Changelog

0.5.0.0

Breaking Changes

• BMP.hs and PNG.hs are now pure. writeBmp and writePng have moved to GBSprite.Export. Import from GBSprite.Export instead of GBSprite.BMP or GBSprite.PNG for file I/O. The pure encoders encodeBmp and encodePng remain in their original modules.
• Eliminated unsafePerformIO from Import.hs. PNG decompression now uses the zlib streaming API (Codec.Compression.Zlib.Internal) for fully pure, exception-free error handling.

New Modules

• GBSprite.Adjust — Canvas-wide color adjustments: grayscale, invert, tint, brightness, contrast, saturation, hue shift, color remapping, posterize, threshold, sepia.
• GBSprite.Filter — Convolution filters: box blur, Gaussian blur (3-pass approximation), sharpen (unsharp mask), Sobel edge detection, bloom (bright extract + blur + additive blend).
• GBSprite.Import — Native BMP and PNG decoding. Read 24/32-bit BMP and 8-bit RGB/RGBA PNG files back into Canvas. Supports all 5 PNG filter types (None, Sub, Up, Average, Paeth). Pure decoders (decodeBmp, decodePng) and IO wrappers (readBmp, readPng).
• GBSprite.Isometric — Isometric projection for 2:1 diamond tiles. World/screen coordinate conversion, point-in-diamond hit testing, depth sorting, diamond drawing/filling, and isometric tilemap rendering.

New Features

• HSL/HSV color space (Color): toHSL, fromHSL, toHSV, fromHSV, and derived transforms (tintColor, invertColor, grayscaleColor, brightenColor, contrastColor, saturateColor, shiftHueColor).
• Arbitrary rotation (Transform): rotateArbitrary with bilinear interpolation for any angle in degrees.
• Bilinear scaling (Transform): scaleBilinear for smooth up/down scaling; scaleTo for exact target dimensions.
• Shear transforms (Transform): shearH and shearV.
• Anti-aliased lines (Draw): drawAALine using Wu's algorithm.
• Cubic Bezier curves (Draw): drawCubicBezier.
• Catmull-Rom splines (Draw): drawCatmullRom — smooth curves through control points.
• Pattern fill (Draw): patternFill — fill a rectangular area with a repeating tile.
• Blend modes (Compose): BlendMultiply, BlendScreen, BlendOverlay, BlendAdditive, BlendSoftLight, BlendDifference via blendCompose.
• Alpha masking (Compose): maskCanvas — clip rendering to a mask's alpha channel.
• Perlin noise (Noise): perlinNoise — gradient noise with dot-product interpolation.
• Worley noise (Noise): worleyNoise — cellular/Voronoi patterns.
• Turbulence (Noise): turbulence — absolute-value FBM for fire/cloud/water textures.
• Palette lerp (Palette): paletteLerp — interpolate between two palettes for day/night transitions.
• Palette extraction (Palette): extractPalette — derive a palette from a canvas using median cut.
• Color quantization (Palette): quantizeColor — map a color to the nearest palette entry.
• Sprite mirroring (Sprite): mirrorSprite — horizontal flip of all frames.
• Sprite trimming (Sprite): trimSprite — crop transparent borders from all frames.
• Animation blending (Animation): blendFrames — cross-fade between two canvases.
• Canvas crop/trim (Canvas): crop, trimTransparent, canvasOpacity.
• Canvas dimension clamping: newCanvas and fromPixels now clamp dimensions to minimum 1.
• Empty string guard: renderText returns a valid 1-pixel-wide canvas for empty input.

Bug Fixes

• Fix Porter-Duff alpha blend (Color): alphaBlend now correctly weights the destination channel by dstA when compositing semi-transparent colors. Previously, the destination RGB contribution was over-weighted when dstA < 255.
• Fix isometric diamond off-by-one (Isometric): drawDiamond and fillDiamond now draw within the tw x th bounding box (previously drew (tw+1) x (th+1) pixels).
• Fix shear direction (Transform): shearH and shearV now shift in the documented direction (positive values shift bottom rows right / right columns down).
• Fix PNG decompression exception (Import): decodePng uses the zlib streaming API for pure error handling — no unsafePerformIO, no caught exceptions.
• Fix bloom luminance (Filter): Bloom threshold now uses BT.709 perceptual weights instead of simple RGB average.
• Fix sprite sheet vertical padding (Sheet): Shelf packing now applies padding between shelves vertically, not just horizontally.
• Fix Perlin gradient vectors (Noise): Diagonal gradients now use exact 1/sqrt(2) instead of truncated 0.707.
• Fix dither performance (Dither): Bayer matrices backed by ByteString for O(1) lookup (was O(n) list traversal per pixel). findClosest now carries best distance in accumulator (halves comparisons).
• Fix wrapHue performance (Color): O(1) modular arithmetic replaces recursive subtract/add loop.
• Fix maskCanvas docstring (Compose): Corrected to say "alpha channel" (was incorrectly "luminance").

Tests

• 591 tests (up from 366). Full coverage of all new modules and bug fixes.

0.4.0.0

Breaking Changes

• Drop vector dependency. Canvas pixel storage changed from Data.Vector.Storable.Vector Word8 to strict ByteString. Users pattern-matching on cPixels will need to update. All public API functions are unchanged.

New

• Native PNG export (GBSprite.PNG): hand-rolled 32-bit RGBA PNG encoder using zlib for DEFLATE compression and a pure CRC32 implementation. PNG export is now always available — no flags, no JuicyPixels.
• GBSprite.Export now re-exports both exportBmp and exportPng.
• 10 new PNG tests (366 total, up from 356).

