From 2b15c001fa1f80ac7be7e2ddec40253d0ce7b4fb Mon Sep 17 00:00:00 2001
From: Roman Nurik Widgets are a feature introduced in Android 1.5. A widget displays an
-application's most important or timely information at a glance, on a user's Home
-screen. The standard Android system image includes several examples of widgets,
-including widgets for Analog Clock, Music, and other applications. Users pick the widgets they want to display on their Home screens by touching
-& holding an empty area of the Home screen, selecting Widgets from the menu,
-and then selecting the widget they want. This document describes how to design a widget so it fits graphically with
-other widgets and with the other elements of the Android Home screen. It also
-describes some standards for widget artwork and some widget graphics tips and
-tricks from the Android team.
-
- For information about developing widgets, see the AppWidgets section of
-the Developer's Guide and the AppWidgets blog post. App widgets (sometimes just "widgets") are a feature introduced in Android 1.5 and vastly
+improved in Android 3.0 and 3.1. A widget can display an application's most timely or otherwise
+relevant information at a glance, on a user's Home screen. The standard Android system image
+includes several widgets, including a widget for the Analog Clock, Music, and other
+applications. Typical Android widgets have three main components: A bounding box, a frame,
-and the widget's graphical controls and other elements. Well-designed widgets
-leave some padding between the edges of the bounding box and the frame, and
-between the inner edges of the frame and the widget's controls. Widgets designed
-to fit visually with other widgets on the Home screen take cues from the other
-elements on the Home screen for alignment; they also use standard shading
-effects. All of these details are described in this document.
- Standard Widget Sizes in Portrait Orientation Figure 1. Example app widgets in Android 4.0. Standard Widget Sizes in Landscape Orientation This document describes how to design a widget so that it fits graphically with other widgets and
+with the other elements of the Android Home screen such as launcher icons and shortcuts. It also
+describes some standards for widget artwork and some widget graphics tips and tricks.
- For information about developing widgets, see the App Widgets section of the Developer's
+Guide. Typical Android app widgets have three main components: A bounding box, a frame, and the widget's
+graphical controls and other elements. App widgets can contain a subset of the View widgets in
+Android; supported controls include text labels, buttons, and images. For a full list of available
+Views, see the Creating the
+App Widget Layout section in the Developer's Guide. Well-designed widgets leave some
+margins between the edges of the bounding box and the frame, and padding between the inner edges of
+the frame and the widget's controls. Figure 2. Widgets generally have margins between the
+bounding box and frame, and padding between the frame and widget controls. Note: As of Android 4.0, app widgets are automatically given
+margins between the widget frame and the app widget's bounding box to provide better alignment with
+other widgets and icons on the user's home screen. To take advantage of this strongly recommended
+behavior, set your application's targetSdkVersion to 14 or
+greater. Widgets designed to fit visually with other widgets on the Home screen take cues from the other
+elements on the Home screen for alignment; they also use standard shading effects. All of these
+details are described in this document. Each widget must define a While the width and height of a cell—as well as the amount of automatic margins applied to
+widgets—may vary across devices, you can use the table below to roughly estimate your widget's
+minimum dimensions, given the desired number of occupied grid cells: The most effective widgets display your application's most useful or timely
-data in the smallest widget size. Users will weigh the usefulness or your widget
-against the portion of the Home screen it covers, so the smaller the better. It is a good practice to be conservative with All widgets must fit within the bounding box of one of the six supported
-widget sizes, or better yet, within a pair of portrait and landscape orientation
-sizes, so your widget looks good when the user switches screen
-orientations. Standard widget sizes illustrates the bounding
-dimensions of the six widget sizes (three in portrait and three in landscape
-orientation). Figure 3. An example music player widget. Standard widget frames illustrates the standard frames
-for the six widget sizes, with links so you can download copies for your own
-use. You don't have to use these frames for your widget, but if you do, your
-widgets are more likely to fit visually with other widgets. Your minimum height should be the height of your two TextViews for the artist and title, plus
+some text margins. Your minimum width should be the minimum usable widths of the
+Play and Next buttons, plus the minimum text width (say, the width
+of 10 characters), plus any horizontal text margins. Again, you don't have to use this effect, but Standard
-widget shadows shows the Photoshop settings used for standard widgets. Figure 4. Example sizes and margins for
+ You can download a
-Photoshop file that contains the three states of the Play button, taken from
-the Music widget, to analyze the Photoshop settings used for the three standard
-button effects. Example calculations are below: Widget alignment tips and tricks describes some
-techniques for aligning your widget's graphics inside the standard frames, along
-with a few other widget graphics tricks. If there is any inherent content padding in your widget background nine-patch, you should add to
+ Windows graphics file format describes the correct
-settings for your widget graphics files. Widgets can be resized horizontally and/or vertically as of Android 3.1, meaning that
+ This is generally a preferred feature for collection widgets such as those based on {@link
+android.widget.ListView} or {@link android.widget.GridView}. There are six standard widget sizes, based on a Home screen grid of 4 x 4
-(portrait) or 4 x 4 (landscape) cells. These dimensions are the bounding boxes
-for the six standard widget sizes. The contents of typical widgets don't draw to
-the edge of these dimensions, but fit inside a frame withing the bounding box,
-as described in Designing a widget. In portrait orientation, each cell is 80 pixels wide by 100 pixels tall (the
-diagram shows a cell in portrait orientation). The three supported widget sizes
-in portrait orientation are:
+ As previously mentioned, Android 4.0 will automatically add small, standard margins to each edge
+of widgets on the Home screen, for applications that specify a It's easy to write a single layout that has custom margins applied for earlier versions of the
+platform, and has no extra margins for Android 4.0 and greater. See Adding Margins to App Widgets
+in the Developer's Guide for information on how to achieve this with layout XML. In landscape orientation, each cell is 106 pixels wide by 74 pixels tall. The
-three supported widget sizes in landscape orientation are: Most widgets will have a solid background rectangle or rounded rectangle shape. It is a best
+practice to define this shape using nine patches; one for each screen density (see Supporting Multiple Screens for details).
