[Feature request] Ability to Identify if the Board is Clean (after using eraser)

[imaagu]

Platforms

dart

Description

Currently, in flutter_drawing_board, there is no straightforward way to check if the drawing board is visually empty.

controller.history keeps all operations (draw + erase), so it cannot be used to detect if the board has visible strokes.

After erasing strokes manually (without calling clear()), there is no direct flag or method to determine whether the board is completely clean.

Why

This makes it difficult for developers to implement features like:

1. Enabling/disabling a "Save" button only when the board has content.
2. Automatically prompting the user when leaving a board that has visible strokes.