我有以下对象的“树”:
JPanel
JScrollPane
JPanel
JPanel
JScrollPane
JTextPane
当使用鼠标滚轮滚动外部JScrollPane时,我遇到一个恼人的问题。一旦鼠标光标触及内部JScrollPane,似乎滚动事件就会传递到JScrollPane中,并且第一个不再处理。这意味着滚动“父”JScrollPane会停止。
是否可以在内部JScrollPane上禁用仅鼠标滚轮?或者更好的是,如果没有要滚动的内容(大部分时间文本窗格仅包含1-3行文本),则禁用滚动,但如果有更多内容,则启用它
答案 0 :(得分:12)
我也遇到了这个恼人的问题,而Sbodd的解决方案对我来说是不可接受的,因为我需要能够在表格和JTextAreas中滚动。我希望该行为与浏览器相同,其中鼠标悬停在可滚动控件上将滚动该控件直到控件达到最低点,然后继续滚动父滚动窗格,通常是整个页面的滚动窗格。
这门课就是这么做的。只需使用它代替常规的JScrollPane即可。我希望它对你有所帮助。
/**
* A JScrollPane that will bubble a mouse wheel scroll event to the parent
* JScrollPane if one exists when this scrollpane either tops out or bottoms out.
*/
public class PDControlScrollPane extends JScrollPane {
public PDControlScrollPane() {
super();
addMouseWheelListener(new PDMouseWheelListener());
}
class PDMouseWheelListener implements MouseWheelListener {
private JScrollBar bar;
private int previousValue = 0;
private JScrollPane parentScrollPane;
private JScrollPane getParentScrollPane() {
if (parentScrollPane == null) {
Component parent = getParent();
while (!(parent instanceof JScrollPane) && parent != null) {
parent = parent.getParent();
}
parentScrollPane = (JScrollPane)parent;
}
return parentScrollPane;
}
public PDMouseWheelListener() {
bar = PDControlScrollPane.this.getVerticalScrollBar();
}
public void mouseWheelMoved(MouseWheelEvent e) {
JScrollPane parent = getParentScrollPane();
if (parent != null) {
/*
* Only dispatch if we have reached top/bottom on previous scroll
*/
if (e.getWheelRotation() < 0) {
if (bar.getValue() == 0 && previousValue == 0) {
parent.dispatchEvent(cloneEvent(e));
}
} else {
if (bar.getValue() == getMax() && previousValue == getMax()) {
parent.dispatchEvent(cloneEvent(e));
}
}
previousValue = bar.getValue();
}
/*
* If parent scrollpane doesn't exist, remove this as a listener.
* We have to defer this till now (vs doing it in constructor)
* because in the constructor this item has no parent yet.
*/
else {
PDControlScrollPane.this.removeMouseWheelListener(this);
}
}
private int getMax() {
return bar.getMaximum() - bar.getVisibleAmount();
}
private MouseWheelEvent cloneEvent(MouseWheelEvent e) {
return new MouseWheelEvent(getParentScrollPane(), e.getID(), e
.getWhen(), e.getModifiers(), 1, 1, e
.getClickCount(), false, e.getScrollType(), e
.getScrollAmount(), e.getWheelRotation());
}
}
}
答案 1 :(得分:1)
可悲的是,显而易见的解决方案(JScrollPane.setWheelScrollingEnabled(false))实际上并没有取消注册MouseWheelEvents,因此它无法达到您想要的效果。
这是一种原始的hackery方式,完全禁用滚动,让MouseWheelEvents到达外部JScrollPane:
for (MouseWheelListener mwl : scrollPane.getMouseWheelListeners()) {
scrollPane.removeMouseWheelListener(mwl);
}
如果对内部JScrollPane执行此操作,它将永远不会响应滚轮事件;外部JScrollPane将获得所有这些。
如果你想“干净利落”,你需要实现自己的ScrollPaneUI,并使用setUI()将其设置为JScrollPane的UI。不幸的是,你不能只扩展BasicScrollPaneUI并禁用它的鼠标滚轮监听器,因为相关的成员变量是私有的,并且ScrollPaneUI的MouseWheelListener安装上没有任何标志或保护。
对于“更好”的解决方案,你必须深入挖掘ScrollPaneUI,找到滚动条可见/不可见的钩子,并在这些点添加/删除MouseWheelListener。 / p>
希望有所帮助!
答案 2 :(得分:1)
@Nemi已经有了一个很好的解决方案。
我把它煮了一点,把下面的方法放在我的库中:
static public void passMouseWheelEventsToParent(final Component pComponent, final Component pParent) {
pComponent.addMouseWheelListener((final MouseWheelEvent pE) -> {
pParent.dispatchEvent(new MouseWheelEvent(pParent, pE.getID(), pE.getWhen(), pE.getModifiers(), 1, 1, pE.getClickCount(), false, pE.getScrollType(), pE.getScrollAmount(), pE.getWheelRotation()));
});
}
答案 3 :(得分:1)
受现有答案的启发,我
MouseWheelEvent
JScrollPane
类的上下文中使用结果是这段代码:
import java.awt.Component;
import java.awt.event.MouseEvent;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
/**
* Passes mouse wheel events to the parent component if this component
* cannot scroll further in the given direction.
* <p>
* This behavior is a little better than Swing's default behavior but
* still worse than the behavior of Google Chrome, which remembers the
* currently scrolling component and sticks to it until a timeout happens.
*
* @see <a href="https://stackoverflow.com/a/53687022">Stack Overflow</a>
*/
public final class MouseWheelScrollListener implements MouseWheelListener {
private final JScrollPane pane;
private int previousValue;
public MouseWheelScrollListener(JScrollPane pane) {
this.pane = pane;
previousValue = pane.getVerticalScrollBar().getValue();
}
public void mouseWheelMoved(MouseWheelEvent e) {
Component parent = pane.getParent();
while (!(parent instanceof JScrollPane)) {
if (parent == null) {
return;
}
parent = parent.getParent();
}
JScrollBar bar = pane.getVerticalScrollBar();
int limit = e.getWheelRotation() < 0 ? 0 : bar.getMaximum() - bar.getVisibleAmount();
if (previousValue == limit && bar.getValue() == limit) {
parent.dispatchEvent(SwingUtilities.convertMouseEvent(pane, e, parent));
}
previousValue = bar.getValue();
}
}
它的用法如下:
JScrollPane pane = new JScrollPane();
pane.addMouseWheelListener(new MouseWheelScrollListener(pane));
一旦创建了此类的实例并将其绑定到滚动窗格,就无法将其重新用于其他组件,因为它会记住垂直滚动条的先前位置。