如果我制作JScrollPane
并在其中添加JPanel
,我希望能够通过点击JScollPane
内的拖动来滚动窗格。
答案 0 :(得分:1)
我制作了一个自定义的JScrollPane,就像使用普通的JScrollPane一样。
import java.awt.Cursor;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.HierarchyEvent;
import java.awt.event.HierarchyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JComponent;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
public class DragScrollPane extends JScrollPane {
private static final long serialVersionUID = 1L;
public DragScrollPane(JComponent objectToMove) {
super(objectToMove);
ViewportDragScrollListener l = new ViewportDragScrollListener(
objectToMove, false);
JViewport gridScrollPaneViewport = getViewport();
gridScrollPaneViewport.addMouseMotionListener(l);
gridScrollPaneViewport.addMouseListener(l);
gridScrollPaneViewport.addHierarchyListener(l);
}
class ViewportDragScrollListener extends MouseAdapter implements
HierarchyListener {
private static final int SPEED = 4;
private static final int DELAY = 10;
private final Cursor dc;
private final Cursor hc = Cursor
.getPredefinedCursor(Cursor.HAND_CURSOR);
private final javax.swing.Timer scroller;
private final JComponent label;
private final Point startPt = new Point();
private final Point move = new Point();
private boolean autoScroll = false;
public ViewportDragScrollListener(JComponent comp, boolean autoScroll) {
this.label = comp;
this.autoScroll = autoScroll;
this.dc = comp.getCursor();
this.scroller = new javax.swing.Timer(DELAY, new ActionListener() {
public void actionPerformed(ActionEvent e) {
JViewport vport = (JViewport) label.getParent();
Point vp = vport.getViewPosition();
vp.translate(move.x, move.y);
label.scrollRectToVisible(new Rectangle(vp, vport.getSize()));
}
});
}
public void hierarchyChanged(HierarchyEvent e) {
JComponent c = (JComponent) e.getSource();
if ((e.getChangeFlags() & HierarchyEvent.DISPLAYABILITY_CHANGED) != 0
&& !c.isDisplayable() && autoScroll) {
scroller.stop();
}
}
@Override
public void mouseDragged(MouseEvent e) {
JViewport vport = (JViewport) e.getSource();
Point pt = e.getPoint();
int dx = startPt.x - pt.x;
int dy = startPt.y - pt.y;
Point vp = vport.getViewPosition();
vp.translate(dx, dy);
label.scrollRectToVisible(new Rectangle(vp, vport.getSize()));
move.setLocation(SPEED * dx, SPEED * dy);
startPt.setLocation(pt);
}
@Override
public void mousePressed(MouseEvent e) {
((JComponent) e.getSource()).setCursor(hc);
startPt.setLocation(e.getPoint());
move.setLocation(0, 0);
if (autoScroll) {
scroller.stop();
}
}
@Override
public void mouseReleased(MouseEvent e) {
((JComponent) e.getSource()).setCursor(dc);
if (autoScroll) {
scroller.start();
}
}
@Override
public void mouseExited(MouseEvent e) {
((JComponent) e.getSource()).setCursor(dc);
move.setLocation(0, 0);
if (autoScroll) {
scroller.stop();
}
}
}
}