Fresco使用DataSubscriber加载gif

Question

当我得到CloseableAnimatedImage的时候，我想通过DataSubscriber by Fresco.But得到gif，我不知道怎么得到它的位图。

 public void getBitmap(String url, final OnBitmapFetchedListener listener) {
            ImageRequest request = ImageRequest.fromUri(Uri.parse(url));

        final ImagePipeline imagePipeline = Fresco.getImagePipeline();
        DataSource<CloseableReference<CloseableImage>>
                dataSource = imagePipeline.fetchDecodedImage(request, null);

        DataSubscriber dataSubscriber = new BaseDataSubscriber<CloseableReference<CloseableImage>>() {

            @Override
            protected void onNewResultImpl(DataSource<CloseableReference<CloseableImage>> closeableReferenceDataSource) {

                CloseableReference<CloseableImage> imageReference = closeableReferenceDataSource.getResult();
                if (imageReference != null) {
                    try {
                        CloseableImage image = imageReference.clone().get();
                        if (image instanceof CloseableAnimatedImage) {
                            //here i get the gif but i don't know how to get the bitmap
                        }    
                    }
                }
            }

我尝试了另一种方法来获得图片的位图：

fun getBitmap(uri: Uri, listener: OnBitmapFetchedListener) {
val request = ImageRequest.fromUri(uri)

val imagePipeline = Fresco.getImagePipeline()
val dataSource = imagePipeline.fetchEncodedImage(request, null)

val dataSubscriber = object : BaseDataSubscriber<CloseableReference<PooledByteBuffer>>() {

    override fun onNewResultImpl(closeableReferenceDataSource: DataSource<CloseableReference<PooledByteBuffer>>) {

        val imageReference = closeableReferenceDataSource.result
        if (imageReference != null) {
            try {
                val image = imageReference.clone().get()

                val inputStream = PooledByteBufferInputStream(image)

                val imageFormat = ImageFormatChecker.getImageFormat(inputStream)

                Log.e("ImageUtil", "imageFormat = ${ImageFormat.getFileExtension(imageFormat)}")
                val bitmap = BitmapFactory.decodeStream(inputStream)

                listener.onSuccess(bitmap)

            } catch (e: IOException) {
                Log.e("ImageUtil", "error:$e")
            } finally {
                imageReference.close()
            }
        }
    }

    override fun onFailureImpl(closeableReferenceDataSource: DataSource<CloseableReference<PooledByteBuffer>>) {
        Log.e("ImageUtil", "fail")

        listener.onFail()
    }
}

这是kotlin代码，我所做的就是使用fetchEncodedImage并获取图片的inputStream。但它总是使用onFailImpl()，我不知道为什么。

Answer 1

似乎真正的问题是如何静态地只显示动画图像的第一帧。目前还不支持这一点，但它将非常容易实现。

Fresco已有ImageDecodeOptions对象。您只需要在其中添加另一个字段：public final boolean decodeAsStaticImage。然后，在ImageDecoder.decodeGif中，您只需更改：

if (GifFormatChecker.isAnimated(is)) {
  return mAnimatedImageFactory.decodeGif(...);
}
return decodeStaticImage(encodedImage);

至：

if (!options.decodeAsStaticImage && GifFormatChecker.isAnimated(is)) {
  return mAnimatedImageFactory.decodeGif(...);
}
return decodeStaticImage(encodedImage);

请随时实现这一点，并向我们的GitHub Fresco repository提出拉取请求。

然后在客户端代码中，您只需要使用ImageRequestBuilder.setImageDecodeOptions为图像请求设置解码选项。