Androidのカメラとギャラリーから画像をキャプチャーする。
このチュートリアルでは、カメラまたはギャラリーから画像を選択し、それをImageViewに表示するアプリケーションを開発します。注意: 以下のコードは、Android Nougat以前のバージョンでは正常に動作します。最新の動作例については、[更新された記事](http://Note: GoogleはAndroidのアルファベットバージョンから外れました。Android QはAndroid 10に名前が変更されました。このチュートリアルはGoogleがこれを行う前に書かれたものなので、記事内の一部にはAndroid Qが表示されています。)をご覧ください。
アンドロイド画像キャプチャの概要
Android Marshmallowが開始されたことにより、ランタイムパーミッションを前面に実装する必要があります。次のパーミッションをAndroid Manifest.xmlファイルのapplicationタグの上に追加してください。
<uses-feature
android:name="android.hardware.camera"
android:required="false" />
<uses-feature
android:name="android.hardware.camera.autofocus"
android:required="false" />
<uses-feature
android:name="android.hardware.camera.flash"
android:required="false" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="ANDROID.PERMISSION.READ_EXTERNAL_STORAGE"/>
Android.hardware.cameraを追加することで、Playストアはカメラのないデバイスにアプリケーションのインストールを検出し、防止します。Intentはアクションを他のアプリケーションに委任する標準的な方法です。ネイティブカメラを起動するためには、Intentにはandroid.provider.MediaStore.ACTION_IMAGE_CAPTUREが必要です。ギャラリーから画像を選択するには、Intentには以下の引数が必要です：Intent.ACTION_GET_CONTENT。このチュートリアルでは、カメラまたはギャラリーから画像を選択し、画像を円形のイメージビューと通常のイメージビューに表示する画像ピッカーを呼び出します。build.gradleファイルに以下の依存関係を追加してください。compile ‘de.hdodenhof:circleimageview:2.1.0’
Androidのイメージキャプチャプロジェクトの構造
Androidで画像をキャプチャするコード
activity_main.xmlのレイアウトは、FABボタンのアイコンが@android:drawable/ic_menu_cameraに変更されることを除いて、同じままです。content_main.xmlは以下の通りです。
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="https://schemas.android.com/apk/res/android"
xmlns:app="https://schemas.android.com/apk/res-auto"
xmlns:tools="https://schemas.android.com/tools"
android:id="@+id/content_main"
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"
android:background="#000000"
app:layout_behavior="@string/appbar_scrolling_view_behavior"
tools:context="com.scdev.imagepicker.MainActivity"
tools:showIn="@layout/activity_main">
<RelativeLayout
android:layout_width="250dp"
android:layout_height="250dp"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:background="@drawable/image_border"
android:clickable="true"
android:orientation="vertical">
<ImageView
android:id="@+id/imageView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:adjustViewBounds="true"
android:scaleType="centerCrop" />
</RelativeLayout>
<de.hdodenhof.circleimageview.CircleImageView
android:id="@+id/img_profile"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_gravity="center_horizontal"
android:src="@drawable/profile"
app:civ_border_width="5dp"
app:civ_border_color="#FFFFFF"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
以下はMainActivity.javaのコードです。
public class MainActivity extends AppCompatActivity {
Bitmap myBitmap;
Uri picUri;
private ArrayList permissionsToRequest;
private ArrayList permissionsRejected = new ArrayList();
private ArrayList permissions = new ArrayList();
private final static int ALL_PERMISSIONS_RESULT = 107;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
fab.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
startActivityForResult(getPickImageChooserIntent(), 200);
}
});
permissions.add(CAMERA);
permissionsToRequest = findUnAskedPermissions(permissions);
//get the permissions we have asked for before but are not granted..
//we will store this in a global list to access later.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (permissionsToRequest.size() > 0)
requestPermissions(permissionsToRequest.toArray(new String[permissionsToRequest.size()]), ALL_PERMISSIONS_RESULT);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* Create a chooser intent to select the source to get image from.<br />
* The source can be camera's (ACTION_IMAGE_CAPTURE) or gallery's (ACTION_GET_CONTENT).<br />
* All possible sources are added to the intent chooser.
*/
public Intent getPickImageChooserIntent() {
// Determine Uri of camera image to save.
