Enhance SD usage preference widget

[Guillaume Rosaire]

In http://www.opensatnav.org/issues/show/8#note-23, user willu asked for a more precise way of setting the max SD usage pref than with a slider.

> One more thing.... I have a 16G sd card. I want to allocate about 1G of space to the cache (including wasted formatting space - so about 2-300M on the slider). That is really hard to select on the slider. I think I'd prefer a different widget. Even text entry would be better.

We should have something like an editable textfield in sync with the slider or better.

[Will Uther (willu-mailinglists)]

It looks like revision 81 made some progress here. There is a problem with that implementation in that it doesn't move the slider when the text is updated. The following patch fixes this:

<pre>
diff --git a/src/com/hlidskialf/android/preference/SeekBarPreference.java b/src/com/hlidskialf/android/preference/SeekBarPreference.java
index e90b5d0..d735277 100644
--- a/src/com/hlidskialf/android/preference/SeekBarPreference.java
+++ b/src/com/hlidskialf/android/preference/SeekBarPreference.java
@@ -122,7 +122,7 @@ public class SeekBarPreference extends DialogPreference implements
   String t = String.valueOf(value);

   mValueText.setText(mSuffix == null ? t : t.concat(mSuffix));
- mValue = value;
+ setProgress(value);

   if (shouldPersist())
    persistInt(value);
</pre>

[Will Uther (willu-mailinglists)]

After a surprisingly long session to get this right, I think I have a better patch (this should be applied instead of the above). It does two things:
* Tries to get the UI right (Mb on the text iff you're not editing the text. Changes made through either method always change the other. Changes always save.)
* Modifies the slider so that it is non-linear and biased towards smaller sizes. The non-linearity is separated into its own methods, currently just sqrt().

This is all just UI work at this stage. I haven't looked at how it affects the on-disk storage (yet).

[Guillaume Rosaire (zerog)]

willu wrote:
> After a surprisingly long session to get this right...

I tried to have it right with the Mb suffix showing at startup but that took too much time indeed ^^, I left how it was at that time.

I thought about using a non linear slider but didn't try to implement it. I'll have a look at your patch this evening.

And indeed, the slider not updating when typing a value was something I didn't notice when testing, I should have seen it.

Thanks

[Guillaume Rosaire (zerog)]

Patch sdPrefs.patch applied in rev 84