commit 1b51937e529d5828964225872a2ae943ccfa095f Author: Sasha Koshka Date: Wed May 3 20:10:23 2023 -0400 Initial commit diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..f288702 --- /dev/null +++ b/LICENSE @@ -0,0 +1,674 @@ + GNU GENERAL PUBLIC LICENSE + Version 3, 29 June 2007 + + Copyright (C) 2007 Free Software Foundation, Inc. + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. + + Preamble + + The GNU General Public License is a free, copyleft license for +software and other kinds of works. + + The licenses for most software and other practical works are designed +to take away your freedom to share and change the works. By contrast, +the GNU General Public License is intended to guarantee your freedom to +share and change all versions of a program--to make sure it remains free +software for all its users. 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But first, please read +. diff --git a/README.md b/README.md new file mode 100644 index 0000000..6a47ffe --- /dev/null +++ b/README.md @@ -0,0 +1,3 @@ +# art + +Art is a simple 2D software drawing library used by Tomo. diff --git a/artutil/util.go b/artutil/util.go new file mode 100644 index 0000000..e5c6892 --- /dev/null +++ b/artutil/util.go @@ -0,0 +1,62 @@ +// Package artutil provides utility functions for working with art's interfaces. +package artutil + +import "art" +import "image" +import "art/shatter" +import "image/color" + +// Fill fills the destination canvas with the given pattern. +func Fill (destination art.Canvas, source art.Pattern) (updated image.Rectangle) { + source.Draw(destination, destination.Bounds()) + return destination.Bounds() +} + +// DrawClip lets you draw several subsets of a pattern at once. +func DrawClip ( + destination art.Canvas, + source art.Pattern, + bounds image.Rectangle, + subsets ...image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + for _, subset := range subsets { + source.Draw(art.Cut(destination, subset), bounds) + updatedRegion = updatedRegion.Union(subset) + } + return +} + +// DrawShatter is like an inverse of DrawClip, drawing nothing in the areas +// specified by "rocks". +func DrawShatter ( + destination art.Canvas, + source art.Pattern, + bounds image.Rectangle, + rocks ...image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + tiles := shatter.Shatter(bounds, rocks...) + return DrawClip(destination, source, bounds, tiles...) +} + +// AllocateSample returns a new canvas containing the result of a pattern. The +// resulting canvas can be sourced from shape drawing functions. I beg of you +// please do not call this every time you need to draw a shape with a pattern on +// it because that is horrible and cruel to the computer. +func AllocateSample (source art.Pattern, width, height int) art.Canvas { + allocated := art.NewBasicCanvas(width, height) + Fill(allocated, source) + return allocated +} + +// Hex creates a color.RGBA value from an RGBA integer value. +func Hex (color uint32) (c color.RGBA) { + c.A = uint8(color) + c.B = uint8(color >> 8) + c.G = uint8(color >> 16) + c.R = uint8(color >> 24) + return +} diff --git a/canvas.go b/canvas.go new file mode 100644 index 0000000..dec8ae6 --- /dev/null +++ b/canvas.go @@ -0,0 +1,111 @@ +package art + +import "image" +import "image/draw" +import "image/color" + +// Image represents an immutable canvas. +type Image interface { + image.Image + RGBAAt (x, y int) color.RGBA +} + +// Canvas is like draw.Image but is also able to return a raw pixel buffer for +// more efficient drawing. This interface can be easily satisfied using a +// BasicCanvas struct. +type Canvas interface { + draw.Image + Buffer () (data []color.RGBA, stride int) +} + +// BasicCanvas is a general purpose implementation of tomo.Canvas. +type BasicCanvas struct { + pix []color.RGBA + stride int + rect image.Rectangle +} + +// NewBasicCanvas creates a new basic canvas with the specified width and +// height, allocating a buffer for it. +func NewBasicCanvas (width, height int) (canvas BasicCanvas) { + canvas.pix = make([]color.RGBA, height * width) + canvas.stride = width + canvas.rect = image.Rect(0, 0, width, height) + return +} + +// FromImage creates a new BasicCanvas from an image.Image. +func FromImage (img image.Image) (canvas BasicCanvas) { + bounds := img.Bounds() + canvas = NewBasicCanvas(bounds.Dx(), bounds.Dy()) + point := image.Point { } + for point.Y = bounds.Min.Y; point.Y < bounds.Max.Y; point.Y ++ { + for point.X = bounds.Min.X; point.X < bounds.Max.X; point.X ++ { + canvasPoint := point.Sub(bounds.Min) + canvas.Set ( + canvasPoint.X, canvasPoint.Y, + img.At(point.X, point.Y)) + }} + return +} + +// you know what it do +func (canvas BasicCanvas) Bounds () (bounds image.Rectangle) { + return canvas.rect +} + +// you know what it do +func (canvas BasicCanvas) At (x, y int) (color.Color) { + if !image.Pt(x, y).In(canvas.rect) { return nil } + return canvas.pix[x + y * canvas.stride] +} + +// you know what it do +func (canvas BasicCanvas) ColorModel () (model color.Model) { + return color.RGBAModel +} + +// you know what it do +func (canvas BasicCanvas) Set (x, y int, c color.Color) { + if !image.Pt(x, y).In(canvas.rect) { return } + r, g, b, a := c.RGBA() + canvas.pix[x + y * canvas.stride] = color.RGBA { + R: uint8(r >> 8), + G: uint8(g >> 8), + B: uint8(b >> 8), + A: uint8(a >> 8), + } +} + +// you know what it do +func (canvas BasicCanvas) Buffer () (data []color.RGBA, stride int) { + return canvas.pix, canvas.stride +} + +// Reallocate efficiently reallocates the canvas. The data within will be +// garbage. This method will do nothing if this is a cut image. +func (canvas *BasicCanvas) Reallocate (width, height int) { + if canvas.rect.Min != (image.Point { }) { return } + + previousLen := len(canvas.pix) + newLen := width * height + bigger := newLen > previousLen + smaller := newLen < previousLen / 2 + if bigger || smaller { + canvas.pix = make ( + []color.RGBA, + ((height * width) / 4096) * 4096 + 4096) + } + canvas.stride = width + canvas.rect = image.Rect(0, 0, width, height) +} + +// Cut returns a sub-canvas of a given canvas. +func Cut (canvas Canvas, bounds image.Rectangle) (reduced BasicCanvas) { + // println(canvas.Bounds().String(), bounds.String()) + bounds = bounds.Intersect(canvas.Bounds()) + if bounds.Empty() { return } + reduced.rect = bounds + reduced.pix, reduced.stride = canvas.Buffer() + return +} diff --git a/doc.go b/doc.go new file mode 100644 index 0000000..06fc9eb --- /dev/null +++ b/doc.go @@ -0,0 +1,2 @@ +// Package art provides a simple 2D drawing library. +package art diff --git a/go.mod b/go.mod new file mode 100644 index 0000000..f4a4203 --- /dev/null +++ b/go.mod @@ -0,0 +1,3 @@ +module art + +go 1.20 diff --git a/icon.go b/icon.go new file mode 100644 index 0000000..552abf2 --- /dev/null +++ b/icon.go @@ -0,0 +1,13 @@ +package art + +import "image" +import "image/color" + +type Icon interface { + // Draw draws the icon to the destination canvas at the specified point, + // using the specified color (if the icon is monochrome). + Draw (destination Canvas, color color.RGBA, at image.Point) + + // Bounds returns the bounds of the icon. + Bounds () image.Rectangle +} diff --git a/inset.go b/inset.go new file mode 100644 index 0000000..f2838a8 --- /dev/null +++ b/inset.go @@ -0,0 +1,82 @@ +package art + +import "image" + +// Side represents one side of a rectangle. +type Side int; const ( + SideTop Side = iota + SideRight + SideBottom + SideLeft +) + +// Inset represents an inset amount for all four sides of a rectangle. The top +// side is at index zero, the right at index one, the bottom at index two, and +// the left at index three. These values may be negative. +type Inset [4]int + +// I