android - 如何将进度条添加到 Picasso 库

Question

如何使用此下载照片的代码向 Picasso 库添加进度条

String Url = "link url";
Picasso.with(G.currentActivity).load(Url).into(imageView);

Answer 1

该功能目前不可用。但是，您可以在 ImageView 顶部放置一个进度条，并在下载图像时附加一个回调，然后隐藏进度条。

<RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="horizontal"
            android:gravity="center_vertical">

  <ImageView
            android:id="@+id/image"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:visibility="gone"
            android:scaleType="center"/>

  <ProgressBar
        style="@android:style/Widget.Holo.Light.ProgressBar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"/>



</RelativeLayout>

然后在你的 Activity 中做这样的事情

import com.squareup.picasso.Callback;

public class MyActivity extends Activity implements Callback {

  private View loaderView;
  private ImageView imageView;

  // ...

  private synchronized void loadImage(Uri uri)
  {
        Picasso.with(this).load(uri)
                .error(R.drawable.ic_error)
                .placeholder(R.drawable.ic_placeholder)
                .resize(getImageWidth(), getImageHeight())

                // passes this object as it's callback when image is loaded
                .centerCrop().into(imageView, this);
  }

  @Override
  public void onSuccess()
  {
    // hide the loader and show the imageview
    loaderView.setVisibility(View.GONE);
    imageView.setVisibility(View.VISIBLE);
  }

  @Override
  public void onError()
  {
    // hide the loader and show the imageview which shows the error icon already
    loaderView.setVisibility(View.GONE);
    imageView.setVisibility(View.VISIBLE);
  }

}