Question

//我的图片保存的路径

/storage/emulated/0/Pictures/CameraExample/JPEG_20150107_152640.jpeg

//这是文件路径之一。

//我需要将最后拍摄的照片排序为第一个在网格视图中显示的第一个图像，现在显示图像，最后一张照片显示在最后。

以下是我的代码

 public class ImageAdapter extends BaseAdapter{


        private Context context;
        private int imageWidth;
        private Activity activity;
        ArrayList<String> itemList = new ArrayList<String>();
        Bitmap bitmap;

        public ImageAdapter(Activity activity,ArrayList<String> itemList,int imageWidth) {
            this.activity = activity;
            this.itemList = itemList;
            this.imageWidth = imageWidth;

        }

        @Override
        public int getCount() {

            return this.itemList.size();
        }

        void add(String path) {
            itemList.add(path);

        }

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

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

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView imageView;

            if (convertView == null) {

                imageView = new ImageView(activity);


            }
        else {
                imageView = (ImageView) convertView;

            }

            imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);

            imageView.setLayoutParams(new GridView.LayoutParams(imageWidth ,imageWidth ));


            bitmap = decodeFile(itemList.get(position), imageWidth, imageWidth);

             imageView.setImageBitmap(bitmap);

            imageView.setOnClickListener( new OnImageClickListener(position));


            return imageView;
        }


        class OnImageClickListener implements View.OnClickListener {

            int position;

            public OnImageClickListener(int position){
                this.position = position;
            }

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(activity, ImageDisplayActivity.class);               

                intent.putExtra("position", position);    

                Log.d("ImageAdapter","Intent.putExtra ");
                activity.startActivity(intent);

            }
        }

        public Bitmap decodeFile(String path, int reqWidth, int reqHeight) {
            try {
                File f = new File(path);     
                BitmapFactory.Options o = new BitmapFactory.Options();

                o.inJustDecodeBounds = true;
                BitmapFactory.decodeStream(new FileInputStream(f), null, o);
                final int REQUIRED_WIDTH = reqWidth;
                final int REQUIRED_HEIGHT = reqHeight;
                int scale = 1;
                while (o.outWidth / scale / 2 >= REQUIRED_WIDTH && o.outHeight / scale / 2 >= REQUIRED_HEIGHT)
                    scale *= 2;

                BitmapFactory.Options o2 = new BitmapFactory.Options();
                o2.inSampleSize = scale;
                return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
            return null;
        }
    }

//最后当我滚动网格视图时。滚动并不是那么顺利。请帮我解决两个问题。

//我的GridView活动类

public class GridViewActivity extends Activity {

    private ImageAdapter imageAdapter;
    private HelperUtils utils;
    private ArrayList<String> itemList = new ArrayList<String>();
    private GridView gridView;
    private int columnWidth;
    private Activity activity;


    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gridview);

        gridView = (GridView) findViewById(R.id.gridView);

        utils = new HelperUtils(this);

        InitilizeGridLayout();

        itemList = utils.getFilePaths();

        imageAdapter = new ImageAdapter(this, itemList, columnWidth);

        gridView.setAdapter(imageAdapter);

    }

    private void InitilizeGridLayout() {

        Resources r = getResources();
        float padding = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, HelperAppConstant.GRID_PADDING, r.getDisplayMetrics());
        columnWidth = (int) ((utils.getScreenWidth() - ((HelperAppConstant.NUM_OF_COLUMNS + 1) * padding)) / HelperAppConstant.NUM_OF_COLUMNS);

        gridView.setNumColumns(HelperAppConstant.NUM_OF_COLUMNS);
        gridView.setColumnWidth(columnWidth);
        gridView.setStretchMode(GridView.NO_STRETCH);
        gridView.setPadding((int) padding, (int) padding, (int) padding, (int) padding);
        gridView.setHorizontalSpacing((int) padding);
        gridView.setVerticalSpacing((int) padding);


    }
}

Answer 1

从Collections.sort(itemList);方法中删除getView。

 @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ImageView imageView;

        if (convertView == null) {
            Log.d("ImageAdapter","Inside the if condition");
            imageView = new ImageView(activity);

        }
    else {
            imageView = (ImageView) convertView;
          }

        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setLayoutParams(new GridView.LayoutParams(imageWidth ,imageWidth ));

       // bitmap = decodeFile(itemList.get(position), imageWidth, imageWidth);

        bitmap = decodeFile(getItem(position), imageWidth, imageWidth);

        imageView.setImageBitmap(bitmap);

        return imageView;
    }

在onCreate方法中填充网格视图之前对列表进行排序。

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_gridview);

        gridView = (GridView) findViewById(R.id.gridView);

        utils = new HelperUtils(this);

        InitilizeGridLayout();

        itemList = utils.getFilePaths();

        Collections.sort(itemList);

        imageAdapter = new ImageAdapter(this, itemList, columnWidth);

        gridView.setAdapter(imageAdapter);

    }

您可以通过创建包含图像文件路径和图像位图的项目列表来关注示例in this link。这样，每次调用getView时都不必解码位图。在填充gridview之前，您可以解码一次。

由于图像按升序排序，您可以将getItem方法替换为下面的方法：

    @Override
    public Object getItem(int position) {
        return this.itemList.get(itemList.size() - 1 - position);
    }

我更新了getView方法。您应该使用getItem(position)代替itemList.get(position)来解码位图。

Answer 2

为了让你的卷轴流畅，你必须用Picasso库显示图像，我有同样的问题！

根据gridview android里面的DATE和TIME对图像进行排序

2 个答案: