fix: remove need for an extra pull

[renancaraujo]

Description

Fixes: #41 (comment)

⚠️ Breaking ⚠️

Ad a breaking change, this delegates the re-fetching trigger from our custom code (reliant on ScrollPsotion) to the SliverList (SlverCosntraints reliant).

This will trigger the re-fetching once the last item in the list is built. That should happen when the viewport hits the bottom of the scrollable cache area.

Now that we rely on the cache area, we don't need scrollExtentThreshold nor the SliverInfiniteList needs to be the last sliver on a CustomScrollView.

Instead, the user can pass cacheExtent to the InfiniteList to customize the cache area of the internal ScrollView. SliverInfiniteList users can pass that to their own CustomScrollView.

The cache area is not exactly the same as cacheExtent since it is applied to both edges of the sliver, not only the trailing one.

Breaking changes:

Public member defaultScrollExtentThreshold was removed. Any tests and implementations that use it will break.

Public members InfiniteList.scrollExtentThreshold and SliverInfiniteList.scrollExtentThreshold were removed. Any implementation that specified these values will break.

Default behavior for InfiniteList.scrollExtentThreshold and SliverInfiniteList.scrollExtentThreshold was to apply defaultScrollExtentThreshold, which was equal to 400 pixels. Now that we rely on cacheExtent, the default value resorts to the frameworks RenderAbstractViewport.defaultCacheExtent. Which is equal to 250 pixels.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore

[b-nugent]

Thanks so much @renancaraujo for taking a crack at this, I'm excited to try it out! 😄

Update: It works smoothly and flawlessly 👏

[felangel]

Thanks so much @renancaraujo for taking a crack at this, I'm excited to try it out! 😄

This is included in v0.6.0 https://pub.dev/packages/very_good_infinite_list 🎉