Transcription

1 Menus, themes and ActionBar Activity communication and Bundle Shared Preferences Event handling More GUI components and Adapters

2 Menus OptionsMenu The main menu for an Activity that displays when the overflow button is pressed. It contains a text menu possibly with icons and an expanded menu when the more menu item is selected. Old devices may have a menu button Some very old apps only have the old menu (long press back button to open...) App Bar (Toolbar or ActionBar) Enables a consistent way for implementing actions and navigation ActionBar can be used from API 11 (from API 7 with v7 appcompat library) ToolBar can be used from API 21 (also from API 7 with v7 appcompat library) ContextMenu A floating list of menu items that displays when a specific Widget/View is long pressed SubMenu A floating list of menu items that displays when a menu item is pressed These types of menus should be made in XML They should be put in the app/res/menu/ resources directory See the BuildingMenus and ActionBar example

3 OptionsMenu with Java public boolean oncreateoptionsmenu(menu menu) { super.oncreateoptionsmenu(menu); // Create and add new menu alternatives // add (int groupid, int itemid, int order, CharSequence title) MenuItem itemabout = menu.add(menu.none, VIEW_ABOUT, Menu.NONE, getstring(r.string.about)); MenuItem itemdonothing = menu.add(menu.none, SOMETHING_ELSE, Menu.NONE, R.string.do_nothing); // Add icons itemabout.seticon(r.drawable.icon); // Add numeric and alphabetic shortcuts itemabout.setshortcut('0', 'o'); // about itemdonothing.setshortcut('1', 'i'); // nothing return true; public boolean onoptionsitemselected(menuitem item) { super.onoptionsitemselected(item); switch (item.getitemid()) { case (VIEW_ABOUT): { Intent aboutintent = new Intent(this, AboutActivity.class); startactivity(aboutintent); // start the new Activity return true;... Old style

4 OptionsMenu etc. in XML public boolean oncreateoptionsmenu(menu menu) { super.oncreateoptionsmenu(menu); // Returns a MenuInflater with this context MenuInflater inflater = getmenuinflater(); // Inflate a menu hierarchy from the specified XML resource inflater.inflate(r.menu.my_menu, menu); return true; XML code in /res/menu/my_menu.xml <?xml version="1.0" encoding="utf-8"?> <menu xmlns:android=" > <item android:id="@+id/menu_about" android:title="@string/menu_about" android:icon="@drawable/icon" /> <item android:id="@+id/menu_do_nothing" android:title="@string/menu_do_nothing" </menu>

5 ContextMenu and SubMenu private String[] choices = {"Press Me", "Try Again", "Change Me"; public void oncreate(bundle savedinstancestate) {... bv = (TextView) findviewbyid(r.id.focus_text); registerforcontextmenu((view) findviewbyid(r.id.focus_text)); XML alt. in BuildingMenus example public void oncreatecontextmenu(contextmenu menu, View v, ContextMenuInfo menuinfo) { super.oncreatecontextmenu(menu, v, menuinfo); if(v.getid() == R.id.focus_text) { SubMenu textmenu = menu.addsubmenu("change Text"); textmenu.add(0, ID_TEXT1, 0, choices[0]); textmenu.add(0, ID_TEXT2, 0, choices[1]); textmenu.add(0, ID_TEXT3, 0, choices[2]); menu.add(0, ID_DEFAULT, 0, "Original Text"); Long press the textview to run oncreatecontextmenu ContextMenu and SubMenu is created and showed public boolean oncontextitemselected(menuitem item) { switch(item.getitemid()) { case ID_DEFAULT: bv.settext(r.string.hello); return true; case ID_TEXT1: case ID_TEXT2: case ID_TEXT3: bv.settext(choices[item.getitemid()-1]); return true; return super.oncontextitemselected(item);

6 App Bar (ActionBar or Toolbar) The App Bar

7 ActionBar Read:

8 OptionsMenu with ActionBar public boolean oncreateoptionsmenu(menu menu) { MenuInflater inflater = getmenuinflater(); inflater.inflate(r.menu.activity_main, menu); return super.oncreateoptionsmenu(menu); <uses-sdk android:minsdkversion="11" android:targetsdkversion="10" /> <activity android:parentactivityname="parentactivity"> </activity> <menu xmlns:android=" > <item android:id="@+id/menu_hide_navigation" android:orderincategory="100" android:icon="@drawable/robot48" android:title="@string/menu_hide_navigation" android:showasaction="ifroom withtext"/> <item android:id="@+id/menu_actionbar_toggle" android:orderincategory="100" android:showasaction="never" android:title="@string/menu_actionbar_toggle" /> </menu> public boolean onoptionsitemselected(menuitem item) { ActionBar actionbar = getactionbar(); switch (item.getitemid()) { case android.r.id.home: // an app icon in action bar when clicked - go to parent - since API 16 handled by parentactivityname in the AndroidManifest file // Intent intent = new Intent(this, ParentActivity.class); // intent.addflags(intent.flag_activity_clear_top Intent.FLAG_ACTIVITY_SINGLE_TOP); // startactivity(intent); NavUtils.navigateUpTo(this, new Intent(this, ActionBarExample.class)); return true; case R.id.menu_actionbar_toggle: if(visible) actionbar.hide(); else actionbar.show(); visible =!visible; return true; case R.id.menu_hide_navigation: getwindow().getdecorview().setsystemuivisibility(view.system_ui_flag_hide_navigation); return true; default: return super.onoptionsitemselected(item); Remove the Menu button in an AVD? Set hw.mainkeys=no in the config.ini file

9 Style, themes and resources By adding custom names in the res/values/styles.xml file your app can have a dark or light theme Icons can be XML programmed to automatically change Get icons: > Design > Downloads <style name="customthemelight" parent="android:theme.holo.light"> <item name="theme_dependent_icon_upload" >@drawable/ic_action_upload_light</item> <item name="theme_dependent_icon_share" >@drawable/ic_action_share_light</item> </style> <style name="customthemedark" parent="android:theme.holo"> <item name="theme_dependent_icon_upload" >@drawable/ic_action_upload_dark</item> <item name="theme_dependent_icon_share" >@drawable/ic_action_share_dark</item> </style> In: res/values/attrs.xml put the "attr" XML format reference In: res/menu/menu.xml files give the attr name <resources> <declare-styleable name="custom_menu"> <attr name="theme_dependent_icon_upload" format="reference"/> <attr name="theme_dependent_icon_share" format="reference"/> </declare-styleable> </resources> In order to display a theme you must set it before setcontentview(your_layout.xml) is called in your Activity. If you want your activity to restart, use recreate(); <item android:id="@+id/menu_item_share" android:orderincategory="100" android:showasaction="ifroom withtext" android:icon="?attr/theme_dependent_icon_share" android:title="@string/menu_item_share"/> if(lighttheme) settheme(r.style.customthemelight); else settheme(r.style.customthemedark);

10 Toolbar 1 The Toolbar is more configurable and a generalization of the ActionBar system Toolbar is a regular View included in a layout like any other View and thereby easier to position, animate and control Multiple distinct ToolBar elements can be defined within a single activity Using ToolBar as an ActionBar Add the v7 support library in the build.gradle (Module:app) file Disable the theme-provided ActionBar in res/values/styles.xml dependencies compile compile compile compile compile { filetree(include: ['*.jar'], dir: 'libs') 'com.android.support:support-v13:24.2.0' 'com.android.support:design:24.2.0' 'com.google.android.gms:play-services:9.4.0' 'com.android.support:appcompat-v7:24.2.0' <resources> <!-- Base application theme. --> <style name="apptheme" parent="theme.appcompat.light.noactionbar"> </style> </resources>

