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我正在尝试在 Android 内置应用程序的图库中显示下载的图像。但我面临着从 sdcard 存储和删除图像的问题。但我可以使用 MediaPlayer 播放歌曲而无需存储歌曲。

像 MediaPlayer 类一样,是否有任何直接类来渲染 url 图像以获得放大和缩小的直接功能?

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2 回答 2

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什么都没有建。您将需要一个图像加载实现和一个捏缩放实现。

以下两个是我个人可以推荐的。

https://github.com/nostra13/Android-Universal-Image-Loader

https://github.com/chrisbanes/PhotoView

public class ImageViewerActivity extends Activity {

public static final String EXTRA_URL = ImageViewerActivity.class.getName() + ".EXTRA_URL";

private ImageView mImageView;

private PhotoViewAttacher mAttacher;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.image_viewer_activity);

    mImageView = (ImageView) findViewById(R.id.iv_photo);

    //retrieve image url from extras
    String url = getIntent().getStringExtra(EXTRA_URL);

    //The MAGIC happens here!
    mAttacher = new PhotoViewAttacher(mImageView);

    ImageLoader.getInstance().loadImage(url, new ImageLoadingListener() {
        @Override
        public void onLoadingStarted(String imageUri, View view) {
            //To change body of implemented methods use File | Settings | File Templates.
        }

        @Override
        public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
            //To change body of implemented methods use File | Settings | File Templates.
        }

        @Override
        public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
            mImageView.setImageBitmap(loadedImage);
            mAttacher.update();
        }

        @Override
        public void onLoadingCancelled(String imageUri, View view) {
            //To change body of implemented methods use File | Settings | File Templates.
        }
    });
}

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

    // Need to call clean-up
    mAttacher.cleanup();
}
}

和布局...

<merge xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent">
<ImageView android:id="@+id/iv_photo"
           android:layout_width="fill_parent"
           android:layout_height="fill_parent" />
</merge>
于 2013-05-06T10:32:59.677 回答
0

请参阅下面的代码以显示具有缩放功能的图像。

public class AndroidZoomActivity extends Activity implements OnTouchListener {

    private static final String TAG = "Touch";

    // These matrices will be used to scale points of the image
    Matrix matrix = new Matrix();
    Matrix savedMatrix = new Matrix();

    // The 3 states (events) which the user is trying to perform
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // these PointF objects are used to record the point(s) the user is touching
    PointF start = new PointF();
    PointF mid = new PointF();
    float oldDist = 1f;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

         ImageView view = (ImageView) findViewById(R.id.im_card);

         view.setImageBitmap((getBitmap("Here ImageURL")));
         view.setOnTouchListener(this);
    }

     @Override
     public boolean onTouch(View v, MotionEvent event) {

     ImageView view = (ImageView) v;
     view.setScaleType(ImageView.ScaleType.MATRIX);
     float scale;

     dumpEvent(event);
     // Handle touch events here...

     switch (event.getAction() & MotionEvent.ACTION_MASK) {
     case MotionEvent.ACTION_DOWN: // first finger down only
     savedMatrix.set(matrix);
     start.set(event.getX(), event.getY());
     Log.d(TAG, "mode=DRAG"); // write to LogCat
     mode = DRAG;
     break;

     case MotionEvent.ACTION_UP: // first finger lifted

     case MotionEvent.ACTION_POINTER_UP: // second finger lifted

     mode = NONE;
     Log.d(TAG, "mode=NONE");
     break;

     case MotionEvent.ACTION_POINTER_DOWN: // first and second finger down

     oldDist = spacing(event);
     Log.d(TAG, "oldDist=" + oldDist);
     if (oldDist > 5f) {
     savedMatrix.set(matrix);
     midPoint(mid, event);
     mode = ZOOM;
     Log.d(TAG, "mode=ZOOM");
     }
     break;

     case MotionEvent.ACTION_MOVE:

