[英]How should I drag a JLabel from one JPanel in a JFrame onto a JTextField in another JPanel in the same JFrame?
简而言之,我想将JLabel
的文本设置为JPanel
( pnlUser
)中的JTextField
的文本,然后将JLabel
从JPanel
拖到整个屏幕上,拖到另一个JPanel
( pnlGrid
)中的另一个JTextField
上。
这是详细信息。
我写了一个“纸牌拼字游戏”程序。 用户可以将文本光标放置在网格单元中(在pnlGrid
为JTextField
),然后键入“用户字母”列表中的字母(在pnlUser
为JTextField
),或者用户可以模拟从“用户字母”中拖动字母“并将其放入pnlGrid
的目标网格单元中。
我之所以说“模拟”,是因为所选字母实际上并没有在屏幕上拖动。 我使用鼠标指针HAND_CURSOR
使拖放尽可能真实,但我还没有弄清楚如何使HAND_CURSOR
“抓住”字母并将其实际拖动到目标位置。
HAND_CURSOR
,该字母被突出显示,但是在“ HAND_CURSOR
”在拖动操作过程中沿网格移动时留在“用户字母”区域中。 当到达pnlGrid
的目标单元格并释放鼠标按钮时,该字母便从“用户字母”中删除,并突然出现在网格单元格中。
因此,该字母或多或少地从“用户字母”“传送”到了网格单元中(请问我,斯科蒂)。 这太抽象了。 我希望用户字母位于HAND_CURSOR的指尖处,并沿着网格拖到将其拖放到的网格单元中,如下面的3张图片所示。
我已经使用JLayeredPane在一个小型测试程序(下面的资源)中成功实现了它,但是我无法在游戏中实现它。 但是直到两天前我对JLayeredPane还是一无所知,所以我真的不知道自己在做什么。 (我改编了一个演示JLayeredPane的Oracle教程程序。)
我刚刚阅读了有关“玻璃窗格”的内容,并认为在下载该演示的源代码之前,实现起来可能会更容易,因为它很长,因此,它是全新的,适应起来会更加困难。
所以我想在花更多的时间沮丧之前,我应该问:
JLayeredPane
或setGlassPane
方法是否合适? 有没有更简便或更好的方法将JLabel
从一个JPanel
拖动到另一个JPanel
?
(该程序中的方法是确定所指向的“用户字母”,将该字母存储在JLabel
,然后确保在mouseDragged
期间, HAND_CURSOR
指尖位于该字母的底部中心。)
package mousemoveletter;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import static java.awt.Color.*;
import java.awt.event.*;
import static javax.swing.SwingUtilities.invokeLater;
public class LayeredPaneDemo extends JPanel
{
private static final int USER7 = 7;
static Cursor HAND = new Cursor(Cursor.HAND_CURSOR);
static Cursor ARROW = new Cursor(Cursor.DEFAULT_CURSOR);
private static JLayeredPane layeredPane;
private static JLabel lblToMove;
private static JPanel pnlUser;
private static JPanel pnlGrid;
private static final JTextField[] txtUser = new JTextField[USER7];
public LayeredPaneDemo() // constructor
{
pnlGrid = new JPanel();
setLayout(new BoxLayout(this, BoxLayout.PAGE_AXIS));
layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(new Dimension(240, 240));
pnlGrid.setSize(140, 140);
pnlGrid.setBorder(new EtchedBorder(RED, GREEN));
pnlGrid.setBackground(YELLOW);
lblToMove = new JLabel("XXX");
lblToMove.setSize(new Dimension(40,40));
layeredPane.add(pnlGrid, 0,0);
layeredPane.add(lblToMove, new Integer(0), -1);
add(layeredPane);
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("LayeredPaneDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JComponent newContentPane = new LayeredPaneDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
makeUser();
frame.add(pnlUser);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
invokeLater(new Runnable()
{
public void run() {
createAndShowGUI();
}
});
}
private static void makeUser(){
pnlUser = new JPanel(new GridLayout(1,USER7));
pnlUser.setPreferredSize(new Dimension(225, 50));
pnlUser.setBackground(Color.green);
pnlUser.setBorder(BorderFactory.createLineBorder(Color.BLUE));
for(int k = 0; k < USER7; k++)
{
txtUser[k] = new JTextField("" + (char)(Math.random()*26+65));
txtUser[k].setName("" + k);
txtUser[k].setEditable(false);
txtUser[k].addMouseMotionListener(new MouseMotionAdapter()
{
public void mouseDragged(MouseEvent e)
{
lblToMove.setCursor(HAND);
int w = Integer.parseInt(e.getComponent().getName());
lblToMove.setText(txtUser[w].getText());
layeredPane.setLayer(lblToMove, 0, 0);
lblToMove.setLocation(e.getX() + (e.getComponent().getWidth())*w,
e.getY() + layeredPane.getHeight() - e.getComponent().getHeight()/2);
};
});
txtUser[k].addMouseListener(new MouseAdapter()
{