11 Toolbar 2 Add a Toolbar to your layout android:fitssystemwindows="true" ensures that the height of the activity is calculated correct <android.support.v7.widget.toolbar xmlns:android=" android:id="@+id/toolbar" /layout/toolbar.xml android:layout_height="wrap_content" Using the Toolbar in an activity xml layout android:layout_width="match_parent" android:fitssystemwindows="true" android:theme="@style/themeoverlay.appcompat.dark.actionbar" android:background="?attr/colorprimarydark"> </android.support.v7.widget.toolbar> <LinearLayout xmlns:android=" xmlns:app=" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <include layout="@layout/toolbar" android:layout_width="match_parent" android:layout_height="wrap_content" /> <RelativeLayout xmlns:android=" android:layout_width="match_parent" android:layout_height="match_parent" android:focusable="true" android:focusableintouchmode="true"> <TextView android:id="@+id/textstatus" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignparentbottom="true" android:layout_centerhorizontal="true" android:text="status : Not connected" android:textsize="16sp" />...

12 Toolbar 3 Use the Toolbar layout... // when using the support library make sure that you import the following import android.support.v7.app.appcompatactivity; import android.support.v7.widget.toolbar; public class MyActivity extends AppCompatActivity { protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_my); // Find the toolbar view inside the activity layout Toolbar toolbar = (Toolbar) findviewbyid(r.id.toolbar); // Sets the Toolbar to act as the ActionBar for this Activity window. // Make sure the toolbar exists in the activity and is not null if (toolbar!= null) { setsupportactionbar(toolbar); // Menu icons are inflated just as they were with actionbar public boolean oncreateoptionsmenu(menu menu) { // Inflate the menu; this adds items to the toolbar if it is present. getmenuinflater().inflate(r.menu.menu_main, menu); return true; // Handle Menu selections as usual as well public boolean onoptionsitemselected(menuitem item) {...

13 Toolbar 4 (SettingsActivity fix) Material Settings and Toolbar with AS Settings Wizard /** * MaterialSettings: * no-actionbar-in-preferenceactivity-after-upgrade-to-support-library-v21/ # savedinstancestate */ protected void onpostcreate(bundle savedinstancestate) { super.onpostcreate(savedinstancestate); LinearLayout root = (LinearLayout)findViewById(android.R.id.list).getParent().getParent().getParent(); Toolbar bar = (Toolbar) LayoutInflater.from(this).inflate(R.layout.settings_toolbar, root, false); root.addview(bar, 0); // insert at top // set correct Toolbar title if(mpreferenceheader!= null) { bar.settitle(mpreferenceheader); bar.setnavigationonclicklistener(new View.OnClickListener() { settings_toolbar.xml public void onclick(view v) { <?xml version="1.0" encoding="utf-8"?> finish(); <android.support.v7.widget.toolbar xmlns:android=" ); xmlns:app=" Full example in MapsProject android:id="@+id/toolbar" app:theme="@style/themeoverlay.appcompat.dark.actionbar" android:layout_width="match_parent" android:layout_height="wrap_content" android:minheight="?attr/actionbarsize" app:navigationcontentdescription="@string/abc_action_bar_up_description" android:background="?attr/colorprimary" app:navigationicon="?attr/homeasupindicator" app:title="@string/action_settings" />

14 Themes and colors Customize the Color Palette If you select a specific Theme Customize the Status and App Bar In styles.xml and colors.xml <resources> <!-- inherit from the material theme --> <style name="apptheme" parent="android:theme.material"> <!-- Main theme colors --> <!-your app branding color for the app bar --> <item name="android:colorprimary">@color/primary</item> <!-darker variant for the status bar and contextual app bars --> <item name="android:colorprimarydark">@color/primary_dark</item> <!-theme UI controls like checkboxes and text fields --> <item name="android:coloraccent">@color/accent</item> <! > <item name="toolbarstyle">@style/widget.appcompat.toolbar</item> </style> </resources> <resources> <! > <color name="primary">#4caf50</color> <color name="primary_dark">#388e3c</color> <color name="accent">#8bc34a</color> </resources>

15 More advanced App Bars 1 Material Design: App Bar

16 More advanced App Bars 2 Implementing Effective Navigation Implement navigation patterns with tabs, swipe views, and navigation drawer you must master fragments before use!

