PicassoImageLoader.java 文件源码

/**
 * Uses the configuration previously applied using this ImageLoader builder to download a
 * resource asynchronously and notify the result to the listener.
 */
private void loadImage() {
  List<Transformation> transformations = getTransformations();
  boolean hasUrl = url != null;
  boolean hasResourceId = resourceId != null;
  boolean hasPlaceholder = placeholderId != null;
  ListenerTarget listenerTarget = getLinearTarget(listener);
  if (hasUrl) {
    RequestCreator bitmapRequest = Picasso.with(context).load(url).tag(PICASSO_IMAGE_LOADER_TAG);
    applyPlaceholder(bitmapRequest).resize(size, size)
        .transform(transformations)
        .into(listenerTarget);
  } else if (hasResourceId || hasPlaceholder) {
    Resources resources = context.getResources();
    Drawable placeholder = null;
    Drawable drawable = null;
    if (hasPlaceholder) {
      placeholder = resources.getDrawable(placeholderId);
      listenerTarget.onPrepareLoad(placeholder);
    }
    if (hasResourceId) {
      drawable = resources.getDrawable(resourceId);
      listenerTarget.onDrawableLoad(drawable);
    }
  } else {
    throw new IllegalArgumentException(
        "Review your request, you are trying to load an image without a url or a resource id.");
  }
}