使用LevelListDrawable实现Html.fromHtml多张图片显示

stackoverflow网站果然强大，帮了我不少忙！

http://stackoverflow.com/questions/16179285/html-imagegetter-textview

首先一段html字符串

String source = "this is a test of <b>ImageGetter</b> it contains " +
"two images: <br/>" +
"<img src=\"http://developer.android.com/assets/images/dac_logo.png\"><br/>and<br/>" +
"<img src=\"http://developer.android.com/assets/images/icon_search.png\">";

然后ImageGetter里面的getDrawable（String souce）方法里面实现

LevelListDrawable d = new LevelListDrawable();
Drawable empty = getResources().getDrawable(R.drawable.ic_launcher);
d.addLevel(0, 0, empty);
d.setBounds(0, 0, empty.getIntrinsicWidth(), empty.getIntrinsicHeight());

new LoadImage().execute(source, d);

这里的LodImage类是一个异步加载类，详见代码了

class LoadImage extends AsyncTask<Object, Void, Bitmap> {

private LevelListDrawable mDrawable;

@Override
protected Bitmap doInBackground(Object... params) {
String source = (String) params[0];
mDrawable = (LevelListDrawable) params[1];
Log.d(TAG, "doInBackground " + source);
try {
InputStream is = new URL(source).openStream();
return BitmapFactory.decodeStream(is);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

@Override
protected void onPostExecute(Bitmap bitmap) {
Log.d(TAG, "onPostExecute drawable " + mDrawable);
Log.d(TAG, "onPostExecute bitmap " + bitmap);
if (bitmap != null) {
BitmapDrawable d = new BitmapDrawable(bitmap);
mDrawable.addLevel(1, 1, d);
mDrawable.setBounds(0, 0, bitmap.getWidth(), bitmap.getHeight());
mDrawable.setLevel(1);
// i don't know yet a better way to refresh TextView
// mTv.invalidate() doesn't work as expected
CharSequence t = mTv.getText();
mTv.setText(t);
}
}
}

目前还不是很了解这个LevelListDrawable，不知道这个
addLevel
(int low, int high,
Drawable
drawable)里的low和hight有什么用途，但是官网有个例子

<level-list xmlns:android="http://schemas.android.com/apk/res/android">
<item android:maxLevel="0" android:drawable="@drawable/ic_wifi_signal_1" />
<item android:maxLevel="1" android:drawable="@drawable/ic_wifi_signal_2" />
<item android:maxLevel="2" android:drawable="@drawable/ic_wifi_signal_3" />
<item android:maxLevel="3" android:drawable="@drawable/ic_wifi_signal_4" />
</level-list>

可能和这里的maxLevel有关，官网说android的手机充电的效果图就是使用这个类实现的，然后循环实现LevelListDrawable.setLevel(int)方法的。