获取 Swing 组件相对于屏幕的位置

Question

我有一个名为 SuggestionField 的 class，它将向用户显示一个项目列表以自动完成他的输入。他让输入显示在 JDialog(suggestionFrame) 中。我需要将 JDialogs 位置设置在其父级下方，但我无法获得相对于屏幕的父级 (JTextField) X 和 Y。

问题示例

import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.Arrays;

public class Runner {
    public static void main(String[] args) {

        JFrame frame = new JFrame();
        String[] items = new String[]{"Tiger", "Wolf", "Car", "Cat", "Space", "Sing", "Scene"};
        SuggestionField suggestionField = new SuggestionField(new ArrayList<>(Arrays.asList(items)), frame);

        frame.setDefaultCloseOperation(3);
        frame.setSize(100, 65);
        frame.setLocationRelativeTo(null);

        JPanel panel = new JPanel();

        panel.setLayout(new GridLayout(1,1));
        panel.add(suggestionField);

        frame.add(panel);

        frame.setVisible(true);

    }


    public static class SuggestionField extends JTextField implements DocumentListener, KeyListener {

        String[] values = new String[0];
        ArrayList<String> displayValues = new ArrayList<>(0);
        JDialog suggestionFrame;
        JPanel suggestionPanel = new JPanel();
        Color backGround = new Color(109, 104, 104, 133);
        Color selectBackGround = new Color(109, 104, 104, 133);
        Color textColor = new Color(5, 19, 88, 255);
        Color selectTextColor = new Color(115, 134, 238, 255);
        BoxLayout bl = new BoxLayout(suggestionPanel, BoxLayout.Y_AXIS);
        int selectedEntry = 0;

        public SuggestionField(ArrayList<String> values, JFrame parentDisplay) {
            this.getDocument().addDocumentListener(this);
            this.addKeyListener(this);
            suggestionFrame = new JDialog(parentDisplay);
            suggestionFrame.add(suggestionPanel);
            suggestionFrame.setUndecorated(true);
            suggestionFrame.setAlwaysOnTop(true);
            suggestionFrame.setFocusable(false);
            suggestionPanel.setFocusable(false);
            bl.maximumLayoutSize(suggestionPanel);
            this.values = values.toArray(this.values).clone();
        }

        public boolean updateSuggestions() {
            boolean added = false;
            boolean add;
            displayValues.clear();
            for (int i = 0;i < values.length;i++) {
                add = true;
                for (int k = 0;k < this.getText().length() && k < values[i].length();k++) {
                    if (values[i].toUpperCase().charAt(k) != this.getText().toUpperCase().charAt(k)) {
                        add = false;
                        break;
                    }
                }
                if (add && !values[i].equalsIgnoreCase(this.getText()) && values[i].length() > this.getText().length()) {
                    added = true;
                    displayValues.add(values[i]);
                }
            }
            return added;
        }

        private void updateDisplay() {

            suggestionFrame.setSize(this.getWidth(), 16 * displayValues.size());
            suggestionPanel.removeAll();
            suggestionPanel.setLayout(new BoxLayout(suggestionPanel, BoxLayout.Y_AXIS));
            for (int i = 0;i < displayValues.size();i++) {
                JLabel a = new JLabel(displayValues.get(i));
                if (i == selectedEntry) {
                    a.setBackground(selectBackGround);
                    a.setForeground(selectTextColor);
                } else {
                    a.setBackground(backGround);
                    a.setForeground(textColor);
                }
                suggestionPanel.add(a);
            }
            suggestionPanel.revalidate();
            suggestionFrame.revalidate();
            suggestionFrame.setLocation(this.getX(), this.getY() + this.getHeight());
            suggestionFrame.setVisible(true);
        }

        @Override
        public void insertUpdate(DocumentEvent e) {
            if (updateSuggestions()) {
                updateDisplay();
            } else suggestionFrame.setVisible(false);
            selectedEntry = 0;
            this.requestFocus();
        }

        @Override
        public void removeUpdate(DocumentEvent e) {
            if (updateSuggestions()) {
                updateDisplay();
            } else suggestionFrame.setVisible(false);
            selectedEntry = 0;
            this.requestFocus();
        }

        @Override
        public void changedUpdate(DocumentEvent e) {

        }

        @Override
        public void keyTyped(KeyEvent e) {

        }

        @Override
        public void keyPressed(KeyEvent e) {
            int ID = e.getKeyCode();
            switch (ID) {

                case 40:
                    if (selectedEntry < displayValues.size() - 1) selectedEntry++;
                    updateDisplay();
                    break;

                case 38:
                    if (selectedEntry > 0) selectedEntry--;
                    updateDisplay();
                    break;

                case 10:
                    this.setText(displayValues.get(selectedEntry));
                    break;

                case 27:
                    suggestionFrame.setVisible(false);
                    break;

            }
            this.requestFocus();
            this.grabFocus();
        }

        @Override
        public void keyReleased(KeyEvent e) {

        }

    }
}

有什么方法可以在 updateDisplay()（第 97 行）方法中获得 suggestionFrame

的 JTextField 的绝对位置

Answer 1

您可以使用 SwingUtilities.convertPointToScreen 来执行此操作。

只需传递 (x, y+height) 和您的输入字段即可获得显示下拉列表的起点。

    JButton component = new JButton();
    Point pt = new Point(component.getLocation());
    pt.y += component.getHeight();
    SwingUtilities.convertPointToScreen(pt, component);

    // pt is now in screen coords... so you can use it to position the pop-up

完整的文档可以在这里找到：https://docs.oracle.com/javase/7/docs/api/javax/swing/SwingUtilities.html

Answer 2

I need to set the JDialogs position to be below its parent..

使用Window.setLocationRelativeTo(Component).

This will just place the JDialog ontop of the JTextFiled

实际上，它比那更微妙。例如，它会考虑对话框是否会离开屏幕，然后将其移回屏幕。如果基于 'location on screen'.

的位置，那是需要明确处理的事情

获取 Swing 组件相对于屏幕的位置

Getting the position of a Swing Component relative to the screen

java

swing

jtextfield

jdialog