Add compatibility for GDAL version 1.7.2 and 2.4.0.

Author: gbburkhardt

src/gov/nasa/worldwind/data/GDALDataRaster.java

@@ -38,8 +38,6 @@
 import org.gdal.gdal.*;
 import org.gdal.gdalconst.gdalconst;
 import org.gdal.osr.SpatialReference;
-import org.gdal.osr.osrConstants;
-
 import java.awt.geom.*;
 import java.io.*;
 import java.nio.*;
@@ -277,7 +275,7 @@ protected SpatialReference readSpatialReference(Dataset ds)
         {
             proj = this.getStringValue(AVKey.SPATIAL_REFERENCE_WKT);
             srs = new SpatialReference(proj);
-            srs.SetAxisMappingStrategy(osrConstants.OAMS_AUTHORITY_COMPLIANT);
+            GDALUtils.setGDAL3axis(srs);
         }
 
         return srs;
@@ -506,10 +504,14 @@ protected Dataset createMaskDataset(int width, int height, Sector sector)
         Dataset ds = drvMem.Create("roi-mask", width, height, 1, gdalconst.GDT_UInt32);
         Band band = ds.GetRasterBand(1);
 
-        // For GDAL 3.x, don't mark band as alpha.
-        // See https://lists.osgeo.org/pipermail/gdal-dev/2019-June/050518.html
-        //band.SetColorInterpretation(gdalconst.GCI_AlphaBand);
-        
+		/*
+		 * Leave the band color interp undefined, otherwise handling of alpha
+		 * won't work as desired for GDAL version 3.1 and up. Doesn't cause a
+		 * problem with versions 1.7.2 and 2.4.0. Check with 'InstallImagery' app.
+		 * See https://lists.osgeo.org/pipermail/gdal-dev/2019-June/050518.html
+		 * 
+		 * band.SetColorInterpretation(gdalconst.GCI_AlphaBand);
+		 */        
         double missingSignal = (double) GDALUtils.ALPHA_MASK;
         band.SetNoDataValue(missingSignal);
         band.Fill(missingSignal);
@@ -530,7 +532,7 @@ protected Dataset createMaskDataset(int width, int height, Sector sector)
      * The purpose of this method is to create the best suited dataset for the requested area. The dataset may contain
      * overviews, so instead of retrieving raster from the highest resolution source, we will compose a temporary
      * dataset from an overview, and/or we may clip only the requested area. This will accelerate reprojection (if
-     * needed), because the reporjection will be done on much smaller dataset.
+     * needed), because the reprojection will be done on much smaller dataset.
      *
      * @param reqWidth  width of the requested area
      * @param reqHeight height of the requested area
@@ -1002,7 +1004,20 @@ else if (srcNumOfBands >= 3)
                 band.SetColorInterpretation(colorInt);
             }
 
-            if (colorInt == gdalconst.GCI_AlphaBand)
+            // Special handling for different GDAL versions. The way ReprojectImage works
+            // with respect to alpha layers was broken, probably starting with version 1.8.0
+            // https://lists.osgeo.org/pipermail/gdal-dev/2019-May/050175.html
+            // It was changed again version 3.1
+            //		https://lists.osgeo.org/pipermail/gdal-dev/2019-June/050517.html
+            //      https://github.com/OSGeo/gdal/commit/b427cb23ff1bc2a5ba2f6634fc3bd90816bb7789
+            //
+            // When there's no alpha band in the source, set the destination dataset alpha band
+            // to no transparency, so that when it's used in ReprojectImage, the resulting 
+            // image is opaque.  Otherwise, leave the existing band alone.
+            if ((colorInt == gdalconst.GCI_AlphaBand) 
+            		&& ((GDALUtils.getGDALversion() < 18) 
+            			|| (GDALUtils.getGDALversion() >= 31)
+            			|| (null == srcBand)))
             {
                 band.Fill((double) GDALUtils.ALPHA_MASK);
             }

src/gov/nasa/worldwind/util/gdal/GDALUtils.java

@@ -45,6 +45,7 @@
 import java.awt.image.*;
 import java.io.*;
 import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.nio.*;
 import java.util.*;
@@ -88,6 +89,25 @@ public class GDALUtils
 
