I've done something very similar (I think) to what you want to do. What I needed to do back then is parse the HTML and set it up back to TextView and I needed to use Html.ImageGetter as well and having the same problem on fetching image on the main thread.
The steps that I did basically:
- Create my own subclass for Drawable to facilitate redraw, I called it URLDrawable
- Return the
URLDrawable in getDrawable method of Html.ImageGetter
- Once
onPostExecute is called, I redraw the container of the Spanned result
Now the code for URLDrawable is as follow
public class URLDrawable extends BitmapDrawable {
// the drawable that you need to set, you could set the initial drawing
// with the loading image if you need to
protected Drawable drawable;
@Override
public void draw(Canvas canvas) {
// override the draw to facilitate refresh function later
if(drawable != null) {
drawable.draw(canvas);
}
}
}
Simple enough, I just override draw so it would pick the Drawable that I set over there after AsyncTask finishes.
The following class is the implementation of Html.ImageGetter and the one that fetches the image from AsyncTask and update the image
public class URLImageParser implements ImageGetter {
Context c;
View container;
/***
* Construct the URLImageParser which will execute AsyncTask and refresh the container
* @param t
* @param c
*/
public URLImageParser(View t, Context c) {
this.c = c;
this.container = t;
}
public Drawable getDrawable(String source) {
URLDrawable urlDrawable = new URLDrawable();
// get the actual source
ImageGetterAsyncTask asyncTask =
new ImageGetterAsyncTask( urlDrawable);
asyncTask.execute(source);
// return reference to URLDrawable where I will change with actual image from
// the src tag
return urlDrawable;
}
public class ImageGetterAsyncTask extends AsyncTask<String, Void, Drawable> {
URLDrawable urlDrawable;
public ImageGetterAsyncTask(URLDrawable d) {
this.urlDrawable = d;
}
@Override
protected Drawable doInBackground(String... params) {
String source = params[0];
return fetchDrawable(source);
}
@Override
protected void onPostExecute(Drawable result) {
// set the correct bound according to the result from HTTP call
urlDrawable.setBounds(0, 0, 0 + result.getIntrinsicWidth(), 0
+ result.getIntrinsicHeight());
// change the reference of the current drawable to the result
// from the HTTP call
urlDrawable.drawable = result;
// redraw the image by invalidating the container
URLImageParser.this.container.invalidate();
}
/***
* Get the Drawable from URL
* @param urlString
* @return
*/
public Drawable fetchDrawable(String urlString) {
try {
InputStream is = fetch(urlString);
Drawable drawable = Drawable.createFromStream(is, "src");
drawable.setBounds(0, 0, 0 + drawable.getIntrinsicWidth(), 0
+ drawable.getIntrinsicHeight());
return drawable;
} catch (Exception e) {
return null;
}
}
private InputStream fetch(String urlString) throws MalformedURLException, IOException {
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpGet request = new HttpGet(urlString);
HttpResponse response = httpClient.execute(request);
return response.getEntity().getContent();
}
}
}
Finally, below is the sample program to demonstrate how things work:
String html = "Hello " +
"<img src='http://www.gravatar.com/avatar/" +
"f9dd8b16d54f483f22c0b7a7e3d840f9?s=32&d=identicon&r=PG'/>" +
" This is a test " +
"<img src='http://www.gravatar.com/avatar/a9317e7f0a78bb10a980cadd9dd035c9?s=32&d=identicon&r=PG'/>";
this.textView = (TextView)this.findViewById(R.id.textview);
URLImageParser p = new URLImageParser(textView, this);
Spanned htmlSpan = Html.fromHtml(html, p, null);
textView.setText(htmlSpan);
