Calculate better context (extent,size) if not given in WMS, WCS ident…

…ify. Fixes #8724
qgis · Oct 16, 2013 · de8a5d6 · de8a5d6
1 parent 7dc20ef
commit de8a5d6
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Showing 2 changed files with 81 additions and 23 deletions.
diff --git a/src/providers/wcs/qgswcsprovider.cpp b/src/providers/wcs/qgswcsprovider.cpp
@@ -1628,28 +1628,52 @@ QgsRasterIdentifyResult QgsWcsProvider::identify( const QgsPoint & thePoint, Qgs
   if ( myExtent.isEmpty() || theWidth == 0 || theHeight == 0 ||
        theWidth > maxSize || theHeight > maxSize )
   {
-    // context missing, use an area around the point and highest resolution if known
+    // context missing, use a small area around the point and highest resolution if known
 
-    // 1000 is bad in any case, either not precise or too much data requests
-    if ( theWidth == 0 ) theWidth = mHasSize ? mWidth : 1000;
-    if ( theHeight == 0 ) theHeight = mHasSize ? mHeight : 1000;
+    double xRes, yRes;
+    //if ( mHasSize )
+    if ( false )
+    {
+      xRes = mCoverageExtent.width()  / mWidth;
+      yRes = mCoverageExtent.height()  / mHeight;
+    }
+    else
+    {
+      // set resolution approximately to 1mm
+      switch ( mCrs.mapUnits() )
+      {
+        case QGis::Meters:
+          xRes = 0.001;
+          break;
+        case QGis::Feet:
+          xRes = 0.003;
+          break;
+        case QGis::Degrees:
+          // max length of degree of latitude on pole is 111694 m
+          xRes = 1e-8;
+          break;
+        default:
+          xRes = 0.001; // expecting meters
+      }
+      yRes = xRes;
+    }
 
-    if ( myExtent.isEmpty() )  myExtent = extent();
+    // 1000x1000 to cache data around
+    theWidth = 1000;
+    theHeight = 1000;
 
-    double xRes = myExtent.width() / theWidth;
-    double yRes = myExtent.height() / theHeight;
+    myExtent = QgsRectangle( thePoint.x() - xRes * theWidth / 2,
+                             thePoint.y() - yRes * theHeight / 2,
+                             thePoint.x() + xRes * theWidth / 2,
+                             thePoint.y() + yRes * theHeight / 2 );
 
     if ( !mCachedGdalDataset ||
          !mCachedViewExtent.contains( thePoint ) ||
          mCachedViewWidth == 0 || mCachedViewHeight == 0 ||
          mCachedViewExtent.width() / mCachedViewWidth - xRes > TINY_VALUE ||
          mCachedViewExtent.height() / mCachedViewHeight - yRes > TINY_VALUE )
     {
-      int half = 50;
-      QgsRectangle extent( thePoint.x() - xRes * half, thePoint.y() - yRes * half,
-                           thePoint.x() + xRes * half, thePoint.y() + yRes * half );
-      getCache( 1, extent, 2*half, 2*half );
-
+      getCache( 1, myExtent, theWidth, theHeight );
     }
   }
   else

diff --git a/src/providers/wms/qgswmsprovider.cpp b/src/providers/wms/qgswmsprovider.cpp
@@ -3991,20 +3991,54 @@ QgsRasterIdentifyResult QgsWmsProvider::identify( const QgsPoint & thePoint, Qgs
   }
 
   QgsRectangle myExtent = theExtent;
-  if ( myExtent.isEmpty() )
+
+  if ( !myExtent.isEmpty() )
   {
-    // use full extent
-    myExtent = extent();
+    // we cannot reliably identify WMS if theExtent is specified but theWidth or theHeight
+    // are not, because we dont know original resolution
+    if ( theWidth == 0 || theHeight == 0 )
+    {
+      return QgsRasterIdentifyResult( ERROR( tr( "Context not fully specified (extent was defined but width and/or height was not)." ) ) );
+    }
   }
-
-  // We don't know highest resolution, so it is difficult to guess any
-  // but that is why theExtent, theWidth, theHeight params are here
-  // Keep resolution in both axis equal! Otherwise silly server (like QGIS mapserver)
-  // fail to calculate coordinate because it is using single resolution average!!!
-  if ( theWidth == 0 ) theWidth = 1000; // just some number
-  if ( theHeight == 0 )
+  else // context (theExtent, theWidth, theHeight) not defined
   {
-    theHeight =  myExtent.height() / ( myExtent.width() / theWidth );
+    // We don't know original source resolution, so we take some small extent around the point.
+
+    double xRes = 0.001; // expecting meters
+
+    // TODO: add CRS as class member
+    QgsCoordinateReferenceSystem crs;
+    if ( crs.createFromOgcWmsCrs( mImageCrs ) )
+    {
+      // set resolution approximately to 1mm
+      switch ( crs.mapUnits() )
+      {
+        case QGis::Meters:
+          xRes = 0.001;
+          break;
+        case QGis::Feet:
+          xRes = 0.003;
+          break;
+        case QGis::Degrees:
+          // max length of degree of latitude on pole is 111694 m
+          xRes = 1e-8;
+          break;
+        default:
+          xRes = 0.001; // expecting meters
+      }
+    }
+
+    // Keep resolution in both axis equal! Otherwise silly server (like QGIS mapserver)
+    // fail to calculate coordinate because it is using single resolution average!!!
+    double yRes = xRes;
+
+    // 1x1 should be sufficient but at least we know that GDAL ECW was very unefficient
+    // so we use 2x2 (until we find that it is too small for some server)
+    theWidth = theHeight = 2;
+
+    myExtent = QgsRectangle( thePoint.x() - xRes, thePoint.y() - yRes,
+                             thePoint.x() + xRes, thePoint.y() + yRes );
   }
 
   // Point in BBOX/WIDTH/HEIGHT coordinates