qgsqmlwidgetwrapper.cpp

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/***************************************************************************
  qgsqmlwidgetwrapper.cpp
 
 ---------------------
 begin                : 25.6.2018
 copyright            : (C) 2018 by Matthias Kuhn
 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.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgsqmlwidgetwrapper.h"
 
#include "qgsattributeform.h"
#include "qgsexpressioncontextutils.h"
#include "qgsmessagelog.h"
#include "qgsvaluerelationfieldformatter.h"
 
#include <QQmlContext>
#include <QQmlEngine>
#include <QString>
#include <QUrl>
 
#include "moc_qgsqmlwidgetwrapper.cpp"
 
using namespace Qt::StringLiterals;
 
QgsQmlWidgetWrapper::QgsQmlWidgetWrapper( QgsVectorLayer *layer, QWidget *editor, QWidget *parent )
  : QgsWidgetWrapper( layer, editor, parent )
{
  connect( this, &QgsWidgetWrapper::contextChanged, this, &QgsQmlWidgetWrapper::setQmlContext );
}
 
bool QgsQmlWidgetWrapper::valid() const
{
  return true;
}
 
QWidget *QgsQmlWidgetWrapper::createWidget( QWidget *parent )
{
  QgsAttributeForm *form = qobject_cast<QgsAttributeForm *>( parent );
 
  if ( form )
  {
    mFormFeature = form->feature();
    connect( form, &QgsAttributeForm::widgetValueChanged, this, [this]( const QString &attribute, const QVariant &newValue, bool attributeChanged ) {
      if ( attributeChanged )
      {
        if ( mRequiresFormScope )
        {
          mFormFeature.setAttribute( attribute, newValue );
          setQmlContext();
        }
      }
    } );
  }
 
  return new QQuickWidget( parent );
}
 
void QgsQmlWidgetWrapper::initWidget( QWidget *editor )
{
  mWidget = qobject_cast<QQuickWidget *>( editor );
 
  if ( !mWidget )
    return;
 
 
  if ( !mQmlFile.open() )
  {
    QgsMessageLog::logMessage( tr( "Failed to open temporary QML file" ) );
    return;
  }
 
  QUrl sourceUrl = QUrl::fromLocalFile( mQmlFile.fileName() );
  sourceUrl.setQuery( u"t=%1"_s.arg( QDateTime::currentSecsSinceEpoch() ) );
  mWidget->setSource( sourceUrl );
 
  mQmlFile.close();
}
 
 
void QgsQmlWidgetWrapper::reinitWidget()
{
  if ( !mWidget )
    return;
 
  mWidget->engine()->clearComponentCache();
 
  initWidget( mWidget );
}
 
void QgsQmlWidgetWrapper::setQmlCode( const QString &qmlCode )
{
  if ( mQmlCode == qmlCode )
  {
    return;
  }
 
  mQmlCode = qmlCode;
 
  bool ok = false;
  const thread_local QRegularExpression
    expRe( QStringLiteral( R"re(expression.evaluate\s*\‍(\s*"(.*)"\))re" ), QRegularExpression::PatternOption::MultilineOption | QRegularExpression::PatternOption::DotMatchesEverythingOption );
  QRegularExpressionMatchIterator matchIt = expRe.globalMatch( mQmlCode );
  while ( !ok && matchIt.hasNext() )
  {
    const QRegularExpressionMatch match = matchIt.next();
    const QgsExpression exp = match.captured( 1 );
    ok = QgsValueRelationFieldFormatter::expressionRequiresFormScope( exp );
  }
  mRequiresFormScope = ok;
 
  if ( !mQmlFile.open() )
  {
    QgsMessageLog::logMessage( tr( "Failed to open temporary QML file" ) );
    return;
  }
 
  mQmlFile.resize( 0 );
  mQmlFile.write( mQmlCode.toUtf8() );
  mQmlFile.close();
}
 
void QgsQmlWidgetWrapper::setQmlContext()
{
  if ( !mWidget )
    return;
 
  const QgsAttributeEditorContext attributecontext = context();
  QgsExpressionContext expressionContext = layer()->createExpressionContext();
  expressionContext << QgsExpressionContextUtils::formScope( mFormFeature, attributecontext.attributeFormModeString() );
  if ( attributecontext.parentFormFeature().isValid() )
  {
    expressionContext << QgsExpressionContextUtils::parentFormScope( attributecontext.parentFormFeature() );
  }
 
  expressionContext.setFeature( mFeature );
 
  QmlExpression *qmlExpression = new QmlExpression();
  qmlExpression->setExpressionContext( expressionContext );
 
  mWidget->rootContext()->setContextProperty( "expression", qmlExpression );
}
 
void QgsQmlWidgetWrapper::setFeature( const QgsFeature &feature )
{
  if ( !mWidget )
    return;
 
  mFeature = feature;
  mFormFeature = feature;
 
  setQmlContext();
}

void QmlExpression::setExpressionContext( const QgsExpressionContext &context )
{
  mExpressionContext = context;
}
 
QVariant QmlExpression::evaluate( const QString &expression ) const
{
  QgsExpression exp = QgsExpression( expression );
  exp.prepare( &mExpressionContext );
  return exp.evaluate( &mExpressionContext );
}