added getLegendGrafic feature to WmsDataProvider - Developed with fun…

…ding from Regione Toscana-SITA better scale management to avoid call getLegendGraphics everytime + some defaults + added code example to manage LegendURL when it will be correctly parsed - Developed with funding from Regione Toscana-SITA
qgis · Oct 18, 2013 · d770843 · d770843
1 parent 03a60d3
commit d770843
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Showing 3 changed files with 231 additions and 1 deletion.
diff --git a/src/core/raster/qgsrasterdataprovider.h b/src/core/raster/qgsrasterdataprovider.h
@@ -24,6 +24,7 @@
 
 #include <QDateTime>
 #include <QVariant>
+#include <QImage>
 
 #include "qgscolorrampshader.h"
 #include "qgscoordinatereferencesystem.h"
@@ -186,6 +187,15 @@ class CORE_EXPORT QgsRasterDataProvider : public QgsDataProvider, public QgsRast
       return QStringList();
     }
 
+    /** \brief Returns the legend rendered as pixmap
+     *  useful for that layer that need to get legend layer remotly as WMS */
+    virtual QImage getLegendGraphic( double scale=0, bool forceRefresh = false )
+    {
+      Q_UNUSED( scale );
+      Q_UNUSED( forceRefresh );
+      return QImage();
+    }
+
     /** \brief Create pyramid overviews */
     virtual QString buildPyramids( const QList<QgsRasterPyramid> & thePyramidList,
                                    const QString & theResamplingMethod = "NEAREST",

diff --git a/src/providers/wms/qgswmsprovider.cpp b/src/providers/wms/qgswmsprovider.cpp
@@ -59,7 +59,6 @@
 #include <QImage>
 #include <QImageReader>
 #include <QPainter>
-#include <QPixmap>
 #include <QSet>
 #include <QSettings>
 #include <QEventLoop>
@@ -84,6 +83,9 @@ QgsWmsProvider::QgsWmsProvider( QString const &uri )
     : QgsRasterDataProvider( uri )
     , mHttpUri( uri )
     , mHttpCapabilitiesResponse( 0 )
+    , mHttpGetLegendGraphicResponse( 0 )
+    , mGetLegendGraphicImage()
+    , mGetLegendGraphicScale( 0 )
     , mImageCrs( DEFAULT_LATLON_CRS )
     , mCachedImage( 0 )
     , mCacheReply( 0 )
@@ -4588,6 +4590,189 @@ void QgsWmsProvider::showMessageBox( const QString& title, const QString& text )
   message->showMessage();
 }
 
