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         // *********************************************************
  23         // TODO: Check this exif library flag before releasing!
  24         /** Flag to specify internal or external library */
  25         private static final boolean USE_INTERNAL_LIBRARY = true;
  26         // *********************************************************
  27
  28         /** Library object to call */
  29         private static ExifLibrary _exifLibrary = null;
  30         /** Flag to set whether failure warning has already been shown */
  31         private static boolean _exifFailWarned = false;
  32
  33         /** Static block to initialise library */
  34         static
  35         {
  36                 String libraryClass = USE_INTERNAL_LIBRARY?"InternalExifLibrary":"ExternalExifLibrary";
  37                 try
  38                 {
  39                         _exifLibrary = (ExifLibrary) Class.forName("tim.prune.jpeg." + libraryClass).newInstance();
  40                 }
  41                 catch (Throwable nolib) {_exifLibrary = null;}
  42         }
  43
  44
  45         /**
  46          * Get the Jpeg data from the given file
  47          * @param inFile file to read
  48          * @return jpeg data, or null if none found
  49          */
  50         public static JpegData getJpegData(File inFile)
  51         {
  52                 try
  53                 {
  54                         // Call library (if found)
  55                         if (_exifLibrary != null) {
  56                                 JpegData data = _exifLibrary.getJpegData(inFile);
  57                                 return data;
  58                         }
  59                 }
  60                 catch (LinkageError nolib) {}
  61                 // Not successful - warn if necessary
  62                 if (!_exifFailWarned)
  63                 {
  64                         JOptionPane.showMessageDialog(null, I18nManager.getText("error.jpegload.exifreadfailed"),
  65                                 I18nManager.getText("error.jpegload.dialogtitle"), JOptionPane.WARNING_MESSAGE);
  66                         _exifFailWarned = true;
  67                 }
  68                 return null;
  69         }
  70
  71         /**
  72          * @return key to use to describe library, matching key for about dialog
  73          */
  74         public static String getDescriptionKey()
  75         {
  76                 String key = USE_INTERNAL_LIBRARY?"internal":"external";
  77                 if (_exifLibrary == null || !_exifLibrary.looksOK()) {key = key + ".failed";}
  78                 return key;
  79         }
  80 }