Taking Photos Simply

Ref : https://developer.android.com/training/camera/photobasics.html

Request Camera Permission

---

If an essential function of your application is taking pictures, then restrict its visibility on Google Play to devices that have a camera. To advertise that your application depends on having a camera, put a<uses-feature> tag in your manifest file:

<manifest ... >
    <uses-feature android:name="android.hardware.camera"
                  android:required="true" />
    ...</manifest>

If your application uses, but does not require a camera in order to function, instead set android:required to false. In doing so, Google Play will allow devices without a camera to download your application. It's then your responsibility to check for the availability of the camera at runtime by callinghasSystemFeature(PackageManager.FEATURE_CAMERA). If a camera is not available, you should then disable your camera features.

Take a Photo with the Camera App

---

The Android way of delegating actions to other applications is to invoke an Intent that describes what you want done. This process involves three pieces: The Intent itself, a call to start the external Activity, and some code to handle the image data when focus returns to your activity.

Here's a function that invokes an intent to capture a photo.

static final int REQUEST_IMAGE_CAPTURE = 1;
private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
    }
}

Get the Thumbnail

---

If the simple feat of taking a photo is not the culmination of your app's ambition, then you probably want to get the image back from the camera application and do something with it.

The Android Camera application encodes the photo in the return Intent delivered to onActivityResult() as a small Bitmap in the extras, under the key"data". The following code retrieves this image and displays it in an ImageView.

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
        Bundle extras = data.getExtras();
        Bitmap imageBitmap = (Bitmap) extras.get("data");
        mImageView.setImageBitmap(imageBitmap);
    }
}

Save the Full-size Photo

---

The Android Camera application saves a full-size photo if you give it a file to save into. You must provide a fully qualified file name where the camera app should save the photo.

Generally, any photos that the user captures with the device camera should be saved on the device in the public external storage so they are accessible by all apps. The proper directory for shared photos is provided by getExternalStoragePublicDirectory(), with the DIRECTORY_PICTURES argument. Because the directory provided by this method is shared among all apps, reading and writing to it requires the READ_EXTERNAL_STORAGE and WRITE_EXTERNAL_STORAGE permissions, respectively. The write permission implicitly allows reading, so if you need to write to the external storage then you need to request only one permission:

<manifest ...>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    ...</manifest>

However, if you'd like the photos to remain private to your app only, you can instead use the directory provided by getExternalFilesDir(). On Android 4.3 and lower, writing to this directory also requires the WRITE_EXTERNAL_STORAGE permission. Beginning with Android 4.4, the permission is no longer required because the directory is not accessible by other apps, so you can declare the permission should be requested only on the lower versions of Android by adding the maxSdkVersion attribute:

<manifest ...>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
                     android:maxSdkVersion="18" />
    ...</manifest>

Note: Files you save in the directories provided by getExternalFilesDir() or getFilesDir() are deleted when the user uninstalls your app.

Once you decide the directory for the file, you need to create a collision-resistant file name. You may wish also to save the path in a member variable for later use. Here's an example solution in a method that returns a unique file name for a new photo using a date-time stamp:

String mCurrentPhotoPath;
private File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = "JPEG_" + timeStamp + "_";
    File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
    File image = File.createTempFile(
        imageFileName,  /* prefix */
        ".jpg",         /* suffix */
        storageDir      /* directory */
    );

    // Save a file: path for use with ACTION_VIEW intents
    mCurrentPhotoPath = "file:" + image.getAbsolutePath();
    return image;
}

With this method available to create a file for the photo, you can now create and invoke the Intent like this:

static final int REQUEST_TAKE_PHOTO = 1;
private void dispatchTakePictureIntent() {
    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
    // Ensure that there's a camera activity to handle the intent
    if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
        // Create the File where the photo should go
        File photoFile = null;
        try {
            photoFile = createImageFile(); // return File
        } catch (IOException ex) {
            // Error occurred while creating the File
            ...
        }
        // Continue only if the File was successfully created
        if (photoFile != null) {
            Uri photoURI = FileProvider.getUriForFile(this,
                                                  "com.example.android.fileprovider",
                                                  photoFile);
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, photoURI);
            startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);
        }
    }
}

Note: We are using getUriForFile(Context, String, File) which returns a content:// URI. For more recent apps targeting Android N and higher, passing a file:// URI across a package boundary causes a FileUriExposedException. Therefore, we now present a more generic way of storing images using a FileProvider.