public void mouseReleased(MouseEvent e)
{
lblToMove.setCursor(ARROW);
}
});
pnlUser.add(txtUser[k]);
}
}
}
感谢@trashgod,我通过关注他到本示例和变体的链接来弄清楚了它; 我将在那里找到的棋盘的拖放调整适应了我自己对“拼字游戏”的特殊需要。
下面的代码不是我的Solitaire Scrabble程序的最终代码,而是概念验证,可能被希望将单元从1xN网格拖到MxM网格的其他人使用。
package components;
import java.awt.*;
import static java.awt.BorderLayout.NORTH;
import static java.awt.BorderLayout.SOUTH;
import java.awt.event.*;
import static java.lang.Integer.parseInt;
import javax.swing.*;
import static javax.swing.WindowConstants.DISPOSE_ON_CLOSE;
import javax.swing.event.MouseInputAdapter;
public class ChessBoard //implements MouseListener, MouseMotionListener
{
static Point parentLocation;
int homeRow, homeCol; // where to restore moved user letter if dropped on occupied cell
static int N = 11; // NxN 'chessboard' squares
static int S = 44; // square dimensions: SxS
static int W ; // chessboard dimensions: WxW
static int USER7 = 7;
static Font dragFont;
static JFrame frame;
JLayeredPane layeredPane;
static JPanel gamePanel, // encompasses both pnlGrid and pnlUser
pnlGrid,
pnlUser;
JLabel userDragLetter = new JLabel(); // main item to drag around or restore if needed
int xAdjustment, yAdjustment; // how to locate drops accurately
String userLetters[] ;
public ChessBoard() // constructor
{
W = S*N;
dragFont = new Font("Courier", Font.PLAIN, S);
userLetters = new String[USER7];
for (int i = 0; i < USER7; i++)
userLetters[i] = "" + (char)(65 + Math.random()*26);
Dimension gridSize = new Dimension(W, W);
Dimension userSize = new Dimension(W, S);
Dimension gameSize = new Dimension(W, (W + S));
frame = new JFrame();
frame.setSize(new Dimension(gameSize)); // DO NOT USE PREFERRED
layeredPane = new JLayeredPane();
layeredPane.setPreferredSize( gameSize ); // NO PREFERRED => NO GRID!
gamePanel = new JPanel();
// **EDIT** LOSE THIS LINE gamePanel.setLayout(new BorderLayout());
gamePanel.setPreferredSize(gameSize);
pnlGrid = new JPanel();
pnlGrid.setLayout(new GridLayout(N, N));
pnlGrid.setPreferredSize( gridSize );
pnlGrid.setBounds(0, 0, gridSize.width, gridSize.height);
pnlUser = new JPanel();
pnlUser.setLayout(new GridLayout(1, N));
pnlUser.setPreferredSize(userSize);
pnlUser.setBounds(0, gridSize.height, userSize.width, userSize.height);
layeredPane.add(pnlGrid, JLayeredPane.DEFAULT_LAYER); // panels to drag over
layeredPane.add(pnlUser, JLayeredPane.DEFAULT_LAYER); // " "
for (int i = 0; i < N; i++){
for (int j = 0; j < N; j++){
JPanel square = new JPanel();
square.setBackground( (i + j) % 2 == 0 ? Color.red : Color.white );
pnlGrid.add( square );
}
}
for (int i = 0; i < N; i++) {
JPanel square = new JPanel(new BorderLayout());
square.setBackground(Color.YELLOW);
pnlUser.add(square);
}
for (int i = 0; i < USER7; i++)
addPiece(i, 0, userLetters[i]);
gamePanel.addMouseListener(new MouseInputAdapter()
{
public void mousePressed (MouseEvent e){mousePressedActionPerformed (e);}
public void mouseReleased(MouseEvent e){mouseReleasedActionPerformed(e);}
});
gamePanel.addMouseMotionListener(new MouseMotionAdapter()
{
public void mouseDragged(MouseEvent me){mouseDraggedActionPerformed(me);}
});
// **EDIT: LOSE THE NEXT TWO LINES AND REPLACE BY THE LINE AFTER THEM**
// gamePanel.add(layeredPane, NORTH);
// gamePanel.add(pnlUser, SOUTH);
gamePanel.add(layeredPane);
}
private void addPiece(int col, int row, String glyph) {
JLabel piece = new JLabel(glyph, JLabel.CENTER);
piece.setFont(dragFont);