Uri outputFileUri = getCaptureImageOutputUri();
List allIntents = new ArrayList();
PackageManager packageManager = getPackageManager();
// collect all camera intents
Intent captureIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
List listCam = packageManager.queryIntentActivities(captureIntent, 0);
for (ResolveInfo res : listCam) {
Intent intent = new Intent(captureIntent);
intent.setComponent(new ComponentName(res.activityInfo.packageName, res.activityInfo.name));
intent.setPackage(res.activityInfo.packageName);
if (outputFileUri != null) {
intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri);
}
allIntents.add(intent);
}
// collect all gallery intents
Intent galleryIntent = new Intent(Intent.ACTION_GET_CONTENT);
galleryIntent.setType("image/*");
List listGallery = packageManager.queryIntentActivities(galleryIntent, 0);
for (ResolveInfo res : listGallery) {
Intent intent = new Intent(galleryIntent);
intent.setComponent(new ComponentName(res.activityInfo.packageName, res.activityInfo.name));
intent.setPackage(res.activityInfo.packageName);
allIntents.add(intent);
}
// the main intent is the last in the list (fucking android) so pickup the useless one
Intent mainIntent = allIntents.get(allIntents.size() - 1);
for (Intent intent : allIntents) {
if (intent.getComponent().getClassName().equals("com.android.documentsui.DocumentsActivity")) {
mainIntent = intent;
break;
}
}
allIntents.remove(mainIntent);
// Create a chooser from the main intent
Intent chooserIntent = Intent.createChooser(mainIntent, "Select source");
// Add all other intents
chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, allIntents.toArray(new Parcelable[allIntents.size()]));
return chooserIntent;
}
/**
* Get URI to image received from capture by camera.
*/
private Uri getCaptureImageOutputUri() {
Uri outputFileUri = null;
File getImage = getExternalCacheDir();
if (getImage != null) {
outputFileUri = Uri.fromFile(new File(getImage.getPath(), "profile.png"));
}
return outputFileUri;
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
Bitmap bitmap;
if (resultCode == Activity.RESULT_OK) {
ImageView imageView = (ImageView) findViewById(R.id.imageView);
if (getPickImageResultUri(data) != null) {
picUri = getPickImageResultUri(data);
try {
myBitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), picUri);
myBitmap = rotateImageIfRequired(myBitmap, picUri);
myBitmap = getResizedBitmap(myBitmap, 500);
CircleImageView croppedImageView = (CircleImageView) findViewById(R.id.img_profile);
croppedImageView.setImageBitmap(myBitmap);
imageView.setImageBitmap(myBitmap);
} catch (IOException e) {
e.printStackTrace();
}
} else {
bitmap = (Bitmap) data.getExtras().get("data");
myBitmap = bitmap;
CircleImageView croppedImageView = (CircleImageView) findViewById(R.id.img_profile);
if (croppedImageView != null) {
croppedImageView.setImageBitmap(myBitmap);
}
imageView.setImageBitmap(myBitmap);
}
}
}
private static Bitmap rotateImageIfRequired(Bitmap img, Uri selectedImage) throws IOException {
ExifInterface ei = new ExifInterface(selectedImage.getPath());
int orientation = ei.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
return rotateImage(img, 90);
case ExifInterface.ORIENTATION_ROTATE_180:
return rotateImage(img, 180);
case ExifInterface.ORIENTATION_ROTATE_270:
return rotateImage(img, 270);
default:
return img;
}
}
private static Bitmap rotateImage(Bitmap img, int degree) {
Matrix matrix = new Matrix();
matrix.postRotate(degree);
Bitmap rotatedImg = Bitmap.createBitmap(img, 0, 0, img.getWidth(), img.getHeight(), matrix, true);
img.recycle();
return rotatedImg;
}
public Bitmap getResizedBitmap(Bitmap image, int maxSize) {
int width = image.getWidth();
int height = image.getHeight();
float bitmapRatio = (float) width / (float) height;
if (bitmapRatio > 0) {
width = maxSize;
height = (int) (width / bitmapRatio);
} else {
height = maxSize;
width = (int) (height * bitmapRatio);
}
return Bitmap.createScaledBitmap(image, width, height, true);
}
/**
* Get the URI of the selected image from {@link #getPickImageChooserIntent()}.<br />
* Will return the correct URI for camera and gallery image.
