滑动后更改recyclerview项目背景 [英] Change recyclerview item background when swiped

问题描述

我正在使用recycler view显示垂直列表，并且正在使用recycler view的渐变背景.当我使用ItemTouchHelper向左或向右滑动项目时，我正在删除recycler view中的项目.

Hi i am showing vertical list using recycler view and i am using a gradient background for recycler view.I am deleting items in recycler view when they are swiped left or right using ItemTouchHelper.

ItemTouchHelper.SimpleCallback simpleCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT|ItemTouchHelper.RIGHT) {
        @Override
        public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
            return false;
        }

        @Override
        public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
            mRecyclerAdapter.removeStock(viewHolder.getAdapterPosition());
        }

        @Override
        public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {
            super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);
            if(actionState!=ItemTouchHelper.ACTION_STATE_IDLE){
                viewHolder.itemView.setBackgroundColor(Color.LTGRAY);
            }
        }
    };
    ItemTouchHelper itemTouchHelper = new ItemTouchHelper(simpleCallback);
    itemTouchHelper.attachToRecyclerView(recyclerView);

在这里，我将物品轻扫时将回收者视图"项目背景更改为浅灰色，但是当回收者视图项目返回到空闲状态时，我想恢复原始背景，即我希望返回该渐变背景. Recylerview xml文件:

Here i am changing recycler view item background to light grey when item is swiped but i want the original background back when recycler view item goes back to idle state i.e i want that gradient background back. Recylerview xml file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@drawable/gradient_background"
tools:context=".ui.StockFragment"
tools:showIn="@layout/activity_main">

<android.support.v7.widget.RecyclerView
    android:id="@+id/recycler_view"
    android:scrollbars="none"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

</RelativeLayout>

可绘制文件:

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
<gradient
    android:type="linear"
    android:startColor="#FF18181F"
    android:endColor="#FF27354D"
    android:angle="90"/>
</shape>

推荐答案

也许您可以在

Perhaps you can try inside of onSelectedChanged(). Alternatively, perhaps you can override clearView() and do the change there after calling the superclass method.

编辑

阅读更多文档后，我现在认为onSelectedChanged()是更改项目开始滑动和进入空闲状态时更改背景的正确位置.检查viewHolder是否不为空，然后检查actionState更改背景的内容.

Having read the documentation more, I now think onSelectedChanged() is the correct place to change the background both for when the item starts swiping and when it returns to idle. Check that the viewHolder is not null and then check the actionState for what to change the background to.

我认为onChildDraw()不适合这样做，因为它已经处于绘制阶段，并且更改视图背景可能会导致再次绘制.

I think onChildDraw() is not the right place to do this because it is already in the drawing phase and changing the view's background there will probably cause another re-draw.

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