tim/prune/jpeg/ExifGateway.java

   1 package tim.prune.jpeg;
   2
   3 import java.io.File;
   4
   5 import javax.swing.JOptionPane;
   6
   7 import tim.prune.I18nManager;
   8
   9 /**
  10  * Skeleton gateway to the Exif functions.
  11  * This is required by Debian to divert Exif handling
  12  * to the external libmetadata-extractor-java library
  13  * instead of the included modified routines.
  14  *
  15  * To use the internal routines, set the USE_INTERNAL_LIBRARY flag to true
  16  * and include the internal classes in the compiled jar.
  17  * To use the external library, set the USE_INTERNAL_LIBRARY flag to false
  18  * and do not export the internal classes.
  19  */
  20 public abstract class ExifGateway
  21 {
  22         /** Library object to call */
  23         private static ExifLibrary _exifLibrary = null;
  24         /** Flag to set whether failure warning has already been shown */
  25         private static boolean _exifFailWarned = false;
  26
  27         /** Static block to initialise library */
  28         static
  29         {
  30                 String libraryClass = ExifLibrarySwitch.USE_INTERNAL_LIBRARY?"InternalExifLibrary":"ExternalExifLibrary";
  31                 try
  32                 {
  33                         _exifLibrary = (ExifLibrary) Class.forName("tim.prune.jpeg." + libraryClass).newInstance();
  34                 }
  35                 catch (Throwable nolib) {_exifLibrary = null;}
  36         }
  37
  38
  39         /**
  40          * Get the Jpeg data from the given file
  41          * @param inFile file to read
  42          * @return jpeg data, or null if none found
  43          */
  44         public static JpegData getJpegData(File inFile)
  45         {
  46                 try
  47                 {
  48                         // Call library (if found)
  49                         if (_exifLibrary != null) {
  50                                 JpegData data = _exifLibrary.getJpegData(inFile);
  51                                 return data;
  52                         }
  53                 }
  54                 catch (LinkageError nolib) {}
  55                 // Not successful - warn if necessary
  56                 if (!_exifFailWarned)
  57                 {
  58                         JOptionPane.showMessageDialog(null, I18nManager.getText("error.jpegload.exifreadfailed"),
  59                                 I18nManager.getText("error.jpegload.dialogtitle"), JOptionPane.WARNING_MESSAGE);
  60                         _exifFailWarned = true;
  61                 }
  62                 return null;
  63         }
  64
  65         /**
  66          * @return key to use to describe library, matching key for about dialog
  67          */
  68         public static String getDescriptionKey()
  69         {
  70                 String key = ExifLibrarySwitch.USE_INTERNAL_LIBRARY?"internal":"external";
  71                 if (_exifLibrary == null || !_exifLibrary.looksOK()) {key = key + ".failed";}
  72                 return key;
  73         }
  74 }