JTextPane阻止在父JScrollPane中滚动

时间:2009-09-04 08:15:05

标签: java swing user-interface jscrollpane jtextpane

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

4 个答案:

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

  • Nemi's answer那里获取代码
  • 将其与kleopatra's answer to a similar question结合使用,以避免冗长地构建MouseWheelEvent
  • 将侦听器提取到其自己的顶级类中,以便可以在无法扩展JScrollPane类的上下文中使用
  • 尽可能内联代码。

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。