java - Fresco:SimpleDraweeView 总是重置

Question

我有一个 SimpleDraweeView，它通过 Controller 处理图像请求:

Postprocessor redMeshPostprocessor = new BasePostprocessor() {
                @Override
                public String getName() {
                    return "redMeshPostprocessor";
                }

                @Override
                public CloseableReference<Bitmap> process(
                        Bitmap sourceBitmap,
                        PlatformBitmapFactory bitmapFactory) {
                    //custom processing on the bitmap and returning it

                }
            };

            ImageRequest request = ImageRequestBuilder.newBuilderWithSource(Uri.parse(coverImage))
                    .setPostprocessor(redMeshPostprocessor)
                    .build();

            PipelineDraweeController controller = (PipelineDraweeController)
                    Fresco.newDraweeControllerBuilder()
                            .setImageRequest(request)
                            .setOldController(iv_cover.getController())
                            // other setters as you need
                            .build();
            iv_cover.setController(controller);

然后，我想通过简单地说来更改 SimpleDraweeView 上的图像:

iv_cover.setImageURI(Uri.parse(url));

问题是，加载第二张图像时，SimpleDraweeView 会在一瞬间显示占位符。如何避免这种情况？希望两个图像之间的过渡无缝且平滑。谢谢!

Answer 1

你可以这样做:

PipelineDraweeController controller = (PipelineDraweeController)
                Fresco.newDraweeControllerBuilder()
                        .setLowResImageRequest(previousRequest)
                        .setImageRequest(newRequest)
                        .setOldController(iv_cover.getController())                           
                        .build();
        iv_cover.setController(controller);

这应该会给你你想要的行为。