Providing Resources :: آموزش برنامه نویسی اندروید

Providing Resources

دوشنبه, ۲ مرداد ۱۳۹۱، ۰۳:۳۷ ب.ظ

Grouping Resource Types

You should place each type of resource in a specific subdirectory of your project's res/ directory. For example, here's the file hierarchy for a simple project:

MyProject/
    src/  
        MyActivity.java  
    res/
        drawable/  
            icon.png  
        layout/  
            main.xml
            info.xml
        values/  
            strings.xml

As you can see in this example, the res/ directory contains all the resources (in subdirectories): an image resource, two layout resources, and a string resource file. The resource directory names are important and are described in table 1.

Table 1. Resource directories supported inside project res/ directory.

Directory	Resource Type
`animator/`	XML files that define property animations.
`anim/`	XML files that define tween animations. (Property animations can also be saved in this directory, but the `animator/` directory is preferred for property animations to distinguish between the two types.)
`color/`	XML files that define a state list of colors. See Color State List Resource
`drawable/`	Bitmap files (`.png`, `.9.png`, `.jpg`, `.gif`) or XML files that are compiled into the following drawable resource subtypes: Bitmap files Nine-Patches (re-sizable bitmaps) State lists Shapes Animation drawables Other drawables See Drawable Resources.
`layout/`	XML files that define a user interface layout. See Layout Resource.
`menu/`	XML files that define application menus, such as an Options Menu, Context Menu, or Sub Menu. See Menu Resource.
`raw/`	Arbitrary files to save in their raw form. To open these resources with a raw `InputStream`, call `Resources.openRawResource()` with the resource ID, which is `R.raw.filename`. However, if you need access to original file names and file hierarchy, you might consider saving some resources in the `assets/` directory (instead of `res/raw/`). Files in `assets/` are not given a resource ID, so you can read them only using `AssetManager`.
`values/`	XML files that contain simple values, such as strings, integers, and colors. Whereas XML resource files in other `res/` subdirectories define a single resource based on the XML filename, files in the `values/` directory describe multiple resources. For a file in this directory, each child of the `<resources>` element defines a single resource. For example, a `<string>` element creates an `R.string` resource and a `<color>` element creates an `R.color` resource. Because each resource is defined with its own XML element, you can name the file whatever you want and place different resource types in one file. However, for clarity, you might want to place unique resource types in different files. For example, here are some filename conventions for resources you can create in this directory: arrays.xml for resource arrays (typed arrays). colors.xml for color values dimens.xml for dimension values. strings.xml for string values. styles.xml for styles. See String Resources, Style Resource, and More Resource Types.
`xml/`	Arbitrary XML files that can be read at runtime by calling `Resources.getXML()`. Various XML configuration files must be saved here, such as a searchable configuration.

Caution: Never save resource files directly inside the res/ directory—it will cause a compiler error.

For more information about certain types of resources, see the Resource Types documentation.

The resources that you save in the subdirectories defined in table 1 are your "default" resources. That is, these resources define the default design and content for your application. However, different types of Android-powered devices might call for different types of resources. For example, if a device has a larger than normal screen, then you should provide different layout resources that take advantage of the extra screen space. Or, if a device has a different language setting, then you should provide different string resources that translate the text in your user interface. To provide these different resources for different device configurations, you need to provide alternative resources, in addition to your default resources.

Providing Alternative Resources

Figure 1. Two different devices, each using different layout resources.

Almost every application should provide alternative resources to support specific device configurations. For instance, you should include alternative drawable resources for different screen densities and alternative string resources for different languages. At runtime, Android detects the current device configuration and loads the appropriate resources for your application.

To specify configuration-specific alternatives for a set of resources:

Create a new directory in res/ named in the form <resources_name>-<config_qualifier>.
- <resources_name> is the directory name of the corresponding default resources (defined in table 1).
- <qualifier> is a name that specifies an individual configuration for which these resources are to be used (defined in table 2).
You can append more than one <qualifier>. Separate each one with a dash.

Caution: When appending multiple qualifiers, you must place them in the same order in which they are listed in table 2. If the qualifiers are ordered wrong, the resources are ignored.
Save the respective alternative resources in this new directory. The resource files must be named exactly the same as the default resource files.

For example, here are some default and alternative resources:

res/
    drawable/   
        icon.png
        background.png    
    drawable-hdpi/  
        icon.png
        background.png

The hdpi qualifier indicates that the resources in that directory are for devices with a high-density screen. The images in each of these drawable directories are sized for a specific screen density, but the filenames are exactly the same. This way, the resource ID that you use to reference the icon.png or background.png image is always the same, but Android selects the version of each resource that best matches the current device, by comparing the device configuration information with the qualifiers in the resource directory name.

Android supports several configuration qualifiers and you can add multiple qualifiers to one directory name, by separating each qualifier with a dash. Table 2 lists the valid configuration qualifiers, in order of precedence—if you use multiple qualifiers for a resource directory, you must add them to the directory name in the order they are listed in the table.

Table 2. Configuration qualifier names.

Configuration	Qualifier Values	Description
MCC and MNC	Examples: `mcc310` `mcc310-mnc004` `mcc208-mnc00` etc.	The mobile country code (MCC), optionally followed by mobile network code (MNC) from the SIM card in the device. For example, `mcc310` is U.S. on any carrier, `mcc310-mnc004` is U.S. on Verizon, and `mcc208-mnc00` is France on Orange. If the device uses a radio connection (GSM phone), the MCC and MNC values come from the SIM card. You can also use the MCC alone (for example, to include country-specific legal resources in your application). If you need to specify based on the language only, then use the language and region qualifier instead (discussed next). If you decide to use the MCC and MNC qualifier, you should do so with care and test that it works as expected. Also see the configuration fields `mcc`, and `mnc`, which indicate the current mobile country code and mobile network code, respectively.
Language and region	Examples: `en` `fr` `en-rUS` `fr-rFR` `fr-rCA` etc.	The language is defined by a two-letter ISO 639-1 language code, optionally followed by a two letter ISO 3166-1-alpha-2 region code (preceded by lowercase "`r`"). The codes are not case-sensitive; the `r` prefix is used to distinguish the region portion. You cannot specify a region alone. This can change during the life of your application if the user changes his or her language in the system settings. See Handling Runtime Changes for information about how this can affect your application during runtime. See Localization for a complete guide to localizing your application for other languages. Also see the `locale` configuration field, which indicates the current locale.
smallestWidth	`sw<N>dp` Examples: `sw320dp` `sw600dp` `sw720dp` etc.	The fundamental size of a screen, as indicated by the shortest dimension of the available screen area. Specifically, the device's smallestWidth is the shortest of the screen's available height and width (you may also think of it as the "smallest possible width" for the screen). You can use this qualifier to ensure that, regardless of the screen's current orientation, your application's has at least `<N>` dps of width available for it UI. For example, if your layout requires that its smallest dimension of screen area be at least 600 dp at all times, then you can use this qualifer to create the layout resources, `res/layout-sw600dp/`. The system will use these resources only when the smallest dimension of available screen is at least 600dp, regardless of whether the 600dp side is the user-perceived height or width. The smallestWidth is a fixed screen size characteristic of the device; the device's smallestWidth does not change when the screen's orientation changes. The smallestWidth of a device takes into account screen decorations and system UI. For example, if the device has some persistent UI elements on the screen that account for space along the axis of the smallestWidth, the system declares the smallestWidth to be smaller than the actual screen size, because those are screen pixels not available for your UI. Thus, the value you use should be the actual smallest dimension required by your layout (usually, this value is the "smallest width" that your layout supports, regardless of the screen's current orientation). Some values you might use here for common screen sizes: 320, for devices with screen configurations such as: 240x320 ldpi (QVGA handset) 320x480 mdpi (handset) 480x800 hdpi (high density handset) 480, for screens such as 480x800 mdpi (tablet/handset). 600, for screens such as 600x1024 mdpi (7" tablet). 720, for screens such as 720x1280 mdpi (10" tablet). When your application provides multiple resource directories with different values for the smallestWidth qualifier, the system uses the one closest to (without exceeding) the device's smallestWidth. Added in API level 13. Also see the `android:requiresSmallestWidthDp` attribute, which declares the minimum smallestWidth with which your application is compatible, and the `smallestScreenWidthDp` configuration field, which holds the device's smallestWidth value. For more information about designing for different screens and using this qualifier, see the Supporting Multiple Screens developer guide.
