// Basic drop event listening/handling example.
// Run the sketch and drop various things on its canvas:
// files/folders, images, rendered html, plain text, etc.

void setup() {
    size(700, 400);
    textSize(16); textLeading(18);
    frame.setTitle("Drop something here...");
}

void draw() {}

// Called when the user drops something on the canvas.
void dropped(Drop drop) {
    // Set the drop location as the frame title
    int x = drop.x;
    int y = drop.y;
    frame.setTitle(
        String.format("Last drop location: x=%d, y=%d", x, y));

    background(50);
    StringBuffer info = new StringBuffer();

    // Is the dropped object text? (For some non-text objects,
    // drop.text() returns the associated path)
    String plain = drop.text();
    if (plain != null)
        info.append("FOUND PLAIN TEXT:\n")
            // grab a preview eg. the 200 first chars
            .append(str_preview(plain, 200))
            .append("\n\n");

    // Is it "rich text"? Eg. dropped from a rendered html or rtf window.
    String rich = drop.richtext();
    if (rich != null)
        info.append("FOUND RICH TEXT:\n")
            .append(str_preview(rich, 200))
            .append("\n\n");

    // Pixel data or file(s) that could be loaded as PImage(s)?
    PImage[] images = drop.images();
    if (images != null) {
        // Display the number of images successfully loaded,
        // use the first image as background
        info.append("FOUND " + images.length + " IMAGES\n\n");
        image(images[0], 0, 0, width, height);
        fill(50, 190); // make it look semi-transparent
        rect(0, 0, width, height);
    }

    // File(s)/folder(s)? Eg. dropped from the OS file explorer.
    String[] paths = drop.paths();
        if (paths != null) {
            info.append("FOUND PATHS/URLS:\n");
            for (String i : paths)
                info.append(i).append('\n');
            info.append('\n');
        }

    fill(255);
    text(info.toString(), 20, 20, width-40, height-40);
}

// Strips leading whitespace, returns the n first characters of s
String str_preview(String s, int n) {
    s = s.trim();
    return s.substring(0, min(n, s.length()));
}

// The code below implements the drop event listening/handling
// and the Drop class. For less clutter put it in a separate
// pde file/tab.

import java.awt.dnd.*;
import java.awt.datatransfer.*;

// Note: droptarget.setActive(false) to stop listening for drops,
// droptarget.isActive() to know the current status (true/false).
DropTarget droptarget =
    new DropTarget(this/*this PFrame*/, new DropTargetAdapter() {
        public void drop(DropTargetDropEvent event) {
            event.acceptDrop(DnDConstants.ACTION_COPY);
            DataFlavor[] flavors = event.getCurrentDataFlavors();
            if (flavors.length == 0)
                error("unsupported data flavor/type");
            else {
                DataFlavor f = flavors[0];
                Object data = null;
                try { data = event.getTransferable().getTransferData(f); }
                catch (Exception e) { error(e.toString()); }
                if (data != null)
                    dropped(new Drop(event, f, data));
            }
            event.dropComplete(true);
        }

        void error(String what) {
            frame.setTitle("*A drop error occured (see console)");
            System.err.println("Drop error:\n" + what);
        }
});

class Drop {
    int x, y;
    Object data;
    DataFlavor flavor;
    DropTargetDropEvent event;

    Drop(DropTargetDropEvent e, DataFlavor f, Object d) {
        event = e;
        flavor = f;
        data = d;
        x = e.getLocation().x;
        y = e.getLocation().y;
    }

    String text() {
        try {
            return (String)
                event.getTransferable()
                     .getTransferData(DataFlavor.stringFlavor);
        }
        catch (Exception e) {}
        return null;
    }

    String richtext() {
        if (flavor.getMimeType().startsWith("text")) {
            Scanner s = data instanceof Reader ? new Scanner((Reader)data) :
                        data instanceof InputStream ? new Scanner((InputStream)data) : null;
            s.useDelimiter("^\\s"); // alien hack to preserve whitespaces
            if (s != null) {
                StringBuilder buf = new StringBuilder(256);
                while (s.hasNext())
                    buf.append(s.next());
                return buf.toString();
            }
        }
        return null;
    }

    File[] files() {
        if (flavor.equals(DataFlavor.javaFileListFlavor)) {
            List
                
                  
                 list = (List
                 
                  ) data;             
                  return 
                  list.toArray(
                  new File[
                  list.
                  size()]);         }         
                  return 
                  null;     }     
                  String[] paths() {         
                  if (data 
                  instanceof URL)             
                  return 
                  new 
                  String[]{ ((URL)data).toString() };         File[] f = files();         
                  if (f != 
                  null) {             
                  int i = f.
                  length;             
                  String[] paths = 
                  new 
                  String[i];             
                  while (i-- > 0)                 paths[i] = f[i].getAbsolutePath();             
                  return paths;         }         
                  return 
                  null;     }     
                  PImage[] images() {         
                  // Single image         
                  if (flavor.
                  equals(DataFlavor.imageFlavor))             
                  return 
                  new 
                  PImage[]{ 
                  new 
                  PImage((Image) data) };         
                  // Load from paths / urls.         
                  // TODO async loading? Skip files with non-image extension?         List<
                  PImage> images = 
                  new 
                  ArrayList<
                  PImage>();         
                  PImage tmp = 
                  null;         
                  if (flavor.
                  equals(DataFlavor.javaFileListFlavor)) {             
                  for (File f : (List
                  
                   ) data)                 
                   if (f.isFile() && f.exists() &&                     (tmp = 
                   loadImage(f.getAbsolutePath())) != 
                   null)                     images.
                   add(tmp);         }         
                   else {             
                   String[] paths = paths();             
                   if (paths != 
                   null)                 
                   for (
                   String path : paths)                     
                   if ((tmp = 
                   loadImage(path)) != 
                   null)                         images.
                   add(tmp);         }         
                   return images.
                   size() == 0 ? 
                   null :                images.toArray(
                   new 
                   PImage[images.
                   size()]);     }     
                   public 
                   String toString() { 
                   return data.toString(); } }