allows you to create an inset in a CSS-ish way: +// +// - One argument: all sides are set to this value +// - Two arguments: the top and bottom sides are set to the first value, and +// the left and right sides are set to the second value. +// - Three arguments: the top side is set by the first value, the left and +// right sides are set by the second vaue, and the bottom side is set by the +// third value. +// - Four arguments: each value corresponds to a side. +// +// This function will panic if an argument count that isn't one of these is +// given. +func I (sides ...int) Inset { + switch len(sides) { + case 1: return Inset { sides[0], sides[0], sides[0], sides[0] } + case 2: return Inset { sides[0], sides[1], sides[0], sides[1] } + case 3: return Inset { sides[0], sides[1], sides[2], sides[1] } + case 4: return Inset { sides[0], sides[1], sides[2], sides[3] } + default: panic("I: illegal argument count.") + } +} + +// Apply returns the given rectangle, shrunk on all four sides by the given +// inset. If a measurment of the inset is negative, that side will instead be +// expanded outward. If the rectangle's dimensions cannot be reduced any +// further, an empty rectangle near its center will be returned. +func (inset Inset) Apply (bigger image.Rectangle) (smaller image.Rectangle) { + smaller = bigger + if smaller.Dx() < inset[3] + inset[1] { + smaller.Min.X = (smaller.Min.X + smaller.Max.X) / 2 + smaller.Max.X = smaller.Min.X + } else { + smaller.Min.X += inset[3] + smaller.Max.X -= inset[1] + } + + if smaller.Dy() < inset[0] + inset[2] { + smaller.Min.Y = (smaller.Min.Y + smaller.Max.Y) / 2 + smaller.Max.Y = smaller.Min.Y + } else { + smaller.Min.Y += inset[0] + smaller.Max.Y -= inset[2] + } + return +} + +// Inverse returns a negated version of the inset. +func (inset Inset) Inverse () (prime Inset) { + return Inset { + inset[0] * -1, + inset[1] * -1, + inset[2] * -1, + inset[3] * -1, + } +} + +// Horizontal returns the sum of SideRight and SideLeft. +func (inset Inset) Horizontal () int { + return inset[SideRight] + inset[SideLeft] +} + +// Vertical returns the sum of SideTop and SideBottom. +func (inset Inset) Vertical () int { + return inset[SideTop] + inset[SideBottom] +} diff --git a/pattern.go b/pattern.go new file mode 100644 index 0000000..ed4be92 --- /dev/null +++ b/pattern.go @@ -0,0 +1,13 @@ +package art + +import "image" + +// Pattern is capable of drawing to a canvas within the bounds of a given +// clipping rectangle. +type Pattern interface { + // Draw draws the pattern onto the destination canvas, using the + // specified bounds. The given bounds can be smaller or larger than the + // bounds of the destination canvas. The destination canvas can be cut + // using canvas.Cut() to draw only a specific subset of a pattern. + Draw (destination Canvas, bounds image.Rectangle) +} diff --git a/patterns/border.go b/patterns/border.go new file mode 100644 index 0000000..b11eb21 --- /dev/null +++ b/patterns/border.go @@ -0,0 +1,89 @@ +package patterns + +import "art" +import "image" + +// Border is a pattern that behaves similarly to border-image in CSS. It divides +// a source canvas into nine sections... +// +// Inset[1] +// ┌──┴──┐ +// ┌─┌─────┬─────┬─────┐ +// Inset[0]─┤ │ 0 │ 1 │ 2 │ +// └─├─────┼─────┼─────┤ +// │ 3 │ 4 │ 5 │ +// ├─────┼─────┼─────┤─┐ +// │ 6 │ 7 │ 8 │ ├─Inset[2] +// └─────┴─────┴─────┘─┘ +// └──┬──┘ +// Inset[3] +// +// ... Where the bounds of section 4 are defined as the application of the +// pattern's inset to the canvas's bounds. The bounds of the other eight +// sections are automatically sized around it. +// +// When drawn to a destination canvas, the bounds of sections 1, 3, 4, 5, and 7 +// are expanded or contracted to fit the given drawing bounds. All sections are +// rendered as if they are Texture patterns, meaning these flexible sections +// will