fix: Fix asset prefix double-prefixing and sprite name stripping

[gnarhard]

Description

Bug 1: Image loading double-prefixes paths

loadAtlasDataImages applied assetsPrefix (designed for Flame.assets, prefix assets/) to Flame.images (prefix assets/images/), causing paths like assets/images/images/packs/textures.png. The image path should be passed directly to img.load() without the assets prefix, as it was in 5.0.5.

Bug 2: _parseRegion strips trailing digits from sprite names

The regex (_?)(\d+)$ in _parseRegion strips trailing digits from all sprite names, assuming they're animation frame indices. This breaks any sprite whose name naturally contains trailing digits (e.g. drohne2 → drohne, cu3 → cu, crystal2 → crystal). In 5.0.5, the name was always kept as-is and the index only came from the explicit index: field in the atlas.

Fix 1: Double-prefixed image paths in loadAtlasDataImages

assetsPrefix (default 'images') was applied to both Flame.assets (prefix assets/) and Flame.images (prefix assets/images/), causing paths like assets/images/images/packs/texture.png.

The else branch in loadAtlasDataImages prepended assetsPrefix to texturePath before passing it to images.load(). Since Flame.images already adds assets/images/, this created a double prefix. The
subsequent stripping logic was fragile — it relied on AssetsCache.prefix aligning with Images.prefix, which silently failed in non-standard configurations.

Changes:

• lib/src/texture_packer_parser.dart — loadAtlasDataImages:
  • Removed assetsPrefix and assets parameters (no longer needed for image loading)
  • Removed the assetsPrefix prefix application block
  • Replaced the toRelative/relativePrefix stripping logic with a simpler approach that directly checks for overlap with img.prefix (both full and partial), independent of AssetsCache configuration
  • Changed texturePath from var to final (no longer reassigned)
• lib/src/texture_packer_atlas.dart — loadAtlas:
  • Removed the now-unnecessary assetsPrefix and assets arguments from the loadAtlasDataImages call
• test/atlas_path_resolution_test.dart:
  • Added test: assetsPrefix is not applied to image paths loaded via Images
  • Added test: subdirectory image paths are not double-prefixed

Fix 2: Aggressive digit stripping from sprite names in _parseRegion

The regex r'(_?)(\d+)$' unconditionally stripped trailing digits from all sprite names and treated them as animation frame indices. This broke any sprite whose name naturally ends in digits (e.g. drohne2 →
drohne, cu3 → cu, vine1 → vine, corruption_sack-1 → corruption_sack-).

v5.1.0 added name-based index extraction that can't distinguish between animation indices (walk_01) and names that end in digits (drohne2). In v5.0.5, the index only came from the explicit index: field in the
atlas file.

Changes:

• lib/src/texture_packer_parser.dart — _parseRegion:
  • Removed the regex-based index extraction block (the indexMatch logic and nameBeforeIndex/extractedIndex variables)
  • finalIndex now only uses the explicit index: field from the atlas, defaulting to -1
  • Region name is the original name from the atlas (with file extension stripped), never modified
• test/naming_index_test.dart:
  • Updated all tests to expect names preserved as-is (image1, image_01, etc.) with index -1
  • Renamed test for explicit index: field to verify it still works
• test/separated_parsing_test.dart:
  • Updated to expect sprite1 preserved as name (not stripped to sprite)
  • Updated getAnimation test to use explicit index: fields in atlas content
• test/atlas_path_resolution_test.dart:
  • Updated existing test to expect preserved names (knight_walk_01, not knight_walk)
  • Added new test verifying explicit index: field still works correctly

Tests

• All 60 existing + new tests pass
• Dart analyzer reports no errors
• New/legacy/whitelist format tests unaffected (they use explicit index: fields)
• Image path tests verify no double-prefixing with default and custom assetsPrefix
• Naming tests verify sprite names with trailing digits are preserved
• Animation test updated to use explicit index: fields (the supported mechanism)

Checklist

• I have followed the Contributor Guide when preparing my PR.
• I have updated/added tests for ALL new/updated/fixed functionality.
• I have updated/added relevant documentation in docs and added dartdoc comments with ///.
• I have updated/added relevant examples in examples or docs.

Breaking Change?

• Yes, this PR is a breaking change.
• No, this PR is not a breaking change.

Related Issues

[spydon]

Looks sensible to me.
Do you want to have a look @s1r1m1r1, since you made these changes?
So that we don't bounce back and forth,

[s1r1m1r1]

I tested this fix,
but when loading from a package, the PNG file for the atlas doesn't load correctly.

Perhaps I should add some fixes for loading images for the atlas from the package.

[s1r1m1r1]

If there are too many changes, it's possible to
revert to just one index pattern: image1, image2, image3, image4, etc.
Revert changes only for package integration.

[gnarhard]

@s1r1m1r1 Thanks for testing this and flagging the package loading issue.

On the index pattern suggestion though, I think the regex-based index extraction should be fully removed rather than scaled back. TexturePacker already handles frame indexing explicitly via the index: field in the atlas file, so the regex was duplicating that behavior and breaking sprite names that naturally end in digits (drohne2, cu3, crystal2, etc.). In 5.0.5 the index only came from the explicit index: field, and that worked correctly.

I'd prefer to keep these as two separate concerns — the index stripping fix stands on its own, and the package loading issue can be addressed independently. Happy to collaborate on the package path fix if you want to share what you're seeing there.