JTextPane阻止在父JScrollPane中滚动 [英] JTextPane prevents scrolling in the parent JScrollPane

问题描述

我有以下对象的树：

JPanel
    JScrollPane
        JPanel
            JPanel
                JScrollPane
                    JTextPane

使用鼠标滚轮滚动时外部JScrollPane我遇到一个烦人的问题。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。

When using the mouse wheel to scroll over the outer JScrollPane I encounter one annoying problem. As soon as the mouse cursor touches the inner JScrollPane, it seems that the scrolling events get passed into that JScrollPane and are not processed anymore by the first one. That means that scrolling the "parent" JScrollPane stops.

是否可以在内部JScrollPane上禁用仅鼠标滚轮？或者甚至更好，如果没有要滚动的内容（大多数情况下文本窗格仅包含1-3行文本），则禁用滚动，但如果有更多内容，则启用它

Is it possible to disable only the mouse wheel on the inner JScrollPane? Or even better, disable scrolling if there is nothing to scroll (most of the time the textpane only contains 1-3 lines of text), but enable it if there is more content?

推荐答案

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。我希望行为与浏览器相同，鼠标悬停在可滚动控件上将滚动该控件直到控件降至最低点，然后继续滚动父滚动窗格，通常是整个页面的滚动窗格。

I have run into this annoying problem also, and Sbodd's solution was not acceptable for me because I needed to be able to scroll inside tables and JTextAreas. I wanted the behavior to be the same as a browser, where the mouse over a scrollable control will scroll that control until the control bottoms out, then continue to scroll the parent scrollpane, usually the scrollpane for the whole page.

这个类就是这样做的。只需使用它代替常规的JScrollPane即可。我希望它对你有所帮助。

This class will do just that. Just use it in place of a regular JScrollPane. I hope it helps you.

/**
 * 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());
    }
}
}

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