*
* @param data the returned data of the activity result
*/
public Uri getPickImageResultUri(Intent data) {
boolean isCamera = true;
if (data != null) {
String action = data.getAction();
isCamera = action != null && action.equals(MediaStore.ACTION_IMAGE_CAPTURE);
}
return isCamera ? getCaptureImageOutputUri() : data.getData();
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
// save file url in bundle as it will be null on scren orientation
// changes
outState.putParcelable("pic_uri", picUri);
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
// get the file url
picUri = savedInstanceState.getParcelable("pic_uri");
}
private ArrayList findUnAskedPermissions(ArrayList wanted) {
ArrayList result = new ArrayList();
for (String perm : wanted) {
if (!hasPermission(perm)) {
result.add(perm);
}
}
return result;
}
private boolean hasPermission(String permission) {
if (canMakeSmores()) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
return (checkSelfPermission(permission) == PackageManager.PERMISSION_GRANTED);
}
}
return true;
}
private void showMessageOKCancel(String message, DialogInterface.OnClickListener okListener) {
new AlertDialog.Builder(this)
.setMessage(message)
.setPositiveButton("OK", okListener)
.setNegativeButton("Cancel", null)
.create()
.show();
}
private boolean canMakeSmores() {
return (Build.VERSION.SDK_INT > Build.VERSION_CODES.LOLLIPOP_MR1);
}
@TargetApi(Build.VERSION_CODES.M)
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
switch (requestCode) {
case ALL_PERMISSIONS_RESULT:
for (String perms : permissionsToRequest) {
if (hasPermission(perms)) {
} else {
permissionsRejected.add(perms);
}
}
if (permissionsRejected.size() > 0) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
if (shouldShowRequestPermissionRationale(permissionsRejected.get(0))) {
showMessageOKCancel("These permissions are mandatory for the application. Please allow access.",
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
//Log.d("API123", "permisionrejected " + permissionsRejected.size());
requestPermissions(permissionsRejected.toArray(new String[permissionsRejected.size()]), ALL_PERMISSIONS_RESULT);
}
}
});
return;
}
}
}
break;
}
}
}
上記のコードからは、多くの推論が導かれる。
- We need to ask for the Camera runtime permissions when the user starts the activity.
- As we are starting the intent to get some result back, we need to call startActivityForResult with the relevant arguments
- Instead of using a dialog to separately call the Intents for Camera and Gallery, we’ve used a method getPickImageChooserIntent() that creates a single chooser intent for all the camera and gallery intents(note the documents intent). Intent.EXTRA_INITIAL_INTENTS is used to add the multiple application intents at one place
- For the camera intent, MediaStore.EXTRA_OUTPUT is passed as an extra to specify the image storage path. Without this you’ll be returned only a small resolution image.
- The URI path for the image returned by camera is fetched inside the method getCaptureImageOutputUri().
- The onActivityResult essentially returns a URI to the image. Some devices do return the bitmap as data.getExtras().get(“data”);.
- When an image is clicked, the camera screen while returning restarts the activity thereby causing the URI stored from the method getCaptureImageOutputUri() to become null. Hence it’s essential that we store and restore that URI using onSaveInstanceState() and onRestoreInstanceState().
- The bitmap is retrieved from the URI in the following line of code. myBitmap = MediaStore.Images.Media.getBitmap(this.getContentResolver(), picUri);
- Devices like Samsung galaxy are known to capture the image in landscape orientation. Retrieving the image and displaying as it is can cause it to be displayed in the wrong orientation. Hence we’ve called the method rotateImageIfRequired(myBitmap, picUri);
- ExifInterface is a class for reading and writing Exif tags in a JPEG file or a RAW image file.
- In the end we call the method getResizedBitmap() to scale the bitmap by width or height(whichever is larger) and set the image to the image view using setImageBitmap.
以下にアプリケーションの動作結果を示します。注：カメラから画像をキャプチャして表示するには、当然ながらスマートフォンでアプリケーションを実行する必要があります。それにて、このチュートリアルは終了です。以下のリンクから、画像キャプチャのためのAndroidプロジェクトをダウンロードすることができます。
Androidのカメラから画像をキャプチャするプロジェクトをダウンロードする