough to prevent an operation from proceeding, while a warning
      33                 :            :  * result will be communicated to users, but not prevent them from proceeding.
      34                 :            :  *
      35                 :            :  * \since QGIS 3.6
      36                 :            :  */
      37                 :          0 : class CORE_EXPORT QgsValidityCheckResult
      38                 :            : {
      39                 :            :   public:
      40                 :            : 
      41                 :            :     //! Result types
      42                 :            :     enum Type
      43                 :            :     {
      44                 :            :       Warning, //!< Warning only, allow operation to proceed but notify user of result
      45                 :            :       Critical, //!< Critical error - notify user of result and prevent operation from proceeding
      46                 :            :     };
      47                 :            : 
      48                 :            :     //! Result type
      49                 :            :     Type type;
      50                 :            : 
      51                 :            :     /**
      52                 :            :      * A short, translated string summarising the result. Ideally a single sentence.
      53                 :            :      */
      54                 :            :     QString title;
      55                 :            : 
      56                 :            :     /**
      57                 :            :      * Detailed description of the result (translated), giving users enough detail for them to resolve
      58                 :            :      * the error.
      59                 :            :      */
      60                 :            :     QString detailedDescription;
      61                 :            : 
      62                 :            :     /**
      63                 :            :      * ID of the check which generated the result. This is usually automatically populated.
      64                 :            :      */
      65                 :            :     QString checkId;
      66                 :            : 
      67                 :            : };
      68                 :            : 
      69                 :            : /**
      70                 :            :  * \class QgsAbstractValidityCheck
      71                 :            :  * \ingroup core
      72                 :            :  * \brief Abstract base class for individual validity checks.
      73                 :            :  *
      74                 :            :  * Validity checks represent objects which can run a test using a QgsValidityCheckContext, and return
      75                 :            :  * the results of the check via QgsValidityCheckResult objects.
      76                 :            :  *
      77                 :            :  * Checks can be used for many different use cases, e.g. validating a layout's contents before allowing
      78                 :            :  * an export to occur, or validating the contents of a Processing model (and warning if required plugin based
      79                 :            :  * providers are not available or if compulsory algorithm parameters have not been populated).
      80                 :            :  *
      81                 :            :  * Subclasses must indicate the type of check they represent via the checkType() method. When checks are performed,
      82                 :            :  * all the registered checks with a matching check type are performed sequentially. The check type also
      83                 :            :  * dictates the subclass of the QgsValidityCheckContext which is given to the subclass' runCheck method.
      84                 :            :  *
      85                 :            :  * Checks must be registered in the application's QgsValidityCheckRegistry, which is accessible via
      86                 :            :  * QgsApplication::validityCheckRegistry().
      87                 :            :  *
      88                 :            :  * \see QgsValidityCheckRegistry
      89                 :            :  *
      90                 :            :  * \since QGIS 3.6
      91                 :            :  */
      92                 :            : class CORE_EXPORT QgsAbstractValidityCheck
      93                 :            : {
      94                 :            : 
      95                 :            :   public:
      96                 :            : 
      97                 :            :     //! Check types
      98                 :            :     enum Type
      99                 :            :     {
     100                 :            :       TypeLayoutCheck = 0, //!< Print layout validity check, triggered on exporting a print layout
     101                 :            :       TypeUserCheck = 10000, //!< Starting point for custom user types
     102                 :            :     };
     103                 :            : 
     104                 :            :     virtual ~QgsAbstractValidityCheck() = default;
     105                 :            : 
     106                 :            :     /**
     107                 :            :      * Creates a new instance of the check and returns it.
     108                 :            :      */
     109                 :            :     virtual QgsAbstractValidityCheck *create() const = 0 SIP_FACTORY;
     110                 :            : 
     111                 :            :     /**
     112                 :            :      * Returns the unique ID of the check.
     113                 :            :      *
     114                 :            :      * This is a non-translated, non-user visible string identifying the check.
     115                 :            :      */
     116                 :            :     virtual QString id() const = 0;
     117                 :            : 
     118                 :            :     /**
     119                 :            :      * Returns the type of the check.
     120                 :            :      */
     121                 :            :     virtual int checkType() const = 0;
     122                 :            : 
     123                 :            :     /**
     124                 :            :      * Prepares the check for execution, and returns TRUE if the check can be run.
     125                 :            :      *
     126                 :            :      * This method is always called from the main thread, and subclasses can implement
     127                 :            :      * it to do preparatory steps which are not thread safe (e.g. obtaining feature
     128                 :            :      * sources from vector layers). It is followed by a call to runCheck(), which
     129                 :            :      * may be performed in a background thread.
     130                 :            :      *
     131                 :            :      * Individual calls to prepareCheck()/runCheck() are run on a new instance of the
     132                 :            :      * check (see create()), so subclasses can safely store state from the prepareCheck() method
     133                 :            :      * ready for the subsequent runCheck() method.
     134                 :            :      *
     135                 :            :      * The \a context argument gives the wider in which the check is being run.
     136                 :            :      */
     137                 :            :     virtual bool prepareCheck( const QgsValidityCheckContext *context, QgsFeedback *feedback )
     138                 :            :     {
     139                 :            :       Q_UNUSED( context )
     140                 :            :       Q_UNUSED( feedback )
     141                 :            :       return true;
     142                 :            :     }
     143                 :            : 
     144                 :            :     /**
     145                 :            :      * Runs the check and returns a list of results. If the check is "passed" and no warnings or errors are generated,
     146                 :            :      * then an empty list should be returned.
     147                 :            :      *
     148                 :            :      * This method may be called in a background thread, so subclasses should take care to ensure that
     149                 :            :      * only thread-safe methods are used. It is always preceded by a call to prepareCheck().
     150                 :            :      *
     151                 :            :      * If a check needs to perform non-thread-safe tests, these should be implemented within prepareCheck()
     152                 :            :      * and stored in the subclass instance to be returned by this method.
     153                 :            :      *
     154                 :            :      * The \a context argument gives the wider in which the check is being run.
     155                 :            :      */
     156                 :            :     virtual QList< QgsValidityCheckResult > runCheck( const QgsValidityCheckContext *context, QgsFeedback *feedback ) = 0;
     157                 :            : 
     158                 :            : };
     159                 :            : 
     160                 :            : #endif // QGSABSTRACTVALIDITYCHECK_H