java Android Scroller 简单示例
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Android Scroller simple example
提问by Artem Caritas
Can anyone gives me simple example about Scroller class? As I understand, it encapsulates scrolling, so I need start calculating and then manually update must ScrollView to new positions. So I just try
谁能给我一个关于 Scroller 类的简单例子？据我了解，它封装了滚动，所以我需要开始计算然后手动更新 must ScrollView 到新位置。所以我只是尝试
Scroller scroller = new Scroller(getApplicationContext());
scroller.startScroll(0, 0, 10, 10, 500);
for (int i = 0; i < 100; i++) {
Log.d("scroller", scroller.getCurrX()+" "+ scroller.getCurrY());
}
All I have in output is just zeros. Where is my mistake?
我在输出中所拥有的只是零。我的错误在哪里？
回答by Thkru
private class Flinger implements Runnable {
private final Scroller scroller;
private int lastX = 0;
Flinger() {
scroller = new Scroller(getActivity());
}
void start(int initialVelocity) {
int initialX = scrollingView.getScrollX();
int maxX = Integer.MAX_VALUE; // or some appropriate max value in your code
scroller.fling(initialX, 0, initialVelocity, 0, 0, maxX, 0, 10);
Log.i(TAG, "starting fling at " + initialX + ", velocity is " + initialVelocity + "");
lastX = initialX;
getView().post(this);
}
public void run() {
if (scroller.isFinished()) {
Log.i(TAG, "scroller is finished, done with fling");
return;
}
boolean more = scroller.computeScrollOffset();
int x = scroller.getCurrX();
int diff = lastX - x;
if (diff != 0) {
scrollingView.scrollBy(diff, 0);
lastX = x;
}
if (more) {
getView().post(this);
}
}
boolean isFlinging() {
return !scroller.isFinished();
}
void forceFinished() {
if (!scroller.isFinished()) {
scroller.forceFinished(true);
}
}
}
Taken from https://stackoverflow.com/a/6219382/1351347
回答by agamov
Last parameter in startScroll()is duration.
Probably your for-loop finishes before the scroller gets anything done :)
And also you should call computeScrollOffset()Try this code, it works:
最后一个参数startScroll()是持续时间。可能您的for-loop 在滚动条完成任何操作之前就完成了 :) 而且您还应该调用computeScrollOffset()Try this code，它可以工作：
Scroller scroller = new Scroller(getApplicationContext());
scroller.startScroll(0, 0, 100, 100, 500);
while (!scroller.isFinished()) {
Log.d("scroller", scroller.getCurrX() + " " + scroller.getCurrY());
scroller.computeScrollOffset();
}