     if (mode == DRAG) {
     matrix.set(savedMatrix);
     matrix.postTranslate(event.getX() - start.x, event.getY()
     - start.y); // create the transformation in the matrix
     // of points
     } else if (mode == ZOOM) {
     // pinch zooming
     float newDist = spacing(event);
     Log.d(TAG, "newDist=" + newDist);
     if (newDist > 5f) {
     matrix.set(savedMatrix);
     scale = newDist / oldDist; // setting the scaling of the
     // matrix...if scale > 1 means
     // zoom in...if scale < 1 means
     // zoom out
     matrix.postScale(scale, scale, mid.x, mid.y);
     }
     }
     break;
     }

     view.setImageMatrix(matrix); // display the transformation on screen

     return true; // indicate event was handled
     }

     /*
     *
     --------------------------------------------------------------------------
     * Method: spacing Parameters: MotionEvent Returns: float Description:
     * checks the spacing between the two fingers on touch
     * ----------------------------------------------------
     */

     private float spacing(MotionEvent event) {
     float x = event.getX(0) - event.getX(1);
     float y = event.getY(0) - event.getY(1);
     return FloatMath.sqrt(x * x + y * y);
     }

     /*
     *
     --------------------------------------------------------------------------
     * Method: midPoint Parameters: PointF object, MotionEvent Returns: void
     * Description: calculates the midpoint between the two fingers
     * ------------------------------------------------------------
     */

     private void midPoint(PointF point, MotionEvent event) {
     float x = event.getX(0) + event.getX(1);
     float y = event.getY(0) + event.getY(1);
     point.set(x / 2, y / 2);
     }

     /** Show an event in the LogCat view, for debugging */
     private void dumpEvent(MotionEvent event) {
     String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
     "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
     StringBuilder sb = new StringBuilder();
     int action = event.getAction();
     int actionCode = action & MotionEvent.ACTION_MASK;
     sb.append("event ACTION_").append(names[actionCode]);

     if (actionCode == MotionEvent.ACTION_POINTER_DOWN
     || actionCode == MotionEvent.ACTION_POINTER_UP) {
     sb.append("(pid ").append(
     action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
     sb.append(")");
     }

     sb.append("[");
     for (int i = 0; i < event.getPointerCount(); i++) {
     sb.append("#").append(i);
     sb.append("(pid ").append(event.getPointerId(i));
     sb.append(")=").append((int) event.getX(i));
     sb.append(",").append((int) event.getY(i));
     if (i + 1 < event.getPointerCount())
     sb.append(";");
     }

     sb.append("]");
     Log.d("Touch Events ---------", sb.toString());
     }

     /**
      * Finctionality for concerting imageURl string into bitmap
      * @param url
      * @return
      */
    public static Bitmap getBitmap(String url) {
        Bitmap bm = null;
        try {
            URL aURL = new URL(url);
            URLConnection conn = aURL.openConnection();
            conn.connect();
            InputStream is = conn.getInputStream();
            BufferedInputStream bis = new BufferedInputStream(is);
            bm = BitmapFactory.decodeStream(new FlushedInputStream(is));
            bis.close();
            is.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return bm;
    }

    static class FlushedInputStream extends FilterInputStream {
        public FlushedInputStream(InputStream inputStream) {
            super(inputStream);
        }

        @Override
        public long skip(long n) throws IOException {
            long totalBytesSkipped = 0L;
            while (totalBytesSkipped < n) {
                long bytesSkipped = in.skip(n - totalBytesSkipped);
                if (bytesSkipped == 0L) {
                    int b = read();
                    if (b < 0) {
                        break; // we reached EOF
                    } else {
                        bytesSkipped = 1; // we read one byte
                    }
                }
                totalBytesSkipped += bytesSkipped;
            }
            return totalBytesSkipped;
        }
    }

}

我希望你现在得到了预期的缩放功能代码。

于 2013-05-06T10:27:32.100 回答