Android Simple Image Gallery

In this post we are going to use the <a href="http://android-pro.blogspot.com/2010/07/android-gallery-control.html">gallery</a> control t construct a simple image gallery.<br />the layout is like the previous <a href="http://android-pro.blogspot.com/2010/07/android-gallery-control.html">post</a>.<br /><br />remeber that the Gallery control is populated by an adapter, so we will create a custom adapter that contains ImageViews to display the images.<br />our custom adapter must inherit from <strong>BaseAdapter</strong> class<br /><pre class="brush:java">package mina.android.GalleryDemo;<br /><br />import java.util.ArrayList;<br />import java.util.List;<br /><br />import android.content.Context;<br />import android.view.View;<br />import android.view.ViewGroup;<br />import android.widget.BaseAdapter;<br />import android.widget.ImageView;<br /><br />public class ImageAdapter extends BaseAdapter {<br /> Context Con;<br /> //array to hold the values of image resources<br /> int [] Resources;<br /> List<imageview> views;<br /> <br /> public ImageAdapter(Context con,int[] resources)<br /> {<br /> Con=con;<br /> Resources=resources;<br /> views=new ArrayList<imageview>(resources.length);<br /> }<br /> <br /> @Override<br /> public int getCount() {<br /> // TODO Auto-generated method stub<br /> return Resources.length;<br /> }<br /><br /> @Override<br /> public Object getItem(int position) {<br /> // TODO Auto-generated method stub<br /> return views.get(position);<br /> //return position;<br /> }<br /><br /> @Override<br /> public long getItemId(int position) {<br /> // TODO Auto-generated method stub<br /> //return views.get(position).getId();<br /> return position;<br /> }<br /><br /> @Override<br /> public View getView(int position, View convertView, ViewGroup parent) {<br /> // TODO Auto-generated method stub<br /> ImageView img=new ImageView(Con);<br /> img.setImageResource(Resources[position]);<br /> views.add(img);<br /> <br /> return img;<br /> }<br /><br />}<br /><br /></pre><br />then in our activity <b>onCreate</b> Method:<br /><pre class="brush:java">int []res=new int[]{R.drawable.wc,R.drawable.wc2,R.drawable.wc3,R.drawable.wc4,R.drawable.wc5};<br /> ItemsInGallery=res.length;<br /> ImageAdapter imgAdapter=new ImageAdapter(this, res);<br /> gallery.setAdapter(imgAdapter);<br /></pre><br />and that was our simple Image gallery.<br />download the application from <a href="http://uploading.com/files/a9camd4a/Gallery%2BDemo2.rar/">here</a>

In this post we are going to use the gallery control t construct a simple image gallery. the layout is like the previous post . remeber tha...

