Question

我正在尝试更改自定义视图组的ImageView背景，同时在视图寻呼机中滑动但不起作用，ImageView的背景无法刷新。我不知道为什么。当我想在自定义视图组中更改ImageView的背景时，会出现此问题。在活动中，我有下一个代码：

公共类Example5扩展了AppCompatActivity {

        private ViewPager view_pager;
        private CustomPagerAdapter pagerAdapter;
        private CustomViewGroup customViewGroup

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_example5);
            Toolbar toolbar = findViewById(R.id.toolbar);
            setSupportActionBar(toolbar);

                    view_pager = findViewById(R.id.view_pager);

                    view_pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                        @Override
                        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

                        }

                        @Override
                        public void onPageSelected(int position) {
                            The problem here when I want to change the background of ImageView inside CustomViewGroup
                            customViewGroupOneImage.changeImage();
                        }

                        @Override
                        public void onPageScrollStateChanged(int state) {

                        }
                    });

                    pagerAdapter = new CustomPagerAdapter(this);
                    view_pager.setAdapter(pagerAdapter);

      customViewGroup = new CustomViewGroup(this);
      }
    }

我的自定义视图组

public class CustomViewGroup extends ViewGroup {

                    private Context context;

                    public CustomViewGroupOneImage(Context context) {
                        super(context);
                        init(context);
                    }

                    public CustomViewGroupOneImage(Context context, AttributeSet attrs) {
                        super(context, attrs);
                        init(context);
                    }

                    public CustomViewGroupOneImage(Context context, AttributeSet attrs, int defStyleAttr) {
                        super(context, attrs, defStyleAttr);
                        init(context);
                    }

                    @Override
                    protected void onLayout(boolean changed, int l, int t, int r, int b) {

                        int width = getWidth();
                        int height = getHeight();

                        View child = getChildAt(0);

                        measureChild(child, width, height);

                        child.layout(0, 0, child.getMeasuredWidth(), child.getMeasuredHeight());
                    }

                    public void changeImage(){

                        ImageView child = (ImageView) getChildAt(0);

                        child.setBackgroundResource(R.drawable.color2);
                    }

                    private void init(Context context){
                        this.context = context;
                        ImageView imageView = new ImageView(context);
                        LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);
                        imageView.setLayoutParams(params);
                        imageView.setBackgroundResource(R.drawable.color1);
                        addView(imageView);
                    }
                }

我的活动布局

<?xml version="1.0" encoding="utf-8"?>
                <RelativeLayout
                    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"
                    app:layout_behavior="@string/appbar_scrolling_view_behavior"
                 tools:context="com.example.wolf.examplecolor.ExampleViewPager.Example5"
                    tools:showIn="@layout/activity_example5">

                    <android.support.v4.view.ViewPager
                        android:id="@+id/view_pager"
                        android:layout_width="match_parent"
                        android:layout_height="200dp"/>
                   <com.example.wolf.examplecolor.ExampleViewPager.Example5.CustomViewGroup
                        android:layout_width="200dp"
                        android:layout_height="200dp"
                        android:layout_below="@id/view_pager"/>
                </RelativeLayout>

但是，如果我有下一个布局，则在滑动视图寻呼机改变ImageView的背景时这是有效的。

<?xml version="1.0" encoding="utf-8"?>           
<RelativeLayout
                    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"
                    app:layout_behavior="@string/appbar_scrolling_view_behavior"
                 tools:context="com.example.wolf.examplecolor.ExampleViewPager.Example5"
                    tools:showIn="@layout/activity_example5">

                    <android.support.v4.view.ViewPager
                        android:id="@+id/view_pager"
                        android:layout_width="match_parent"
                        android:layout_height="200dp"/>


                    <ImageView
                        android:id="@+id/img_image"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_below="@id/view_pager" />

                </RelativeLayout>

后来改变了viewpager的监听器

        public class Example5 extends AppCompatActivity {


            private ViewPager view_pager;
            private ImageView img_image;
            private CustomPagerAdapter pagerAdapter;
            private CustomViewGroup customViewGroup

            @Override
            protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.activity_example5);
                Toolbar toolbar = findViewById(R.id.toolbar);
                setSupportActionBar(toolbar);

                view_pager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                            @Override
                            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

                            }

                            @Override
                            public void onPageSelected(int position) {    
img_image.setBackgroundResource(R.drawable.color2);

                            }

                            @Override
                            public void onPageScrollStateChanged(int state) {
                            }
                        });


             img_image = findViewById(R.id.img_image);
                    img_image.setBackgroundResource(R.drawable.color1);

          }
        }

由于

Greetting。

Answer 1

MainActivity

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);


    // Set the content of the activity to use the activity_main.xml layout file
    setContentView(R.layout.activity_main);

    // Find the view pager that will allow the user to swipe between fragments
    ViewPager viewPager = (ViewPager) findViewById(R.id.viewPager);


    // Create an adapter that knows which fragment should be shown on each page
    SimpleFragmentPagerAdapter adapter = new SimpleFragmentPagerAdapter(getSupportFragmentManager());


    // Set the adapter onto the view pager
    viewPager.setAdapter(adapter);





}

MainActivity.xml

<android.support.v4.view.ViewPager
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/viewPager"

   />

Java Class, Image1.java

public View onCreateView(LayoutInflater layoutInflater,ViewGroup container,Bundle savedInstanceState){

   return  layoutInflater.inflate(R.layout.image1,container,false);

image1.xml

<ImageView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:src="@drawable/green"
    android:scaleType="centerCrop"/>

Try with more java class similar to Image1.java class and xml of image1.

滑动视图寻呼机时如何更改自定义视图组的ImageView背景？

1 个答案: