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>
