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diff --git a/jniwrap/README b/jniwrap/README new file mode 100644 index 00000000..05a015f5 --- /dev/null +++ b/jniwrap/README @@ -0,0 +1,209 @@ + -------------------- J P R O J . 4 -------------------- + +This is the first release of a JNI wrap of the main proj4 functions. + +PLEASE read the following information. + +For more information on the JPROJ4 maintenance please contact me through the +web page at: + + http://www.hydrologis.com + + --------------------------------------------------- + + + +Compilation: +------------- + +With the right flag during configuration time (see ./configure --help), the +native part of the jproj lib is compiled inside the main proj library and the +java part is automatically built into the jproj.jar library. + +The java part on it's own part is compiled by running ant inside the "jniwrap" folder. +This will compile the classes and archive them in a jar library. +This applies to Linux, Macos and Windows (and virtually to every system +supporting java). + + +Requirements: +------------- + +Beyond the ones already put by proj, you need: +- j2sdk, the java standard development kit +- ant, to run the build +- doxygen for the documentation generation + + +Documentation: +-------------- + +The documentation is held inside the code and can be retrieved by running +doxygen inside the folder jniwrap. This will create the html format +documentation inside of jniwrap/docs + + +License: +-------- + +GPL + + +Authors: +-------- + +Andrea Antonello (andrea.antonello@hydrologis.com) + + +Usage & a fast example: +----------------------- + +The jproj.jar is all is needed to implement proj support in java applications. +The whole job is done by the proj4, so there are just a couple of functions that +be used. + +The best way is to see everything through an example. +In the following example we read projection informations and data from a file +and then transform the data and query the information. + +________________________________________________________________________________ +First step: +create a text file, let's say test.txt, with the following in it: +srcProj: +proj=latlong +datum=WGS84 +destProj: +init=epsg:32632 +rows: 1 +46 11 194.0 + + +This contains info about a source and destination projection, the number of data +triplets and then the data (in this case just one point) + + +________________________________________________________________________________ +Step two: +create a test code. Simply copy the following into a file called Main.java. The +code is commented to see what we are doing: + + +import java.io.BufferedReader; +import java.io.File; +import java.io.FileInputStream; +import java.io.IOException; +import java.io.InputStreamReader; +import java.util.LinkedHashMap; + +import org.proj4.Proj4; +import org.proj4.ProjectionData; + + +public class Main +{ + + public static void main(String[] args) throws IOException + { + // print out the usage if no argument was given + if (args.length < 1) + { + System.out.println(); + System.out.println("Usage: Proj datafile"); + System.out.println(); + System.exit(0); + } + + // now the input file is going to be read + BufferedReader br = new BufferedReader(new InputStreamReader( + new FileInputStream(new File(args[0])))); + LinkedHashMap mapHeader = new LinkedHashMap(); + // read the header + String line = null; + for (int i = 0; i < 3; i++) + { + if ((line = br.readLine()) != null) + { + String[] header = line.split(":", 2); + if (header.length <= 2) + { + mapHeader.put(header[0].trim(), header[1].trim()); + } + else + { + System.out.println("Wrong file format"); + System.exit(0); + } + } + } + // with what you see above, the header was read + + // now I can define the number of rows of data triplets + int rows = new Integer((String) mapHeader.get("rows")).intValue(); + + double[][] testCoord = new double[rows][2]; + double[] testValues = new double[rows]; + System.out.println("Source coordinates and values:"); + + // start reading the data + for (int i = 0; i < rows; i++) + { + if ((line = br.readLine()) != null) + { + String[] values = line.split(" +"); + if (values.length == 3) + { + testCoord[i][0] = new Double(values[0].trim()).doubleValue(); + testCoord[i][1] = new Double(values[1].trim()).doubleValue(); + testValues[i] = new Double(values[2].trim()).doubleValue(); + System.out.println("x = " + testCoord[i][0] + " y = " + + testCoord[i][1] + " z = " + testValues[i]); + } + else + { + System.out.println("Wrong file format or empty line found"); + } + } + } + + // create the dataset + // this is necessary to be able to transform + ProjectionData dataTP = new ProjectionData(testCoord, testValues); + + // here we go with the instantiation of the proj4 object + Proj4 testProjection = new Proj4((String) mapHeader.get("srcProj"), + (String) mapHeader.get("destProj")); + + // the instantiation of the proj4 object instantiated also the projection + // objects for source and destination projection + // therefore we can already print the projection infos: + testProjection.printSrcProjInfo(); + testProjection.printDestProjInfo(); + + // and transform, passing as parameter the created dataset: + testProjection.transform(dataTP, 1, 1); + + // if we need the parameters as Hashmap for a later use: + LinkedHashMap testMap = testProjection.getSrcProjInfo(); + + // and let us print them to screen to see them + System.out.println(); + System.out.println("Proj as a Hashmap"); + System.out.println("******************************************************"); + System.out.println(testMap.toString()); + + } + +} + + +________________________________________________________________________________ +Step three +compile the Main code: +we assume that proj was compiled with the right flag to support jproj. +Therefore we have a library called jproj.jar. +Thus we compile the Main.java with the command: + +javac -classpath <path to the jar library>/jproj.jar Main.java + +and execute the created test case with: + +java -cp .:<path to the jar library>/jproj.jar -Djava.library.path=<path to the libproj, if needed> Main test.txt + +That's it, enjoy! |