+Nine-patches can be created with the draw9patch tool, or simply with a
+graphics editing program such as Adobe® Photoshop. This will allow the widget background shape
+to take up the entire available space. The nine-patch should be edge-to-edge with no transparent
+pixels providing extra margins, save for perhaps a few border pixels for subtle
+drop shadows or other subtle effects. Note: Just like with controls in activities, you should ensure
+that interactive controls have distinct visual focused and pressed states using state list
+drawables. For each of the six standard widget sizes there is a standard frame. You can
-click the images of the frames in this section to download a Photoshop file for
-that frame, which you can use for your own widgets.
+ Figure 5. Nine-patch border pixels indicating stretchable
+regions and content padding. Some app widgets, such as those using a {@link android.widget.StackView}, have a transparent
+background. For this case, each individual item in the StackView should use a nine-patch background
+that is edge-to-edge with little or no border transparent pixels for margins. For the contents of the widget, you should use flexible layouts such as {@link
+android.widget.RelativeLayout}, {@link android.widget.LinearLayout}, or {@link
+android.widget.FrameLayout}. Just as your activity layouts must adapt to different physical screen
+sizes, widget layouts must adapt to different Home screen grid cell sizes. Below is an example layout that a music widget showing text information and two buttons can use.
+It builds upon the previous discussion of adding margins depending on OS version. You can apply a shadow effect to your widget's artwork, so it matches other
-standard Android widgets, using the following settings in the Photoshop Layer
-Style dialog box. If you now take a look at the example music widget from the previous section, you can begin to
+use flexible layouts attributes like so: The Android team has developed a few tricks for aligning widget artwork
-within standard widget bounding boxes and frames, so the widget aligns visually
-with other widgets and the other elements of the Home screen, as well as other
-techniques for creating widgets.
+ Figure 6. Excerpt flexible layouts and attributes. Cut the widget artwork asset" based on the full size of a cell, including any
-padding you want. (That is, for a 4 x 1 widget, cut the asset at 320 by 100
-pixels.) When a user adds the widget to their home screen, on an example Android 4.0 device where each
+grid cell is 80dp × 100dp in size and 16dp of margins are automatically applied on all sizes,
+the widget will be stretched, like so: Figure 7. Music widget sitting on an example 80dp x 100dp
+grid with 16dp of automatic margins added by the system. Note: The current Android widget templates were designed
-using a custom gradient angle, which means the 9-patch techniques can't be used
-to optimize the size of the asset. However, 9-patch techniques were used to set
-the content area padding. When starting to design a new widget, or updating an existing widget, it's a good idea to first
+look at the widget design templates below. The downloadable package below includes nine-patch
+background graphics, XML, and source Adobe® Photoshop files for multiple screen densities, OS
+version widget styles, and widget colors. The template package also contains graphics useful for
+making your entire widget or parts of your widget (e.g. buttons) interactive. Save your widget artwork using the appropriate bounding box size in PNG-24
-format on a transparent background and in 8-bit color. Figure 8. Excerpts from the App Widget Templates Pack
+(medium-density, dark, Android 4.0/previous styles, default/focused/pressed states). You can obtain the latest App Widget Templates Pack archive using the link below:Quickview
-
In this document
-
+
+Downloads
+
+
See also
-
Standard widget anatomy
+
-
-
-
Designing a widget
+
-
+Standard Widget Anatomy
+
+
+
+Determining a size for your widget
+
+minWidth and minHeight, indicating the
+minimum amount of space it should consume by default. When users add a widget to their Home screen,
+it will generally occupy more than the minimum width and height you specify. Android Home screens
+offer users a grid of available spaces into which they can place widgets and icons. This grid can
+vary by device; for example, many handsets offer a 4x4 grid, and tablets can offer a larger, 8x7
+grid. When your widget is added, it will be stretched to occupy the minimum number of cells,
+horizontally and vertically, required to satisfy its minWidth and
+minHeight constraints. As we discuss in Designing Widget
+Layouts and Background Graphics below, using nine-patch backgrounds and flexible layouts for app
+widgets will allow your widget to gracefully adapt to the device's Home screen grid and remain
+usable and aesthetically awesome.
