File indexing completed on 2024-04-28 04:41:51

 /***************************************************************************
  *   Copyright (C) 2018 by Emmanuel Lepage Vallee                          *
  *   Author : Emmanuel Lepage Vallee <emmanuel.lepage@kde.org>             *
  *                                                                         *
  *   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 3 of the License, or     *
  *   (at your option) any later version.                                   *
  *                                                                         *
  *   This program is distributed in the hope that it will be useful,       *
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  *   GNU General Public License for more details.                          *
  *                                                                         *
  *   You should have received a copy of the GNU General Public License     *
  *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
  **************************************************************************/
 #ifndef KQUICKITEMVIEWS_SIZEHINTPROXYMODEL_H
 #define KQUICKITEMVIEWS_SIZEHINTPROXYMODEL_H
 
 // Qt
 #include <QtCore/QIdentityProxyModel>
 #include <QtCore/QVariant>
 #include <QJSValue>
 #include <QQmlScriptString>
 
 class SizeHintProxyModelPrivate;
 
 /**
  * This proxy model allows to predict the final size of a view delegate.
  *
  * This model needs to be implemented when both of the following things are
  * used:
  *
  * * A scrollbar or anything that depends on `contentHeight` being correct
  * * A non uniform delegate size
  *
  * Back in the QtWidgets days, the QItemDelegate/QStyledItemDelegate had the
  * `sizeHint` method. It was easy to use because it was the same class that
  * performed the painting so it had all the necessary knowledge to return
  * the correct value. In QML, however, it's not the case. Predicting the size
  * may or may not require knowledge of the style that are not officially in
  * public APIs. That being said, it should usually be possible to gather the
  * data in one way or another.
  *
  * This class is part of the public C++ API so the `sizeHint` method can be
  * re-implemented. Otherwise it is specified in JavaScript.
  */
 class Q_DECL_EXPORT SizeHintProxyModel : public QIdentityProxyModel
 {
     Q_OBJECT
 public:
     /**
      * Return the width for a QModelIndex.
      *
      * All roles and all constants constants are exposed as variables in the
      * expression.
      */
     Q_PROPERTY(QQmlScriptString widthHint READ widthHint WRITE setWidthHint)
 
     /**
      * Return the width for a QModelIndex.
      *
      * All roles and all constants constants are exposed as variables in the
      * expression.
      */
     Q_PROPERTY(QQmlScriptString heightHint READ heightHint WRITE setHeightHint)
 
     /**
      * Add variables to the sizeHint callback context that likely wont change
      * over time. This is useful to store font metrics and static sizes.
      *
      * The function is called when the model changes or invalidateContext is
      * called.
      */
     Q_PROPERTY(QJSValue constants READ constants WRITE setConstants)
 
     /**
      * When `dataChanged` on the model is called with a list of invalidated roles
      * matching the entries in this list, assume the size hint needs to be
      * recomputed.
      *
      * When used with the other KQuickItemViews views, they will be notified.
      *
      * Note that the constants wont be invalidated.
      */
     Q_PROPERTY(QStringList invalidationRoles READ invalidationRoles WRITE setInvalidationRoles)
 
     explicit SizeHintProxyModel(QObject* parent = nullptr);
     virtual ~SizeHintProxyModel();
 
     virtual void setSourceModel(QAbstractItemModel *newSourceModel) override;
 
     QQmlScriptString widthHint() const;
     void setWidthHint(const QQmlScriptString& value);
 
     QQmlScriptString heightHint() const;
     void setHeightHint(const QQmlScriptString& value);
 
     QJSValue constants() const;
     void setConstants(const QJSValue& value);
 
     QStringList invalidationRoles() const;
     void setInvalidationRoles(const QStringList& l);
 
     Q_INVOKABLE QSizeF sizeHintForIndex(const QModelIndex& idx);
 
     Q_INVOKABLE QVariant getRoleValue(const QModelIndex& idx, const QString& roleName) const;
 
 public Q_SLOTS:
     /**
      * Call this when the values in the constants may have changed.
      */
     void invalidateConstants();
 
 private:
     SizeHintProxyModelPrivate* d_ptr;
     Q_DECLARE_PRIVATE(SizeHintProxyModel)
 };
 
 Q_DECLARE_METATYPE(SizeHintProxyModel*)
 
 #endif