preliminary support for overviews in proxydb directory (#2432)

git-svn-id: https://svn.osgeo.org/gdal/trunk/gdal@16704 f0d54148-0727-0410-94bb-9a71ac55c965
judajake · Apr 2, 2009 · ee2963b · ee2963b
1 parent 982d04d
commit ee2963b
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diff --git a/gcore/gdal_pam.h b/gcore/gdal_pam.h
@@ -150,6 +150,9 @@ class CPL_DLL GDALPamDataset : public GDALDataset
     virtual CPLErr      SetMetadataItem( const char * pszName,
                                          const char * pszValue,
                                          const char * pszDomain = "" );
+    virtual char      **GetMetadata( const char * pszDomain = "" );
+    virtual const char *GetMetadataItem( const char * pszName,
+                                         const char * pszDomain = "" );
 
     virtual char      **GetFileList(void);
 

diff --git a/gcore/gdaldefaultoverviews.cpp b/gcore/gdaldefaultoverviews.cpp
@@ -163,6 +163,21 @@ void GDALDefaultOverviews::Initialize( GDALDataset *poDSIn,
         }
     }
 
+/* -------------------------------------------------------------------- */
+/*      If we still don't have an overview, check to see if we have     */
+/*      overview metadata referencing a remote (ie. proxy) dataset.     */
+/* -------------------------------------------------------------------- */
+    if( poODS == NULL )
+    {
+        const char *pszProxyOvrFilename = 
+            poDS->GetMetadataItem( "OVERVIEW_FILE", "OVERVIEWS" );
+        if( pszProxyOvrFilename != NULL )
+        {
+            osOvrFilename = pszProxyOvrFilename;
+            poODS = (GDALDataset *) GDALOpen(osOvrFilename,GA_Update);
+        }
+    }
+
 /* -------------------------------------------------------------------- */
 /*      If we have an overview dataset, then mark all the overviews     */
 /*      with the base dataset  Used later for finding overviews         */
@@ -458,6 +473,25 @@ GDALDefaultOverviews::BuildOverviews(
         eErr = GTIFFBuildOverviews( osOvrFilename, nBands, pahBands, 
                                     nNewOverviews, panNewOverviewList, 
                                     pszResampling, pfnProgress, pProgressData );
+
+        // Probe for proxy overview filename. 
+        if( eErr == CE_Failure )
+        {
+            CPLDebug( "GDALDefaultOverviews", "GTIFFBuildOverviews failed, request proxy overview" );
+            const char *pszProxyOvrFilename = 
+                poDS->GetMetadataItem("FILENAME","ProxyOverviewRequest");
+
+            if( pszProxyOvrFilename != NULL )
+            {
+                CPLDebug( "GDALDefaultOverviews", 
+                          "got %s", pszProxyOvrFilename );
+                osOvrFilename = pszProxyOvrFilename;
+                eErr = GTIFFBuildOverviews( osOvrFilename, nBands, pahBands, 
+                                            nNewOverviews, panNewOverviewList, 
+                                            pszResampling, 
+                                            pfnProgress, pProgressData );
+            }
+        }
 
         if( eErr == CE_None )
         {

diff --git a/gcore/gdalpamdataset.cpp b/gcore/gdalpamdataset.cpp
@@ -1119,6 +1119,43 @@ CPLErr GDALPamDataset::SetMetadataItem( const char *pszName,
     return GDALDataset::SetMetadataItem( pszName, pszValue, pszDomain );
 }
 
+/************************************************************************/
+/*                          GetMetadataItem()                           */
+/************************************************************************/
+
+const char *GDALPamDataset::GetMetadataItem( const char *pszName, 
+                                             const char *pszDomain )
+
+{
+    CPLDebug( "GDALPamDataset", "GetMetadataItem(%s,%s)", 
+              pszName, pszDomain );
+
+    if( pszDomain == NULL || !EQUAL(pszDomain,"ProxyOverviewRequest") )
+        return GDALDataset::GetMetadataItem( pszName, pszDomain );
+
+    CPLString osPrelimOvr = GetDescription();
+    osPrelimOvr += ".ovr";
+
+    const char *pszProxyOvrFilename = PamAllocateProxy( osPrelimOvr );
+    if( pszProxyOvrFilename == NULL )
+        return NULL;
+
+    SetMetadataItem( "OVERVIEW_FILE", pszProxyOvrFilename, "OVERVIEWS" );
+
+    return pszProxyOvrFilename;
+}
+
+/************************************************************************/
+/*                            GetMetadata()                             */
+/************************************************************************/
+
+char **GDALPamDataset::GetMetadata( const char *pszDomain )
+
+{
+//    if( pszDomain == NULL || !EQUAL(pszDomain,"ProxyOverviewRequest") )
+        return GDALDataset::GetMetadata( pszDomain );
+}
+
 /************************************************************************/
 /*                             TryLoadAux()                             */
 /************************************************************************/