ViewPump

View inflation you can intercept.

ViewPump installs a custom LayoutInflater via a ContextThemeWrapper and provides an API of pre/post-inflation interceptors.

Getting started

Dependency

Include the dependency Download (.aar) :

dependencies {
    implementation 'io.github.inflationx:viewpump:2.1.0'
}

Usage

Define your interceptor. Below is a somewhat arbitrary example of a post-inflation interceptor that prefixes the text in a TextView.

public class TextUpdatingInterceptor implements Interceptor {
    @Override
    public InflateResult intercept(Chain chain) {
        InflateResult result = chain.proceed(chain.request());
        if (result.view() instanceof TextView) {
            // Do something to result.view()
            // You have access to result.context() and result.attrs()
            TextView textView = (TextView) result.view();
            textView.setText("[Prefix] " + textView.getText());
        }
        return result;
    }
}

Below is an example of a pre-inflation interceptor that returns a CustomTextView when a TextView was defined in the layout's XML.

public class CustomTextViewInterceptor implements Interceptor {
    @Override
    public InflateResult intercept(Chain chain) {
        InflateRequest request = chain.request();
        if (request.name().endsWith("TextView")) {
            CustomTextView view = new CustomTextView(request.context(), request.attrs());
            return InflateResult.builder()
                    .view(view)
                    .name(view.getClass().getName())
                    .context(request.context())
                    .attrs(request.attrs())
                    .build();
        } else {
            return chain.proceed(request);
        }
    }
}

Installation

Create a ViewPump instance via ViewPump.builder() and add your interceptors. The order of the interceptors is important since they form the interceptor chain of requests and results.

An interceptor may choose to return a programmatically instantiated view rather than letting the default inflation occur, in which case interceptors added after it will be skipped. For this reason, it is better to add your post-inflation interceptors before the pre-inflation interceptors

ViewPump viewPump = ViewPump.builder()
    .addInterceptor(new TextUpdatingInterceptor())
    .addInterceptor(new CustomTextViewInterceptor())
    .build()

Once the instance is created (via dependency injection or otherwise), provide it to your relevant context via wrapping the Activity context:

@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(ViewPumpContextWrapper.wrap(newBase, viewPump));
}

You're good to go!

To see more ideas for potential use cases, check out the Recipes wiki page.

Testing

If you need to test views in isolation (i.e. not under the indirect umbrella of an Activity), you need to set factory2 manually in order for ViewPump to work.

val context = ViewPumpContextWrapper.wrap(textContext, viewPump)
LayoutInflater.from(context).factory2 = FakeFactory2() // Can be a stub that just returns null

// Now inflate your view
val view = LayoutInflater.from(context).inflate(R.layout.view, null)

Otherwise, no factory2 instance will be set in the underlying LayoutInflater and subsequently ViewPump will never be called during inflation.

Collaborators

Licence

Copyright 2017 InflationX

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

jayyuz/ViewPump