App Components (HowTo)

Activities

TODO

Widgets

We are using Widgets as they are defined in googles documentation: developer.android.com/guide/topics/appwidgets

more information

Structure

Java
.../widgets/<title>Widget.java	Manages the lifecycle of the widget and updates the content.
.../widgets/<title>WidgetConfigureActivity.java	If the widget needs any configuration this Activity is used. It can be opened whenever a new widget is created or via an intend(optional)
.../widgets/<title>WidgetService.java	Manages the collection view items in a adapter like manner (optional).
Res
.../drawable/widget_<title>_preview.png	Preview image of the widget, is shown when the user wants to add a widget to the homescreen.
.../layout/<title>_widget.xml	The main layout of the widget, you can only use items here, that work with widgets.
.../layout/activity_<title>_widget_configuration.xml	The layout of the widget configuration activity (optional).
.../layout/<title>_widget_item.xml	If you are using a collection view, the item layout is defined here (optional)
.../xml/<title>_widget_info.xml	The configuration file of the widget (See widget configuration).

Available Views

• Layouts: FrameLayout, LinearLayout and RelativeLayout.
• Views: AnalogClock, Button, Chromometer, ImageButton, ImageView, ProgressBar and TextView.
• Adapter Views: GridView, ListView, StackView, ViewFlipper and AdapterViewFlipper (These require a collection view widget).

Widget Configuration

Example Configuration

<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:initialKeyguardLayout="@layout/timetable_widget"
    android:initialLayout="@layout/timetable_widget"
    android:minHeight="110dp"
    android:minResizeHeight="60dp"
    android:minResizeWidth="220dp"
    android:minWidth="250dp"
    android:previewImage="@drawable/widget_timetable_preview"
    android:resizeMode="horizontal|vertical"
    android:updatePeriodMillis="15000"
    android:widgetCategory="home_screen|keyguard"
    tools:targetApi="jelly_bean_mr1" />

Interesting Configuration Items

• android:initialLayout: The main layout file of the widget
• android:previewImage: The preview image of the widget
• android:widgetCategory: Where this widget can be used, eg. homescreen and keyguard (=lockscreen)
• android:resizeMode: In which directions the widget can be resized
• android:min(Resize)Width/Height: The size boundaries of the widget
• android:updatePeriodMillis: How often the system should refresh the data on the widget in ms (this wakes the device, so if you have to update more then every hour user androids alarm functionalities)