Changeset 14815

Timestamp:

07/04/08 23:18:22 (5 months ago)

Author:

warmerdam

Message:

improve overview generation documentation

Files:

• trunk/gdal/gcore/gdaldataset.cpp (modified) (2 diffs)
• trunk/gdal/gcore/gdalrasterband.cpp (modified) (1 diff)
• trunk/gdal/gcore/overview.cpp (modified) (6 diffs)

trunk/gdal/gcore/gdaldataset.cpp

@@ -1172 +1172 @@
- * This method is the same as the C function GDALBuildOverviews().
- *
-
-
+
- * @param nOverviews number of overviews to build. 
- * @param panOverviewList the list of overview decimation factors to build. 
@@ -1192 +1191 @@
- *                              GDALDummyProgress, NULL );
- * </pre>
+ *
+ * @see GDALRegenerateOverviews()
- */
-

trunk/gdal/gcore/gdalrasterband.cpp

@@ -1976 +1976 @@
- * from a practical point of view. 
- *
-
-
+
- * @param nOverviews number of overviews to build. 
- * @param panOverviewList the list of overview decimation factors to build. 

trunk/gdal/gcore/overview.cpp

@@ -580 +580 @@
-/*                      GDALRegenerateOverviews()                       */
-/************************************************************************/
+
+/**
+ * Generate downsampled overviews.
+ *
+ * This function will generate one or more overview images from a base
+ * image using the requested downsampling algorithm.  It's primary use
+ * is for generating overviews via GDALDataset::BuildOverviews(), but it
+ * can also be used to generate downsampled images in one file from another
+ * outside the overview architecture.
+ *
+ * The output bands need to exist in advance. 
+ *
+ * The full set of resampling algorithms is documented in 
+ * GDALDataset::BuildOverviews().
+ *
+ * @param hSrcBand the source (base level) band. 
+ * @param nOverviewCount the number of downsampled bands being generated.
+ * @param pahOvrBands the list of downsampled bands to be generated.
+ * @param pszResampling Resampling algorithm (eg. "AVERAGE"). 
+ * @param pfnProgress progress report function.
+ * @param pProgressData progress function callback data.
+ * @return CE_None on success or CE_Failure on failure.
+ */
-CPLErr 
-GDALRegenerateOverviews( GDALRasterBandH hSrcBand,
-s
+Count
-                         const char * pszResampling, 
-                         GDALProgressFunc pfnProgress, void * pProgressData )
@@ -596 +619 @@
-    GDALColorTable* poColorTable = NULL;
-
+    if( pfnProgress == NULL )
+        pfnProgress = GDALDummyProgress;
+
-    if (EQUALN(pszResampling,"AVER",4) &&
-        poSrcBand->GetColorInterpretation() == GCI_PaletteIndex)
@@ -624 +650 @@
-/*      amount of computation.                                          */
-/* -------------------------------------------------------------------- */
-s
+Count
-        return GDALRegenerateCascadingOverviews( poSrcBand, 
-s
+Count
-                                                 pszResampling, 
-                                                 pfnProgress,
@@ -734 +760 @@
-        }
-        
-s
+Count
-        {
-            if( eType == GDT_Float32 )
@@ -756 +782 @@
-    {
-        GDALOverviewMagnitudeCorrection( (GDALRasterBandH) poSrcBand, 
-s
+Count
-                                         (GDALRasterBandH *) papoOvrBands,
-                                         GDALDummyProgress, NULL );
@@ -764 +790 @@
-/*      It can be important to flush out data to overviews.             */
-/* -------------------------------------------------------------------- */
-s
+Count
-        papoOvrBands[iOverview]->FlushCache();
-