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.
remember that there is a sample demo application for the gallery to download at the end of the postwe can use the gallery to display String items using a simple
ArrayAdapter.so lets see how to create a gallery that displays the word "Hello" in several languages:
the layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android_orientation="vertical"
android_layout_width="fill_parent"
android_layout_height="fill_parent"
>
<TextView
android_layout_width="fill_parent"
android_layout_height="wrap_content"
android_text="Gallery Demo"
/>
<Gallery
android_id="@+id/gallery"
android_layout_width="fill_parent"
android_layout_height="wrap_content"
android_gravity="center_horizontal"
android_spacing="100px"
/>
</LinearLayout>
and in the
OnCreate method
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
gallery=(Gallery)findViewById(R.id.gallery);
//String array holding the values
String [] text=new String[]{"Hello","Hi","Alloha","Bonjour","Hallo","¡Hola"};
//Array adapter to display our values in the gallery control
ArrayAdapter arr=new ArrayAdapter(this, android.R.layout.simple_gallery_item, text);
gallery.setAdapter(arr);
}
the gallery will be like this
we can increse the spacing between the items by increasing the value of
android:spacing property.
we can display a scroll bar to indicate the position of the current selected item in the gallery like this:
<Gallery
android_id="@+id/gallery"
android_layout_width="fill_parent"
android_layout_height="wrap_content"
android_gravity="center_horizontal"
android_spacing="100px"
android_scrollbars="horizontal"
android_scrollbarFadeDuration="0"
android_scrollX="100px"
/>
setting the
android:scrollbarFadeDuration="0" makes the scroll bar always visible.
The
android:scrollX property defines the initial scroll offset of the scroll bar which is the initial distance that the gallery is scrolled for.
Handling Gallery Eventssince the gallery is a selction Control (a adapter view) so it can register a
OnItemSelectedListener to handle the selection of items within the gallery.
final String [] text=new String[]{"Hello","Hi","Alloha","Bonjour","Hallo","¡Hola"};
gallery.setOnItemSelectedListener(new OnItemSelectedListener() {
@Override
public void onItemSelected(AdapterView parent, View view,
int position, long id) {
// TODO Auto-generated method stub
TextView txt=(TextView)findViewById(R.id.txt);
txt.setText(text[position].toString());
}
@Override
public void onNothingSelected(AdapterView parent) {
// TODO Auto-generated method stub
}
});
now the final step is to add two navigation buttons: Next and Previous to navigate throught the items in the gallery.
the layout is gonna be like this:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android_orientation="vertical"
android_layout_width="fill_parent"
android_layout_height="fill_parent"
>
<TextView
android_layout_width="fill_parent"
android_layout_height="wrap_content"
android_text="Gallery Demo"
android_id="@+id/txt"
/>
<Gallery
android_id="@+id/gallery"
android_layout_width="fill_parent"
android_layout_height="wrap_content"
android_gravity="center_horizontal"
android_spacing="100px"
android_scrollbars="horizontal"
android_scrollbarFadeDuration="0"
android_scrollX="100px"
/>
<LinearLayout
android_layout_width="fill_parent"
android_layout_height="wrap_content"
android_orientation="horizontal"
android_layout_marginTop="5px"
>
<Button
android_text="Previous"
android_layout_width="wrap_content"
android_layout_height="wrap_content"
android_id="@+id/btnPrev"
android_onClick="onClick"
/>
<Button
android_text="Next"
android_layout_width="wrap_content"
android_layout_height="wrap_content"
android_id="@+id/btnNext"
android_onClick="onClick"
/>
</LinearLayout>
</LinearLayout>
now in order to keep track of the index of the currently selected item we need to define two variables
//Variable to store the number of items in the gallery
int ItemsInGallery=0;
int CurrentIndex=0;
and the navigation buttons click handlers:
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch(v.getId())
{
case R.id.btnNext:
//Increase the index
CurrentIndex++;
//if reached the end of the gallery, then start from the first item
if(CurrentIndex>ItemsInGallery-1)
CurrentIndex=0;
gallery.setSelection(CurrentIndex,true);
txt.setText(String.valueOf(CurrentIndex));
break;
case R.id.btnPrev:
//Decrease the index
CurrentIndex=CurrentIndex-1;
//If reached the first item, then return to the last item in the gallery
if(CurrentIndex<0)
CurrentIndex=ItemsInGallery-1;
gallery.setSelection(CurrentIndex,true);
txt.setText(String.valueOf(CurrentIndex));
break;
}
}
you can download a sample program from here
Dalam hal desain sebenarnya tidak jauh beda dengan Android Lollipop ketika memperkenalkan Material Design. Pada Android M diperlihatkan Material Design yang disempurnakan agar terihat lebih flat dan modern.
Android M memperkenalkan beberapa fitur terbaru yang tentunya pada sistem yang mendukung seperti Android Pay, versi terbaru dari Google Wallet dengan menggunakan NFC.
Aplikasi Untuk Pengguna Smartphone Android yang Wajib Dimiliki - Ketika anda baru mempunyai Hp smartphone berbasis OS Android, apa yang anda pikirkan untuk membuat ponsel anda terlihat menarik dan berguna agar tidak terlalu membosankan dalam menggunakan ponsel tersebut. Biasanya yang di pikirkan adalah Aplikasi.
