Changelog

0.5.2.0

Performance

Library-wide optimization pass targeting large canvas rendering (4K / procedural generation). Drawing primitives are now orders of magnitude faster on large canvases.

• Canvas: copy-and-poke drawing (Canvas): All drawing primitives (drawLine, drawRect, fillRect, drawCircle, fillCircle, hLine, floodFill) now copy the pixel buffer once and write directly into the copy. Previously, each pixel write copied the entire buffer via ByteString split/concat. A fillCircle of radius 100 on a 1000×1000 canvas went from ~31,000 full buffer copies to 1.
• Canvas: mapPixels calls function once per pixel — was 4× (once per RGBA channel). Functions like grayscale, adjustBrightness, shiftHue, applyLUT, etc. all benefit.
• Canvas: getPixel uses unsafeIndex — eliminates 4 redundant bounds checks per read (after inBounds check). Benefits bilinear sampling in scaling/rotation.
• Canvas: pixelFold tracks coordinates directly — eliminates div/mod per pixel.
• Canvas: fromPixels uses direct pokes — no intermediate list allocation.
• Draw: single-copy polygon/ellipse/curve rendering (Draw): fillPolygon, fillEllipse, drawEllipse, drawPolygon, drawArc, drawBezier, drawCubicBezier, drawCatmullRom, drawAALine, and patternFill now collect all pixels/spans and apply in a single buffer copy via the new bulk APIs.
• Transform: generateCanvasPixels eliminates per-byte division (Transform): All transforms (flipH/flipV, rotate*, scaleNearest, scaleBilinear, scaleTo, shearH/shearV, outline, dropShadow) now compute one color per pixel instead of dispatching per byte. Eliminates ~16 integer divisions per pixel — significant at 4K (8M+ pixels).
• Noise: bitmask LCG hash (Noise): LCG hash uses bitwise .&. instead of mod 2^31 (~10–20× faster per hash). Perlin gradient index uses .&. for power-of-2 table size. All noise generators use generateCanvasPixels for the same div/mod elimination.
• VFX: bulk ring drawing (VFX): Ring outlines use bulkSetPixels (1 buffer copy) instead of per-pixel setPixel chains. LCG uses bitmask.
• Gradient: generateCanvasPixels (Gradient): Same per-pixel div/mod elimination.
• Dither: generateCanvasPixels (Dither): Same per-pixel div/mod elimination.
• Tilemap: bulk tile stamping (Tilemap): stampTile uses bulkSetPixels instead of per-pixel setPixel loop.
• Text: bulk glyph rendering (Text): Glyph bit-blitting uses bulkSetPixels instead of per-bit setPixel loop.

New Features

• Bulk drawing APIs (Canvas): generateCanvasPixels, bulkSetPixels, bulkHSpans, bulkBlendPixels — low-level batch operations for efficient custom drawing. Used internally by all optimized primitives, also exported for user code.

Tests

• 615 tests (all passing — exact pixel-level output preserved).

0.5.1.0

New Features

• Simplex noise (Noise): simplexNoise — triangular-grid noise with fewer directional artifacts than Perlin. Same API as perlinNoise.
• LUT color grading (Adjust): ColorLUT type with trilinear interpolation. identityLUT, applyLUT, modifyLUT for composable grading, plus presets warmLUT, coolLUT, cinematicLUT.

Tests

• 615 tests.

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. 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)