如何在 GridView Widget 中设置固定数量的项目？

Question

我有 GridView 小部件，它由从 ArrayList 中获取的 40 张图像填充，问题是当小部件试图加载超过 40 个位置时，它会产生大约数百个带有 "loading" 文本的空白单元格。如果项目数量固定为 40，则不会发生这种情况，但如何做到这一点？

这是我的 RemoteViewsFactory class:

public class WidgetRemoteViewsFactory implements RemoteViewsService.RemoteViewsFactory {
    private Context ctx;
    private Cursor cursor;
    private ArrayList<Bitmap> photos = new ArrayList<>(40);

    public WidgetRemoteViewsFactory(Context applicationContext, Intent intent) {
        ctx = applicationContext;
    }

    @Override
    public void onCreate() {

    }

    @Override
    public void onDataSetChanged() {

        String[] projection = new String[]{
                MediaStore.Images.ImageColumns._ID,
                MediaStore.Images.ImageColumns.DATA,
                MediaStore.Images.ImageColumns.BUCKET_DISPLAY_NAME,
                MediaStore.Images.ImageColumns.DATE_TAKEN,
                MediaStore.Images.ImageColumns.MIME_TYPE
        };
        cursor = ctx.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, projection, null,
                null, MediaStore.Images.ImageColumns.DATE_TAKEN + " DESC");

        cursor.moveToFirst();
        for (int i = 1; i <= 39; i++) {
            Bitmap bmp = BitmapFactory.decodeFile(cursor.getString(1));
            photos.add(bmp);
            cursor.moveToNext();
            Log.d(TAG, "loop iteration" + i );
        }
    }


    @Override
    public void onDestroy() {
        if (cursor != null) {
            cursor.close();
        }
    }

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

    @Override
    public RemoteViews getViewAt(int position) {
        if (position == AdapterView.INVALID_POSITION ||
                cursor == null || !cursor.moveToPosition(position) || photos == null || photos.size() == 0 || position >= photos.size()) {
            return null;
        }
            RemoteViews views = new RemoteViews(ctx.getPackageName(), R.layout.widget_item);
            Bitmap img = resizeBitmapFitXY(250, 150, photos.get(position));
            views.setImageViewBitmap(R.id.imageView, img);
            return views;
    }

    @Override
    public RemoteViews getLoadingView() {
        return null;
    }

    @Override
    public int getViewTypeCount() {
        return 1;
    }

    @Override
    public long getItemId(int position) {
        return cursor.moveToPosition(position) ? cursor.getLong(0) : position;
    }

    @Override
    public boolean hasStableIds() {
        return true;
    }





    public Bitmap resizeBitmapFitXY(int width, int height, Bitmap bitmap){
        Bitmap background = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        float originalWidth = bitmap.getWidth(), originalHeight = bitmap.getHeight();
        Canvas canvas = new Canvas(background);
        float scale, xTranslation = 0.0f, yTranslation = 0.0f;
        if (originalWidth > originalHeight) {
            scale = height/originalHeight;
            xTranslation = (width - originalWidth * scale)/2.0f;
        }
        else {
            scale = width / originalWidth;
            yTranslation = (height - originalHeight * scale)/2.0f;
        }
        Matrix transformation = new Matrix();
        transformation.postTranslate(xTranslation, yTranslation);
        transformation.preScale(scale, scale);
        Paint paint = new Paint();
        paint.setFilterBitmap(true);
        canvas.drawBitmap(bitmap, transformation, paint);
        return background;
    }
}

Answer 1

您需要替换此代码

        cursor.moveToFirst();
        for (int i = 1; i <= 39; i++) {
            Bitmap bmp = BitmapFactory.decodeFile(cursor.getString(1));
            photos.add(bmp);
            cursor.moveToNext();
            Log.d(TAG, "loop iteration" + i );
        }

并改为

          if (cursor!=null && cursor.getCount()>0) {
                while (cursor.moveToNext()) {
                    Bitmap bmp = BitmapFactory.decodeFile(cursor.getString(1));
                    photos.add(bmp);
                    Log.d(TAG, "loop iteration" + i );
                }
            }

the problem that you used a fixed size in the for loop for (int i = 1; i <= 39; i++)

and the solution is to use while() loop to get all the item from the cursor and add it to your list

评论后更新答案：

Q: if you decide in the loop to load only 40 and not to load the blank text

你必须这样做

 @Override
    public int getCount() {
        return 40;
    }

如何在 GridView Widget 中设置固定数量的项目？

How to set fixed quantity of items in GridView Widget?

java

android

gridview

android-bitmap