{"id":1249,"date":"2010-02-25T21:50:50","date_gmt":"2010-02-25T21:50:50","guid":{"rendered":"http:\/\/dalelane.co.uk\/blog\/?p=1249"},"modified":"2010-02-25T22:21:57","modified_gmt":"2010-02-25T22:21:57","slug":"why-i-havent-written-twittoday-for-android","status":"publish","type":"post","link":"https:\/\/dalelane.co.uk\/blog\/?p=1249","title":{"rendered":"Why I haven’t written TwitToday for Android"},"content":{"rendered":"

(or “looking at the limitations of the Android home screen widgets framework”)<\/h3>\n

\"Twitter<\/a>A couple of years ago, I wrote a Windows Mobile app called TwitToday<\/a> : a Twitter widget for the “Today screen” (the default screen when the phone is on, with all apps closed or minimised). <\/p>\n

The rationale was that it was useful to have a way to post a tweet quickly when you don’t want to have to wait for a full-blown client to start.<\/p>\n

Or if you don’t want to incur the battery or memory cost of leaving a client running all the time.
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\n\"A<\/a>Android has a “Home screen”, which is similar to the Today screen on Windows Mobile. And it has support for widgets<\/a>. This led several people to ask me why I never ported TwitToday to Android. <\/p>\n

The short answer is that I did try, but the current state of the widgets framework made it impossible. <\/p>\n

I tried to write a TwitToday widget back when the Android widgets framework was first introduced in Android 1.5<\/a>. <\/p>\n

It all started quite well: <\/p>\n

    \n
  1. I wrote the Android Service<\/a> that would carry out the background task of posting a tweet. No problems there – it worked fine.\n<\/li>\n
  2. I wrote the widget XML to define the GUI. This is what you can see running in the screenshot. And it works… sort of. It has a text box that you can type up to 140 characters into. And if you press the button, it causes a chunk of code to get invoked. <\/li>\n<\/ol>\n

    The problem came when I tried to link the two together: to get the Service that posts tweets to obtain the String from the text box in my widget. <\/p>\n

    This isn’t possible. Android’s widget framework as it currently stands is geared around displaying information to the user, not collecting user input. <\/p>\n

    The API access to widgets at runtime is to go through an intermediate layer called RemoteViews<\/a> – an Android mechanism that lets you implement a View within another process (in this case, the Home screen’s process). <\/p>\n

    Look at the Reference page for RemoteViews<\/a>. RemoteViews only provide “setter” methods. No “getter” methods. My code can set the text in the text box (so I could display tweets that I download from twitter.com). But it can’t get it. <\/p>\n

    So after the user types in their tweet, and presses the button, my code has no way to get the String that they typed in. <\/p>\n

    Dammit. <\/p>\n

    I haven’t seen this explained in the Android developer docs, but I should’ve guessed from the guide to creating App Widgets<\/a>: <\/p>\n

    … you must be aware that App Widget layouts are based on RemoteViews, which do not support every kind of layout or view widget. <\/p>\n

    A RemoteViews object (and, consequently, an App Widget) can support … the following widget classes: <\/p>\n