屏幕旋转发生时,ImageView不保留图像

Question

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Parcelable;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

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




        Button cameraClick = (Button) findViewById(R.id.click);
        iv = (ImageView) findViewById(R.id.imageView1);

        final Bitmap data = (Bitmap) getLastNonConfigurationInstance();
        if (data == null) { 

           iv.setImageBitmap(bTemp);
        }


        cameraClick.setOnClickListener(myhandler);

    }


    OnClickListener myhandler = new OnClickListener() {
        public void onClick(View v) {
            Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
            startActivityForResult(intent, 0);
        }
      };


    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Bitmap bm = (Bitmap) data.getExtras().get("data");
        iv.setImageBitmap(bm);

    }


    @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;
    }




    @Override
    @Deprecated
    public Object onRetainNonConfigurationInstance() {
        bTemp = iv.getDrawingCache();
        return bTemp;
    }


}

我正在使用imageview来存储使用Camera Intent捕获的图像,但是当屏幕旋转时图像会丢失.我尝试使用onRetainNonConfigurationInstance()但它不起作用

而且我不想把图像写成文件.

Answer 1

您可以通过在Manifest文件中设置orientation和screensize标志来避免重新创建活动

android:configChanges="keyboard|orientation|screenSize"

如果需要,您可以实现onConfigurationChanged()在方向更改时调用的内容.更多信息请访问http://developer.android.com/guide/topics/resources/runtime-changes.html#HandlingTheChange

Answer 2

这可能对你有所帮助......

@Override
protected void onSaveInstanceState(Bundle outState) {
    BitmapDrawable drawable = (BitmapDrawable) imageView.getDrawable();
    Bitmap bitmap = drawable.getBitmap();
    outState.putParcelable("image", bitmap);
    super.onSaveInstanceState(outState);
}

protected void onCreate(Bundle savedInstanceState) {
     if(savedInstanceState != null) {
        Bitmap bitmap = savedInstanceState.getParcelable("image");
        imageView.setImageBitmap(bitmap);
     }
}

Answer 3

getLastNonConfigurationInstance()返回一个活动实例。您可以从该实例中获取以前的值：

在你的onCreate()：

YourActivity prevActivity = (YourActivity) getLastNonConfigurationInstance();

if(prevActivity!= null) { 
      this.bTemp = prevActivity.bTemp;
   }

你的onRetainNonConfigurationInstance()方法应该是：

@Override
@Deprecated
public Object onRetainNonConfigurationInstance() {
    return bTemp;
}

你的 'onActivityResult()` 方法应该是：

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    bTemp = (Bitmap) data.getExtras().get("data");
    iv.setImageBitmap(bTemp);
}