!7

p-substance {

  if (l(args) != 0) new Viewer().showFile(new File(join(" ", args)));

  else inputFilePath("Image to view", voidfunc(File file) { new Viewer().showFile(file) });

}

sclass Viewer {

  ImageSurface is;

  File file;

  void showFile(final File file) {

    assertTrue("File not found: " + absolutePath(file), file.exists());

    this.file = file;

    bool first = is == null;

    is = showImage_centered(is, file.getName(), loadBufferedImage(file));

    awt { is.zoomToWindow(); }

    if (first) {  

      registerLeftKey(getFrame(is), r { nextFile(-1) });

      registerRightKey(getFrame(is), r { nextFile(1) });

      registerMinusKeys(is, r { is.zoomOut(1.5) });

      registerPlusKeys(is, r { is.zoomIn(1.5) });

      registerKey(is, KeyEvent.VK_A, "A", r { is.setZoom(1.0) });

      registerKey(is, KeyEvent.VK_W, "W", r { is.zoomToWindow() });

      hideConsole();

    }

  }

  void nextFile(int offset) {

    L<File> files = asList(listFilesOnly(file.getParentFile()));

    int i = indexOfPred(files, func(File f) { eq(f.getName(), file.getName()) });

    showFile(get(files, mod(i+offset, l(files))));

  }

}