+
+
-
+
+
+
+ # of Cells
+
(Columns or Rows)Available Size (dp)
+
(minWidth or
+ minHeight)
+
+ 1
+ 40dp
+
+
+ 2
+ 110dp
+
+
+ 3
+ 180dp
+
+
+ 4
+ 250dp
+
+
+ …
+ …
+
+
+
+n
+ 70 × n − 30
+ minWidth and minHeight,
+specifying the minimum size that renders the widget in a good default state. For an example of how
+to provide a minWidth and minHeight, suppose you have a music player
+widget that shows the currently playing song artist and title (vertically stacked), a
+Play button, and a Next button:
+
-minWidth/minHeight calculations. We chose 144dp as an example good minimum
+width for the text labels.
+
-minWidth = 144dp + (2 × 8dp) + (2 × 56dp) =
+ 272dpminHeight = 48dp + (2 × 4dp) = 56dpminWidth and minHeight accordingly.Resizable widgets
+minWidth and minHeight effectively become the default size for
+the widget. You can specify the minimum widget size using minResizeWidth and
+minResizeHeight; these values should specify the size below which the widget would be
+illegible or otherwise unusable.Standard widget sizes
+Adding margins to your app widget
-
-
+
-Cells Pixels
-4 x 1 320 x 100
-3 x 3 240 x 300
-2 x 2 160 x 200 targetSdkVersion of 14
+or greater. This helps to visually balance the Home screen, and thus we recommend that you
+do not add any extra margins outside of your app widget's background shape in Android
+4.0.
-
+
-Cells Pixels
-4 x 1 424 x 74
-3 x 3 318 x 222
-2 x 2 212 x 148 Designing Widget Layouts and Background Graphics
-
Standard widget frames
-
-
4x1_Widget_Frame_Landscape.psd
3x3_Widget_Frame_Landscape.psd
2x2_Widget_Frame_Landscape.psd
+<FrameLayout
+ android:layout_width="match_parent"
+ android:layout_height="match_parent"
+ android:layout_margin="@dimen/widget_margin">
+ <LinearLayout
+ android:layout_width="match_parent"
+ android:layout_height="match_parent"
+ android:orientation="horizontal"
+ android:background="@drawable/my_widget_background">
-
+Standard widget shadows
+ <TextView
+ android:id="@+id/song_info"
+ android:layout_width="0dp"
+ android:layout_height="match_parent"
+ android:layout_weight="1" />
-
Widget graphics tips and tricks
-
-
+
+
-
Using the App Widget Templates Pack
-XML:. This
-technique references the original artwork, in this case
-"background.9.png", and instructs the device to dither it as
-needed.Widget graphics file format
-
-
Descendants of these classes are not supported.
+Widgets should not generally extend to screen edges and should not visually be flush with other widgets, so you should add margins on all sides around your widget frame.
+ +As of Android 4.0, app widgets are automatically given padding between the widget frame and the app widget's bounding box to provide better alignment with other widgets and icons on the user's home screen. To take advantage of this strongly recommended behavior, set your application's targetSdkVersion to 14 or greater.
+ +It's easy to write a single layout that has custom margins applied for earlier versions of the platform, and has no extra margins for Android 4.0 and greater:
+ +targetSdkVersion to 14 or greater.+<FrameLayout + android:layout_width="match_parent" + android:layout_height="match_parent" + android:layout_margin="@dimen/widget_margin"> + + <LinearLayout + android:layout_width="match_parent" + android:layout_height="match_parent" + android:orientation="horizontal" + android:background="@drawable/my_widget_background"> + … + </LinearLayout> + +</FrameLayout> ++ +
res/values/ to provide the pre-Android 4.0 custom margins, and one in res/values-v14/ to provide no extra padding for Android 4.0 widgets:
+
+ res/values/dimens.xml:
+
<dimen name="widget_margin">15dp</dimen>+ +
res/values-v14/dimens.xml:
+
<dimen name="widget_margin">0dp</dimen>+
Another option is to simply build extra margins into your nine-patch background assets by default, and provide different nine-patches with no margins for API level 14 or later.
+ +