Removed

• juicy-pixels flag and GBSprite.Export.PNG — replaced by native GBSprite.PNG.
• vector dependency — pixel data backed by strict ByteString instead of Vector.Storable. Same performance characteristics, fewer dependencies.

Dependencies

• base, bytestring, zlib — that's it. Down from base, bytestring, vector, optional JuicyPixels.

0.3.0.1

Fixes

• Fix BMP roundtrip test leaking temp files — tests now clean up after themselves.
• Replace partial !! with safe indexing in BMP test.
• Fix CI: run haddock before build to avoid stale .hi files causing 0% doc coverage.
• Fix README: correct encodeBmp return type, add missing API sections (Palette, Sprite, Tilemap), add missing exported functions.

0.3.0.0

Bug Fixes

• Fix drawEllipse midpoint algorithm: region 2 now continues from where region 1 ended instead of restarting at (rx, 0). Ellipses now correctly plot all four cardinal edge pixels.
• Fix safeSetPixel in VFX.hs: use setPixel directly instead of fillCircle with radius 0.
• Replace partial minimum/maximum with safe folds in fillPolygon (Draw.hs) and computeMaxWidth (Sheet.hs).
• Fix grayscale4 palette: was a duplicate of gameboy (green-tinted). Now uses evenly-spaced true grayscale (0, 85, 170, 255).

Performance

• Replace 16 lazy foldl with strict foldl' across Draw.hs, VFX.hs, Sheet.hs, Tilemap.hs, and Text.hs.

Internal

• 356 tests (up from 105): comprehensive coverage of all modules.
• CI and cabal: tested-with upgraded from GHC 9.6 to GHC 9.8.
• Publish workflow: replace sed version-patching with tag/cabal version verification.

0.2.1.2

• Change license from MIT to BSD-3-Clause.

Bug Fixes

• Fix maximum crash on empty list in packSheet (Sheet.hs).
• Replace partial !! with safe indexing in Bayer dithering (Dither.hs).
• Fix -Wname-shadowing warning in test suite.

Documentation

• Fix README Animation API section (wrong type name and signatures).
• Add gb-vector as ecosystem companion in README.

Internal

• CI: cross-platform build matrix (Linux, macOS, Windows).

0.2.1.1

• Remove unused containers dependency.

0.2.1.0

Performance

Library-wide elimination of O(n²) per-pixel setPixel/VS.// mutation. All pixel-producing functions now use single-pass VS.generate for O(n) performance.

• NineSlice: renderNineSlice — rewritten for large target sizes that previously stalled.
• Transform: flipH, flipV, rotate90, rotate180, rotate270, scaleNearest, outline, dropShadow — all rewritten with direct index computation.
• Compose: stamp, stampAlpha — single-pass with inline source/destination byte reads.
• Gradient: linearGradient, radialGradient, diagonalGradient — generate directly from coordinate math.
• Noise: valueNoiseColor, fbm — generate noise samples directly into output vector.
• Dither: orderedDither — single-pass palette reduction.

0.2.0.0

New Modules

• GBSprite.Noise: Procedural noise generation — valueNoise, valueNoiseColor, fbm (fractal Brownian motion). Deterministic LCG with bilinear interpolation and smoothstep.
• GBSprite.Gradient: Gradient generation — linearGradient (horizontal/vertical), radialGradient, diagonalGradient.
• GBSprite.NineSlice: UI panel scaling — NineSlice type with configurable border regions, renderNineSlice preserves corners and edges at any target size.
• GBSprite.Dither: Ordered dithering — orderedDither with Bayer2, Bayer4, Bayer8 matrices for palette reduction. Classic retro cross-hatch patterns.
• GBSprite.Export.PNG: Separated from Export.hs, eliminating CPP. Only built when juicy-pixels flag is enabled.

Bug Fixes

• Eliminate CPP from Export.hs — split into GBSprite.Export (BMP, always available) and GBSprite.Export.PNG (optional).

Internal

• 105 pure tests (up from 62)
• 12 new Draw function tests (drawThickLine, drawPolygon, fillPolygon, drawEllipse, fillEllipse, drawBezier, drawRoundRect, fillRoundRect)
• CI: ormolu glob src/**/*.hs replaces hardcoded file list
• CI: jobs chained so lint/format gate build (saves Actions minutes on failure)
• Metadata: cabal-version 3.0, stability experimental, CHANGELOG.md

0.1.0.0

Initial release.

Canvas & Color

• Canvas type: width, height, RGBA pixel vector
• Color type with lerp, multiply, alphaBlend, withAlpha, scaleAlpha
• Bounds-checked getPixel / setPixel (out-of-bounds returns transparent)

Drawing Primitives

• Lines: drawLine, drawThickLine
• Rectangles: drawRect, fillRect, drawRoundRect, fillRoundRect
• Circles: drawCircle, fillCircle
• Ellipses: drawEllipse, fillEllipse
• Polygons: drawPolygon, fillPolygon
• Curves: drawBezier, drawArc

Transforms

• flipH, flipV, rotate90, rotate180, rotate270
• scaleNearest: nearest-neighbour scaling

Composition

• stamp: blit with transparency
• overlay: layer multiple canvases

Animation

• Animation type with Loop, Once, PingPong modes
• Frame indexing with animationDone predicate

Sprites & Sheets

• Sprite type: multi-frame sprite container
• packSheet: bin-packing sprite sheet atlas

Text

• renderText: bitmap font text rendering
• textWidth: measure text width in pixels

VFX

• explosion: animated explosion effect
• ring: expanding ring effect
• flash: screen flash frames

Palettes

• Palette type with indexed color lookup
• paletteSwap: remap colors
• Built-in: gameboy (4-color Game Boy palette)

Export

• exportBmp: native BMP file export (always available)
• exportPng: PNG export via JuicyPixels (optional juicy-pixels flag)