Android監聽ScrollView滑動距離的簡單處理

2022-02-16 16:00:20

本文範例為大家分享了Android監聽ScrollView滑動距離的具體方法，供大家參考，具體內容如下

使用ScrollView時，有時候我們需要要獲取它滑動的距離，Android的API給我們提供了設定監聽的方法：

scrollView.setOnScrollChangeListener(new View.OnScrollChangeListener() {
            @Override
            public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {

            }
        });

很遺憾的是：Call requires API 23
點進去看下View裡面的OnScrollChangeListener在哪個方法裡面監聽位置：

/**
     * This is called in response to an internal scroll in this view (i.e., the
     * view scrolled its own contents). This is typically as a result of
     * {@link #scrollBy(int, int)} or {@link #scrollTo(int, int)} having been
     * called.
     *
     * @param l Current horizontal scroll origin.
     * @param t Current vertical scroll origin.
     * @param oldl Previous horizontal scroll origin.
     * @param oldt Previous vertical scroll origin.
     */
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        notifySubtreeAccessibilityStateChangedIfNeeded();

        if (AccessibilityManager.getInstance(mContext).isEnabled()) {
            postSendViewScrolledAccessibilityEventCallback();
        }

        mBackgroundSizeChanged = true;
        if (mForegroundInfo != null) {
            mForegroundInfo.mBoundsChanged = true;
        }

        final AttachInfo ai = mAttachInfo;
        if (ai != null) {
            ai.mViewScrollChanged = true;
        }

        if (mListenerInfo != null && mListenerInfo.mOnScrollChangeListener != null) {
            mListenerInfo.mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt);
        }
    }

一看其實實現不難，不就是自定義個ScrollView, 裡面多寫個監聽，實現如下：

import android.content.Context;
import android.util.AttributeSet;
import android.widget.ScrollView;

/**
 * Created by hucanhui on 16/7/28.
 */
public class ObservableScrollView extends ScrollView{
    private OnScollChangedListener onScollChangedListener = null;

    public ObservableScrollView(Context context) {
        super(context);
    }

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

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

    public void setOnScollChangedListener(OnScollChangedListener onScollChangedListener) {
        this.onScollChangedListener = onScollChangedListener;
    }

    @Override
    protected void onScrollChanged(int x, int y, int oldx, int oldy) {
        super.onScrollChanged(x, y, oldx, oldy);
        if (onScollChangedListener != null) {
            onScollChangedListener.onScrollChanged(this, x, y, oldx, oldy);
        }
    }

    public interface OnScollChangedListener {

        void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy);

    }
}

使用簡單：

scrollView.setOnScollChangedListener(new ObservableScrollView.OnScollChangedListener() {
            @Override
            public void onScrollChanged(ObservableScrollView scrollView, int x, int y, int oldx, int oldy){
            }
        });

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支援it145.com。

Android監聽ScrollView滑動距離的簡單處理

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