[wcs] safer and faster rendering of WCS layers

wonder-sk · wonder-sk · commit d3342ad3aa3b · 2019-05-30T13:47:01.000+02:00
Redering of WCS layers has been quite inefficient since introduction of multi-threaded rendering in QGIS 2.4: whenever map rendering was starting, copying of WCS provider involved running full initialization of WCS provider which typically does three(!) network requests in the constructor (get capabilities + 2x check to work around some incompatibilities of WCS servers). This was both slow and potentially dangerous because of embedded QEventLoop for the network requests. This is now gone and when WCS provider gets cloned (e.g. when starting map rendering), it just gets copy of data without any extra work. Avoiding embedded QEventLoop fixes a crash in 3D view when loading tiles. Fixes #28800 Fixes #26706
diff --git a/src/providers/wcs/qgswcscapabilities.cpp b/src/providers/wcs/qgswcscapabilities.cpp
@@ -59,6 +59,30 @@ QgsWcsCapabilities::QgsWcsCapabilities( QgsDataSourceUri const &uri )
   retrieveServerCapabilities();
 }
 
+QgsWcsCapabilities::QgsWcsCapabilities( const QgsWcsCapabilities &other )
+  : QObject()
+  , mUri( other.mUri )
+  , mVersion( other.mVersion )
+  , mCapabilitiesResponse( other.mCapabilitiesResponse )
+  , mCapabilitiesDom( other.mCapabilitiesDom )
+  , mServiceExceptionReportDom( other.mServiceExceptionReportDom )
+  , mCapabilities( other.mCapabilities )
+  , mCoveragesSupported( other.mCoveragesSupported )
+    // intentionally omitted:
+    // - mCapabilitiesReply
+    // - mErrorTitle
+    // - mError
+    // - mErrorFormat
+  , mCoverageCount( other.mCoverageCount )
+  , mCoverageParents( other.mCoverageParents )
+  , mCoverageParentIdentifiers( other.mCoverageParentIdentifiers )
+  , mUserName( other.mUserName )
+  , mPassword( other.mPassword )
+  , mCacheLoadControl( other.mCacheLoadControl )
+{
+}
+
+
 void QgsWcsCapabilities::parseUri()
 {
   mCacheLoadControl = QNetworkRequest::PreferNetwork;
diff --git a/src/providers/wcs/qgswcscapabilities.h b/src/providers/wcs/qgswcscapabilities.h
@@ -91,6 +91,8 @@ class QgsWcsCapabilities : public QObject
      *
      */
     explicit QgsWcsCapabilities( QgsDataSourceUri const &uri );
+    //! copy constructor
+    explicit QgsWcsCapabilities( const QgsWcsCapabilities &other );
     QgsWcsCapabilities() = default;
 
     void setUri( QgsDataSourceUri const &uri );
diff --git a/src/providers/wcs/qgswcsprovider.cpp b/src/providers/wcs/qgswcsprovider.cpp
@@ -355,6 +355,63 @@ QgsWcsProvider::QgsWcsProvider( const QString &uri, const ProviderOptions &optio
   QgsDebugMsg( QStringLiteral( "Constructed OK, provider valid." ) );
 }
 
