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Resources

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  1. Resources Definition: A value or a file bound to an application • Binding to an application • Create child directories under the res folder • Store files or XML specifications in the child directories • Examples • Symbolic constants • Icons, Pictures, audio, and video • Drawable components • UI layouts • XML file specifications • Menus and Layouts

  2. Naming Resource Subdirectories Syntax: <reservedName>[ [-<modifier>] … ]* • Parent Directory: res • Reserved Names: values, layout, drawable, xml, raw, anim • Modifiers: http://developer.android.com/guide/topics/resources/providing-resources.html • Platform versions: -v3, -v2, -v4, etc. • Navigation: -trackball, -wheel, -stylus, -finger, etc. • Keyboard: -12key, -querty, -nokeys • Screen density: -ldpi, -mdpi,-hdpi,-xdpi • Orientation: -land, -port • Screen size: -small, -normal, -large, -xlarge • Screen height or width: -w720dp, -h1024dp, etc. • Language and/or region: -en, -fr, -en-US, -fr, etc. • Examples (Note: for complex specifications, the order is important) • values-fr for Symbolic constants in french • layout-landscape • Complex resource specification: drawable-fr-land-xlarge-v4

  3. Subdirectory Operation • Subdirectories with modifiers • Android first searches the least device-specific directory • Android then searches subdirectories that are more specific • Levels of subdirectories reflect combined device parameters • Subdirectories without modifiers • The default subdirectory has no modifiers (the default) • If a resource does not exist in a subdirectory with modifiers, Android looks for the resource in the default subdirectory • It is wise to always include a default, providing resources for the most common device configuration • Subdirectories with modifiers override the defaults • Runtime exceptions occur when resources cannot be found

  4. Layouts (res/layout/main.xml) <?xml version="1.0" encoding="utf-8"> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <TextView android:id="@+id/note" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> <Button android:id="@+id/ok" android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/button_ok" /> </LinearLayout> fill_parent deprecated replaced with match_parent after version 2.0 + means create symbolic constant if not already defined Java access: setContentView(R.layout.main); // R.layout.file_name mText = (EditText) findViewById(R.id.note); // Get the widget

  5. Symbolic Constants Defined with XML files in one of the res/values subdirectories • Purpose • Localize the values outside the source code • Enables easy changes without modifying code • Enables adaptations for different localities and configurations, without maintaining multiple loads • Examples • res/values-en contains strings in English; res/values-fr contains strings translated to French • res/values-sp contains color combinations that are appropriate to Spanish culture, like yellow for emphasis rather than red

  6. Defining Symbolic Constants • How? Create XML files in the res/values subdirectories • Operation • Android gathers the XML files and merges their contents • Each build automatically generates the file R.java • Stored in a gen subdirectory (gen/com.example.android.notes) • Contains integer codes corresponding to each symbol • Application code addresses these codes using R.<type>.name • XML files references existing codes using @<type>/name • All modifier subfolders should use the same type and name values so the code device and location independent

  7. String Constants • Typically defined in strings.xml <?xml version="1.0" encoding="utf-8"?> <resources> <string name="menu_revert">Revert</string> <string name="resolve_edit">Edit note</string> <string name="title_edit">Edit note</string> </resources> • Access from Java code • setTitle(getResources().getText(R.string.title_edit)); • setTitle(activity.getResources().getString(R.string.title_edit)); • menu.add(0, REVERT_ID, 0, R.string.menu_revert) // group,id,order,text • Access from androidManifest.xml: <intent-filter android:label="@string/resolve_edit"> • Note:getString() returns a plain string, getText() can return a styled string Note: For some controls, getResources().getText() is not necessary

  8. Arrays of Strings • String Arrays: strings.xml or any xml file name • Declaration:<string-array name="colors"> <item>red</item><item>green</item><item>blue</item></string-array> • Java: String[] = activity.getResources().getStringArray(R.array.colors); • Plurals: strings.xml or any xml file name • Declaration:<plurals name="group"><item quantity="1">one</item> <item quantity="2">couple</item> <item quantity="3">few</item> <item quantity="other">some</item></plurals> • Java: String s = activity.getResources().getQuantityString(R.plurals.group, 3);

  9. Other Symbolic Constants • Colors: Typically colors.xml • Declaration: <color name="emphasize">#ff0000</color> • Java:activity.getResources.getColor(R.color.emphasize); • Dimensions: Typically dimens.xml; Units of measure are px, in, mm, pt, dp, sp • Declaration: <dimension name="border">5px</dimen> • Java:activity.getResources.getDimension(R.dimen.border); • Attributes: Typically attrs.xml; Customize the application based on parameters • Declaration: <declare-styleable name="styles"> <attr name="tiling"> <flag name="center" value="0"/><flag name="stretch" value="1"/> <flag name="repeat" value="2"/> </attr> • Java: String str = getString(R.styleable.styles.tiling, 2); // Get “repeat” Note: dp or sp = density independent or scale independent pixels