17 Passing a Bundle What's the correct way to pass a bundle to the activity that is being launched from the current one? // You have a few options 1) Use the Bundle from the Intent Intent mintent = new Intent(this, Example.class); Bundle extras = mintent.getextras(); extras.putstring(key, value); 2) Create a new Bundle Intent mintent = new Intent(this, Example.class); Bundle mbundle = new Bundle(); mbundle.putstring(key, value); mintent.putextras(mbundle); 3) Use the putextra() shortcut method of the Intent Intent mintent = new Intent(this, Example.class); mintent.putextra(key, value); // Then, in the launched Activity, you would read them via String value = getintent().getextras().getstring(key); NOTE: Bundles have "get" and "put" methods for all the primitive types, advanced Parcelables, and Serializables. I just used Strings for demonstrational purposes.

18 Communication between Activities with explicit Intents 1 MainActivity (MainActivity example) not all code is present here public class MainActivity extends Activity implements View.OnClickListener { // we must implement onclick() since we implements View.OnClickListener interface in our class public void onclick(view view){ //create a new intent and explicit specify that it's target is SecondaryActivity... Intent intent = new Intent(this /*getapplicationcontext() or view.getcontext()*/, SecondaryActivity.class); //load the intent with a key "mykey" and assign it's value //to be whatever has been entered into the text field... intent.putextra("mykey", medittext1.gettext().tostring()); //launch the secondary activity and send the intent along with it //note that a request code is passed in as well so that when the //secondary activity returns control to this activity, //we can identify the source of the request... // startactivity(intent); // if we just want to start the other Activity with no return result startactivityforresult(intent, SECONDARY_ACTIVITY_REQUEST_CODE); // we need a handler for when the secondary activity finishes it's work and returns control // to this activity... we don't handle the resultcode Activity.RESULT_OK in this example protected void onactivityresult(int requestcode, int resultcode, Intent intent) { super.onactivityresult(requestcode, resultcode, intent); Bundle extras = intent.getextras(); medittext1.settext(extras!= null? extras.getstring("returnkey"):"nothing returned");

19 Communication between Activities with explicit Intents 2 SecondaryActivity - (MainActivity example) not all code is present here public void oncreate(bundle savedinstancestate) { if(savedinstancestate!= null)// if the activity is being resumed and instancestate have been saved mintentstring = savedinstancestate.getstring("mykey"); else { // check to see if a Bundle is present, the MainActivity may have called us Bundle extras = getintent().getextras(); // retrieves a map of extended data from the intent if(extras!= null){ mintentstring = extras.getstring("mykey");// get parameters from the Bundle out of the Intent else mintentstring = "nothing passed in"; // default init // set the textbox to display mintentstring medittext2.settext(mintentstring); public void onclick(view view){ mintentstring = medittext2.gettext().tostring(); //create a new intent... Intent intent = new Intent(); //add "returnkey" as a key and assign it the value //in the textbox... intent.putextra("returnkey", medittext2.gettext().tostring()); //get ready to send the result back to the caller (MainActivity) //and put our intent into it (RESULT_OK will tell the caller that //we have successfully accomplished our task.. setresult(activity.result_ok, intent); //close this Activity... finish(); Remember to create the SecondaryActivity in the AndroidManifest! <activity android:name= ".SecondaryActivity" <intent-filter> <action android:name= "android.intent.action.view"/> <category android:name= "android.intent.category.default"/> </intent-filter> </activity>

20 Shared Preferences 1 Storing and reading current preferences (data) in a simple Name (Key) Value pair format can be very handy in your application Saving application/ui settings and other properties to a limited Bundle Use with the proper lifecycle methods At next invokation/call the App can read the last used values easy If the App name is se.du.gpsmap" the shared preferences data is stored in a XML file under the /data/data/se.du.gpsmap/shared_prefs directory The datatypes: int, long, float, String and boolean are supported // Either MODE_PRIVATE, MODE_WORLD_READABLE or MODE_WORLD_WRITEABLE SharedPreferences myprefs = getsharedpreferences("myprefs", Activity.MODE_PRIVATE); // SharedPreferences myprefs = PreferenceManager.getDefaultSharedPreferences(this); // store preference SharedPreferences.Editor prefseditor = myprefs.edit(); prefseditor.putstring("url_1", urltext.gettext().tostring()); // You have to commit otherwise the changes will not be remembered prefseditor.commit(); // at once, prefseditor.apply(); will do it in background // read preference String lastvalue_1 = myprefs.getstring(string key, String defaultvalue);

