Question

我有完整尺寸的照片存储在SD卡上，然后重新调整尺寸并显示在List-view中。我遇到的麻烦是，我目前拥有的代码存在以下问题。

需要很长时间才能让屏幕呈现页面，有时我会得到一个'ANR'
一旦屏幕渲染，ListView的滚动就会非常不连贯，不适合用途。

下面是我的代码

@Override
public void setViewImage(ImageView v, String imagePath) {
  if(imagePath==null || "".equals(imagePath)) {
    return;
  }

  try {
     Drawable d = ImageUtils.getThumbnailDrawable(getResources(), imagePath,             
                                                  v.getDrawable().getIntrinsicWidth(),
                                                  v.getDrawable().getIntrinsicHeight());
     if(d!=null) {
    v.setImageDrawable(d); 
     }
  } catch (Exception e) {
     Log.e(ACTIVITY_SERVICE, e.getMessage(), e);
  }
}

ImageUtils.getThumbnailDrawable方法如下所示

/**
 * Creates a thumbnail image that will be resized to the size of the supplied
 * ImageView
 * @param resources
 * @param path
 * @param width  - the required width of the image
 * @param height - the required height of the image 
 * @return
 */
public static BitmapDrawable getThumbnailDrawable(Resources resources, String path, int width, int height) {
    Bitmap b = BitmapFactory.decodeFile(path);
    if(b==null) {
      return null;
    }

    int imageWidth  = b.getWidth();
    int imageHeight = b.getHeight();

    int orientation = getOrientation(path);
    Matrix mat = new Matrix();

    if (orientation == ExifInterface.ORIENTATION_NORMAL || orientation == ExifInterface.ORIENTATION_ROTATE_180) {
        //landscape photo
        if (orientation == ExifInterface.ORIENTATION_ROTATE_180) {
            mat.postRotate(180);
        }
    } else if (orientation == ExifInterface.ORIENTATION_ROTATE_90 || orientation == ExifInterface.ORIENTATION_ROTATE_270) {
        //portrait photo
        if(orientation == ExifInterface.ORIENTATION_ROTATE_90) {
          mat.postRotate(90);   
        } else {
          mat.postRotate(270);
        }   

        //Image is in landscape mode and after rotation will be portrait
        imageHeight=b.getWidth();
        imageWidth=b.getHeight();
    } else {
        return null;  //Cannot proceed
    }

    //Scale based on width
        float scaleWidth  = (float)(width)/imageWidth;
        float scaleHeight = (float)(height)/imageHeight;

        if(scaleWidth > scaleHeight) {          
            mat.postScale(scaleHeight, scaleHeight);
        } else {

            mat.postScale(scaleWidth, scaleWidth);
        }

        Bitmap resized = Bitmap.createBitmap(b, 0, 0, b.getWidth(), b.getHeight(), mat, true);

        b.recycle();
        b = null;

        return new BitmapDrawable(resources, resized);
    }   
}

此代码目前正在UI线程上运行，我怀疑如果我将其设为Asynctask它会运行得更好，但我认为它不会解决缓慢的渲染和滚动问题。

我想知道在拍摄相机图像的同时创建缩略图是否更为理想？

由于

我已经尝试过Picasso，但现在ListView会显示出来，但是10行非常小，没有填充任何TextView，也没有填充ImageView。我将SimpleCursorAdapter扩展如下

私有类CustomReportCursorAdapter扩展SimpleCursorAdapter { 私有最终上下文上下文;

@SuppressLint("NewApi")
public CustomReportCursorAdapter(Context context, int layout, ReportCursor cursor, String[] FROM, int[] TO, int i) {
    super(context, layout, cursor, FROM, TO, i);
    this.context=context;
}


@Override
public void setViewImage(ImageView v, String imagePath) {
  if(imagePath==null || "".equals(imagePath)) {
    return;
  }
  Picasso.with(context).load(imagePath).fit().into(v);
}

}

ListView的每一行的相应布局如下

   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        android:orientation="horizontal"
        android:background="#FFFFFF"
        android:layout_marginBottom="5dp">

        <LinearLayout android:layout_width="wrap_content" 
                      android:layout_height="wrap_content"
                      android:background="#000000"
                      android:orientation="vertical"
                      android:layout_margin="1dp">

          <ImageView
            android:id="@+id/camera_icon1"
            android:contentDescription="@string/new_report_image_description"
            android:src="@drawable/camera_icon_list_view" 
            android:scaleType="centerCrop"
            android:layout_margin="1dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

        <View
            android:layout_height="2dp"
            android:layout_width="fill_parent"
            android:background="#FFFFFF" />

        <ImageView
            android:id="@+id/camera_icon2"
            android:contentDescription="@string/new_report_image_description"
            android:src="@drawable/camera_icon_list_view" 
            android:scaleType="centerCrop"
            android:layout_margin="1dp"                    
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
        </LinearLayout>

        <LinearLayout android:layout_width="fill_parent" 
                      android:layout_height="fill_parent"
                      android:orientation="vertical"
                      android:background="#000000"
                      android:layout_margin="1dp">
       <LinearLayout android:layout_width="fill_parent" 
                      android:layout_height="fill_parent"
                      android:orientation="vertical"
                      android:background="#CC6600"
                      android:layout_margin="1dp">
        <TextView
            android:id="@+id/report_type"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/new_report_images"
            android:textAppearance="?android:attr/textAppearanceMedium" />
        <TextView
            android:id="@+id/report_sub_type"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:text="@string/new_report_images"
            android:textAppearance="?android:attr/textAppearanceMedium" />

          </LinearLayout>     
        </LinearLayout>
    </LinearLayout>

由于

为ListView创建缩略图的最佳方式

0 个答案: