使用 Android GridView 的键盘导航不会滚动网格 [英] Keyboard navigation with Android GridView doesn't scroll grid

问题描述

我正在尝试使用键盘在项目的 GridView 中导航.

I'm trying to use a keyboard to navigate through a GridView of items.

在简短的演示中，它只包含一个 GridView(包含带有 android:focusable="true" 的项目视图)，你可以看到没有一个项目获得焦点 - 网格就是东西滚动(项目不会变成橙色).

In the short demo, which only contains a GridView (containing item views with android:focusable="true"), you can see that none of the items gain focus - the grid is the thing that scrolls (the items don't turn orange).

添加 android:descendantFocusability="afterDescendants" 允许首先聚焦每个项目，但仍然不会继续滚动 GridView，因此您可以向下导航:

Adding the android:descendantFocusability="afterDescendants" allows each item to be focused first, but still, doesn't continue to scroll the GridView so you can navigate down:

单击一个项目(使用鼠标或按下 Return 键，如果该项目已聚焦，在后代聚焦性修复后)会将项目变成蓝色 - 表示它处于按下状态.

Clicking on an item (with mouse or by pressing Return if the item was focused, after the descendent focusability fix) turns an item blue - indicating it's in pressed state.

@layout/activity_my.xml:

@layout/activity_my.xml:

<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/listview"
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:numColumns="2" />

@layout/dummy_item.xml:

@layout/dummy_item.xml:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/dummy_item_parent"
  android:layout_width="match_parent"
  android:layout_height="150dp"
  android:gravity="center"
  android:focusable="true"
  android:clickable="true"
  android:background="@drawable/item_background" />

@drawable/item_background.xml:

@drawable/item_background.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
  <item android:state_pressed="true" android:drawable="@android:color/holo_blue_light" />
  <item android:state_focused="true" android:drawable="@android:color/holo_orange_light" />
  <item android:drawable="@android:color/holo_red_light" />
</selector>

MyActivity.java(带有 ListAdapter):

MyActivity.java (with ListAdapter):

public class MyActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my);

        AbsListView listview = (AbsListView) findViewById(R.id.listview);
        listview.setAdapter(new DummyAdapter(getLayoutInflater()));
    }

    private static class DummyAdapter extends BaseAdapter {

        private static final int COUNT = 25;

        private final LayoutInflater layoutInflater;

        DummyAdapter(LayoutInflater layoutInflater) {
            this.layoutInflater = layoutInflater;
        }

        @Override
        public int getCount() {
            return COUNT;
        }

        @Override
        public String getItem(int position) {
            return "Item " + position;
        }

        @Override
        public long getItemId(int position) {
            return position;
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            View view = convertView;
            if (view == null) {
                view = layoutInflater.inflate(R.layout.dummy_item, parent, false);
            }
            ((TextView) view).setText(getItem(position));
            return view;
        }

    }

}

将 GridView 交换为 ListView，而不更改适配器或项目视图/项目视图属性，将按预期运行 - 项目可以聚焦并且 ListView 将滚动到底部，以便所有项目都可以使用只是键盘输入.此外，将 RecyclerView 与 LinearLayoutManager/GridLayoutManager 一起使用也可以正常工作.

Swapping the GridView for a ListView, without changing the adapter, or the item views/item view attributes, will behave as expected - items can be focused and the ListView will scroll to the bottom, so that all items can be focused using just keyboard input. Also, using a RecyclerView with LinearLayoutManager / GridLayoutManager will also work correctly.

我已经在 API 16 和 22 上尝试过，结果相同.我已经尝试将 GridView 上的 android:descendantFocusability 属性设置为 afterDescendents，结果相同.

I have tried this on API 16 and 22 with the same results. I have tried settings the android:descendantFocusability attribute on the GridView to afterDescendents with the same result.

推荐答案

我尝试了您的代码，但它不适用于 GridView，正如您所说，但我对 ListView 也有一些问题.ListView 滚动正确，但只突出显示每个页面的第一项.

I tried your code and it doesn't work with GridView, as you said, but i have some issue also with ListView. The ListView scrolls correctly, but only the first item of every page is highlighted.

通过这些小的修改，您可以在 GridView 和 ListView 上实现您想要的效果.

With these little modifications you can achieve the effect you want on both GridView and ListView.

删除activity_my.xml中的android:descendantFocusability:

Remove android:descendantFocusability in activity_my.xml:

<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/listview"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:numColumns="2" />

删除 dummy_item.xml 中的 android:focusable:

Remove android:focusable in dummy_item.xml:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/dummy_item_parent"
    android:layout_width="match_parent"
    android:layout_height="150dp"
    android:gravity="center"
    android:clickable="true"
    android:background="@drawable/item_background" />

在 item_background.xml 中从 android:state_focused 更改为 android:state_selected:

Change from android:state_focused to android:state_selected in item_background.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@android:color/holo_blue_light" />
    <item android:state_selected="true" android:drawable="@android:color/holo_orange_light" />
    <item android:drawable="@android:color/holo_red_light" />
</selector>

这篇关于使用 Android GridView 的键盘导航不会滚动网格的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！