如何在 Android 中向 ViewPager 添加进度条

问题描述

如何在 Android 中为 ViewPager 添加进度条?

How can I add a progress bar to a ViewPager in Android?

我的情况是我必须在 ViewPager 中加载 imageURL.当用户滑动页面时，如果 ImageURL 没有加载，我需要显示进度条/正在加载 GIF 图片.

My scenario is that I have to load imageURL's in a ViewPager. When the user swipes the pager, if the ImageURL is not loaded I need to show the progress bar/loading GIF image.

有可能吗?

推荐答案

我认为 Satya 正在考虑以下类似的事情.在您的 viewpager 适配器类中，您应该有这个方法:

I think Satya was thinking to something like this in the following. In your viewpager adapter class you should have this method:

@Override
            public Object instantiateItem(View collection, final int position) {

                LayoutInflater inflater = (LayoutInflater) collection.getContext()
                        .getSystemService(Context.LAYOUT_INFLATER_SERVICE);


                final FrameLayout imageLayout = (FrameLayout) inflater.inflate(R.layout.fotopager_buttons, null);
                final ImageView imageView = (ImageView) imageLayout.findViewById(R.id.image);
                final ProgressBar spinner = (ProgressBar) imageLayout.findViewById(R.id.loading);

                imageLoader.displayImage(Gallery.get_big_image_url(position), imageView, options, new ImageLoadingListener() {
                    @Override
                    public void onLoadingStarted() {
                    spinner.setVisibility(View.VISIBLE);
                    }

                    @Override
                    public void onLoadingFailed() {
                    spinner.setVisibility(View.GONE);
                    imageView.setImageResource(android.R.drawable.ic_delete);
                    }

                    @Override
                    public void onLoadingComplete() {
                    spinner.setVisibility(View.GONE);
                    }
                    });


                views.put(position, iv);

                ((ViewPager) collection).addView(imageLayout,0);

                return imageLayout;
}

还有像这样的 R.layout.fotopager_buttons.xml:

And the R.layout.fotopager_buttons.xml like that:

<?xml version="1.0" encoding="utf-8"?>

<ImageView
    android:id="@+id/image"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:adjustViewBounds="true" />

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

您可以在此处查看 imageLoader 类的其余部分:https://github.com/nostra13/Android-Universal-Image-Loader/blob/master/UniversalImageLoaderExample/src/com/nostra13/example/universalimageloader/ImagePagerActivity.java

You can see the rest of the imageLoader class here: https://github.com/nostra13/Android-Universal-Image-Loader/blob/master/UniversalImageLoaderExample/src/com/nostra13/example/universalimageloader/ImagePagerActivity.java

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