Available width	`w<N>dp` Examples: `w720dp` `w1024dp` etc.	Specifies a minimum available screen width, in `dp` units at which the resource should be used—defined by the `<N>` value. This configuration value will change when the orientation changes between landscape and portrait to match the current actual width. When your application provides multiple resource directories with different values for this configuration, the system uses the one closest to (without exceeding) the device's current screen width. The value here takes into account screen decorations, so if the device has some persistent UI elements on the left or right edge of the display, it uses a value for the width that is smaller than the real screen size, accounting for these UI elements and reducing the application's available space. Added in API level 13. Also see the `screenWidthDp` configuration field, which holds the current screen width. For more information about designing for different screens and using this qualifier, see the Supporting Multiple Screens developer guide.
Available height	`h<N>dp` Examples: `h720dp` `h1024dp` etc.	Specifies a minimum available screen height, in "dp" units at which the resource should be used—defined by the `<N>` value. This configuration value will change when the orientation changes between landscape and portrait to match the current actual height. When your application provides multiple resource directories with different values for this configuration, the system uses the one closest to (without exceeding) the device's current screen height. The value here takes into account screen decorations, so if the device has some persistent UI elements on the top or bottom edge of the display, it uses a value for the height that is smaller than the real screen size, accounting for these UI elements and reducing the application's available space. Screen decorations that are not fixed (such as a phone status bar that can be hidden when full screen) are not accounted for here, nor are window decorations like the title bar or action bar, so applications must be prepared to deal with a somewhat smaller space than they specify. Added in API level 13. Also see the `screenHeightDp` configuration field, which holds the current screen width. For more information about designing for different screens and using this qualifier, see the Supporting Multiple Screens developer guide.
Screen size	`small` `normal` `large` `xlarge`	`small`: Screens that are of similar size to a low-density QVGA screen. The minimum layout size for a small screen is approximately 320x426 dp units. Examples are QVGA low density and VGA high density. `normal`: Screens that are of similar size to a medium-density HVGA screen. The minimum layout size for a normal screen is approximately 320x470 dp units. Examples of such screens a WQVGA low density, HVGA medium density, WVGA high density. `large`: Screens that are of similar size to a medium-density VGA screen. The minimum layout size for a large screen is approximately 480x640 dp units. Examples are VGA and WVGA medium density screens. `xlarge`: Screens that are considerably larger than the traditional medium-density HVGA screen. The minimum layout size for an xlarge screen is approximately 720x960 dp units. In most cases, devices with extra large screens would be too large to carry in a pocket and would most likely be tablet-style devices. Added in API level 9. Note: Using a size qualifier does not imply that the resources are only for screens of that size. If you do not provide alternative resources with qualifiers that better match the current device configuration, the system may use whichever resources are the best match. Caution: If all your resources use a size qualifier that is larger than the current screen, the system will not use them and your application will crash at runtime (for example, if all layout resources are tagged with the `xlarge` qualifier, but the device is a normal-size screen). Added in API level 4. See Supporting Multiple Screens for more information. Also see the `screenLayout` configuration field, which indicates whether the screen is small, normal, or large.
Screen aspect	`long` `notlong`	`long`: Long screens, such as WQVGA, WVGA, FWVGA `notlong`: Not long screens, such as QVGA, HVGA, and VGA Added in API level 4. This is based purely on the aspect ratio of the screen (a "long" screen is wider). This is not related to the screen orientation. Also see the `screenLayout` configuration field, which indicates whether the screen is long.
Screen orientation	`port` `land`	`port`: Device is in portrait orientation (vertical) `land`: Device is in landscape orientation (horizontal) This can change during the life of your application if the user rotates the screen. See Handling Runtime Changes for information about how this affects your application during runtime. Also see the `orientation` configuration field, which indicates the current device orientation.
UI mode	`car` `desk` `television appliance`	`car`: Device is displaying in a car dock `desk`: Device is displaying in a desk dock `television`: Device is displaying on a television, providing a "ten foot" experience where its UI is on a large screen that the user is far away from, primarily oriented around DPAD or other non-pointer interaction `appliance`: Device is serving as an appliance, with no display Added in API level 8, television added in API 13. This can change during the life of your application if the user places the device in a dock. You can enable or disable some of these modes using `UiModeManager`. See Handling Runtime Changes for information about how this affects your application during runtime.