+QImage QgsWmsProvider::getLegendGraphic( double scale, bool forceRefresh )
+{
+  // TODO manage return basing of getCapablity => avoid call if service is not available
+  // some services dowsn't expose getLegendGraphic in capabilities but adding LegendURL in
+  // the layer tags inside capabilities
+  QgsDebugMsg( "entering." );
+
+  if ( !scale && !mGetLegendGraphicScale)
+  {
+    QgsDebugMsg( QString( "No scale factor set" ) );
+    return QImage();
+  }
+
+  if ( scale && scale != mGetLegendGraphicScale )
+  {
+    forceRefresh = true;
+    QgsDebugMsg( QString( "Download again due to scale change from: %1 to: %2" ).arg( mGetLegendGraphicScale ).arg( scale ) );
+  }
+
+  if ( forceRefresh )
+  {
+    if ( scale )
+    {
+      mGetLegendGraphicScale = scale;
+    }
+
+    // if style is not defined, set as "default"
+    QString currentStyle("default");
+    if ( mActiveSubStyles[0] != "" )
+    {
+      currentStyle = mActiveSubStyles[0];
+    }
+
+    // add WMS GetGraphicLegend request
+    // TODO set sld version using instance var something like mSldVersion
+    // TODO at this moment LSD version can be get from LegendURL in getCapability,but parsing of
+    // this tag is not complete. Below the code that should work if pasing whould correct
+    //     if ( mActiveSubLayers[0] == mCapabilities.capability.layer.name )
+    //     {
+    //       foreach( QgsWmsStyleProperty style,  mCapabilities.capability.layer.style )
+    //       {
+    //         if ( currentStyle == style.name )
+    //         {
+    //           url.setUrl( style.legendUrl[0].onlineResource.xlinkHref, QUrl::StrictMode );
+    //         }
+    //       }
+    //     } // is a sublayer
+    //     else if ( mActiveSubLayers[0].contains( mCapabilities.capability.layer.name ) )
+    //     {
+    //       foreach( QgsWmsLayerProperty layerProperty, mCapabilities.capability.layer.layer )
+    //       {
+    //         if ( mActiveSubLayers[0] == layerProperty.name )
+    //         {
+    //           foreach( QgsWmsStyleProperty style, layerProperty.style )
+    //           {
+    //             if ( currentStyle == style.name )
+    //             {
+    //               url.setUrl( style.legendUrl[0].onlineResource.xlinkHref, QUrl::StrictMode );
+    //             }
+    //           }
+    //         }
+    //       }
+    //     }
+    QUrl url( mIgnoreGetMapUrl ? mBaseUrl : getMapUrl(), QUrl::StrictMode );
+    setQueryItem( url, "SERVICE", "WMS" );
+    setQueryItem( url, "VERSION", mCapabilities.version );
+    setQueryItem( url, "SLD_VERSION", "1.1.0" ); // can not determine SLD_VERSION
+    setQueryItem( url, "REQUEST", "GetLegendGraphic" );
+    setQueryItem( url, "LAYER", mActiveSubLayers[0] );
+    setQueryItem( url, "STYLE", currentStyle );
+    setQueryItem( url, "SCALE", QString::number( scale, 'f') );
+    setQueryItem( url, "FORMAT", mImageMimeType );
+
+    mError = "";
+
+    QNetworkRequest request( url );
+    setAuthorization( request );
+    request.setAttribute( QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferNetwork );
+    request.setAttribute( QNetworkRequest::CacheSaveControlAttribute, true );
+
+    QgsDebugMsg( QString( "getlegendgraphics: %1" ).arg( url.toString() ) );
+    mGetLegendGraphicReply = QgsNetworkAccessManager::instance()->get( request );
+
+    connect( mGetLegendGraphicReply, SIGNAL( finished() ), this, SLOT( getLegendGraphicReplyFinished() ) );
+    connect( mGetLegendGraphicReply, SIGNAL( downloadProgress( qint64, qint64 ) ), this, SLOT( getLegendGraphicReplyProgress( qint64, qint64 ) ) );
+
+    while ( mGetLegendGraphicReply )
+    {
+      QCoreApplication::processEvents( QEventLoop::ExcludeUserInputEvents, WMS_THRESHOLD );
+    }
+  }
+  else
+  {
+    QgsDebugMsg( "get cached pixmap." );
+  }
+
+  QgsDebugMsg( "exiting." );
+
+  return mGetLegendGraphicImage; 
+}
+
+void QgsWmsProvider::getLegendGraphicReplyFinished()
+{
+  QgsDebugMsg( "entering." );
+  if ( mGetLegendGraphicReply->error() == QNetworkReply::NoError )
+  {
+    QgsDebugMsg( "reply ok" );
+    QVariant redirect = mGetLegendGraphicReply->attribute( QNetworkRequest::RedirectionTargetAttribute );
+    if ( !redirect.isNull() )
+    {
+      emit statusChanged( tr( "GetLegendGraphic request redirected." ) );
+
+      const QUrl& toUrl = redirect.toUrl();
+      mGetLegendGraphicReply->request();
+      if ( toUrl == mGetLegendGraphicReply->url() )
+      {
+        mErrorFormat = "text/plain";
+        mError = tr( "Redirect loop detected: %1" ).arg( toUrl.toString() );
+        QgsMessageLog::logMessage( mError, tr( "WMS" ) );
+        mHttpGetLegendGraphicResponse.clear();
+      }
+      else
+      {
+        QNetworkRequest request( toUrl );
+        setAuthorization( request );
+        request.setAttribute( QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferNetwork );
+        request.setAttribute( QNetworkRequest::CacheSaveControlAttribute, true );
+
+        mGetLegendGraphicReply->deleteLater();
+        QgsDebugMsg( QString( "redirected GetLegendGraphic: %1" ).arg( redirect.toString() ) );
+        mGetLegendGraphicReply = QgsNetworkAccessManager::instance()->get( request );
+
+        connect( mGetLegendGraphicReply, SIGNAL( finished() ), this, SLOT( getLegendGraphicReplyFinished() ) );
+        connect( mGetLegendGraphicReply, SIGNAL( downloadProgress( qint64, qint64 ) ), this, SLOT( getLegendGraphicReplyProgress( qint64, qint64 ) ) );
+        return;
+      }
+    }
+
+    QVariant status = mGetLegendGraphicReply->attribute( QNetworkRequest::HttpStatusCodeAttribute );
+    if ( !status.isNull() && status.toInt() >= 400 )
+    {
+      QVariant phrase = mGetLegendGraphicReply->attribute( QNetworkRequest::HttpReasonPhraseAttribute );
+      showMessageBox( tr( "GetLegendGraphic request error" ), tr( "Status: %1\nReason phrase: %2" ).arg( status.toInt() ).arg( phrase.toString() ) );
+    }
+    else
+    {
+      QImage myLocalImage = QImage::fromData( mGetLegendGraphicReply->readAll() ) ;
+      if ( myLocalImage.isNull() )
+      {
+        QgsMessageLog::logMessage( tr( "Returned legend image is flawed [URL: %2]" )
+                                    .arg( mGetLegendGraphicReply->url().toString() ), tr( "WMS" ) );
+      }
+      else
+      {
+        mGetLegendGraphicImage = myLocalImage;
+
+#ifdef QGISDEBUG
+        QString filename = QDir::tempPath() + "/GetLegendGraphic.png";
+        mGetLegendGraphicImage.save(filename);
+        QgsDebugMsg( "saved GetLegendGraphic result in debug ile: "+filename );
+#endif
+      }
+    }
+  }
+  else
+  {
+    mErrorFormat = "text/plain";
+    mError = tr( "Download of GetLegendGraphic failed: %1" ).arg( mGetLegendGraphicReply->errorString() );
+    QgsMessageLog::logMessage( mError, tr( "WMS" ) );
+    mHttpGetLegendGraphicResponse.clear();
+  }
+
+  mGetLegendGraphicReply->deleteLater();
+  mGetLegendGraphicReply = 0;
+}
+
+void QgsWmsProvider::getLegendGraphicReplyProgress( qint64 bytesReceived, qint64 bytesTotal )
+{
+  QString msg = tr( "%1 of %2 bytes of GetLegendGraphic downloaded." ).arg( bytesReceived ).arg( bytesTotal < 0 ? QString( "unknown number of" ) : QString::number( bytesTotal ) );
+  QgsDebugMsg( msg );
+  emit statusChanged( msg );
+}
+
 /**
  * Class factory to return a pointer to a newly created
  * QgsWmsProvider object