21 Shared Preferences 2 Data stored with onsaveinstancestate() will only be held in memory until the whole application is closed (no other activity is launched in front of it) Save in onpause() before the Activity is killable and restore in oncreate() public class SaveActivity extends Activity { public static final String MY_PREFS = "SaveActivityPrefs"; public static final String TEXT_INPUT = "text_input"; private EditText textinput; public void oncreate(bundle savedinstancestate) { textinput = (EditText) findviewbyid(r.id.text_input); if(savedinstancestate!= null) // if the activity is being resumed {... else{ // restore UI state from when last run of the application SharedPreferences settings = getsharedpreferences(my_prefs, MODE_PRIVATE); String currentinput = settings.getstring(text_input, ""); textinput.settext(currentinput); protected void onpause() { String currentinput = textinput.gettext().tostring(); // save UI state by getting a SharedPreferences editor SharedPreferences settings = getsharedpreferences(my_prefs, MODE_PRIVATE); SharedPreferences.Editor editor = settings.edit(); editor.putstring(text_input, currentinput); editor.commit(); // commit the edits super.onpause();

22 Shared Preferences Framework Android provides a standardized framework for setting preferences across all applications The framework uses categories and screens to group related settings PreferenceCategory is used to declare a set of preferences into one category PreferenceScreen presents a group of preferences in a new screen Possible elements to put preferences in are: CheckBox, EditText, List, MultiSelectList, Ringtone and Switch - Preference The Android system then generates a UI to manipulate the created preferences in the file: res/xml/preferences.xml These preferences are stored in shared preferences, which means they can be retrieved by using the getpreference() methods Resources which describe the preference framwork

23 Shared Preferences Framework Default settings etc. are stored in: res/xml/preferences.xml ListPreference store string arrays in: res/values/arrays.xml

24 Creating a Preference file Right click res/xml > New > XML Resource File Example content <PreferenceScreen xmlns:android=" > <PreferenceCategory android:title="@string/prefcat_general_title1" > <EditTextPreference android:defaultvalue="@string/pref_ueid_default" android:key="@string/pref_ueid" android:summary="@string/pref_ueid_summary" android:title="@string/pref_ueid_title" /> <ListPreference android:defaultvalue="@string/pref_low_speed_default" android:entries="@array/low_speed_names" android:entryvalues="@array/low_speed_values" android:key="@string/pref_low_speed" android:summary="@string/pref_low_speed_summary" android:title="@string/pref_low_speed_title" /> </PreferenceCategory> <PreferenceCategory android:title="@string/prefcat_general_title2"> <CheckBoxPreference android:key="@string/pref_admin_developer_mode" android:defaultvalue="@string/pref_admin_developer_mode_default" android:title="@string/pref_admin_developer_mode_title" android:summary="@string/pref_admin_developer_mode_summary" android:selectable="false"/> <EditTextPreference android:defaultvalue="@string/pref_http_server_url_default" android:key="@string/pref_http_server_url" android:summary="@string/pref_http_server_url_summary" android:title="@string/pref_http_server_url_title" android:dependency="@string/pref_admin_developer_mode"/> <CheckBoxPreference android:key="@string/pref_use_encryption" android:defaultvalue="@string/pref_use_encryption_default" android:title="@string/pref_use_encryption_title" android:summary="@string/pref_use_encryption_summary" android:dependency="@string/pref_admin_developer_mode"/> </PreferenceCategory> </PreferenceScreen>

