Imageview and PagerAdapter

Question

Voglio mettere le immagini in ogni pagina del mio ViewPager (come un libro). Quelle immagini provenienti da un elenco di URL:

mio adattatore simile a questa:

private class MyPagerAdapter extends PagerAdapter{ 

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

/** 
* Create the page for the given position. The adapter is responsible 
* for adding the view to the container given here, although it only 
* must ensure this is done by the time it returns from 
* {@link #finishUpdate()}. 
* 
* @param container The containing View in which the page will be shown. 
* @param position The page position to be instantiated. 
* @return Returns an Object representing the new page. This does not 
* need to be a View, but can be some other container of the page. 
*/ 
    @Override 
    public Object instantiateItem(View collection, int position) { 
     // Create Views 
     ScrollView view = new ScrollView(cxt); 
     RelativeLayout container = new RelativeLayout(cxt); 
     TextView text = new TextView(cxt); 
     text.setId(1); 
     ImageView[] image = new ImageView[18]; 
     // Parameters 
     LayoutParams container_params = new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT); 
     LayoutParams text_params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); 
     LayoutParams content_params = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); 
     content_params.addRule(RelativeLayout.BELOW, text.getId()); 

     view.setLayoutParams(container_params); 
     container.setLayoutParams(container_params); 
     text.setLayoutParams(text_params); 
     //image.setLayoutParams(content_params); 

     // set 

     for(int i = 0; i < position; i++){ 
      image[i] = new ImageView(cxt); 
      image[i].setLayoutParams(content_params); 
      createimage(image[i], list_url.get(position)); 
      container.addView(image[i]); 
     } 
     text.setText(list_url.get(position).toString()); 
     // add 
     view.addView(container); 
     container.addView(text); 
     //container.addView(image); 
     ((ViewPager) collection).addView(view,0); 
     return view; 
    } 

/** 
* Remove a page for the given position. The adapter is responsible 
* for removing the view from its container, although it only must ensure 
* this is done by the time it returns from {@link #finishUpdate()}. 
* 
* @param container The containing View from which the page will be removed. 
* @param position The page position to be removed. 
* @param object The same object that was returned by 
* {@link #instantiateItem(View, int)}. 
*/ 
    @Override 
    public void destroyItem(View collection, int position, Object view) { 
      ((ViewPager) collection).removeView((ScrollView) view); 
    } 



    @Override 
    public boolean isViewFromObject(View view, Object object) { 
      return view==((ScrollView)object); 
    } 


/** 
* Called when the a change in the shown pages has been completed. At this 
* point you must ensure that all of the pages have actually been added or 
* removed from the container as appropriate. 
* @param container The containing View which is displaying this adapter's 
* page views. 
*/ 
    @Override 
    public void finishUpdate(View arg0) {} 


    @Override 
    public void restoreState(Parcelable arg0, ClassLoader arg1) {} 

    @Override 
    public Parcelable saveState() { 
      return null; 
    } 

    @Override 
    public void startUpdate(View arg0) {} 

} 

e prendo quelle immagini grazie ad un AsyncTask:

private class CreateImage extends AsyncTask<String, Void, Drawable> { 
ImageView image; 
public CreateImage(ImageView img) { 
    image = img; 
} 
protected void onPreExecute() { 
} 

protected Drawable doInBackground(String... urls) { 
    InputStream is; 
    Drawable d = null ; 
    try { 
     is = (InputStream)new URL(urls[0]).getContent(); 
     d = Drawable.createFromStream(is, "Image"); 
     return d; 
    } catch (MalformedURLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } catch (IOException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 
    return d; 
} 
protected void onPostExecute(Drawable d) { 
    image.setBackgroundDrawable(d); 
} 
private Drawable ImageOperations(Context ctx, String url) { 
    try { 
    URL imageUrl = new URL(url); 
    InputStream is = (InputStream) imageUrl.getContent(); 
    Drawable d = Drawable.createFromStream(is, "src"); 
    return d; 
    } catch (MalformedURLException e) { 
    e.printStackTrace(); 
    return null; 
    } catch (IOException e) { 
    e.printStackTrace(); 
    return null; 
    } 
    } 
} 
public void createimage(ImageView img, String url){ 
new CreateImage(img).execute(url); 
} 

la cosa è che doesn' lavorare affatto

Answer 1

Sono dispiace che sia stato un errore, ma wow non riesco nemmeno a descrivere -> non ho messo il permesso:

<uses-permission android:name="android.permission.INTERNET"></uses-permission> 

e ho messo

d.setBounds(0, 0, d.getIntrinsicWidth(), d.getIntrinsicWidth()); 

int l'OnPostExecute perché non ho wan le immagini sono tutte strane.

Answer 2

for(int i = 0; i < position; i++){ image[i] = new ImageView(cxt); image[i].setLayoutParams(content_params); createimage(image[i], list_url.get(position)); container.addView(image[i]); }

Non penso che si debba farlo in un ciclo for. Si può forse guardare l'esempio nella libreria di compatibilità. Penso che istanzia automaticamente un oggetto per una posizione. Ecco un esempio che ho trovato dopo googling-

@Override 
    public Object instantiateItem(View collection, int position) { 
     TextView tv = new TextView(cxt); 
     tv.setText("Bonjour PAUG " + position); 
     tv.setTextColor(Color.WHITE); 
     tv.setTextSize(30); 

     ((ViewPager) collection).addView(tv,0); 

     return tv; 
    } 

Answer 3

non ho mai usato un PagerAdapter prima, ma dubito che si possa restituire una vista in instantiateItem e poi solo dopo che scarica la risorsa (nel AsyncTask). Quando il AsyncTask imposta l'immagine di sfondo, penso che sia troppo tardi, l'adattatore è già tornato la vista ...

Avrete probabilmente bisogno di invalidare la vista ad un certo punto ...