通用图像加载器和查看寻呼机的图像缩放问题

Question

我想在ImagePagerActivity中使用ImageViewZoom和Universal Image Loader.

我可以缩放图像,滑动到下一个图像.但是当图像处于变焦位置时,我正面临问题.

如果图像被缩放并且我处于中心位置,如果我想要看到同一图像的右侧部分并向左滑动它将转到下一个图像.请帮我这样做.

这是我的XML代码:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="1dip" >

  <it.sephiroth.android.library.imagezoom.ImageViewTouch
     android:layout_weight="1"
     android:id="@+id/image"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:scaleType="fitCenter" />

  <ProgressBar
    android:id="@+id/loading"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:visibility="gone" />

</FrameLayout>

编辑:

谢谢NOSTRA,现在我可以用下面的代码控制缩放和滑动.但多点触控变焦的问题.我无法用两根手指进行缩放.

这是我以前的代码(用两根手指正常工作):

public class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {


        @Override
        public boolean onScale( ScaleGestureDetector detector ) {
            Log.d( LOG_TAG, "onScale" );
            float span = detector.getCurrentSpan() - detector.getPreviousSpan();
            float targetScale = mCurrentScaleFactor * detector.getScaleFactor();
            if ( mScaleEnabled ) {
                targetScale = Math.min( getMaxZoom(), Math.max( targetScale, getMinZoom()-0.1f ) );
                zoomTo( targetScale, detector.getFocusX(), detector.getFocusY() );
                mCurrentScaleFactor = Math.min( getMaxZoom(), Math.max( targetScale, getMinZoom()-1.0f ) );
                mDoubleTapDirection = 1;
                invalidate();
                return true;
            }
            return false;
        }
    }

以下是修改过的:

public class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            externalScaleListener.onScaleBegin();
                return super.onScaleBegin(detector);
        }
        @Override
        public void onScaleEnd(ScaleGestureDetector detector) {
            externalScaleListener.onScaleEnd(mCurrentScaleFactor);
        }
    }

Answer 1

首先,您必须能够收听图像缩放.ImageViewTouch不支持此功能(例如,支持gesture-imageview),因此您应该自己实现它.

改变ImageViewTouch.java如下:

public class ImageViewTouch extends ImageViewTouchBase {

    ...

    private OnPageScaleListener externalScaleListener;

    public void setOnScaleListener(OnPageScaleListener onScaleListener) {
        this.externalScaleListener = onScaleListener;
    }

    public interface OnPageScaleListener {
        void onScaleBegin();

        void onScaleEnd(float scale);
    }

    @Override
    protected void onZoom(float scale) {
        super.onZoom(scale);
        if (!mScaleDetector.isInProgress()) {
            mCurrentScaleFactor = scale;
            externalScaleListener.onScaleEnd(scale);
        }
    }

    public class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            externalScaleListener.onScaleBegin();
                return super.onScaleBegin(detector);
        }

        ...

        @Override
        public void onScaleEnd(ScaleGestureDetector detector) {
            externalScaleListener.onScaleEnd(mCurrentScaleFactor);
        }
    }

    ...
}

然后ViewPager在您的应用程序中使用下一个实现:

import android.content.Context;
import android.support.v4.view.ViewPager;
import android.util.AttributeSet;
import android.view.MotionEvent;

/**
 * {@link ViewPager} which can be deactivated (ignore touch events)
 * 
 * @author Sergey Tarasevich
 * @created 19.07.2012
 */
public class DeactivableViewPager extends ViewPager {

    private boolean activated = true;

    public DeactivableViewPager(Context context) {
        super(context);
    }

    public DeactivableViewPager(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void activate() {
        activated = true;
    }

    public void deactivate() {
        activated = false;
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent event) {
        if (activated) {
            try {
                return super.onInterceptTouchEvent(event);
            } catch (Exception e) { // sometimes happens
                return true;
            }
        } else {
        return false;
    }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        try {
            return super.onTouchEvent(event);
        } catch (Exception e) {
            return true;
        }
    }
}

然后在ViewPager的适配器中,您应该为ImageViewTouch设置下一个比例监听器:

ImageViewTouch imageView = ...;
imageView.setOnScaleListener(new OnPageScaleListener() {
    @Override
    public void onScaleBegin() {
        viewPager.deactivate();
    }

    @Override
    public void onScaleEnd(float scale) {
        if (scale > 1.0) {
            viewPager.deactivate();
        } else {
            viewPager.activate();
        }
    }
});

imageLoader.displayImage(url, imageView, ...);

并且不要忘记maxImage***ForMemoryCache在ImageLoader的配置中设置大值,这样UIL在解码到Bitmaps时不会缩小原始图像的比例:

ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(getApplicationContext())
        ...
        .memoryCacheExtraOptions(3000, 3000)
        ...
        .build();