  10. Color Drawable Resources • Declaration: Define in res/values with any xml file name <resources><drawable name="red_rect">#f00</drawable> </resources> • Access in XML <TextView android:layout_width="match_parent" layout_height="wrap_content" android:textAlign:center" android:background="@drawable/red_rect" /> • Java: label.setBackgroundResource(R.drawable.red_rect); Drawables can be bit map pictures: jpg, png, gif or shapes which are Series of rectangles, ovals and polygons, or various other visual effects

  11. Drawable in the background myShape.xml <?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="oval"> <gradient android:centerX="0.5" android:centerY="0.5" /> <solid android:color="#666666"/> <size android:width="120dp" android:height="120dp"/> </shape> Apply to layout <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/myshape" android:orientation="vertical" >

  12. Animations • Step 1: create an animation in XML • Step 2: load the animationa = AnimationUtils.loadAnimation(getApplicationContext(), R.anim.fade); • Attach listeners to the animation if desireda.setAnimationListener(this); • Apply the animation to a view and starttext.startAnimation(a);

  13. Animation Resources Create flashy animations on an Android device Purpose: vary scale factors, rotations, or colors from a starting to ending value over a period of time • Create an XML file in res/anim • Example: <set xmlns:android="http://schemas.android.com/apk/res/android" android:interpolator="@android:anim/accelerate_interpolator"> <scale android:fromXScale="0" android:toXScale="1" android:fromYScale="0.1" android:toYScale="1.0" android:duration="5000" android:pivotX="50%" android:pivotY="50%” // Zoom from the center android:startOffset="1000" /></set> • Access from Java: R.anim.foo where foo.xml is the file in res/anim

  14. Animation Example <?xml version="1.0" encoding="utf-8" ?> <set xmlns:android=http://schemas.android.com/apk/res/android android:interpolator = "@android:anim/accelerate_interpolator" > <rotate android:fromDegrees="0" android:toDegrees="160" android:pivotX= "50%" android:pivotY= "50%" android:startOffset= "500" android:duration="1000" /> <scale android:fromXScale= "1.0" android:toXScale="0" android:fromYScale= "1.0" android:toYScale= "0" android:pivotX= "50%" android:pivotY= "50%" android:startOffset = "500" android:duration= "500" /> <alpha android:fromAlpha=“1.0“ android:toAlpha="0" android:startOffset= "500" android:duration= "500" /> Accelerate interpolator: starts slowly and accelerates

  15. Animation of List of Pictures Store in file named: android_anim.xml <animation-list xmlns:android="http://schemas.android.com/apk/res/android" android:oneshot= "false" > <item android:drawable="@drawable/pic1" android:duration="500“/> <item android:drawable="@drawable/pic1" android:duration="500“/> <item android:drawable="@drawable/pic1" android:duration="500“/> </animation-list> ImageView view = (ImageView)findViewById(R.id.IV_android); view.setBackgroundResource(R.drawable.android_anim); AnimationDrawable animation = (AnimationDrawable)androidIV.getBackground(); animation.start(); XML views are identified by an id value

  16. Themes and Styles Definitions Style:A presentation format applied to either views, spannables or entire applications Spannable: A special type of string that can be styled within a view Theme: A style that applies to an entire activity or application

  17. Style Definition Syntax <?xml version="1.0" encoding="utf-8"?><resources>    <style name="style_name"        parent="@[package:]style/style_to_inherit">        <item name="[package:]style_property_name"> style_value</item> …         <item name="[package:]style_property_name"> style_value</item>    </style></resources>

  18. Defining a Style Resource • XML Definition (stored in res/values)<?xml version="1.0" encoding="utf-8"?><resources>    <style name=“MyStyle" parent="@style/Text">        <item name="android:textSize">20sp</item>        <item name="android:textColor">#008</item>    </style></resources> • Usage in a view:<TextViewandroid:id="@+id/errorText" style="@style/MyStyle" /> • Activity theme: <activity android:theme=@style/MyStyle"> • Android Application theme: <application android:theme="@android:style/Theme.NoTitleBar">

  19. Formatting and Styling • Formatting Strings (format is like using the C sprintf method)XML declaration: <string name="hi">Hello, %1$s!</string>Java usage: String text = String.format(context.getString(R.string.hi), user); • Styling a String XML declaration: <string name="bi"> <b><i>bold and italic</b></i> </string> Java usage: textView.setText(Html.fromHtml(R.string.bi), TextView.BufferType.SPANNABLE); • Styling part of a StringXML declaration: <string name=“ital">< i>Italics</i> to emphasize</string>Note: <b>, <i>, <u>, <sup>, <sub>, <strike>,<big>, <small>, <monospace> are ok Java usage: Spannable text = (Spannable)view.getText(); TextAppearanceSpan style = new TextAppearanceSpan(context, R.style, ital); text.setSpan(style, 0, 5, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE); Note: applies style from characters 0 to 5 excluding end points

  20. Applying a style to a view • XML declaration:<style name="highlight"> <item name="android:textColor">#ff0000</item> <item name="android:textStyle">bold</item> </style> • Java usage: textView.setTextAppearance(activity, R.style.highlight); • XML usage <EditTextandroid:id="@+id/myEditText“ android:layout_width="match_parent“android:layout_height="wrap_content" android:text="@android:string/httpErrorBadURL" android:style="@style/highlight“ android:textColor="?android:textColor" /> Notes +id/myEditText: Create id if not defined, @android:string/httpErrorBadURL: An android system message, ?android:textColor: Access the current theme’s text color

  21. Refer to a Theme in an Application <manifest xmlns:android=http://schemas.android.com/apk/res/android package="com.myapp.themetest" android:versionCode="1" android:versionName="1.0" > <uses-sdkandroid:minSdkVersion="14" android:targetSdkVersion="15" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/Theme.MyAppTheme" > <activity android:name=".MainActivity" android:label="@string/title_activity_main" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>

  22. Creating a Style Holo Dark <resources xmlns:android="http://schemas.android.com/apk/res/android"> <style name="Theme.MyAppTheme" parent="android:style/Theme.Holo.Light"> // Inheritance <item name="android:actionBarStyle"> @style/Theme.MyAppTheme.ActionBar</item> </style> <style name="Theme.MyAppTheme.ActionBar" parent="android:style/Widget.Holo.Light.ActionBar"> <item name="android:background">#FF4444</item> </style> // Change color of action bar Holo Light

  23. A popup menu in XML (popup.xml in res/menu folder) <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/refresh" android:title="@string/refresh" /> <item android:id="@+id/settings" android:title="@string/settings" /> </menu> public void CreatePopupMenu(View v) { PopupMenu menu = new PopupMenu(this, v); MenuInflaterinflater = mypopupmenu.getMenuInflater(); inflater.inflate(R.menu.popup, menu.getMenu()); menu.show();  }

  24. Respond to popup menu @Override  public booleanonMenuItemClick(MenuItem arg0) { switch (arg0.getItemId()) { case R.id.refresh: showToast(getText(R.string.refresh));   return true;   case R.id.option2: showToast(getText(R.string.settings));   return true; default:   return super.onContextItemSelected(arg0);  }

  25. Many Resources <?xml version="1.0" encoding="utf-8"?> <resources> <string name="app_name">To Do List</string> <plurals name="androidPlural"> <item quantity="one">One android</item> <item quantity="other">%d androids</item> </plurals> <color name="app_background">#FF0000FF</color> <color name= "app_foreground“>#FFFF”</color> <dimen name="default_border">5dp</dimen> <string-array name="string_array"> <item>Item 1</item> <item>Item 2</item> <item>Item 3</item> </string-array> <array name="integer_array"> <item>3</item><item>2</item><item>1</item> </array> <dimen name="standard_border">5dp</dimen> </resources> Best Practice: put resource categories in their own individual files

  26. File Resources • Images: Drop in a res/drawable subfolder; Codecs: jpg, gif, png • XML files to parse: Drop in a res/xml subfolder • Arbitrary files:Drop in a res/raw subfolder or /assets • Most files are pre-compiled during the build. These files are not • res/raw files have an R.java ID. For example R.raw.foo without an extension for foo.png or foo.txt. This approach requires lower case alphanumeric characters and periods.getResources().openRawResource(R.raw.myfilename). • Files stored in /assets do not have an R.java ID. Access using Java input stream programming using a fully qualified path name.InputStream is = getAssets().open("myFolder/somefile.txt"); • Examples of use: Video files or XML files that the application parses using Java DOM or SAX classes

  27. Third Presentation Implementation of the class project • Describe how it works and give a demo • Use an actual device if possible • Specifically discuss innovations that you implemented • Discuss possible improvements that focus on making the application more exciting for users. • Discuss the advantages or disadvantages of using JavaScript or native Android applications, your preferences, and the reasoning behind your position.

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