Now, you need to configure the FileProvider. In your app's manifest, add a provider to your application:

<application>
   ...
   <provider
        android:name="android.support.v4.content.FileProvider"
        android:authorities="com.example.android.fileprovider"
        android:exported="false"
        android:grantUriPermissions="true">
        <meta-data
            android:name="android.support.FILE_PROVIDER_PATHS"
            android:resource="@xml/file_paths"></meta-data>
    </provider>
    ...</application>

Make sure that the authorities string matches the second argument to getUriForFile(Context, String, File). In the meta-data section of the provider definition, you can see that the provider expects eligible paths to be configured in a dedicated resource file, res/xml/file_paths.xml. Here is the content required for this particular example:

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path name="my_images" path="Android/data/com.example.package.name/files/Pictures" />
</paths>

The path component corresponds to the path that is returned by getExternalFilesDir() when called with Environment.DIRECTORY_PICTURES. Make sure that you replace com.example.package.name with the actual package name of your app. Also, checkout the documentation of FileProvider for an extensive description of path specifiers that you can use besides external-path.

Add the Photo to a Gallery

When you create a photo through an intent, you should know where your image is located, because you said where to save it in the first place. For everyone else, perhaps the easiest way to make your photo accessible is to make it accessible from the system's Media Provider.

Note: If you saved your photo to the directory provided by getExternalFilesDir(), the media scanner cannot access the files because they are private to your app.

The following example method demonstrates how to invoke the system's media scanner to add your photo to the Media Provider's database, making it available in the Android Gallery application and to other apps.

private void galleryAddPic() {
    Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
    File f = new File(mCurrentPhotoPath);
    Uri contentUri = Uri.fromFile(f);
    mediaScanIntent.setData(contentUri);
    this.sendBroadcast(mediaScanIntent);
}

Decode a Scaled Image

Managing multiple full-sized images can be tricky with limited memory. If you find your application running out of memory after displaying just a few images, you can dramatically reduce the amount of dynamic heap used by expanding the JPEG into a memory array that's already scaled to match the size of the destination view. The following example method demonstrates this technique.

private void setPic() {
    // Get the dimensions of the View
    int targetW = mImageView.getWidth();
    int targetH = mImageView.getHeight();

    // Get the dimensions of the bitmap
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();
    bmOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
    int photoW = bmOptions.outWidth;
    int photoH = bmOptions.outHeight;

    // Determine how much to scale down the image
    int scaleFactor = Math.min(photoW/targetW, photoH/targetH);

    // Decode the image file into a Bitmap sized to fill the View
    bmOptions.inJustDecodeBounds = false;
    bmOptions.inSampleSize = scaleFactor;
    bmOptions.inPurgeable = true;

    Bitmap bitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
    mImageView.setImageBitmap(bitmap);
}

接下來看sample code

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.main);

mImageView = (ImageView) findViewById(R.id.imageView1);
mVideoView = (VideoView) findViewById(R.id.videoView1);
mImageBitmap = null;
mVideoUri = null;

//  三個button... 同時建立他的listener function

Button picBtn = (Button) findViewById(R.id.btnIntend);
setBtnListenerOrDisable( 
      picBtn, 
      mTakePicOnClickListener,
      MediaStore.ACTION_IMAGE_CAPTURE);

Button picSBtn = (Button) findViewById(R.id.btnIntendS);
setBtnListenerOrDisable( 
      picSBtn, 
      mTakePicSOnClickListener,
      MediaStore.ACTION_IMAGE_CAPTURE);

Button vidBtn = (Button) findViewById(R.id.btnIntendV);
setBtnListenerOrDisable( 
      vidBtn, 
      mTakeVidOnClickListener,
      MediaStore.ACTION_VIDEO_CAPTURE);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO) {
   mAlbumStorageDirFactory = new FroyoAlbumDirFactory();
} else {
   mAlbumStorageDirFactory = new BaseAlbumDirFactory();
}

}

//  當按下   picBtn  Button  就會呼叫 mTakePicOnClickListener() 

Button.OnClickListener mTakePicOnClickListener = 
   new Button.OnClickListener() {
   @Override   public void onClick(View v) {
      dispatchTakePictureIntent(ACTION_TAKE_PHOTO_B);
   }
};

//  然後就會呼叫 dispatchTakePictureIntent()

private void dispatchTakePictureIntent(int actionCode) {


   //  註冊  ACTION_IMAGE_CAPTURE intent
   Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

   switch(actionCode) {
   case ACTION_TAKE_PHOTO_B: // full size picture
      File f = null;
      
      try {
         f = setUpPhotoFile();
         mCurrentPhotoPath = f.getAbsolutePath();
         takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f));
      } catch (IOException e) {
         e.printStackTrace();
         f = null;
         mCurrentPhotoPath = null;
      }
      break;

   default:
      break;       
   } // switch
   startActivityForResult(takePictureIntent, actionCode);
}

private File setUpPhotoFile() throws IOException {
   
   File f = createImageFile();
   mCurrentPhotoPath = f.getAbsolutePath();
   
   return f;
}

private File createImageFile() throws IOException {
   // Create an image file name   String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
   String imageFileName = JPEG_FILE_PREFIX + timeStamp + "_";
   File albumF = getAlbumDir();
   File imageF = File.createTempFile(imageFileName, JPEG_FILE_SUFFIX, albumF);
   return imageF;
}

就跟網站寫的說明差不多的code.....