Android Gallery Control

In Android the Gallery control is a selection control that displays items in a horizontal gallery. the items in the gallery appear beside each other. they can appear separated by a pre-defined space.<br /><br /><span style="color: red;">remember that there is a sample demo application for the gallery to download at the end of the post</span><br /><br />we can use the gallery to display String items using a simple <strong>ArrayAdapter.</strong><br />so let's see how to create a gallery that displays the word "Hello" in several languages:<br /><br />the layout:<br /><pre class="brush:xml"><?xml version="1.0" encoding="utf-8"?><br /><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"<br /> android:orientation="vertical"<br /> android:layout_width="fill_parent"<br /> android:layout_height="fill_parent"<br /> ><br /><TextView <br /> android:layout_width="fill_parent" <br /> android:layout_height="wrap_content" <br /> android:text="Gallery Demo"<br /> /><br /> <Gallery<br /> android:id="@+id/gallery"<br /> android:layout_width="fill_parent" <br /> android:layout_height="wrap_content"<br /> android:gravity="center_horizontal"<br /> android:spacing="100px"<br /> <br /> /><br /></LinearLayout><br /></pre><br />and in the <b>OnCreate</b> method<br /><pre class="brush:java">@Override<br /> public void onCreate(Bundle savedInstanceState) {<br /> super.onCreate(savedInstanceState);<br /> setContentView(R.layout.main);<br /> gallery=(Gallery)findViewById(R.id.gallery);<br /> //String array holding the values<br /> String [] text=new String[]{"Hello","Hi","Alloha","Bonjour","Hallo","¡Hola"};<br /> //Array adapter to display our values in the gallery control<br /> ArrayAdapter<string> arr=new ArrayAdapter<string>(this, android.R.layout.simple_gallery_item, text);<br />gallery.setAdapter(arr);<br />}<br /></pre><br />the gallery will be like this<br /><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Gallery%20Control/gallery.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" hw="true" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Gallery%20Control/gallery.jpg" width="224" /></a></div><br />we can increse the spacing between the items by increasing the value of <strong>android:spacing</strong> property.<br /><br />we can display a scroll bar to indicate the position of the current selected item in the gallery like this:<br /><pre class="brush:xml"><Gallery<br /> android:id="@+id/gallery"<br /> android:layout_width="fill_parent" <br /> android:layout_height="wrap_content"<br /> android:gravity="center_horizontal"<br /> android:spacing="100px"<br /> android:scrollbars="horizontal"<br /> android:scrollbarFadeDuration="0"<br /> android:scrollX="100px"<br /> /><br /><br /></pre><br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Gallery%20Control/gallery2.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" hw="true" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Gallery%20Control/gallery2.jpg" width="223" /></a></div><br />setting the <b>android:scrollbarFadeDuration="0"</b> makes the scroll bar always visible.<br /><br />The <b>android:scrollX</b> property defines the initial scroll offset of the scroll bar which is the initial distance that the gallery is scrolled for.<br /><br /><span style="font-size: large;">Handling Gallery Events</span><br />since the gallery is a selction Control (a adapter view) so it can register a <b>OnItemSelectedListener</b> to handle the selection of items within the gallery.<br /><br /><pre class="brush:java">final String [] text=new String[]{"Hello","Hi","Alloha","Bonjour","Hallo","¡Hola"};<br />gallery.setOnItemSelectedListener(new OnItemSelectedListener() {<br /><br /> @Override<br /> public void onItemSelected(AdapterView parent, View view,<br /> int position, long id) {<br /> // TODO Auto-generated method stub<br /> TextView txt=(TextView)findViewById(R.id.txt);<br /> txt.setText(text[position].toString());<br /> }<br /><br /> @Override<br /> public void onNothingSelected(AdapterView parent) {<br /> // TODO Auto-generated method stub<br /> <br /> }<br /> });<br /></pre><br /><br />now the final step is to add two navigation buttons: Next and Previous to navigate throught the items in the gallery.<br />the layout is gonna be like this:<br /><pre class="brush:xml"><?xml version="1.0" encoding="utf-8"?><br /><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"<br /> android:orientation="vertical"<br /> android:layout_width="fill_parent"<br /> android:layout_height="fill_parent"<br /> ><br /><TextView <br /> android:layout_width="fill_parent" <br /> android:layout_height="wrap_content" <br /> android:text="Gallery Demo"<br /> android:id="@+id/txt"<br /> /><br /> <Gallery<br /> android:id="@+id/gallery"<br /> android:layout_width="fill_parent" <br /> android:layout_height="wrap_content"<br /> android:gravity="center_horizontal"<br /> android:spacing="100px"<br /> android:scrollbars="horizontal"<br /> android:scrollbarFadeDuration="0"<br /> android:scrollX="100px"<br /> /><br /> <LinearLayout<br /> android:layout_width="fill_parent"<br /> android:layout_height="wrap_content"<br /> android:orientation="horizontal"<br /> android:layout_marginTop="5px"<br /> > <br /> <Button <br /> android:text="Previous"<br /> android:layout_width="wrap_content"<br /> android:layout_height="wrap_content"<br /> android:id="@+id/btnPrev"<br /> android:onClick="onClick"<br /> /><br /> <Button <br /> android:text="Next"<br /> android:layout_width="wrap_content"<br /> android:layout_height="wrap_content"<br /> android:id="@+id/btnNext"<br /> android:onClick="onClick"<br /> /><br /><br /> </LinearLayout> <br /> <br /></LinearLayout><br /><br /></pre><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Gallery%20Control/gallery3.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" hw="true" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Gallery%20Control/gallery3.jpg" width="226" /></a></div><br />now in order to keep track of the index of the currently selected item we need to define two variables<br /><pre class="brush:java">//Variable to store the number of items in the gallery<br /> int ItemsInGallery=0;<br /> int CurrentIndex=0;<br /></pre><br />and the navigation buttons click handlers:<br /><pre class="brush:java">@Override<br /> public void onClick(View v) {<br /> // TODO Auto-generated method stub<br /> switch(v.getId())<br /> {<br /> case R.id.btnNext:<br /> //Increase the index<br /> CurrentIndex++;<br /> //if reached the end of the gallery, then start from the first item<br /> if(CurrentIndex>ItemsInGallery-1)<br /> CurrentIndex=0;<br /> gallery.setSelection(CurrentIndex,true);<br /> txt.setText(String.valueOf(CurrentIndex));<br /> break;<br /> case R.id.btnPrev:<br /> //Decrease the index<br /> CurrentIndex=CurrentIndex-1;<br /> //If reached the first item, then return to the last item in the gallery<br /> if(CurrentIndex<0)<br /> CurrentIndex=ItemsInGallery-1;<br /> gallery.setSelection(CurrentIndex,true);<br /> txt.setText(String.valueOf(CurrentIndex));<br /> break;<br /> }<br /> }<br /></pre>you can download a sample program from <a href="http://uploading.com/files/m41mc713/Gallery%2BDemo.rar/">here</a>

