refactor: add TVGCanvas params (fit, filterQuality, alignment) and introduce PlayState

[TaeBbong]

Summary

• Small refactors to improve clarity and flexibility, addressing items previously marked with NOTES/FIXME.
• This PR has no dependency with existing PR Rename app namespace in examples #27.

Changes

1. TVGCanvas

   • Expose fit, filterQuality, alignment as constructor params (were hardcoded defaults).

2. Thorvg play state

   • Replace multiple boolean flags with PlayState enum for readability and state safety.

Before → After

Play state

// before
// FIXME: should be an enumeration for each status
bool isPlaying = false;
bool deleted = false;

// after
enum PlayState { stopped, playing, deleted }
PlayState state = PlayState.stopped;

Update flow

// before
if (deleted) throw Exception('Thorvg is already deleted');
// ...
isPlaying = false;

// after
if (state == PlayState.deleted) throw Exception('Thorvg is already deleted');
// ...
state = PlayState.stopped;

[Copilot]

Pull Request Overview

This PR refactors the ThorVG library to improve code clarity and flexibility by replacing boolean state flags with an enum and exposing previously hardcoded canvas parameters.

• Introduced PlayState enum to replace multiple boolean flags for better state management
• Exposed fit, filterQuality, and alignment as constructor parameters in TVGCanvas
• Updated all state checks to use the new enum values instead of boolean flags

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
lib/src/thorvg.dart	Replaced boolean state flags with PlayState enum and updated all state validation logic
lib/src/lottie.dart	Added constructor parameters for canvas rendering options and updated repaint logic

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[tinyjin]

Thank you. Please check comments

[tinyjin]

enum PlayState { stopped, playing, destroyed }

Purpose is to align with existing web player states

[tinyjin]

Also wondering if we need paused state

[hermet]

Pause/Resume functions are quite general, essential functions as a player.

If we select either Paused vs Frozen -> Paused win.

Eventually, we might need these enough status definition.

    Uninitialized             //any file is not loaded yet. 
    Loading (optional)    //this needs only player supports async loading
    Ready
    Playing
    Paused
    Frozen      
    Stopped
    Error
    Destroyed       //Hmm... Is it possible to query this?

[hermet]

• The player needs to support user event listening for activation and deactivation events (such as for Frozen).

[tinyjin]

@TaeBbong
Could you please rebase to fix conflict?

[TaeBbong]

@TaeBbong Could you please rebase to fix conflict?

@tinyjin It's done now!