JPanel panel = (JPanel) pnlUser.getComponent(col + row * N);
piece.setName("piece " + glyph + " @ " + row + " " + col);
panel.add(piece);
}
void mousePressedActionPerformed(MouseEvent e)
{
userDragLetter = null; // signal that we're not dragging if no piece is in the square
gamePanel.setCursor(new Cursor(Cursor.HAND_CURSOR));
Component c = pnlGrid.findComponentAt(e.getX(), e.getY());
if(c != null)
return; // Illegal to click pnlGrid
c = pnlUser.findComponentAt(e.getX(), e.getY() - pnlGrid.getHeight());
if(c == null | c instanceof JPanel)
return; // letter already played; can't drag empty cell
parentLocation = c.getParent().getLocation();
xAdjustment = parentLocation.x - e.getX();
yAdjustment = parentLocation.y - e.getY() + gamePanel.getHeight() - pnlUser.getHeight();
userDragLetter = (JLabel)c;
userDragLetter.setPreferredSize(new Dimension(S, S)); // prevent 2 letters in a square
userDragLetter.setLocation(e.getX() + xAdjustment, e.getY() + yAdjustment);
layeredPane.add(userDragLetter, JLayeredPane.DRAG_LAYER);
homeRow = parseInt(userDragLetter.getName().substring(10,11)); // save restore location
homeCol = parseInt(userDragLetter.getName().substring(12,13));
}
void mouseDraggedActionPerformed(MouseEvent me)
{
if (userDragLetter == null)
return; // nothing to drag
int x = me.getX() + xAdjustment; // make sure grid cell will be chosen in-bounds
int xMax = layeredPane.getWidth() - userDragLetter.getWidth();
x = Math.min(x, xMax);
x = Math.max(x, 0);
int y = me.getY() + yAdjustment;
int yMax = layeredPane.getHeight() - userDragLetter.getHeight();
y = Math.min(y, yMax);
y = Math.max(y, 0);
if(y >= pnlGrid.getHeight())
return; // can't drag to location off grid
userDragLetter.setLocation(x, y);
}
void mouseReleasedActionPerformed(MouseEvent e)
{
//**EDIT: CHANGED NEXT LINE**
gamePanel.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
if (userDragLetter == null)
return; // nothing to drag; nothing to release
// Make sure the chess piece is no longer painted on the layered pane
userDragLetter.setVisible(false);
layeredPane.remove(userDragLetter);
userDragLetter.setVisible(true);
int xMax = layeredPane.getWidth() - userDragLetter.getWidth();
int x = Math.min(e.getX(), xMax);
x = Math.max(x, 0);
int yMax = layeredPane.getHeight()- userDragLetter.getHeight();
int y = Math.min(e.getY(), yMax);
y = Math.max(y, 0);
Component c = pnlGrid.findComponentAt(x, y); // find deepest nested child component
if(c == null) // then grid cell is unoccupied so ...
c = pnlUser.findComponentAt(x, y); // see if there's a letter there ...
if(c == null | (c instanceof JLabel)){ // and if illegal or there is one, put it back...
userDragLetter.setLocation(parentLocation.x + xAdjustment,
parentLocation.y + yAdjustment + gamePanel.getHeight());
userDragLetter.setVisible(true);
addPiece(homeCol, homeRow,userDragLetter.getName().substring(6,7));
layeredPane.remove(userDragLetter);
return;
}
else // but if NO letter ...
{
Container parent = (Container)c;
parent.add( userDragLetter ); // put one in the grid cell
parent.validate();
}
userDragLetter.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
}
public static void main(String[] args)
{
new ChessBoard();
frame.add(gamePanel);
frame.setDefaultCloseOperation( DISPOSE_ON_CLOSE );
// frame.setResizable( false );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
}
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