/**
  * Image Loader for the Moving Map Navigator Demonstrator Applet
  * @author Robert J Morton
  * @version 12 Dec 2007 
  * Extended for sandboxed jar-file operation Wed 01 Feb 2017 12:34:27 BRST */

import java.awt.Component;     // Java Abstract Windowing Toolkit
import java.awt.MediaTracker;  // for the new-fangled 1.1 event handling
import java.awt.image.BufferedImage;
import javax.imageio.*;
import java.io.*;   // file input/output handling
import java.net.*;  // for downloading data from the remote server


public class imgldr {
  private movmap mm;        // instance reference to the movmap applet
  private msgpanel mp;      // instance reference for message panel
  private MediaTracker MT;  // to track when the images have been loaded
  private int ls, L;        // load switch, language switch

  private boolean 
    LdgImgs = true,
    MTerror = false,  // true = that MT encountered an error
    loadFTT = true,   // to avoid erase + repaint of loading message
    errorFTT = true;  // and load-error message once every refresh cycle

  private String 
    cb,  // code base: protocol + file path of image files
    S[] = {"local directory", "jar file", "remote server"},
    M[][] = {
      { "Loading images from server...",
        "Error: couldn't load images.",
        "Images Loaded."
      },
      { "Carregando imagens do servidor...",
        "Erro: não foi possível carregar imagens.",
        "Imagens carregadas."
      }
    };


  imgldr(movmap mm, msgpanel mp, int ls, int L, String cb) {
    this.mm = mm;  // instance reference to the movmap applet
    this.mp = mp;  // instance of message panel
    this.ls = ls;  // loading switch
    this.L = L;    // language switch
    this.cb = cb;  // codebase URL

    /* Create media MT and register the images.
    The Media Tracker monitors the progress of load-
    ing process for of each of the four image files. */

    MT = new MediaTracker(mm);
    movmap.IMG1 = getImg("clouds1.png"); 
    if(movmap.IMG1 != null)
      MT.addImage(movmap.IMG1,0);
    movmap.IMG2 = getImg("clouds2.png");
    if(movmap.IMG2 != null)
      MT.addImage(movmap.IMG2,0);
    movmap.IMG3 = getImg("clouds3.png");
    if(movmap.IMG3 != null)
      MT.addImage(movmap.IMG3,0);
    movmap.IMG4 = getImg("clouds4.png");
    if(movmap.IMG4 != null)
      MT.addImage(movmap.IMG4,0);
  }


  private BufferedImage getImg(String F) {
    BufferedImage I = null;
    try {
      switch(ls) {
        case 0:
          I = ImageIO.read(new File(F));
          break;
        case 1:
          I = ImageIO.read(getClass().getResourceAsStream(F));
          break;
        case 2:
          I = ImageIO.read(new URL(cb + F));
      }
    } catch (IOException e) {
      System.out.println("Couldn't load " + F + " from " + S[ls] + ".");
      System.out.println(e);
    }
    return I;
  }


  boolean awaitingImages() {
    if(loadFTT) {  // if this is the first time through here
      mp.showMsg(M[L][0],true,true);
      loadFTT = false;  // avoid repeating display every cycle      
    }
    try {
      MT.waitForAll();  // keep checking the MT for a signal
    }
    catch(InterruptedException e){  // if the MT does not say anything
      return true;                  // return without servicing the thread
    }
    return false;  // drops thru when MT gives a completion signal 
  }


  boolean imagesLoaded() {
    if(MT == null)  // If MT has been killed
      return true;  // say that loading has finished

    if(LdgImgs) {  // If loading still in progress
      int ts = MT.statusAll(false);

      /* if the loading process has completed but a media MT error 
      has occurred, indicate an image loading failure */

      if((ts & MediaTracker.ERRORED) != 0) {
        MTerror = true;

        /* If this is the first time through here, display
        the appropriate error message and set flag to avoid
        repeating display of the message every cycle. */

        if(errorFTT) {
          mp.showMsg(M[L][1],false,true);
          errorFTT = false;
        }
      }

      /* if MT has completed its task, indicate
      that image loading has terminated.  */

      if(ts == MediaTracker.COMPLETE) {LdgImgs = false;}
   }

   /* Else the image loading process has just finished, so kill the
      MT and refresh the message display if not already done. */
    else {
      killTracker();
      mp.showMsg(M[L][2],true,true);
    }
    return false; 
  }


  void killTracker() {  // remove (de-register) the images from the MT
    if(MT != null) {
      MT.removeImage(movmap.IMG1, 0);
      MT.removeImage(movmap.IMG2, 0);
      MT.removeImage(movmap.IMG3, 0);
      MT.removeImage(movmap.IMG4, 0);
      MT = null;  // then kill the MT
    } 
  }

  boolean TrackerError(){return MTerror;}
}