检测鼠标悬停在非JComponent对象上

Question

正如标题所述，我试图检测鼠标悬停在一个不是JComponent的对象上。现在我有一个绿色的JPanel窗口。当您左键单击这个JPanel时，您创建了一个点。

我想做的是有额外的信息显示当我悬停在这些点。然而，我甚至不知道如何开始检测，如果我把鼠标悬停在一个点。我试图查看MouseListener接口，但我找不到任何人使用MouseListener与对象的任何例子。我只看到人们将mousellistener与JComponents一起使用。我希望有这个鼠标悬停检测代码在我的点类，如果可能的话，以保持我的代码干净。

JPanel代码

class Map extends JPanel implements MouseListener {

public static ArrayList<Point> points = new ArrayList<Point>(); //array for the points

public Map() {
this.setBackground(Color.green);
this.setPreferredSize(new Dimension(1280, 720));
this.addMouseListener(this);
}

public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D graphics = (Graphics2D) g;

drawPoints(graphics);
}

private void drawPoints(Graphics2D graphics) {
for(int i = 0; i < points.size(); i++) {
points.get(i).drawPoint(graphics);
}
}

@Override
public void mouseClicked(MouseEvent e) {
}
@Override
public void mousePressed(MouseEvent e) {
if(e.getButton() == MouseEvent.BUTTON1) { //Left Click
points.add(new Point(e.getX(), e.getY()));
repaint();
}
else if(e.getButton() == MouseEvent.BUTTON3) { //right click

for(int i = points.size() - 1; i >= 0; i--) { //loop backwards so if points overlap remove the one on top first
Point current = points.get(i);
if( Math.abs( e.getX() - current.x ) < current.size/2 && Math.abs( e.getY() - current.y ) < current.size/2 ) {
points.remove(i);
repaint();
break;
}
}
}
}
@Override
public void mouseReleased(MouseEvent e) {

}
@Override
public void mouseEntered(MouseEvent e) {
}
@Override
public void mouseExited(MouseEvent e) {

}

}

点代码

public class Point {
public int x, y;
public int size = 10;

public Point(int x, int y) {
this.x = x;
this.y = y;
}

public Point() {
this.x = 0;
this.y = 0;
}

public void drawPoint(Graphics2D graphics) {
graphics.setPaint(Color.black);
graphics.setStroke(new BasicStroke(5));
graphics.drawOval(x - (size/2), y - (size/2), size, size);
graphics.setPaint(Color.red);
graphics.fillOval(x - (size/2), y - (size/2), size, size);
}

public void drawInfo(Graphics2D graphics) {
graphics.drawString("test", x, y);
}

}

Answer 1

我在一个类似包跟踪程序的程序中也遇到了同样的问题，在那里我绘制了矩形。

如果它们只是点，我会检查鼠标移动时鼠标线是否与点线相同。

@Override
public void mouseMoved(MouseEvent e) {
entered = false;

if(point.x == e.getX() && point.y == e.getY()){
entered = true;
}
}

如果，像我的例子，绘制的对象有宽度和高度，它会变得更混乱。

@Override
public void mouseMoved(MouseEvent e) {
entered = false;

if((e.getX() <= point.x+width) && (e.getX() >= point.x)){
if((e.getY() <= point.y+height) && (e.getY() >= point.y)){
entered = true;
}
}
}