我，我开始探索 Android，我有点卡在我的第一个问题上。旋转屏幕后，我的 ImageView 在宽度和高度上返回 0。第一次上传照片时它工作正常，但是一旦我翻转屏幕它就会返回 0。我试图在 onResume 和 onRestoresavedInstance 方法中获取它，但我失败了。有谁知道如何解决这个问题？
先感谢您。:)
布局
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<EditText
android:id="@+id/text_email"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/email" />
<EditText
android:id="@+id/text_nickname"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/nickname" />
<Button
android:id="@+id/button_take_photo"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:onClick="takePhoto"
android:text="@string/photo_button" />
<ImageView
android:id="@+id/image_viewer"
android:layout_width="match_parent"
android:contentDescription="@string/photo_taken"
android:background="@android:color/black"
android:layout_height="0dip"
android:layout_weight="1"
android:gravity="top"
android:adjustViewBounds="true" />
</LinearLayout>
代码
public class MainActivity extends Activity {
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
private String fileUri;
private ImageView mImageView;
private EditText nickTextView;
private EditText mailTextView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initUI();
}
@Override
public void onResume() {
super.onResume();
try {
if (this.fileUri != null) {
setPic();
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
// Save UI state changes to the savedInstanceState.
// This bundle will be passed to onCreate if the process is
// killed and restarted.
savedInstanceState.putString("fileUri", this.fileUri);
savedInstanceState.putString("nick", this.nickTextView.getText()
.toString());
savedInstanceState.putString("email", this.mailTextView.getText()
.toString());
super.onSaveInstanceState(savedInstanceState);
}
// onRestoreInstanceState
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
this.fileUri = savedInstanceState.getString("fileUri");
this.nickTextView.setText(savedInstanceState.getString("nick"));
this.mailTextView.setText(savedInstanceState.getString("email"));
}
public void takePhoto(View view) {
if (checkCameraHardware(this)) {
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
this.fileUri = getOutputMediaFilePath();
File temp = new File(fileUri);
intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(temp));
startActivityForResult(intent,
MainActivity.CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
} else {
System.out
.println("This hardware does not support camera features!!!");
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
// galleryAddPic();
try {
setPic();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} else if (resultCode == RESULT_CANCELED) {
System.out.println("User cancelled the image capture");
} else {
System.out.println("Image capture failed, advise user");
}
}
}
private void initUI() {
// Get the image view
mImageView = (ImageView) findViewById(R.id.image_viewer);
// Get the text views
nickTextView = (EditText) findViewById(R.id.text_nickname);
mailTextView = (EditText) findViewById(R.id.text_email);
}
private String getOutputMediaFilePath() {
File storageDir = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
// Create an image file name
String timeStamp = new SimpleDateFormat("yyyyMMddHHmmss")
.format(new Date());
String imageFileName = "liftoff_" + timeStamp + ".jpg";
File image = new File(storageDir, imageFileName);
return image.getAbsolutePath();
}
private boolean checkCameraHardware(Context context) {
if (context.getPackageManager().hasSystemFeature(
PackageManager.FEATURE_CAMERA)) {
// this device has a camera
return true;
} else {
// no camera on this device
return false;
}
}
private void galleryAddPic() {
Intent mediaScanIntent = new Intent(
Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
File f = new File(fileUri);
Uri contentUri = Uri.fromFile(f);
mediaScanIntent.setData(contentUri);
this.sendBroadcast(mediaScanIntent);
}
private void setPic() throws Exception {
// Get the dimensions of the bitmap
BitmapFactory.Options bmOptions = new BitmapFactory.Options();
bmOptions.inJustDecodeBounds = true;
BitmapFactory.decodeFile(fileUri, bmOptions);
int photoW = bmOptions.outWidth;
int photoH = bmOptions.outHeight;
// Get the dimensions of the View
int targetH = mImageView.getHeight();
int targetW = mImageView.getWidth();
// Put correct orientation
Matrix matrix = new Matrix();
ExifInterface exif = new ExifInterface(this.fileUri);
String orientation = exif.getAttribute(ExifInterface.TAG_ORIENTATION);
if (orientation.equals(ExifInterface.ORIENTATION_NORMAL)) {
// Do nothing. The original image is fine.
} else if (orientation.equals(ExifInterface.ORIENTATION_ROTATE_90 + "")) {
photoW = bmOptions.outHeight;
photoH = bmOptions.outWidth;
matrix.postRotate(90);
} else if (orientation
.equals(ExifInterface.ORIENTATION_ROTATE_180 + "")) {
matrix.postRotate(180);
} else if (orientation
.equals(ExifInterface.ORIENTATION_ROTATE_270 + "")) {
matrix.postRotate(270);
photoW = bmOptions.outHeight;
photoH = bmOptions.outWidth;
}
// 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(fileUri, bmOptions);
Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0,
bitmap.getWidth(), bitmap.getHeight(), matrix, true);
mImageView.setImageBitmap(resizedBitmap);
}