JavaFX file listview with icon and file name

Question

In a JavaFX dialog, I would like to show a list of files with their icons and file names.

It was easy to find how to get an icon for a file extension:

Answer 1

Here is an example for a list view with file icons:

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.embed.swing.SwingFXUtils;
import javafx.scene.Scene;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
import javafx.util.Callback;

import javax.swing.filechooser.FileSystemView;

public class ListViewCellFactory2 extends Application {

    ListView list = new ListView();
    ObservableList data = FXCollections.observableArrayList(
            "a.msg", "a1.msg", "b.txt", "c.pdf", 
            "d.html", "e.png", "f.zip",
            "g.docx", "h.xlsx", "i.pptx");

    @Override
    public void start(Stage stage) {
        VBox box = new VBox();
        Scene scene = new Scene(box, 200, 200);
        stage.setScene(scene);
        stage.setTitle("ListViewSample");
        box.getChildren().addAll(list);
        VBox.setVgrow(list, Priority.ALWAYS);

        list.setItems(data);

        list.setCellFactory(new Callback, ListCell>() {
            @Override
            public ListCell call(ListView list) {
                return new AttachmentListCell();
            }
        });

        stage.show();
    }

    private static class AttachmentListCell extends ListCell {
        @Override
        public void updateItem(String item, boolean empty) {
            super.updateItem(item, empty);
            if (empty) {
                setGraphic(null);
                setText(null);
            } else {
                Image fxImage = getFileIcon(item);
                ImageView imageView = new ImageView(fxImage);
                setGraphic(imageView);
                setText(item);
            }
        }
    }

    public static void main(String[] args) {
        launch(args);
    }


    static HashMap mapOfFileExtToSmallIcon = new HashMap();

    private static String getFileExt(String fname) {
        String ext = ".";
        int p = fname.lastIndexOf('.');
        if (p >= 0) {
            ext = fname.substring(p);
        }
        return ext.toLowerCase();
    }

    private static javax.swing.Icon getJSwingIconFromFileSystem(File file) {

        // Windows {
        FileSystemView view = FileSystemView.getFileSystemView();
        javax.swing.Icon icon = view.getSystemIcon(file);
        // }

        // OS X {
        //final javax.swing.JFileChooser fc = new javax.swing.JFileChooser();
        //javax.swing.Icon icon = fc.getUI().getFileView(fc).getIcon(file);
        // }

        return icon;
    }

    private static Image getFileIcon(String fname) {
        final String ext = getFileExt(fname);

        Image fileIcon = mapOfFileExtToSmallIcon.get(ext);
        if (fileIcon == null) {

            javax.swing.Icon jswingIcon = null; 

            File file = new File(fname);
            if (file.exists()) {
                jswingIcon = getJSwingIconFromFileSystem(file);
            }
            else {
                File tempFile = null;
                try {
                    tempFile = File.createTempFile("icon", ext);
                    jswingIcon = getJSwingIconFromFileSystem(tempFile);
                }
                catch (IOException ignored) {
                    // Cannot create temporary file. 
                }
                finally {
                    if (tempFile != null) tempFile.delete();
                }
            }

            if (jswingIcon != null) {
                fileIcon = jswingIconToImage(jswingIcon);
                mapOfFileExtToSmallIcon.put(ext, fileIcon);
            }
        }

        return fileIcon;
    }

    private static Image jswingIconToImage(javax.swing.Icon jswingIcon) {
        BufferedImage bufferedImage = new BufferedImage(jswingIcon.getIconWidth(), jswingIcon.getIconHeight(),
                BufferedImage.TYPE_INT_ARGB);
        jswingIcon.paintIcon(null, bufferedImage.getGraphics(), 0, 0);
        return SwingFXUtils.toFXImage(bufferedImage, null);
    }

}

EDIT: On a HDPI monitor, the file icons are clipped.

1. What has to be done to have the icons entirely displayed in the row?
2. How can I retrieve the scale factor from Java?