repeat to fill in any empty space. +// +// This pattern can be used to make a static image texture into something that +// responds well to being resized. +type Border struct { + art.Canvas + art.Inset +} + +// Draw draws the border pattern onto the destination canvas within the given +// bounds. +func (pattern Border) Draw (destination art.Canvas, bounds image.Rectangle) { + drawBounds := bounds.Canon().Intersect(destination.Bounds()) + if drawBounds.Empty() { return } + + srcSections := nonasect(pattern.Bounds(), pattern.Inset) + srcTextures := [9]Texture { } + for index, section := range srcSections { + srcTextures[index].Canvas = art.Cut(pattern, section) + } + + dstSections := nonasect(bounds, pattern.Inset) + for index, section := range dstSections { + srcTextures[index].Draw(destination, section) + } +} + +func nonasect (bounds image.Rectangle, inset art.Inset) [9]image.Rectangle { + center := inset.Apply(bounds) + return [9]image.Rectangle { + // top + image.Rectangle { + bounds.Min, + center.Min }, + image.Rect ( + center.Min.X, bounds.Min.Y, + center.Max.X, center.Min.Y), + image.Rect ( + center.Max.X, bounds.Min.Y, + bounds.Max.X, center.Min.Y), + + // center + image.Rect ( + bounds.Min.X, center.Min.Y, + center.Min.X, center.Max.Y), + center, + image.Rect ( + center.Max.X, center.Min.Y, + bounds.Max.X, center.Max.Y), + + // bottom + image.Rect ( + bounds.Min.X, center.Max.Y, + center.Min.X, bounds.Max.Y), + image.Rect ( + center.Min.X, center.Max.Y, + center.Max.X, bounds.Max.Y), + image.Rect ( + center.Max.X, center.Max.Y, + bounds.Max.X, bounds.Max.Y), + } +} diff --git a/patterns/doc.go b/patterns/doc.go new file mode 100644 index 0000000..0e6a1b4 --- /dev/null +++ b/patterns/doc.go @@ -0,0 +1,3 @@ +// Package patterns provides a basic set of types that satisfy the Pattern +// interface. +package patterns diff --git a/patterns/texture.go b/patterns/texture.go new file mode 100644 index 0000000..e44e643 --- /dev/null +++ b/patterns/texture.go @@ -0,0 +1,77 @@ +package patterns + +import "art" +import "image" + +// Texture is a pattern that tiles the content of a canvas both horizontally and +// vertically. +type Texture struct { + art.Canvas +} + +// Draw tiles the pattern's canvas within the given bounds. The minimum +// point of the pattern's canvas will be lined up with the minimum point of the +// bounding rectangle. +func (pattern Texture) Draw (destination art.Canvas, bounds image.Rectangle) { + dstBounds := bounds.Canon().Intersect(destination.Bounds()) + if dstBounds.Empty() { return } + + dstData, dstStride := destination.Buffer() + srcData, srcStride := pattern.Buffer() + srcBounds := pattern.Bounds() + + // offset is a vector that is added to points in destination space to + // convert them to points in source space + offset := srcBounds.Min.Sub(bounds.Min) + + // calculate the starting position in source space + srcPoint := dstBounds.Min.Add(offset) + srcPoint.X = wrap(srcPoint.X, srcBounds.Min.X, srcBounds.Max.X) + srcPoint.Y = wrap(srcPoint.Y, srcBounds.Min.Y, srcBounds.Max.Y) + srcStartPoint := srcPoint + + // for each row + dstPoint := image.Point { } + for dstPoint.Y = dstBounds.Min.Y; dstPoint.Y < dstBounds.Max.Y; dstPoint.Y ++ { + srcPoint.X = srcStartPoint.X + dstPoint.X = dstBounds.Min.X + dstYComponent := dstPoint.Y * dstStride + srcYComponent := srcPoint.Y * srcStride + + // for each pixel in the row + for { + // draw pixel + dstIndex := dstYComponent + dstPoint.X + srcIndex := srcYComponent + srcPoint.X + dstData[dstIndex] = srcData[srcIndex] + + // increment X in source space. wrap to start if out of + // bounds. + srcPoint.X ++ + if srcPoint.X >= srcBounds.Max.X { + srcPoint.X = srcBounds.Min.X + } + + // increment X in destination space. stop drawing this + // row if out of bounds. + dstPoint.X ++ + if dstPoint.X >= dstBounds.Max.X { + break + } + } + + // increment