How to implement custom scrolling for Android views?

To achieve a customized scrolling effect, you can follow these steps:

1. Create a custom View class that inherits from View.
2. Override the onTouchEvent method in a custom View class to handle scroll gestures. You can use the GestureDetector class to handle the gesture events.
3. In a custom View class, define properties related to scrolling, such as the scroll offset and the maximum scrolling range.
4. Draw scrolling content in the onDraw method of a custom View class. You can perform drawing operations using the Canvas class.
5. Update the scrolling offset in the computeScroll method of the custom View class and call the invalidate method to trigger a redraw.
6. Implement the scrolling effect in a custom View’s parent container by calling the scrollTo or scrollBy method.

Here is a simple example code demonstrating how to achieve a custom View scrolling effect.

public class CustomScrollView extends View {

    private GestureDetector mGestureDetector;

    private int mScrollX;
    private int mScrollY;

    public CustomScrollView(Context context) {
        super(context);
        init(context);
    }

    public CustomScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public CustomScrollView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context) {
        mGestureDetector = new GestureDetector(context, new ScrollGestureListener());
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 绘制滚动内容
        // 使用mScrollX和mScrollY来确定绘制的起始位置
        // ...
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return mGestureDetector.onTouchEvent(event);
    }

    private class ScrollGestureListener extends GestureDetector.SimpleOnGestureListener {

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            // 处理滚动手势事件
            // 更新mScrollX和mScrollY的值
            // 调用invalidate方法触发重绘
            // ...
            return true;
        }
    }
}

When using this custom view, you need to place it in a parent container and call the scrollTo or scrollBy method in the parent container to achieve scrolling effects. For example:

CustomScrollView scrollView = new CustomScrollView(this);
scrollView.scrollTo(100, 0); // 滚动到指定的位置

In this way, you can achieve the scrolling effect of a custom view. Please make the necessary modifications and extensions according to your specific needs.