Android home screen widget textsize dynamically

Question

There are applications that offer the ability to change the font size of a text in a home screen widget. One example is https://play.google.com/store/apps/details?id=org.zooper.zwfree

However home screen widgets only can carry RemoteViews so setting the textSize of a TextView dynamically will not work.

As I see it there are two possibilities to change the text size dynamically:

• Add for every text size another layout.xml file. Those files merely differ in the TextView's textSize value. When the user wants to change the textsize, the respective layout has to be loaded.

• Draw a Bitmap instead of creating a View like here https://stackoverflow.com/a/4411060/883083

My question is: Is there a third possibility left?

Answer 1

If you're targeting API level 16 or above, you can try the following:

Sadly the whole thing depends on knowing the widget size, which is only possible in API 16+.

1. Override the AppWidgetProvider.onAppWidgetOptionsChanged callback
   or get the same Bundle later via AppWidgetManager.getAppWidgetOptions
2. Extract the size of the widget:
   • options.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_WIDTH)
   • options.getInt(AppWidgetManager.OPTION_APPWIDGET_MAX_WIDTH)
   • options.getInt(AppWidgetManager.OPTION_APPWIDGET_MIN_HEIGHT)
   • options.getInt(AppWidgetManager.OPTION_APPWIDGET_MAX_HEIGHT)
3. Deduce your TextView's width from the widget size
   (best if you have it match_parent to the root of the widget, mind margins/paddings)
   
4. If you have complex layout you can alternatively
   • inflate the whole widget in your app space
     widget = LayoutInflater.from(context).inflate(R.layout.widget, null)
   • Simulate a layout based on the framework:
     widget.measure(MeasureSpec.makeMeasureSpec(widgetWidth, MeasureSpec.EXACTLY), ...).
   • Get your TextView's size: widget.findViewById(R.id.myText).getMeasuredWidth()
5. Use something like refitText here to find your optimal size
6. Set the calculated size via RemoteViews.setTextViewTextSize

Note: I didn't implement this method, just thought about it.

Try not to do this on every update, cache the results (even in preferences), widget options shouldn't change often.