row in source space. wrap to start if out of + // bounds. + srcPoint.Y ++ + if srcPoint.Y >= srcBounds.Max.Y { + srcPoint.Y = srcBounds.Min.Y + } + } +} + +func wrap (value, min, max int) int { + difference := max - min + value = (value - min) % difference + if value < 0 { value += difference } + return value + min +} diff --git a/patterns/uniform.go b/patterns/uniform.go new file mode 100644 index 0000000..1780dfa --- /dev/null +++ b/patterns/uniform.go @@ -0,0 +1,20 @@ +package patterns + +import "art" +import "image" +import "art/shapes" +import "art/artutil" +import "image/color" + +// Uniform is a pattern that draws a solid color. +type Uniform color.RGBA + +// Draw fills the bounding rectangle with the pattern's color. +func (pattern Uniform) Draw (destination art.Canvas, bounds image.Rectangle) { + shapes.FillColorRectangle(destination, color.RGBA(pattern), bounds) +} + +// Uhex creates a new Uniform pattern from an RGBA integer value. +func Uhex (color uint32) (uniform Uniform) { + return Uniform(artutil.Hex(color)) +} diff --git a/shapes/doc.go b/shapes/doc.go new file mode 100644 index 0000000..98eb8f6 --- /dev/null +++ b/shapes/doc.go @@ -0,0 +1,11 @@ +// Package shapes provides some basic shape drawing routines. +// +// A word about using patterns with shape routines: +// +// Most drawing routines have a version that samples from other canvases, and a +// version that samples from a solid color. None of these routines can use +// patterns directly, but it is entirely possible to have a pattern draw to an +// off-screen canvas and then draw a shape based on that canvas. As a little +// bonus, you can save the canvas for later so you don't have to render the +// pattern again when you need to redraw the shape. +package shapes diff --git a/shapes/ellipse.go b/shapes/ellipse.go new file mode 100644 index 0000000..7097336 --- /dev/null +++ b/shapes/ellipse.go @@ -0,0 +1,231 @@ +package shapes + +import "art" +import "math" +import "image" +import "image/color" + +// TODO: redo fill ellipse, stroke ellipse, etc. so that it only takes in +// destination and source, using the bounds of destination as the bounds of the +// ellipse and the bounds of source as the "clipping rectangle". Line up the Min +// of both canvases. + +func FillEllipse ( + destination art.Canvas, + source art.Canvas, + bounds image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + dstData, dstStride := destination.Buffer() + srcData, srcStride := source.Buffer() + + offset := source.Bounds().Min.Sub(destination.Bounds().Min) + drawBounds := + source.Bounds().Sub(offset). + Intersect(destination.Bounds()). + Intersect(bounds) + if bounds.Empty() { return } + updatedRegion = bounds + + point := image.Point { } + for point.Y = drawBounds.Min.Y; point.Y < drawBounds.Max.Y; point.Y ++ { + for point.X = drawBounds.Min.X; point.X < drawBounds.Max.X; point.X ++ { + if inEllipse(point, bounds) { + offsetPoint := point.Add(offset) + dstIndex := point.X + point.Y * dstStride + srcIndex := offsetPoint.X + offsetPoint.Y * srcStride + dstData[dstIndex] = srcData[srcIndex] + } + }} + return +} + +func StrokeEllipse ( + destination art.Canvas, + source art.Canvas, + bounds image.Rectangle, + weight int, +) { + if weight < 1 { return } + + dstData, dstStride := destination.Buffer() + srcData, srcStride := source.Buffer() + + drawBounds := destination.Bounds().Inset(weight - 1) + offset := source.Bounds().Min.Sub(destination.Bounds().Min) + if drawBounds.Empty() { return } + + context := ellipsePlottingContext { + plottingContext: plottingContext { + dstData: dstData, + dstStride: dstStride, + srcData: srcData, + srcStride: srcStride, + weight: weight, + offset: offset, + bounds: bounds, + }, + radii: image.Pt(drawBounds.Dx() / 2, drawBounds.Dy() / 2), + } + context.center = drawBounds.Min.Add(context.radii) + context.plotEllipse() +} + +type