25 Connecting a ListPreference Note that for the ListPreference, android:entries attribute are defined Example of res/values/arrays.xml and working with the preference XML file via UI <?xml version="1.0" encoding="utf-8"?> <resources> <string-array name="locale_names"> <item>automatic (default)</item> <item>english</item> <item>swedish</item> </string-array> <string-array name="locale_values"> <item></item> <item>en</item> <item>se</item> </string-array> <string-array name="video_resolution_names"> <item>480p (480x800), 2.5 Mbps, 30 fps (default)</item> <item>720p (720x1280), 5 Mbps, 30 fps</item> </string-array> <string-array name="video_resolution_values"> <item>480</item> <item>720</item> </string-array> </resources>

26 Shared Preferences Framework A settings/preference class which extends PreferenceActivity public class MyPreferences extends PreferenceActivity { private SharedPreferences myprefs; private OnSharedPreferenceChangeListener msplistener; protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); Log.d(Consts.TAG, "MyPreferences oncreate executes..."); addpreferencesfromresource(r.xml.preferences); // gets a SharedPreferences instance that points to the default file // that is used by the preference framework in the given context myprefs = PreferenceManager.getDefaultSharedPreferences(this); // View all current preferences and values in logcat Map<String,?> localmap = myprefs.getall(); Log.d(Consts.TAG, localmap.tostring()); // Use instance field for listener // It will not be gc'd as long as this instance is kept referenced msplistener = new SharedPreferences.OnSharedPreferenceChangeListener() { public void onsharedpreferencechanged(sharedpreferences prefs, String key) { Log.d(Consts.TAG, "pref changed: " + key); ;

27 Using Preference Fragments Of course after API 11 settings are fragment based // Fragments provide a more flexible architecture for your application, compared // to using activities alone, no matter what kind of activity you're building public static class SettingsFragment extends PreferenceFragment { public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); // Load the preferences from an XML resource addpreferencesfromresource(r.xml.preferences);... // you can then add this fragment to an Activity just // as you would for any other Fragment public class SettingsActivity extends Activity { protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); // Display the fragment as the main content // Return the FragmentManager for interacting with // fragments associated with this activity getfragmentmanager() // Start a series of edit operations on the // Fragments associated with this FragmentManager.beginTransaction().replace(android.R.id.content, new SettingsFragment()).commit();

28 Use the AS Wizard - SettingsActivity May make things a bit advanced/complicated? Wizard adds fragment (two pane) adaptable code (prev. slide) Java SettingsActivity which extends from AppCompatPreferenceActivity XML pref_headers.xml which contains tablet setting headers and the corresponding underlying pref_data_sync.xml, pref_general.xml and pref_notification.xml // If you choose to use this settings framwork you must be able to extend/edit the XML and code a little bit. Specifically the note the methods: public Preference findpreference (CharSequence key) // Finds a Preference based on its key private static void bindpreferencesummarytovalue(preference preference) // Binds a preference's summary to its value // Bind the summaries of EditText/List/Dialog/Ringtone preferences // to their values. When their values change, their summaries are // updated to reflect the new value, per the Android Design guidelines. bindpreferencesummarytovalue(findpreference("example_text")); bindpreferencesummarytovalue(findpreference("example_list")); Full example in MapsProject

29 Event Handlers 1 Most user interaction with an Android device is captured by the system and sent to a corresponding callback method For example, if the physical Back button is pressed, the onbackpressed() method is called Event listeners as View.OnClickListener() etc. are however the preferred method when available because they avoid the class extension overhead The system first sends any KeyEvent to the appropriate callback method in the in-focus activity or view Callbacks onkeyup(), onkeydown(), onkeylongpress() Physical key press callbacks ontrackballevent(), ontouchevent() Trackball and touchscreen press callbacks OnFocusChanged() Called when the view gains or loses focus

30 Event Handlers 2 Implement the "Press BACK again to exit" Toast user pattern User must click the phones back button again within two seconds private boolean doublebacktoexitpressedonce = false; /** Called when the activity has detected the user's press of the back key. The default implementation simply finishes the current activity, but you can override this to do whatever you want. */ public void onbackpressed() { if (doublebacktoexitpressedonce) { super.onbackpressed(); return; this.doublebacktoexitpressedonce = true; Utils.showToastMessage(this, "Press BACK again to exit"); // Causes the Runnable r to be added to the message queue, to be run after the specified amount // of time elapses. The runnable will be run on the thread to which this handler is attached. new Handler().postDelayed(new Runnable() { public void run() { doublebacktoexitpressedonce = false;, 2000);

