jueves, 31 de octubre de 2013

Adjust image size to avoid memory issues with images so big

this is the code for decoding images inside a rectangle:


        private int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
     // Raw height and width of image
     final int height = options.outHeight;
     final int width = options.outWidth;
     int inSampleSize = 1;
 
     if (height > reqHeight || width > reqWidth) {
 
         // Calculate ratios of height and width to requested height and width
         final int heightRatio = Math.round((float) height / (float) reqHeight);
         final int widthRatio = Math.round((float) width / (float) reqWidth);
 
         // Choose the smallest ratio as inSampleSize value, this will guarantee
         // a final image with both dimensions larger than or equal to the
         // requested height and width.
         inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
     }
 
     return inSampleSize;
 }
 
 private Bitmap decodeBitmapFromResource(byte[] data,
         int reqWidth, int reqHeight) {

     // First decode with inJustDecodeBounds=true to check dimensions
     final BitmapFactory.Options options = new BitmapFactory.Options();
     options.inJustDecodeBounds = true;
     
     BitmapFactory.decodeByteArray(data, 0, data.length,options);

     // Calculate inSampleSize
     options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
     

     // Decode bitmap with inSampleSize set
     options.inJustDecodeBounds = false;
     
     return BitmapFactory.decodeByteArray(data, 0, data.length,options);
     
 }


Then you can use it in this way:


byte[] data = getImageFromUrl(url);
    
if(data!=null){
    bitmap = decodeBitmapFromResource(data, image_size, image_size);
}

Horizontal View Swipe Eclipse Example

via: http://just-another-blog.net/

The Goal is to implement horizontal View swiping with Tabs in Android like the Google Play Store.
HorizontalViewSwiping
I used the default code from Eclipse.
public class MainActivity extends FragmentActivity {

 /**
  * The {@link android.support.v4.view.PagerAdapter} that will provide
  * fragments for each of the sections. We use a
  * {@link android.support.v4.app.FragmentPagerAdapter} derivative, which
  * will keep every loaded fragment in memory. If this becomes too memory
  * intensive, it may be best to switch to a
  * {@link android.support.v4.app.FragmentStatePagerAdapter}.
  */
 SectionsPagerAdapter mSectionsPagerAdapter;

 /**
  * The {@link ViewPager} that will host the section contents.
  */
 ViewPager mViewPager;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);

  // Create the adapter that will return a fragment for each of the three
  // primary sections of the app.
  mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

  // Set up the ViewPager with the sections adapter.
  mViewPager = (ViewPager) findViewById(R.id.pager);
  mViewPager.setAdapter(mSectionsPagerAdapter);

 }

 @Override
 public boolean onCreateOptionsMenu(Menu menu) {
  // Inflate the menu; this adds items to the action bar if it is present.
  getMenuInflater().inflate(R.menu.main, menu);
  return true;
 }

 /**
  * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
  * one of the sections/tabs/pages.
  */
 public class SectionsPagerAdapter extends FragmentPagerAdapter {

  public SectionsPagerAdapter(FragmentManager fm) {
   super(fm);
  }

  @Override
  public Fragment getItem(int position) {
   // getItem is called to instantiate the fragment for the given page.
   // Return a DummySectionFragment (defined as a static inner class
   // below) with the page number as its lone argument.
   Fragment fragment = new DummySectionFragment();
   Bundle args = new Bundle();
   args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
   fragment.setArguments(args);
   return fragment;
  }

  @Override
  public int getCount() {
   // Show 3 total pages.
   return 3;
  }

  @Override
  public CharSequence getPageTitle(int position) {
   Locale l = Locale.getDefault();
   switch (position) {
   case 0:
    return getString(R.string.title_section1).toUpperCase(l);
   case 1:
    return getString(R.string.title_section2).toUpperCase(l);
   case 2:
    return getString(R.string.title_section3).toUpperCase(l);
   }
   return null;
  }
 }

 /**
  * A dummy fragment representing a section of the app, but that simply
  * displays dummy text.
  */
 public static class DummySectionFragment extends Fragment {
  /**
   * The fragment argument representing the section number for this
   * fragment.
   */
  public static final String ARG_SECTION_NUMBER = "section_number";

  public DummySectionFragment() {
  }

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
   View rootView = inflater.inflate(R.layout.fragment_main_dummy, container, false);
   TextView dummyTextView = (TextView) rootView.findViewById(R.id.section_label);
   dummyTextView.setText(Integer.toString(getArguments().getInt(ARG_SECTION_NUMBER)));
   return rootView;
  }
 }

}

The Layout XML for the MainActivity:
<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/pager"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >

<!--
This title strip will display the currently visible page title, as well as the page
titles for adjacent pages.
-->

<android.support.v4.view.PagerTitleStrip
android:id="@+id/pager_title_strip"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_gravity="top"
android:background="#33b5e5"
android:paddingBottom="4dp"
android:paddingTop="4dp"
android:textColor="#fff" />

</android.support.v4.view.ViewPager>

The Layout XML for the DummyFragment:
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity$DummySectionFragment" >

<TextView
android:id="@+id/section_label"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

</RelativeLayout>

Instead of the Dummy Fragment you can create your own Fragments.
Just create a new java class that extends “Fragment”.
You can attach your own Fragments to the “MainActivity” that way:
 @Override
 public Fragment getItem(int position) {
  Fragment fragment = new Fragment();
  switch (position) {
  case 0:
   return fragment = new Fragment1();
  case 1:
   return fragment = new Fragment2();
  case 2:
   return fragment = new Fragment3();
  default:
   break;
  }
  return fragment;

That’s all


FIX: I think there's a mistake here: try:
 @Override
 public Fragment getItem(int position) {
  Fragment fragment = new Fragment();
  switch (position) {
  case 0:
   return new Fragment1();
  case 1:
   return new Fragment2();
  case 2:
   return new Fragment3();
  default:
   break;
  }
  return fragment;
via: http://just-another-blog.net/