ellipsePlottingContext struct { + plottingContext + radii image.Point + center image.Point +} + +func (context ellipsePlottingContext) plotEllipse () { + x := float64(0) + y := float64(context.radii.Y) + + // region 1 decision parameter + decision1 := + float64(context.radii.Y * context.radii.Y) - + float64(context.radii.X * context.radii.X * context.radii.Y) + + (0.25 * float64(context.radii.X) * float64(context.radii.X)) + decisionX := float64(2 * context.radii.Y * context.radii.Y * int(x)) + decisionY := float64(2 * context.radii.X * context.radii.X * int(y)) + + // draw region 1 + for decisionX < decisionY { + points := []image.Point { + image.Pt(-int(x) + context.center.X, -int(y) + context.center.Y), + image.Pt( int(x) + context.center.X, -int(y) + context.center.Y), + image.Pt(-int(x) + context.center.X, int(y) + context.center.Y), + image.Pt( int(x) + context.center.X, int(y) + context.center.Y), + } + if context.srcData == nil { + context.plotColor(points[0]) + context.plotColor(points[1]) + context.plotColor(points[2]) + context.plotColor(points[3]) + } else { + context.plotSource(points[0]) + context.plotSource(points[1]) + context.plotSource(points[2]) + context.plotSource(points[3]) + } + + if (decision1 < 0) { + x ++ + decisionX += float64(2 * context.radii.Y * context.radii.Y) + decision1 += decisionX + float64(context.radii.Y * context.radii.Y) + } else { + x ++ + y -- + decisionX += float64(2 * context.radii.Y * context.radii.Y) + decisionY -= float64(2 * context.radii.X * context.radii.X) + decision1 += + decisionX - decisionY + + float64(context.radii.Y * context.radii.Y) + } + } + + // region 2 decision parameter + decision2 := + float64(context.radii.Y * context.radii.Y) * (x + 0.5) * (x + 0.5) + + float64(context.radii.X * context.radii.X) * (y - 1) * (y - 1) - + float64(context.radii.X * context.radii.X * context.radii.Y * context.radii.Y) + + // draw region 2 + for y >= 0 { + points := []image.Point { + image.Pt( int(x) + context.center.X, int(y) + context.center.Y), + image.Pt(-int(x) + context.center.X, int(y) + context.center.Y), + image.Pt( int(x) + context.center.X, -int(y) + context.center.Y), + image.Pt(-int(x) + context.center.X, -int(y) + context.center.Y), + } + if context.srcData == nil { + context.plotColor(points[0]) + context.plotColor(points[1]) + context.plotColor(points[2]) + context.plotColor(points[3]) + } else { + context.plotSource(points[0]) + context.plotSource(points[1]) + context.plotSource(points[2]) + context.plotSource(points[3]) + } + + if decision2 > 0 { + y -- + decisionY -= float64(2 * context.radii.X * context.radii.X) + decision2 += float64(context.radii.X * context.radii.X) - decisionY + } else { + y -- + x ++ + decisionX += float64(2 * context.radii.Y * context.radii.Y) + decisionY -= float64(2 * context.radii.X * context.radii.X) + decision2 += + decisionX - decisionY + + float64(context.radii.X * context.radii.X) + } + } +} + +// FillColorEllipse fills an ellipse within the destination canvas with a solid +// color. +func FillColorEllipse ( + destination art.Canvas, + color color.RGBA, + bounds image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + dstData, dstStride := destination.Buffer() + + realBounds := bounds + bounds = bounds.Intersect(destination.Bounds()).Canon() + if bounds.Empty() { return } + updatedRegion = bounds + + point := image.Point { } + for point.Y = bounds.Min.Y; point.Y < bounds.Max.Y; point.Y ++ { + for point.X = bounds.Min.X; point.X < bounds.Max.X; point.X ++ { + if inEllipse(point, realBounds) { + dstData[point.X + point.Y * dstStride] = color + } + }} + return +} + +// StrokeColorEllipse is similar to FillColorEllipse, but it draws an inset +// outline of an ellipse instead. +func StrokeColorEllipse ( + destination art.Canvas, + color color.RGBA, + bounds image.Rectangle, + weight