[bug/problem] Deprecation Fix for withOpacity in Flutter 3.27.2

[AyushMaji]

Describe the bug/problem

In our app, the function Theme.of(context).colorScheme.surfaceContainerHighest.withOpacity(0.5) is used 48 times across 32 pages to apply opacity to colors. However, in Flutter version 3.27.2 and later, the withOpacity function has been deprecated. This requires updating our code to align with the latest Flutter version.

Steps to Reproduce the bug/problem

Screenshot - https://drive.google.com/file/d/1Zxj_vd1-ufqfxvTMRn4GQ3970V8s4ZjW/view?usp=sharing

Solution

To resolve this issue, we can replace the deprecated function with:
Theme.of(context).colorScheme.surfaceContainerHighest.withAlpha((0.5 * 255).round());
In Flutter's newer versions, withOpacity expects an integer-based opacity value. Since opacity values typically range from 0.0 to 1.0, multiplying by 255 converts it into an integer scale (0 to 255), which aligns with the updated API requirements.

Device Info (The device where you encountered this issue)

• OS: MacOS
• Version: Sequoia 15.0.1

[AyushMaji]

i have fixed this issue and made a PR #586 (comment)