=======================================================================

fragment example

Ref : https://developer.android.com/training/basics/fragments/creating.html

Create a Fragment Class

To create a fragment, extend the Fragment class, then override key lifecycle methods to insert your app logic, similar to the way you would with an Activity class.

One difference when creating a Fragment is that you must use the onCreateView() callback to define the layout. In fact, this is the only callback you need in order to get a fragment running. For example, here's a simple fragment that specifies its own layout:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.ViewGroup;
public class ArticleFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.article_view, container, false);
    }
}

Just like an activity, a fragment should implement other lifecycle callbacks that allow you to manage its state as it is added or removed from the activity and as the activity transitions between its lifecycle states. For instance, when the activity's onPause() method is called, any fragments in the activity also receive a call to onPause().

More information about the fragment lifecycle and callback methods is available in the Fragments developer guide.

Add a Fragment to an Activity using XML

While fragments are reusable, modular UI components, each instance of a Fragment class must be associated with a parent FragmentActivity. You can achieve this association by defining each fragment within your activity layout XML file.

Note: FragmentActivity is a special activity provided in the Support Library to handle fragments on system versions older than API level 11. If the lowest system version you support is API level 11 or higher, then you can use a regular Activity.

Here is an example layout file that adds two fragments to an activity when the device screen is considered "large" (specified by the large qualifier in the directory name).

res/layout-large/news_articles.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">

    <fragment android:name="com.example.android.fragments.HeadlinesFragment"
              android:id="@+id/headlines_fragment"
              android:layout_weight="1"
              android:layout_width="0dp"
              android:layout_height="match_parent" />

    <fragment android:name="com.example.android.fragments.ArticleFragment"
              android:id="@+id/article_fragment"
              android:layout_weight="2"
              android:layout_width="0dp"
              android:layout_height="match_parent" />
</LinearLayout>

Tip: For more about creating layouts for different screen sizes, read Supporting Different Screen Sizes.

Then apply the layout to your activity:

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.news_articles);
    }
}

If you're using the v7 appcompat library, your activity should instead extend AppCompatActivity, which is a subclass of FragmentActivity. For more information, read Adding the App Bar).

Building a Flexible UI

When designing your application to support a wide range of screen sizes, you can reuse your fragments in different layout configurations to optimize the user experience based on the available screen space.

For example, on a handset device it might be appropriate to display just one fragment at a time for a single-pane user interface. Conversely, you may want to set fragments side-by-side on a tablet which has a wider screen size to display more information to the user.

Figure 1. Two fragments, displayed in different configurations for the same activity on different screen sizes. On a large screen, both fragments fit side by side, but on a handset device, only one fragment fits at a time so the fragments must replace each other as the user navigates.

The FragmentManager class provides methods that allow you to add, remove, and replace fragments to an activity at runtime in order to create a dynamic experience.

Add a Fragment to an Activity at Runtime

---

Rather than defining the fragments for an activity in the layout file—as shown in the previous lesson with the <fragment> element—you can add a fragment to the activity during the activity runtime. This is necessary if you plan to change fragments during the life of the activity.

To perform a transaction such as add or remove a fragment, you must use the FragmentManager to create a FragmentTransaction, which provides APIs to add, remove, replace, and perform other fragment transactions.

If your activity allows the fragments to be removed and replaced, you should add the initial fragment(s) to the activity during the activity's onCreate()method.

An important rule when dealing with fragments—especially when adding fragments at runtime—is that your activity layout must include a container View in which you can insert the fragment.

The following layout is an alternative to the layout shown in the previous lesson that shows only one fragment at a time. In order to replace one fragment with another, the activity's layout includes an empty FrameLayout that acts as the fragment container.

Notice that the filename is the same as the layout file in the previous lesson, but the layout directory does not have the large qualifier, so this layout is used when the device screen is smaller than large because the screen does not fit both fragments at the same time.

res/layout/news_articles.xml:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_container"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Inside your activity, call getSupportFragmentManager() to get a FragmentManager using the Support Library APIs. Then call beginTransaction() to create a FragmentTransaction and call add() to add a fragment.

You can perform multiple fragment transaction for the activity using the same FragmentTransaction. When you're ready to make the changes, you must call commit().

