How to add onClick on image.asset in flutter?

I read other answers and found that you were having issues with border, try this solution.

GestureDetector(
  onTap: () {}, // Image tapped
  child: Image.asset(
    'assets/cat.jpg',
    fit: BoxFit.cover, // Fixes border issues
    width: 110.0,
    height: 110.0,
  ),
)

If you want splash effects, then use Ink.image or Ink with decoration.

InkWell(
  onTap: () {}, // Image tapped
  splashColor: Colors.white10, // Splash color over image
  child: Ink.image(
    fit: BoxFit.cover, // Fixes border issues
    width: 100,
    height: 100,
    image: AssetImage(
      'assets/cat.jpg,
    ),
  ),
)

Material(
        child: InkWell(
          onTap: () {},
          child: ClipRRect(
              borderRadius: BorderRadius.circular(20.0),
              child: Image.asset('assets/cat.jpg',
                  width: 110.0, height: 110.0),
            ),
        ),
    )