java - JScrollPane - 平滑滚动

Question

我有一个 block 增量适中的 JScrollPane (125)。我想对其应用平滑/慢速滚动，这样它在滚动时不会跳跃(或跳过)。我该怎么做？

我想像 Windows 8 那样滚动。

如有任何帮助，我们将不胜感激!

Answer 1

您可以在滚动过程中使用javax.swing.Timer 来实现平滑的滚动效果。如果您是从组件外部触发它，那么类似这样的事情将起作用(其中 component 是 JScrollPane 中的组件):

final int target = visible.y;
final Rectangle current = component.getVisibleRect();
final int start = current.y;
final int delta = target - start;
final int msBetweenIterations = 10;

Timer scrollTimer = new Timer(msBetweenIterations, new ActionListener() {
    int currentIteration = 0;
    final long animationTime = 150; // milliseconds
    final long nsBetweenIterations = msBetweenIterations * 1000000; // nanoseconds
    final long startTime = System.nanoTime() - nsBetweenIterations; // Make the animation move on the first iteration
    final long targetCompletionTime = startTime + animationTime * 1000000;
    final long targetElapsedTime = targetCompletionTime - startTime;

    @Override
    public void actionPerformed(ActionEvent e) {
        long timeSinceStart = System.nanoTime() - startTime;
        double percentComplete = Math.min(1.0, (double) timeSinceStart / targetElapsedTime);

        double factor = getFactor(percentComplete);
        current.y = (int) Math.round(start + delta * factor);
        component.scrollRectToVisible(current);
        if (timeSinceStart >= targetElapsedTime) {
            ((Timer) e.getSource()).stop();
        }
    }
});
scrollTimer.setInitialDelay(0);
scrollTimer.start();

getFactor 方法是从线性函数到缓动函数的转换，将根据您的感受将其实现为其中之一:

private double snap(double percent) {
    return 1;
}

private double linear(double percent) {
    return percent;
}

private double easeInCubic(double percent) {
    return Math.pow(percent, 3);
}

private double easeOutCubic(double percent) {
    return 1 - easeInCubic(1 - percent);
}

private double easeInOutCubic(double percent) {
    return percent < 0.5
            ? easeInCubic(percent * 2) / 2
            : easeInCubic(percent * -2 + 2) / -2 + 1;
}

这可能也适用于在组件内工作，因此当用户滚动时，它会按照这些行执行某些操作。

或者，如果可能，您可以使用 JavaFX，它对动画的支持比 Swing 好得多。