For example, here's how to add a fragment to the previous layout:

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
public class MainActivity extends FragmentActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.news_articles);   // frmae layout

        // Check that the activity is using the layout version with
        // the fragment_container FrameLayout
        if (findViewById(R.id.fragment_container) != null) {

            // However, if we're being restored from a previous state,
            // then we don't need to do anything and should return or else
            // we could end up with overlapping fragments.
            if (savedInstanceState != null) {
                return;
            }

            // Create a new Fragment to be placed in the activity layout
            HeadlinesFragment firstFragment = new HeadlinesFragment();

            // In case this activity was started with special instructions from an
            // Intent, pass the Intent's extras to the fragment as arguments
            firstFragment.setArguments(getIntent().getExtras());

            // Add the fragment to the 'fragment_container' FrameLayout
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.fragment_container, firstFragment).commit();
        }
    }
}

Because the fragment has been added to the FrameLayout container at runtime—instead of defining it in the activity's layout with a <fragment> element—the activity can remove the fragment and replace it with a different one.

Replace One Fragment with Another

The procedure to replace a fragment is similar to adding one, but requires the replace() method instead of add().

Keep in mind that when you perform fragment transactions, such as replace or remove one, it's often appropriate to allow the user to navigate backward and "undo" the change. To allow the user to navigate backward through the fragment transactions, you must call addToBackStack() before you commit the FragmentTransaction.

Note: When you remove or replace a fragment and add the transaction to the back stack, the fragment that is removed is stopped (not destroyed). If the user navigates back to restore the fragment, it restarts. If you do not add the transaction to the back stack, then the fragment is destroyed when removed or replaced.

Example of replacing one fragment with another:

// Create fragment and give it an argument specifying the article it should show
ArticleFragment newFragment = new ArticleFragment();
Bundle args = new Bundle();
args.putInt(ArticleFragment.ARG_POSITION, position);
newFragment.setArguments(args);
FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack so the user can navigate back
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);
// Commit the transaction
transaction.commit();

check sample   

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.news_articles);  //  指定 news_articles.xml 為layout

    if (findViewById(R.id.fragment_container) != null) {

    // However, if we're being restored from a previous state,    // then we don't need to do anything and should return or else    // we could end up with overlapping fragments.    if (savedInstanceState != null) {
        return;
    }

    // Create an instance of ExampleFragment
    HeadlinesFragment firstFragment = new HeadlinesFragment();

    // In case this activity was started with special instructions from an Intent,    // pass the Intent's extras to the fragment as arguments    firstFragment.setArguments(getIntent().getExtras());

    // Add the fragment to the 'fragment_container' FrameLayout    getSupportFragmentManager().beginTransaction()
            .add(R.id.fragment_container, firstFragment).commit();
}

}

news_articles.xml 的內容如下
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:id="@+id/fragment_container"    android:layout_width="match_parent"    android:layout_height="match_parent" />

//  HeadlinesFragment  class 的內容如下: 

public class HeadlinesFragment extends ListFragment {
    OnHeadlineSelectedListener mCallback;

    // The container Activity must implement this interface so the frag can deliver messages    public interface OnHeadlineSelectedListener {
    /** Called by HeadlinesFragment when a list item is selected */      public void onArticleSelected(int position);
    }

    @Override
public void onStart() {
    super.onStart();

    // When in two-pane layout, set the listview to highlight the selected list item    // (We do this during onStart because at the point the listview is available.)    if (getFragmentManager().findFragmentById(R.id.article_fragment) != null) {
        getListView().setChoiceMode(ListView.CHOICE_MODE_SINGLE);
    }
}

}

// onArticleSelected 的內容如下 

public void onArticleSelected(int position) {
    // The user selected the headline of an article from the HeadlinesFragment
    // Capture the article fragment from the activity layout    ArticleFragment articleFrag = (ArticleFragment)
            getSupportFragmentManager().findFragmentById(R.id.article_fragment);

    if (articleFrag != null) {
        // If article frag is available, we're in two-pane layout...
        // Call a method in the ArticleFragment to update its content        articleFrag.updateArticleView(position);

    } else {
        // If the frag is not available, we're in the one-pane layout and must swap frags...
        // Create fragment and give it an argument for the selected article        ArticleFragment newFragment = new ArticleFragment();
        Bundle args = new Bundle();
        args.putInt(ArticleFragment.ARG_POSITION, position);
        newFragment.setArguments(args);
        FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

        // Replace whatever is in the fragment_container view with this fragment,        // and add the transaction to the back stack so the user can navigate back        transaction.replace(R.id.fragment_container, newFragment);
        transaction.addToBackStack(null);

        // Commit the transaction        transaction.commit();
    }
}

Communicating with Other Fragments

In order to reuse the Fragment UI components, you should build each as a completely self-contained, modular component that defines its own layout and behavior. Once you have defined these reusable Fragments, you can associate them with an Activity and connect them with the application logic to realize the overall composite UI.

Often you will want one Fragment to communicate with another, for example to change the content based on a user event. All Fragment-to-Fragment communication is done through the associated Activity. Two Fragments should never communicate directly.