+QgsWcsProvider::QgsWcsProvider( const QgsWcsProvider &other, const QgsDataProvider::ProviderOptions &providerOptions )
+  : QgsRasterDataProvider( other.dataSourceUri(), providerOptions )
+  , mHttpUri( other.mHttpUri )
+  , mBaseUrl( other.mBaseUrl )
+  , mIdentifier( other.mIdentifier )
+  , mTime( other.mTime )
+  , mFormat( other.mFormat )
+  , mValid( other.mValid )
+  , mCapabilities( other.mCapabilities )
+  , mCoverageSummary( other.mCoverageSummary )
+  , mSrid( other.mSrid )
+  , mCoverageExtent( other.mCoverageExtent )
+  , mWidth( other.mWidth )
+  , mHeight( other.mHeight )
+  , mXBlockSize( other.mXBlockSize )
+  , mYBlockSize( other.mYBlockSize )
+  , mHasSize( other.mHasSize )
+  , mBandCount( other.mBandCount )
+  , mGdalDataType( other.mGdalDataType )
+  , mSrcGdalDataType( other.mSrcGdalDataType )
+  , mColorTables( other.mColorTables )
+  , mExtentForLayer( other.mExtentForLayer )
+  , mCrsForLayer( other.mCrsForLayer )
+  , mQueryableForLayer( other.mQueryableForLayer )
+  , mCoverageCrs( other.mCoverageCrs )
+    // intentionally omitted:
+    // - mCachedData
+    // - mCachedMemFilename
+    // - mCachedMemFile
+    // - mCachedGdalDataset
+    // - mCachedError
+    // - mCachedViewExtent
+    // - mCachedViewWidth
+    // - mCachedViewHeight
+  , mMaxWidth( other.mMaxWidth )
+  , mMaxHeight( other.mMaxHeight )
+    // intentionally omitted:
+    // - mErrorCaption
+    // - mError
+    // - mErrorFormat
+  , mCoordinateTransform( other.mCoordinateTransform )
+  , mExtentDirty( other.mExtentDirty )
+  , mGetFeatureInfoUrlBase( other.mGetFeatureInfoUrlBase )
+  , mServiceMetadataURL( other.mServiceMetadataURL )
+  , mAuth( other.mAuth )
+  , mIgnoreGetCoverageUrl( other.mIgnoreGetCoverageUrl )
+  , mIgnoreAxisOrientation( other.mIgnoreAxisOrientation )
+  , mInvertAxisOrientation( other.mInvertAxisOrientation )
+  , mCrs( other.mCrs )
+  , mFixBox( other.mFixBox )
+  , mFixRotate( other.mFixRotate )
+  , mCacheLoadControl( other.mCacheLoadControl )
+{
+  mCachedMemFilename = QStringLiteral( "/vsimem/qgis/wcs/%0.dat" ).arg( reinterpret_cast<std::uintptr_t>( this ) );
+}
+
+
 bool QgsWcsProvider::parseUri( const QString &uriString )
 {
 
@@ -431,7 +488,8 @@ QgsWcsProvider::~QgsWcsProvider()
 QgsWcsProvider *QgsWcsProvider::clone() const
 {
   QgsDataProvider::ProviderOptions providerOptions;
-  QgsWcsProvider *provider = new QgsWcsProvider( dataSourceUri(), providerOptions );
+  providerOptions.transformContext = transformContext();
+  QgsWcsProvider *provider = new QgsWcsProvider( *this, providerOptions );
   provider->copyBaseSettings( *this );
   return provider;
 }
diff --git a/src/providers/wcs/qgswcsprovider.h b/src/providers/wcs/qgswcsprovider.h
@@ -118,6 +118,8 @@ class QgsWcsProvider : public QgsRasterDataProvider, QgsGdalProviderBase
      */
     explicit QgsWcsProvider( const QString &uri, const QgsDataProvider::ProviderOptions &providerOptions );
 
+    //! copy constructor
+    explicit QgsWcsProvider( const QgsWcsProvider &other, const QgsDataProvider::ProviderOptions &providerOptions );
 
     ~QgsWcsProvider() override;
 

Original file line number	Diff line number	Diff line change
`@@ -91,6 +91,8 @@ class QgsWcsCapabilities : public QObject`
`91`	`91`	`*`
`92`	`92`	`*/`
`93`	`93`	`explicit QgsWcsCapabilities( QgsDataSourceUri const &uri );`
	`94`	`+ //! copy constructor`
	`95`	`+ explicit QgsWcsCapabilities( const QgsWcsCapabilities &other );`
`94`	`96`	`QgsWcsCapabilities() = default;`
`95`	`97`
`96`	`98`	`void setUri( QgsDataSourceUri const &uri );`