Night mode	`night` `notnight`	`night`: Night time `notnight`: Day time Added in API level 8. This can change during the life of your application if night mode is left in auto mode (default), in which case the mode changes based on the time of day. You can enable or disable this mode using `UiModeManager`. See Handling Runtime Changes for information about how this affects your application during runtime.
Screen pixel density (dpi)	`ldpi` `mdpi` `hdpi` `xhdpi` `nodpi` `tvdpi`	`ldpi`: Low-density screens; approximately 120dpi. `mdpi`: Medium-density (on traditional HVGA) screens; approximately 160dpi. `hdpi`: High-density screens; approximately 240dpi. `xhdpi`: Extra high-density screens; approximately 320dpi. Added in API Level 8 `nodpi`: This can be used for bitmap resources that you do not want to be scaled to match the device density. `tvdpi`: 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. This qualifier was introduced with API level 13. There is a 3:4:6:8 scaling ratio between the four primary densities (ignoring the tvdpi density). So, a 9x9 bitmap in ldpi is 12x12 in mdpi, 18x18 in hdpi and 24x24 in xhdpi. If you decide that your image resources don't look good enough on a television or other certain devices and want to try tvdpi resources, the scaling factor is 1.33mdpi. For example, a 100px x 100px image for mdpi screens should be 133px x 133px for tvdpi. Note:* Using a density qualifier does not imply that the resources are only for screens of that density. If you do not provide alternative resources with qualifiers that better match the current device configuration, the system may use whichever resources are the best match. See Supporting Multiple Screens for more information about how to handle different screen densities and how Android might scale your bitmaps to fit the current density.
Touchscreen type	`notouch` `finger`	`notouch`: Device does not have a touchscreen. `finger`: Device has a touchscreen that is intended to be used through direction interaction of the user's finger. Also see the `touchscreen` configuration field, which indicates the type of touchscreen on the device.
Keyboard availability	`keysexposed` `keyshidden` `keyssoft`	`keysexposed`: Device has a keyboard available. If the device has a software keyboard enabled (which is likely), this may be used even when the hardware keyboard is not exposed to the user, even if the device has no hardware keyboard. If no software keyboard is provided or it's disabled, then this is only used when a hardware keyboard is exposed. `keyshidden`: Device has a hardware keyboard available but it is hidden and the device does not have a software keyboard enabled. `keyssoft`: Device has a software keyboard enabled, whether it's visible or not. If you provide `keysexposed` resources, but not `keyssoft` resources, the system uses the `keysexposed` resources regardless of whether a keyboard is visible, as long as the system has a software keyboard enabled. This can change during the life of your application if the user opens a hardware keyboard. See Handling Runtime Changes for information about how this affects your application during runtime. Also see the configuration fields `hardKeyboardHidden` and `keyboardHidden`, which indicate the visibility of a hardware keyboard and and the visibility of any kind of keyboard (including software), respectively.
Primary text input method	`nokeys` `qwerty` `12key`	`nokeys`: Device has no hardware keys for text input. `qwerty`: Device has a hardware qwerty keyboard, whether it's visible to the user or not. `12key`: Device has a hardware 12-key keyboard, whether it's visible to the user or not. Also see the `keyboard` configuration field, which indicates the primary text input method available.
Navigation key availability	`navexposed` `navhidden`	`navexposed`: Navigation keys are available to the user. `navhidden`: Navigation keys are not available (such as behind a closed lid). This can change during the life of your application if the user reveals the navigation keys. See Handling Runtime Changes for information about how this affects your application during runtime. Also see the `navigationHidden` configuration field, which indicates whether navigation keys are hidden.
Primary non-touch navigation method	`nonav` `dpad` `trackball` `wheel`	`nonav`: Device has no navigation facility other than using the touchscreen. `dpad`: Device has a directional-pad (d-pad) for navigation. `trackball`: Device has a trackball for navigation. `wheel`: Device has a directional wheel(s) for navigation (uncommon). Also see the `navigation` configuration field, which indicates the type of navigation method available.
Platform Version (API level)	Examples: `v3` `v4` `v7` etc.	The API level supported by the device. For example, `v1` for API level 1 (devices with Android 1.0 or higher) and `v4` for API level 4 (devices with Android 1.6 or higher). See the Android API levels document for more information about these values. Caution: Android 1.5 and 1.6 only match resources with this qualifier when it exactly matches the platform version. See the section below about Known Issues for more information.

Note: Some configuration qualifiers have been added since Android 1.0, so not all versions of Android support all the qualifiers. Using a new qualifier implicitly adds the platform version qualifier so that older devices are sure to ignore it. For example, using a w600dp qualifier will automatically include the v13 qualifier, because the available-width qualifier was new in API level 13. To avoid any issues, always include a set of default resources (a set of resources with no qualifiers). For more information, see the section about Providing the Best Device Compatibility with Resources.

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