Orientation & Localization

Transcription

1 Orientation & Localization Overview Lecture: Open Up Your My Pet App Handling Rotations Serializable Landscape Layouts Localization Alert Dialogs 1

2 Handling Rotations When the device is rotated, the device configuration is changed Device Configuration changes force your activity to be destroyed and recreated Configurations are composed of: Screen Orientation Screen Density Screen Size Keyboard Type Dock Mode Language And more Handling Rotations Create a new folder under res called: layout-land Make a copy of your layout and place in this folder Or, in the Design panel for the layout: Design panel s Create Landscape Variant will make a new version with all the same widgets and Ids 2

3 Handling Rotations Both layouts need the same filename for this to work (assigned the same resource ID) *layoutname*-land is a configuration qualifier Android figures out what layout to use based on the device Fixing Rotations The new layout does not fix the data reset problem! We need to store values across device config changes There are several ways to do this, here is the protected void onsaveinstancestate(bundle outstate) This method is called by Android before: onpause() only time it is guaranteed! 3

4 Fixing Rotations The bundle lets us stores key value pairs of strings and other limited types (serializable) Remember the bundle during the oncreate method that was passed to the super class? onsaveinstancestate Bundle oncreate We want to send the mode we are in as well as information on our Pet Our class Pet must be made SERIALIZABLE My Pet Serializable! Making a class serializable can be complex, all variables within a class need to be serializable (or transient): private class Pet implements Serializable { String type; int hitpoints; int attackpower; int stamina; int maxhitpoints; int maxstamina; int coststamina_train = 2; int coststamina_eat = 1; } 4

5 My Pet Serializable! Serialization converting an object in to a byte representation that captures its state Object can be written to a file and retrieved Handled by ObjectInputStream and ObjectOutputStream in Java You must typecast the object once you retrieve it Implement the empty interface java.io.serializable Fixing Rotations Override the method and put the value in the bundle provided public void onsaveinstancestate(bundle savedinstancestate) { super.onsaveinstancestate(savedinstancestate); savedinstancestate.putint(key_pet, this.pet); } oncreate: Check for the bundle and grab the index: if(savedinstancestate!= null) { mprofileindex = savedinstancestate.getserializable(key_pet); } 5

6 Fixing Rotations Not Quite Yet We still need to fix the mode And update the visuals appropriately Add a new Mode Key and save the state Check the bundle for the mode and update appropriately Localization Localization the process of providing the appropriate resources for your app based on the device s language settings Android devices are used worldwide Customization of your app to handle various locales and spoken languages increases you re the number of potential customers Localization can be for any resource, but we will be primarily focusing on text 6

7 Localization Language settings are part of the device s configuration Localization is handled through configuration qualifiers You create folders within res with names specific to the language you are supporting Folders with no qualifier ( the ones you normally see) will be the default used when no folder is found for the current settings Localization Android Studio features an easier way: 7

8 Localization Or Localization Setup Folders Config qualifiers for folders come from ISO codes: French and Spanish values can be supported by creating the following folders under res values-fr raw-fr values-es raw-es Regional differences can also be supported: values-en-rus values-en-rgb 8

9 Localization Setup Folders Use a translator to create some basic text across English, French and Spanish Create your strings in your native language in a strings.xml file Copy and paste this file into the other language folders or let Android Studio do it for you Paste in your translated text for each Localization Setup Folders To see the changes on your device, you ll need to set the language in Settings->Personal->Language & input 9

10 Localization Setup Folders You may feel tempted to throw all your resources is a folder specifically for English DON T DO THIS! You need a default directory, otherwise then a qualifier can t be found, it will crash the application Keep your native language in default, because displaying something is always better than a crashed app Localization A Note on Configuration Qualifiers There is a hierarchy of configuration qualifiers used by android to determine what resources to use: 1. Mobile Country Code 2. Language Code 3. Layout Direction 4. Smallest Width 5. Available Width 6. Available Height 7. Screen Size

11 Localization A Note on Configuration Qualifiers Android determines the resources to use by REMOVING resources that don t meet the needs of the configuration first It steps down the hierarchy and remove those that don t fulfill the current level When one configuration is left, it uses that one (which very well might be the default) You can have multiple qualifiers on a folder: values es land (Spanish language with landscape) Note that the order must follow the hierarchy! Lab Finish the life-cycle app if you didn t already Create a new layout for the landscape orientation and swap between them Try localization and convert your app to another language Try it on both the emulator and your device! 11