Android - Class Html - fromHtml - How does it work?

Question

I'm using Html.fromHtml to get the contents of a description tag (in a feed XML) and it works fine

Description tag:

<description><![CDATA[<div class="K2FeedIntroText"><p><img style="margin: 10px; float: left;" alt="block curta" src="http://loc.grupolusofona.pt/images/stories/destaques/block%20curta.jpg" height="110" width="120" />Quatro Horas Descalço é o nome da curta-metragem, realizada por Ico Costa, que se estreia mundialmente no 7.º Festival Internacional de Cinema de Roma, nos dias 12 e 13 de novembro, em competição no Cinema XXI.</p>

]]>

But as I go look into the documentation it says:

Returns displayable styled text from the provided HTML string. Any <img> tags in the HTML will display as a generic replacement image which your program can then go through and replace with real images.

So my question is: how can i do what it says there "which your program can then go through and replace with the real image" ?

I know how to get the img url via RegEx using a Pattern, i just wanted to know how can i use the class to "go through and replace it with the image"

Please say something if i was unclear and ill try to explain it better.

EDIT:

Well, i'm trying to implement this in a simple rss reader (and trying to keep it as simple as possible code-wise)

I'm using a DOM Parser and i'm using a map = HashMap<String, Spanned> to store the values of each child node, along with a KEY:

map.put(KEY_DESC, Html.fromHtml(parser.getValue(e, KEY_DESC)));

In the comments of the answer i found a useful link from which i created a new Class (URLImageParser) and tried to use it like so:

map.put(KEY_DESC, htmlSpan);

Where htmlSpan would be the result of:

this.textView = (TextView)this.findViewById(R.id.textview);
URLImageParser p = new URLImageParser(textView, this);
Spanned htmlSpan = Html.fromHtml(html, p, null);
textView.setText(htmlSpan);

I also created a android:visibility="gone" TextView just in case it needed to store the values in a TextView (maybe i interpreted it wrong)

My original thought was that htmlSpan was of the type Spanned so it would fit in my HashMap just fine.

For uploading to ListView i'm using a SimpleAdapter like so:

    ListAdapter adapter = new SimpleAdapter(this, menuItems, R.layout.linhafeed, 
            new String[] { KEY_TITLE, KEY_DESC, KEY_PUBDATE, KEY_LINK },
            new int[] { R.id.title, R.id.desc, R.id.pub, R.id.link });

Where menuItems is ArrayList<HashMap<String,Spanned>>

Something i got wrong here ?

Answer 1

Html.fromHtml(...) will replace any <img ... /> tag with an ImageSpan and a special 'object replacement character' (\uFFFC).

To get the actual image to show up, it looks like there are two options:

• implement an ImageGetter that returns the image to display as a Drawable. If I recall correctly, this won't allow you to offload the image loading to a different thread, because it expects the result to be returned right away. Hence, this should suffice for local resources (and probably also any assets in a device's local storage, provided there are no potentially long-running operations required; i.e. scaling, cropping, applying effects etc).
• do a second pass over the Spanned result and replace any \uFFFC occurrences. You should be able to get the source (url) of the image from every ImageSpan using the getSource() method. Unfortunately, it doesn't look there are any setters to update the Drawable once loaded, so I'm guessing you may need to replace the ImageSpan with a new one, passing in the loaded image in the constructor.

A third alternative, which may be a bit more heavy-weight than above, is to use a WebView rather than a TextView. That way you don't have to deal with any of the image loading yourself, as it's built into the widget.