In Android the Gallery control is a selection control that displays items in a horizontal gallery. the items in the gallery appear beside ea...

How to rotate the Android Emulator ?

To rotate the Android Emulator, just disable the <b>Num Lock</b> key and and use the <b>7</b> and the <b>9</b> in the num pad to rotate the emulator and change its layout from portrait to landscape.<br /><br />If you are working on a laptop you can do the same thing by pressing  <strong>Fn(Function)+7</strong> or <strong>Fn+9</strong>.

To rotate the Android Emulator, just disable the Num Lock key and and use the 7 and the 9 in the num pad to rotate the emulator and chang...

Android Intents: Part3: Intent Filters

<div dir="ltr" style="text-align: left;" trbidi="on">Android components like activities can also serve implicit intents. but to do so they have to filter all implicit intents in order to serve only the intents they desire to serve. this is done using intent filters.<br /><br />Suppose you want to create an activity that acts as the default dialer activity. You must associate an intent filter with this activity in order to that this activity serve the dial intents only.<br /><br />Let's demonstrate a simple example which is creating an application with one activity that we want to make it a dialer activity.<br /><br />Create a new android project, create an activity and name it <strong>Dialer.</strong><br /><br />In the AndroidManifest.xml file of this application add the following to the <strong>Dialer</strong> activity:<br /><pre><intent-filter android:priority="100" ><br /> <action android:name="android.intent.action.DIAL" /><br /> <category android:name="android.intent.category.DEFAULT" /><br /> <data android:scheme="tel"/><br /> </intent-filter></pre><strong>to become:</strong><br /><pre class="brush:xml"><activity android:name=".Dialer"<br /> android:label="@string/app_name"><br /> <intent-filter><br /> <action android:name="android.intent.action.MAIN" /><br /> <category android:name="android.intent.category.LAUNCHER" /><br /> </intent-filter><br /> <intent-filter android:priority="100" ><br /> <action android:name="android.intent.action.DIAL" /><br /> <category android:name="android.intent.category.DEFAULT" /><br /> <data android:scheme="tel"/><br /> </intent-filter><br /> </activity></pre>Now what we have done is adding an intent filter to that activity. this intent filter has the following properties:<br /><ol><li>Action: the type of implicit intents that this activity responds to. in our case it is the dial action. higher numbers represent higher priority.</li><li>Priority: about the priority of that activity over other activities that respond to the same type of intents.</li><li>Category: Implicit intents have built-in categories. in order that an implicit intent be captured by our activity, the implicit intent category must match our activity category.</li><li>Data: adds data specification scheme to the intent filter.</li></ol>So if any other application has the following module to launch the dialer:<br /><pre class="brush:java">Intent in=new Intent(Intent.ACTION_DIAL, Uri.parse("tel:000"));<br /> startActivity(in);</pre>The user will see the following dialog offering him/her the choice between the default dialer and our custom dialer.<br /><div class="separator" style="clear: both; text-align: center;"><a href="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Intents%203/intentfilters.bmp" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="170" l6="true" src="http://dl.dropbox.com/u/2624328/Android%20Pro/2010/July/Intents%203/intentfilters.bmp" width="200" /></a></div></div>

Android components like activities can also serve implicit intents. but to do so they have to filter all implicit intents in order to serve ...