/**
  * 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.io.*;              // file input/output handling
import java.net.*;             // for downloading data from remote server
import java.awt.image.BufferedImage;
import javax.imageio.*;


public class imgldr {
  private movmap mm;             // instance reference to the movmap applet
  private msgpanel mp;           // instance reference for message panel
  private MediaTracker tracker;  // to track when the images have been loaded

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

  private int ls, L;  // load switch, language switch
  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 a Media Tracker and register the images to be downloaded.
    The Media tracker monitors the progress of loading  process for of
    each of the four image files. */

    tracker = new MediaTracker(mm);

    movmap.IMG1 = getImg("clouds1.png"); 
    if(movmap.IMG1 != null) {
       tracker.addImage(movmap.IMG1,0);
    }
    movmap.IMG2 = getImg("clouds2.png");
    if(movmap.IMG2 != null) {
       tracker.addImage(movmap.IMG2,0);
    }
    movmap.IMG3 = getImg("clouds3.png");
    if(movmap.IMG3 != null) {
       tracker.addImage(movmap.IMG3,0);
    }
    movmap.IMG4 = getImg("clouds4.png");
    if(movmap.IMG4 != null) {
       tracker.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      
    }
    // Keep checking the tracker for a completion signal.
    try { tracker.waitForAll(); }

    /* If the tracker does not say anything
    return without servicing the thread. */
    catch(InterruptedException e){ return true; }

    return false;  // drops through when tracker gives a completion signal 
  }


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

    if(loadingImages) {  // If loading still in progress

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

      int ts = tracker.statusAll(false);
      if((ts & MediaTracker.ERRORED) != 0) {
        trackerError = 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 tracker has completed its task, indicate
      that image loading has terminated. */

      if(ts == MediaTracker.COMPLETE) {
        loadingImages = false;
      }
    }
    /* Else the image loading process has just finished, so kill the
    tracker 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 tracker
    if(tracker != null) {
      tracker.removeImage(movmap.IMG1,0);
      tracker.removeImage(movmap.IMG2,0);
      tracker.removeImage(movmap.IMG3,0);
      tracker.removeImage(movmap.IMG4,0);
      tracker = null;  // then kill the tracker
    } 
  }

  boolean TrackerError(){return trackerError;}
}