DEVELOPING DIFFERENT SCREEN SIZES ANDROID

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Developing For Different Screen Sizes

Android Development Tutorial

Android powers hundreds of device types with several different screen sizes, ranging from small phones to large TV sets. Therefore, it’s important that you design your application to be compatible with all screen sizes so it’s available to as many users as possible.

But being compatible with different device types is not enough. Each screen size offers different possibilities and challenges for user interaction, so in order to truly satisfy and impress your users, your application must go beyond merely supporting multiple screens: it must optimize the user experience for each screen configuration.

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Supporting Multiple Screens

• Explicitly declare in the manifest which screen sizes your application supports

  By declaring which screen sizes your application supports, you can ensure that only devices with the screens you support can download your application. Declaring support for different screen sizes can also affect how the system draws your application on larger screens—specifically, whether your application runs in screen compatibility mode.
  To declare the screen sizes your application supports, you should include the <supports-screens> element in your manifest file.

• Provide different layouts for different screen sizes

  By default, Android resizes your application layout to fit the current device screen. In most cases, this works fine. In other cases, your UI might not look as good and might need adjustments for different screen sizes. For example, on a larger screen, you might want to adjust the position and size of some elements to take advantage of the additional screen space, or on a smaller screen, you might need to adjust sizes so that everything can fit on the screen.
  The configuration qualifiers you can use to provide size-specific resources are small, normal, large, and xlarge. For example, layouts for an extra large screen should go in layout-xlarge/.
  Beginning with Android 3.2 (API level 13), the above size groups are deprecated and you should instead use thesw<N>dp configuration qualifier to define the smallest available width required by your layout resources. For example, if your multi-pane tablet layout requires at least 600dp of screen width, you should place it in layout-sw600dp/. Using the new techniques for declaring layout resources is discussed further in the section about Declaring Tablet Layouts for Android 3.2.

• Provide different bitmap drawables for different screen densities

  By default, Android scales your bitmap drawables (.png, .jpg, and .gif files) and Nine-Patch drawables (.9.pngfiles) so that they render at the appropriate physical size on each device. For example, if your application provides bitmap drawables only for the baseline, medium screen density (mdpi), then the system scales them up when on a high-density screen, and scales them down when on a low-density screen. This scaling can cause artifacts in the bitmaps. To ensure your bitmaps look their best, you should include alternative versions at different resolutions for different screen densities.
  The configuration qualifiers you can use for density-specific resources are ldpi (low), mdpi (medium), hdpi (high), and xhdpi (extra high). For example, bitmaps for high-density screens should go in drawable-hdpi/.

The size and density configuration qualifiers correspond to the generalized sizes and densities described in Range of screens supported, above.

Note: If you're not familiar with configuration qualifiers and how the system uses them to apply alternative resources, readProviding Alternative Resources for more information.

At runtime, the system ensures the best possible display on the current screen with the following procedure for any given resource:

1. The system uses the appropriate alternative resource Based on the size and density of the current screen, the system uses any size- and density-specific resource provided in your application. For example, if the device has a high-density screen and the application requests a drawable resource, the system looks for a drawable resource directory that best matches the device configuration. Depending on the other alternative resources available, a resource directory with the hdpi qualifier (such as drawable-hdpi/) might be the best match, so the system uses the drawable resource from this directory.
2. If no matching resource is available, the system uses the default resource and scales it up or down as needed to match the current screen size and density The "default" resources are those that are not tagged with a configuration qualifier. For example, the resources in drawable/ are the default drawable resources. The system assumes that default resources are designed for the baseline screen size and density, which is a normal screen size and a medium density. As such, the system scales default density resources up for high-density screens and down for low-density screens, as appropriate.

Screen characteristic	Qualifier	Description
Size	small	Resources for small size screens.
	normal	Resources for normal size screens. (This is the baseline size.)
	large	Resources for large size screens.
	xlarge	Resources for extra large size screens.
Density	ldpi	Resources for low-density (ldpi) screens (~120dpi).
	mdpi	Resources for medium-density (mdpi) screens (~160dpi). (This is the baseline density.)
	hdpi	Resources for high-density (hdpi) screens (~240dpi).
	xhdpi	Resources for extra high-density (xhdpi) screens (~320dpi).
	nodpi	Resources for all densities. These are density-independent resources. The system does not scale resources tagged with this qualifier, regardless of the current screen's density.
	tvdpi	Resources for screens somewhere between mdpi and hdpi; approximately 213dpi. This is not considered a "primary" density group. It is mostly intended for televisions and most apps shouldn't need it—providing mdpi and hdpi resources is sufficient for most apps and the system will scale them as appropriate. If you find it necessary to provide tvdpi resources, you should size them at a factor of 1.33*mdpi. For example, a 100px x 100px image for mdpi screens should be 133px x 133px for tvdpi.
Orientation	land	Resources for screens in the landscape orientation (wide aspect ratio).
	port	Resources for screens in the portrait orientation (tall aspect ratio).
Aspect ratio	long	Resources for screens that have a significantly taller or wider aspect ratio (when in portrait or landscape orientation, respectively) than the baseline screen configuration.
	notlong	Resources for use screens that have an aspect ratio that is similar to the baseline screen configuration.

You need to create different layout for diff screen size. Support all screen you need to create following layout: Low density Small screens QVGA 240x320 (120dpi): layout-small-ldpi (240x320) layout-small-land-ldpi (320x240) Low density Normal screens WVGA400 240x400 (x432) (120dpi): layout-ldpi (240 x 400 ) layout-land-ldpi (400 x 240 ) Medium density Normal screens HVGA 320x480 (160dpi): layout-mdpi (320 x 480 ) layout-land-mdpi (480 x 320 ) Medium density Large screens HVGA 320x480 (160dpi): layout-large-mdpi (320 x 480 ) layout-large-land-mdpi (480 x 320) Galaxy Tab ( 240 dpi ): layout-large (600 x 1024) layout-large-land (1024 x 600) High density Normal screens WVGA800 480x800 (x854) (240 dpi): layout-hdpi (480 x 800) layout-land-hdpi (800 x 480) Xoom (medium density large but 1280x800 res) (160 dpi): layout-xlarge (800 x 1280) layout-xlarge-land (1280 x 800) Also add following code in .manifest file: <supports-screens android:smallScreens="true" android:normalScreens="true" android:largeScreens="true" android:xlargeScreens="true" android:anyDensity="true" />