• 1. 自定义View仿抖音视频加载BufferLineView
• 2. 自定义视频选帧控件
• 3. 自定义View 视频截取控件

项目中需要做一个拖动控件，推动框对应回调选取视频对应帧做封面，效果如下：

image.png

实现思路可以借助google ViewDragHelper类 ：

  viewDragHelper = ViewDragHelper.create(this, new ViewDragHelper.Callback() {
            @Override
            public boolean tryCaptureView(@NonNull View child, int pointerId) {
                return dragView == child;
            }

            @Override
            public int clampViewPositionHorizontal(@NonNull View child, int left, int dx) {
               
                return moveToLeft;
            }
        });

• tryCaptureView ：绑定拖动的子view
• clampViewPositionHorizontal 水平滑动 子view拖动的距离。
• 下面看具体实现思路：

package com.example.seebar;

import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.constraintlayout.widget.ConstraintLayout;
import androidx.customview.widget.ViewDragHelper;

/**
 * @author 桂雁彬
 * @date 2019-12-18.
 * GitHub:
 * email：guiyanbing@100tal.com
 * description：
 */
public class DragItemView extends ConstraintLayout {
    ViewDragHelper viewDragHelper;
    private View dragView;

    public DragItemView(Context context) {
        this(context, null);
    }

    public DragItemView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public DragItemView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initView();
    }

    private void initView() {
        viewDragHelper = ViewDragHelper.create(this, new ViewDragHelper.Callback() {
            @Override
            public boolean tryCaptureView(@NonNull View child, int pointerId) {
                return dragView == child;
            }

            @Override
            public int clampViewPositionHorizontal(@NonNull View child, int left, int dx) {
                int moveToLeft = left;
                if (left < 0) {
                    moveToLeft = 0;
                }


                int maxMoveDistance = leftToRightDistance - child.getWidth();
                if (left > maxMoveDistance) {
                    moveToLeft = maxMoveDistance;
                    Log.d("==tag==1","left:"+left);

                }
                if (callBack != null) {
                    callBack.onItemSelect((float) moveToLeft / maxMoveDistance);
                }

                Log.d("==tag==","left:"+left);
                Log.d("==tag==","dx:"+dx);
                Log.d("==tag==","leftToRightDistance:"+leftToRightDistance);
                Log.d("==tag==","maxMoveDistance:"+maxMoveDistance);
                Log.d("==tag==","child.getWidth():"+child.getWidth());



                return moveToLeft;
            }
        });
    }

    private int leftToRightDistance;

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        leftToRightDistance = getRight() - getLeft();
    }

    public void setDragView(View view) {
        dragView = view;
    }

    public void setDragViewWidth(int width) {
        if (dragView != null) {
            ViewGroup.LayoutParams layoutParams = dragView.getLayoutParams();
            if (layoutParams != null) {
                layoutParams.width = width;
                dragView.setLayoutParams(layoutParams);
            }
        }
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        return viewDragHelper.shouldInterceptTouchEvent(ev);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        viewDragHelper.processTouchEvent(event);
        return true;
    }

    public void setCallBack(ICallBack callBack) {
        this.callBack = callBack;
    }

    private ICallBack callBack;

    public interface ICallBack {
        void onItemSelect(float progress);
    }
}

上面在 clampViewPositionHorizontal 中根据滑动的距离拦截最终返回子view对应拖动的距离。

实现思路就是这样简单。只需要传入需要拖动子 view 返回对应子view拖动距离就行。

• 下面是子view 对应布局：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000"
    tools:ignore="ResourceName">

    <com.example.seebar.DragItemView
        android:id="@+id/viewSlice"
        android:layout_width="0dp"
        android:layout_height="54dp"
        android:layout_marginStart="16dp"
        android:layout_marginEnd="16dp"
        android:layout_marginBottom="80dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent">

        <View
            android:id="@+id/viewVideoSelect"
            android:layout_width="30dp"
            android:layout_height="0dp"
            android:background="@drawable/shape_produce_video_cover_select"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
    </com.example.seebar.DragItemView>


</androidx.constraintlayout.widget.ConstraintLayout>