diff --git a/src/providers/wms/qgswmsprovider.h b/src/providers/wms/qgswmsprovider.h
@@ -632,6 +632,19 @@ class QgsWmsProvider : public QgsRasterDataProvider
     QStringList subLayerStyles() const;
 
 
+    /**
+     * \brief Get GetLegendGraphic if service available otherwise QImage() 
+     * BEAWARE call it the first time specifying scale parameter otherwise it always return QImage()
+     * \todo some services dowsn't expose getLegendGraphic in capabilities but adding LegendURL in 
+     * the layer tags inside capabilities, but LegendURL parsing is still not developed => getLegendGraphic is
+     * always called assuming that error means service is not available. Other drowback is that SLD_VERSION
+     * is inside LegendURL, so at this moment it is fixed to 1.1.0 waiting a correct parsing of LegendURL
+     * in getCapability
+     * \param scale Optional parameter that is the Scale of the wms layer
+     * \param forceRefresh Optional bool parameter to force refresh getLegendGraphic call 
+     */
+    QImage getLegendGraphic( double scale = 0, bool forceRefresh = false );
+
     // TODO: Get the WMS connection
 
     // TODO: Get the table name associated with this provider instance
@@ -736,6 +749,8 @@ class QgsWmsProvider : public QgsRasterDataProvider
     void capabilitiesReplyProgress( qint64, qint64 );
     void identifyReplyFinished();
     void tileReplyFinished();
+    void getLegendGraphicReplyFinished();
+    void getLegendGraphicReplyProgress( qint64, qint64 );
 
   private:
     void showMessageBox( const QString& title, const QString& text );
@@ -913,6 +928,21 @@ class QgsWmsProvider : public QgsRasterDataProvider
      */
     QDomDocument mCapabilitiesDom;
 
+    /**
+     * GetLegendGraphic of the WMS (raw)
+     */
+    QByteArray mHttpGetLegendGraphicResponse;
+
+    /**
+     * GetLegendGraphic WMS Pixmap result
+     */
+    QImage mGetLegendGraphicImage;
+
+    /**
+     * GetLegendGraphic scale for the WMS Pixmap result
+     */
+    double mGetLegendGraphicScale;
+
     /**
      * Last Service Exception Report from the WMS
      */
@@ -1003,6 +1033,11 @@ class QgsWmsProvider : public QgsRasterDataProvider
      */
     QNetworkReply *mCapabilitiesReply;
 
+    /**
+     * The reply to the GetLegendGraphic request
+     */
+    QNetworkReply *mGetLegendGraphicReply;
+
     /**
      * The reply to the capabilities request
      */