我试图在滚动时解决有关gridview中混合图像的问题。我已经在这里看到了关于这个问题的类似帖子,但不幸的是我还没有解决它。
我使用asynctask在gridView中加载图像,我在网格中只有imageView 。
谢谢!
这是我的代码:
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
ImageView img;
if (convertView == null) {
img = new ImageView(GalleryActivity.this);
WindowManager wm = (WindowManager) GalleryActivity.this.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
Point size = new Point();
display.getSize(size);
int width = size.x;
width = width / 3 - 4;
img.setLayoutParams(new AbsListView.LayoutParams(width, width));
img.setScaleType(ImageView.ScaleType.CENTER_CROP);
} else {
img = (ImageView) convertView;
}
File dics = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM);
File dir = new File(dics, "yyy");
if (!dir.exists() && !dir.mkdirs()) {
img.setImageResource(holder(position + 1));
} else {
String file_name = dir.getAbsolutePath() + "/" + (position + 1) + ".jpg";
if (new File(file_name).exists()) {
BitmapWorkerTask task = new BitmapWorkerTask(img);
task.execute(file_name);
items[position].setStatus(1);
} else {
img.setImageResource(holder(position + 1));
}
}
return img;
}
class BitmapWorkerTask extends AsyncTask<String, Void, Bitmap> {
private final WeakReference<ImageView> imageViewReference;
private String data;
public BitmapWorkerTask(ImageView imageView) {
imageViewReference = new WeakReference<ImageView>(imageView);
}
// Decode image in background.
@Override
protected Bitmap doInBackground(String... params) {
data = params[0];
return decodeSampledBitmapFromResource(data,100,100);
}
// Once complete, see if ImageView is still around and set bitmap.
@Override
protected void onPostExecute(Bitmap bitmap) {
if (imageViewReference != null && bitmap != null) {
final ImageView imageView = imageViewReference.get();
if (imageView != null) {
imageView.setImageBitmap(bitmap);
}
}
}
}
public Bitmap decodeSampledBitmapFromResource(String resId,
int reqWidth, int reqHeight) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(resId,options);
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(resId);
}
public int calculateInSampleSize(
BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
final int halfHeight = height / 2;
final int halfWidth = width / 2;
while ((halfHeight / inSampleSize) >= reqHeight
&& (halfWidth / inSampleSize) >= reqWidth) {
inSampleSize *= 2;
}
}
return inSampleSize;
}
答案 0 :(得分:1)
问题背后的原因是BitmapWorkerTask
没有通过启动顺序完成,因此它可以覆盖旧版本的最新结果。
为了避免这种情况,您必须为每个视图保留一个BitmapWorkerTask
,如果它仍在工作则取消旧视图,这样它就不会覆盖新BitmapWorkerTask
的结果
您可以使用setTag
和getTag
方法来实现此目的,并保留对每个视图的最新BitmapWorkerTask
的引用。
答案 1 :(得分:0)
在启动图像加载线程时,您没有将Tag设置为ImageView,当线程完成作业时,为什么将图像设置为屏幕上的当前显示。 你应该在 BitmapWorkerTask 类中传递一些id作为参数。