31 Event Handlers 3 Physical buttons are most for programming games and other specific usages when events listners are not available or usable. The Power button, RECENTS and HOME key are intercepted by the system and do not reach the application. Some buttons as the BACK key should intercept onkeyup() because they might not be physical keys. public boolean onkeydown(int keycode, KeyEvent event) { if (keycode == KeyEvent.KEYCODE_CAMERA) { return true; // consume event, hence do nothing on camera button // let event propagate in class tree return super.onkeydown(keycode, event); Example

32 Detect Touch and Gestures A "touch gesture" occurs when a user places one or more fingers on the touch screen, and your application interprets that pattern of touches as a particular gesture There are correspondingly two phases to gesture detection 1. Gathering data about touch events 2. Interpreting the data to see if it meets the criteria for any of the gestures your app supports Gather Data When a user places one or more fingers on the screen, this triggers the callback ontouchevent() on the View that received the touch events. For each sequence of touch events (position, pressure, size, addition of another finger, etc.) that is ultimately identified as a gesture, ontouchevent() is fired several times The gesture starts when the user first touches the screen, continues as the system tracks the position of the user's finger(s), and ends by capturing the final event of the user's fingers leaving the screen. Throughout this interaction, the MotionEvent delivered to ontouchevent() provides the details of every interaction. Your app can use the data provided by the MotionEvent to determine if a gesture it cares about happened

33 Detect Touch To intercept touch events in an Activity or View, override the ontouchevent() callback /** */ public boolean ontouchevent(motionevent event) { // get pointer index from the event object int pointerindex = event.getactionindex(); // get pointer ID int pointerid = event.getpointerid(pointerindex); // get masked (not specific to a pointer) action int action = event.getactionmasked(); switch(action) { case (MotionEvent.ACTION_DOWN) : Log.d(TAG,"Action was DOWN"); return true; case (MotionEvent.ACTION_MOVE) : Log.d(TAG, "Action was MOVE"); return true; case (MotionEvent.ACTION_UP) : Log.d(TAG,"Action was UP"); return true; case (MotionEvent.ACTION_CANCEL) : Log.d(TAG,"Action was CANCEL"); return true; case (MotionEvent.ACTION_OUTSIDE) : Log.d(TAG,"Movement occurred outside bounds " + "of current screen element"); return true; default : return super.ontouchevent(event); See the touch and gesture SwiperDiaper example project

34 Detect Gestures Android provides the GestureDetector class for detecting common gestures. Some of the gestures it supports include ondown(), onlongpress(), onfling() etc. You can use GestureDetector in conjunction with ontouchevent() public class MainActivity extends Activity implements GestureDetector.OnGestureListener, GestureDetector.OnDoubleTapListener { private static final String TAG = MainActivity.class.getSimpleName(); private TextView textmessage; private GestureDetector mgesturedetector; protected void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); // Instantiate the gesture detector with the application context and an implementation of GestureDetector.OnGestureListener mgesturedetector = new GestureDetector(this, this); // Set the gesture detector as the double tap listener. mgesturedetector.setondoubletaplistener(this); textmessage = (TextView)findViewById(R.id.textMessage); public boolean onscroll(motionevent motionevent, MotionEvent motionevent1, float v, float v1) { Log.d(TAG,"onScroll: " + motionevent.tostring()); textmessage.settext("onscroll"); return true; public boolean onfling(motionevent motionevent, MotionEvent motionevent1, float v, float v1) { Log.d(TAG,"onFling: " + motionevent.tostring()); textmessage.settext("onfling"); return true; public boolean ontouchevent(motionevent event) { // Analyzes the given motion event and if applicable triggers the appropriate callbacks on the GestureDetector.OnGestureListener supplied mgesturedetector.ontouchevent(event); // Be sure to call the superclass implementation return super.ontouchevent(event);...

