Flutter Tips: How to avoid blinking of images when they are loaded for the first time

The problem

In this small post I will show you how to avoid 'blinking images' when they are loaded into AssetImage widget for the first time.

In Flutter I use Hero Widget for cross widget animations. When the user navigates to another view I want widget to 'fly' into new scene with a smooth animation. But, as you can see in the gif below, it is not so smooth:

no_precache_small.gif

The issue is caused by spending too much time loading image from the assets. After the image is rendered at least once, it is cached and next renders do not take so much time. But how do we make sure that first render is smooth?

The Solution

Use precacheImage ! You can call it from didUpdateDependencies:

 @override
  void didChangeDependencies() {
    List<AssetImage> allImages =
    BackgroundImage.getRandomImageForType(ImageType.LANDING)
        .getAllAvailableImages();
    allImages.forEach((AssetImage image) {
      precacheImage(image, context);
    });
    super.didChangeDependencies();
  }

Now all renders of Hero Widget are smooth and do not blink or have instantaneous size changes:

preache_small.gif

Dmytro Gladkyi

Flutter + Frontend developer. Love Functional Programming.

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