如何将第一个位置的背景设置为默认值? [英] How to set background in the first position as default?

问题描述

关注代码:

Fragment1.cs:

public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
    view = inflater.Inflate(Resource.Layout.fragment_1, container, false);
    gridView = (GridView)view.FindViewById(Resource.Id.grid_view);

    gridView.ItemClick += (sender, e) =>
    {
        if (view_1 != null)
        {
            view_1.SetBackgroundColor(Color.Transparent);
        }
        view_1 = e.View;
        e.View.SetBackgroundColor(Color.ParseColor("#FFC107"));
    };

    adapter = new ArrayAdapter<string>(Activity, Resource.Layout.item_1, numbers);

    gridView.Adapter = adapter;

    return view;
}

item_1.axml:

<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@android:id/text1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textAppearance="?android:attr/textAppearanceListItemSmall"
    android:gravity="center"
    android:paddingStart="?android:attr/listPreferredItemPaddingStart"
    android:paddingEnd="?android:attr/listPreferredItemPaddingEnd"
    android:minHeight="?android:attr/listPreferredItemHeightSmall" />

fragment_1.axml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <GridView
        android:id="@+id/grid_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:numColumns="4"
        android:columnWidth="40dp"
        android:verticalSpacing="15dp"
        android:horizontalSpacing="1dp"
        android:paddingTop="2dp"
        android:stretchMode="columnWidth"
        android:layout_centerInParent="true" />
</RelativeLayout>

示例图片:

我想在第一个位置涂上黄色.

I want to paint yellow in the first position.

我想在OnCreateView的第一个位置做背景，可以吗?

I want to make the background in the first position in OnCreateView, is it possible?

我有一个带有数字的网格视图，我需要在第一个位置加载背景，即数字 1.我该怎么做?

I have a gridview with numbers I need to load a background in the first position which is the number 1. How can I do this?

推荐答案

就像 ListView 一样，GridView 也重用了它的子元素.所以如果使用 View.GetChildAt(position) 并设置背景颜色.您将获得多个带有背景颜色的视图.

Just Like ListView, GridView also reuses its children. So if use View.GetChildAt(position) and set the background color. you will get multiple views rendered with background color.

所以，如果你只希望第一个孩子用背景颜色渲染，你必须在 position==0 时将 Adapter 重写为 SetBackgroundColor 并清除颜色如果 position!=0:

So, if you only want the first child to be rendered with background color, you have to rewrite the Adapter to SetBackgroundColor when position==0 and clear the color if position!=0:

自定义适配器的 GetView 方法:

The GetView method of your custom adapter:

public override View GetView(int position, View convertView, ViewGroup parent)
{
    View view=null;
    if (convertView != null)
    {
        view = convertView;
    }
    else
    {
        view = LayoutInflater.FromContext(parent.Context).Inflate(Resource.Layout.item1,null);
    }

    if (position == 0)
    {
        view.SetBackgroundColor(Android.Graphics.Color.Yellow);
    }
    else
    {
        view.SetBackgroundColor(Android.Graphics.Color.Transparent);
    }

    (view as TextView).Text = _items[position];
    return view;
}

更新:

以下是Adapter的完整代码:

Here is the complete codes of Adapter:

public class MyGridViewAdapter : BaseAdapter
{
    string[] _items;
    public MyGridViewAdapter(string[] items)
    {
        _items = items;
    }
    public override int Count => _items.Length;

    public override Java.Lang.Object GetItem(int position)
    {
        return _items[position];
    }

    public override long GetItemId(int position)
    {
        return 0;
    }

    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        View view=null;
        if (convertView != null)
        {
            view = convertView;
        }
        else
        {
            view = LayoutInflater.FromContext(parent.Context).Inflate(Resource.Layout.item1,null);
        }

        if (position == 0)
        {
            view.SetBackgroundColor(Android.Graphics.Color.Yellow);
        }
        else
        {
            view.SetBackgroundColor(Android.Graphics.Color.Transparent);
        }

        (view as TextView).Text = _items[position];
        return view;
    }
}

这篇关于如何将第一个位置的背景设置为默认值?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！