35 Seekbar and Spinner <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android=" android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="10px" android:orientation="vertical"> <SeekBar android:layout_height="wrap_content" android:layout_marginbottom="15px" android:layout_width="fill_parent" /> <Spinner android:layout_margintop="15px" android:layout_height="wrap_content" android:layout_width="fill_parent" /> </LinearLayout> spinner_seekbar.xml spinner_entry.xml <?xml version="1.0" encoding="utf-8"?> <TextView xmlns:android=" android:gravity="center" android:textcolor="#000" android:textsize="40sp" android:layout_width="fill_parent" android:layout_height="wrap_content"> </TextView>

36 Adapters 1 An Adapter represents a bridge between data (such as an array or list) and a View (such as a ListView or a Spinner) The Adapter creates the child views representing individual data The adapter automatically updates the view(s) if the underlying data is changed // create a list/array private static final String[] moceans = { "Pacific", "Atlantic", "Indian", "Arctic", "Southern" ; // bind the array to the spinner mfavoriteocean = (Spinner) findviewbyid(r.id.spinner); ArrayAdapter<String> madapter = new ArrayAdapter<String>(this, R.layout.spinner_entry); madapter.setdropdownviewresource(r.layout.spinner_entry); for(int idx=0; idx<moceans.length; idx++) madapter.add(moceans[idx]); mfavoriteocean.setadapter(madapter);

37 Adapters 2 The listener can access underlying data via the adapter A spinner does not support item click events. Calling this method will raise an exception. You must use OnItemSelectedListener() instead mfavoriteocean.setonitemselectedlistener(new OnItemSelectedListener() { public void onitemselected(adapterview<?> parent, View view, int position, long id) { showtoastmessage("spinner: " + parent.getitematposition(position).tostring()); public void onnothingselected(adapterview<?> parent) { showtoastmessage("spinner onnothingselected!"); );

38 Seekbar, Spinner and ArrayAdapter public class UITest extends Activity { private static final String[] moceans = { "Pacific", "Atlantic", "Indian", "Arctic", "Southern" ; private SeekBar mseekbar; private Spinner mfavoriteocean; public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.spinner_seekbar); mfavoriteocean = (Spinner) findviewbyid(r.id.spinner); ArrayAdapter<String> madapter = new ArrayAdapter<String>(this, R.layout.spinner_entry); madapter.setdropdownviewresource(r.layout.spinner_entry); for(int idx=0; idx<moceans.length; idx++) madapter.add(moceans[idx]); mfavoriteocean.setadapter(madapter); mfavoriteocean.setonitemselectedlistener(new OnItemSelectedListener() { public void onitemselected(adapterview<?> parent, View view, int position, long id) { showtoastmessage("spinner: " + parent.getitematposition(position).tostring()); public void onnothingselected(adapterview<?> parent) { showtoastmessage("spinner onnothingselected!"); ); mseekbar = (SeekBar) findviewbyid(r.id.seekbar1); mseekbar.setprogress(50); mseekbar.setonseekbarchangelistener(new SeekBar.OnSeekBarChangeListener() { public void onprogresschanged(seekbar seekbar, int progress, boolean fromuser) { if(fromuser){ //showtoastmessage("seekbar: " + progress); mtv1.settext("seekbar: " + progress); public void onstarttrackingtouch(seekbar seekbar) { public void onstoptrackingtouch(seekbar seekbar) { ); private void showtoastmessage(string msg){ Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();

39 Lab review - Android Lab2 List with topics you need to understand before next laboration You must be able or know how to Understand all the previous points from former labs Make a new app from scratch on your own with recepies (solutions) from other apps Manage View.OnClickListener touch events (anyone of the 4 button event methods) Create additional Activities in an app Manage SharedPreferences in a PreferenceActivity Understand and be able to use the lifecycle methods plus the onrestoreinstancestate and onsaveinstancestate methods Use UI things as OptionsMenu, ActionBar/Toolbar and AlertDialog etc.