     public enum LatLonOrder { latLonCRSauthority, longitudeLatitude };
     private static LatLonOrder latLonOrder = LatLonOrder.latLonCRSauthority;
+    private static int GDALversion = 0;	// integer to avoid floating point compare
+    /**
+     * return major*10 + minor, e.g., 34 is version 3.4
+     */
+    public static int getGDALversion() {
+    	return GDALversion;
+    }
+    private static void initGDALversion()
+    {
+    	int major, minor;
+    	String versionNum = gdal.VersionInfo("VERSION_NUM");
+    	major = Integer.parseInt(versionNum.substring(0,1));
+    	if (versionNum.length() == 4) {
+    		minor = Integer.parseInt(versionNum.substring(1,2));
+    	} else {
+    		minor = Integer.parseInt(versionNum.substring(2,3));
+    	}
+    	GDALversion = major*10 + minor;
+    }
 
     static
     {
@@ -152,36 +172,35 @@ public enum LatLonOrder { latLonCRSauthority, longitudeLatitude };
             String msg = Logging.getMessage("generic.LibraryLoadedOK", gdal.VersionInfo("--version"));
             Logging.logger().info(msg);
 
+            initGDALversion();
+
             // For GDAL 3.x, the PROJ6 library is used, which requires the location of the 'proj.db' file.
             // References:
             //      https://github.com/OSGeo/gdal/issues/1191
             //      https://github.com/OSGeo/gdal/pull/1658/
             //
-        	String projdbPath = System.getenv("PROJ_LIB");
-        	if (projdbPath != null) {
-        		Logging.logger().info("env PROJ_LIB = " + projdbPath);
-        	} else {
-        		String versionNum = gdal.VersionInfo("VERSION_NUM");
-        		if (Integer.parseInt(versionNum.substring(0,1)) >= 3) {
-        			Method setProj = null;
-        			try {
-        				setProj = org.gdal.osr.osr.class.getMethod("SetPROJSearchPath", String.class);
-        			} catch (NoSuchMethodException e) {}
-
-        			if (setProj != null) {
-        				// Search for proj.db
-        				for (String dir : searchDirs) {
-        					projdbPath = findGdalProjDB(dir);
-        					if (projdbPath != null) {
-        						setProj.invoke(null, projdbPath);
-        						Logging.logger().info("proj.db in " + projdbPath + " (discovered)");
-        						break;
-        					}
-        				}
-        			} 
-        		}
-        		if (projdbPath == null)
-        			Logging.logger().severe("*** ERROR - GDAL requires PROJ_LIB env var to locate 'proj.db'");            			
+            
+    		if (GDALversion >= 30) {
+    			String projdbPath = System.getenv("PROJ_LIB");
+    			if (projdbPath != null) {
+    				Logging.logger().info("env PROJ_LIB = " + projdbPath);
+    			} else {
+    				// For GDAL 3.x, can set location programmatically
+    				try {
+    					Method setProj = org.gdal.osr.osr.class.getMethod("SetPROJSearchPath", String.class);
+    					// Search for proj.db
+    					for (String dir : searchDirs) {
+    						projdbPath = findGdalProjDB(dir);
+    						if (projdbPath != null) {
+    							setProj.invoke(null, projdbPath);
+    							Logging.logger().info("proj.db in " + projdbPath + " (discovered)");
+    							break;
+    						}
+    					}
+    				} catch (NoSuchMethodException e) {}
+    			}
+    			if (projdbPath == null)
+    				Logging.logger().severe("*** ERROR - GDAL requires PROJ_LIB env var to locate 'proj.db'");            			
         	}
 
         	listAllRegisteredDrivers();
@@ -216,9 +235,12 @@ public static void setGDAL3axis(SpatialReference srs)
         	Field v = org.gdal.osr.osrConstants.class.getField("OAMS_TRADITIONAL_GIS_ORDER");
         	setAxis.invoke(srs, v.getInt(v));
         	latLonOrder = LatLonOrder.longitudeLatitude;
-        } catch (Exception e) {
-        	e.printStackTrace();
-        }
+        } catch (NoSuchMethodException e) {
+        } catch (NoSuchFieldException e) {
+        } catch (InvocationTargetException e) {
+        } catch (IllegalAccessException e) {
+		} catch (IllegalArgumentException e) {
+		}
     }
 
     public static LatLonOrder getLatLonOrder() { return latLonOrder; }