android中长按时如何在网格视图中删除选定的图像

Question

我是 android 开发者的新手，在完成了一些示例应用程序之后，我开始研究网格视图的概念。这里我尝试实现以下逻辑。

1.当长按图片时，选中的图片应突出显示。 2.需要知道选中的图片才能删除选中的图片。

我已经完成从图库中选择图像，现在我需要长按图像并使用删除按钮删除相同的图像。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/btn_browse"
        android:text="Browse"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/btn_delete"
        android:text="Delete"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <GridView
        android:id="@+id/grid_view"
        android:layout_width="match_parent"
        android:layout_height="660dp"
        android:columnWidth="90dp"
        android:gravity="center"
        android:horizontalSpacing="10dp"
        android:numColumns="3"
        android:stretchMode="columnWidth"
        android:verticalSpacing="10dp" />
</LinearLayout>

//适配器类

class ImageAdapter extends BaseAdapter {
//Context c|ass is use to bind xm| with java

    private Context mcontext;

    ArrayList<Uri> ImageUriList = new ArrayList<Uri>();
    //Right c|ick and generate constructor
    //imp|ement methods then auto generate

    //Constructor ...Rigth c|ick and generate constructor
    public ImageAdapter(Context mcontext, ArrayList<Uri> image) {
        this.mcontext = mcontext;
        ImageUriList = image;
    }

    @Override
    public int getCount() {
        return (ImageUriList == null) ? 0 : ImageUriList.size();
    }

    @Override
    public Object getItem(int position) {
        return ImageUriList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {     
        ImageView imageView =new ImageView(mcontext);
        imageView.setImageURI(ImageUriList.get(position));
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setLayoutParams(new GridView.LayoutParams(340,340));
        return imageView;
    }

}

// 主活动

public class MainActivity extends AppCompatActivity {

    public static final int BROWSE_RESULT = 1;
    ImageAdapter imageAdapter;
    ArrayList<Uri> imagesUri = new ArrayList<Uri>();
    GridView gridView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Button btn_browse;
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridView= findViewById(R.id.grid_view);

        gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
              //  imagesUri.remove(i) ;
                gridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);
                //imageAdapter.notifyDataSetChanged();
                Toast.makeText(MainActivity.this, i + " Value ", Toast.LENGTH_SHORT).show();
                return false;
            }
        });

        btn_browse = findViewById(R.id.btn_browse);

        btn_browse.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                f_openImageExplorer(); 
            }
        });
    }

    public void f_openImageExplorer() {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(intent, BROWSE_RESULT);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode,Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == BROWSE_RESULT) {
            if (resultCode == MainActivity.RESULT_OK) {
                if (data.getClipData() != null) {
                    Toast.makeText(this,Integer.toString(resultCode) , Toast.LENGTH_SHORT).show();
                    int imageCount = data.getClipData().getItemCount();
                    for(int i = 0; i< imageCount;i++){
                        Uri imageUri = data.getClipData().getItemAt(i).getUri();
                        imagesUri.add(imageUri);                        
                        imageAdapter= new ImageAdapter(getBaseContext(), imagesUri);
                        gridView.setAdapter(imageAdapter);
                        imageAdapter.notifyDataSetChanged();
                    }
                }
                else
                {
                    Uri singleImageUri = data.getData();
                    imagesUri.add(singleImageUri);
                    ImageAdapter imageAdapter= new ImageAdapter(getBaseContext(), imagesUri);
                    gridView.setAdapter(imageAdapter);
                    imageAdapter.notifyDataSetChanged();
                }
            }
        }
    }
}

Answer 1

在您的MainActivity 中，您可以跟踪所有点击的图像并将它们的位置保存在单独的ArrayList 中 - 在您的删除 Button 中，您可以检查点击项目的位置并将它们从主列表中删除 - 之后该操作已完成，只需使用新列表更新您的 ImageAdapter：

ArrayList<int> clickedImagesIdx = new ArrayList<int>();

 gridView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
    @Override
    public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
        gridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);
        ...
        clickedImagesIdx.add(i);
        return false;
    }
});

 deleteBtn.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        if (clickedImagesIdx.size() > 0) {

            for (int i = 0; i < clickedImagesIdx.size(); i++) {
                imagesUri.remove(i);
            }

            clickedImagesIdx.clear();

            // here you will need to submit the new Uri list to your adapter 
            // and use notifyDataSetChange();
        }
    }
});