android - 如何与 viewpager 共享图像 Intent ？

Question

我需要开发一个应用程序，当用户按下共享按钮时，我需要能够从ViewPager 中的ImageView共享图像 .

我的问题:

• 当我按下共享按钮时，ImageView 缓存下一个Image 而不是当前的 .

  public class MainActivity extends Activity {    private ViewPager pager;       private ImageView Imgv;
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      pager = (ViewPager) findViewById(R.id.pager);
      final Integer[] imageUrls={
          R.drawable.img1 , R.drawable.img2 , R.drawable.img3 , R.drawable.img4
      };
      pager.setAdapter(new MyAdapter(imageUrls));
  
      Button share = (Button) findViewById(R.id.share);
      share.setOnClickListener(new View.OnClickListener() {
  
          public void onClick(View v) {
              // TODO Auto-generated method stub
              Imgv.setDrawingCacheEnabled(true);
              Bitmap icon = Imgv.getDrawingCache();
              ByteArrayOutputStream bytes = new ByteArrayOutputStream();
              icon.compress(Bitmap.CompressFormat.JPEG, 100, bytes);
              File file = new File(Environment.getExternalStorageDirectory() + File.separator + "temporary_file.jpg");
              try {
                  file.createNewFile();
                  FileOutputStream  fo = new FileOutputStream(file);
                  fo.write(bytes.toByteArray());
              } catch (IOException e) {                       
                      e.printStackTrace();
              }
  
              Intent shareIntent = new Intent(android.content.Intent.ACTION_SEND);
              shareIntent.setType("image/jpeg");
              Uri uri = Uri.parse("file:///sdcard/temporary_file.jpg");
              shareIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
              shareIntent.putExtra(Intent.EXTRA_STREAM,uri);
              startActivity(shareIntent);
          }
      });
  }
  
  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
      getMenuInflater().inflate(R.menu.activity_main, menu);
      return true;
  }
  private class MyAdapter extends PagerAdapter {
  
      private LayoutInflater inflater;
      private Integer[] fimg;
  
      public MyAdapter(Integer[] fimg ) {
          this.fimg=fimg;
  
          inflater = getLayoutInflater();
  
      }
  
      @Override
      public Object instantiateItem(View collection,  int position  ) {
  
  
          final View imageLayout = inflater.inflate(R.layout.imgview, null);
  
         Imgv =  (ImageView)imageLayout.findViewById(R.id.full_image_view); 
  
  
  
  
  
          Imgv.setBackgroundResource(fimg[position]);
  
  
  
  
  
  
  
  
           ((ViewPager) collection).addView(imageLayout ,0);
  
  
             return imageLayout;  
  
         }  
  
  
  
  
      @Override
      public int getItemPosition(Object object) {
          // TODO Auto-generated method stub
          return super.getItemPosition(object);
      }
  
      @Override
      public int getCount() {
          return fimg.length;
      }
      @Override
      public void destroyItem(View container, int position, Object object) {
          ((ViewPager) container).removeView((View) object);
      } 
      @Override
      public boolean isViewFromObject(View view, Object object) {
          // TODO Auto-generated method stub
          return view==((View)object);
      }
  
        @Override  
        public void restoreState(Parcelable arg0, ClassLoader loader) {}  
  
        @Override  
        public Parcelable saveState() {  
            return null;  
        }  
        @Override
          public void startUpdate(View container) {
          }
        @Override
          public void finishUpdate(View container) {
  
          }
  

Answer 1

因为你认为 Imgv 是 ViewPager 中当前可见页面的 ImageView。但事实并非如此。在您的情况下，Imgv 是来自最后一个膨胀页面的 ImageView，但不是当前可见页面。

我建议你给 ImageView 添加标签:

Imgv.setBackgroundResource(fimg[position]);
Imgv.setTag(position);  // add this line

然后你可以通过标签找到你的ImageView:

ImageView Imgv = (ImageView)pager.findViewWithTag(pager.getCurrentItem());
Imgv.setDrawingCacheEnabled(true);
...