int, +) ( + updatedRegion image.Rectangle, +) { + if weight < 1 { return } + + dstData, dstStride := destination.Buffer() + insetBounds := bounds.Inset(weight - 1) + + context := ellipsePlottingContext { + plottingContext: plottingContext { + dstData: dstData, + dstStride: dstStride, + color: color, + weight: weight, + bounds: bounds.Intersect(destination.Bounds()), + }, + radii: image.Pt(insetBounds.Dx() / 2, insetBounds.Dy() / 2), + } + context.center = insetBounds.Min.Add(context.radii) + context.plotEllipse() + return +} + +func inEllipse (point image.Point, bounds image.Rectangle) bool { + point = point.Sub(bounds.Min) + x := (float64(point.X) + 0.5) / float64(bounds.Dx()) - 0.5 + y := (float64(point.Y) + 0.5) / float64(bounds.Dy()) - 0.5 + return math.Hypot(x, y) <= 0.5 +} diff --git a/shapes/line.go b/shapes/line.go new file mode 100644 index 0000000..566ee3a --- /dev/null +++ b/shapes/line.go @@ -0,0 +1,110 @@ +package shapes + +import "art" +import "image" +import "image/color" + +// ColorLine draws a line from one point to another with the specified weight +// and color. +func ColorLine ( + destination art.Canvas, + color color.RGBA, + weight int, + min image.Point, + max image.Point, +) ( + updatedRegion image.Rectangle, +) { + updatedRegion = image.Rectangle { Min: min, Max: max }.Canon() + updatedRegion.Max.X ++ + updatedRegion.Max.Y ++ + + data, stride := destination.Buffer() + bounds := destination.Bounds() + context := linePlottingContext { + plottingContext: plottingContext { + dstData: data, + dstStride: stride, + color: color, + weight: weight, + bounds: bounds, + }, + min: min, + max: max, + } + + if abs(max.Y - min.Y) < abs(max.X - min.X) { + if max.X < min.X { context.swap() } + context.lineLow() + + } else { + if max.Y < min.Y { context.swap() } + context.lineHigh() + } + return +} + +type linePlottingContext struct { + plottingContext + min image.Point + max image.Point +} + +func (context *linePlottingContext) swap () { + temp := context.max + context.max = context.min + context.min = temp +} + +func (context linePlottingContext) lineLow () { + deltaX := context.max.X - context.min.X + deltaY := context.max.Y - context.min.Y + yi := 1 + + if deltaY < 0 { + yi = -1 + deltaY *= -1 + } + + D := (2 * deltaY) - deltaX + point := context.min + + for ; point.X < context.max.X; point.X ++ { + context.plotColor(point) + if D > 0 { + D += 2 * (deltaY - deltaX) + point.Y += yi + } else { + D += 2 * deltaY + } + } +} + +func (context linePlottingContext) lineHigh () { + deltaX := context.max.X - context.min.X + deltaY := context.max.Y - context.min.Y + xi := 1 + + if deltaX < 0 { + xi = -1 + deltaX *= -1 + } + + D := (2 * deltaX) - deltaY + point := context.min + + for ; point.Y < context.max.Y; point.Y ++ { + context.plotColor(point) + if D > 0 { + point.X += xi + D += 2 * (deltaX - deltaY) + } else { + D += 2 * deltaX + } + } +} + +func abs (n int) int { + if n < 0 { n *= -1} + return n +} diff --git a/shapes/plot.go b/shapes/plot.go new file mode 100644 index 0000000..6749768 --- /dev/null +++ b/shapes/plot.go @@ -0,0 +1,47 @@ +package shapes + +import "image" +import "image/color" + +// FIXME? drawing a ton of overlapping squares might be a bit wasteful. + +type plottingContext struct { + dstData []color.RGBA + dstStride int + srcData []color.RGBA + srcStride int + color color.RGBA + weight int + offset image.Point + bounds image.Rectangle +} + +func (context plottingContext) square (center image.Point) (square image.Rectangle) { + return image.Rect(0, 0, context.weight, context.weight). + Sub(image.Pt(context.weight / 2, context.weight / 2)). + Add(center). + Intersect(context.bounds) +} + +func (context plottingContext) plotColor (center image.Point) { + square := context.square(center) + for y := square.Min.Y; y < square.Max.Y; y ++ { + for x := square.Min.X; x < square.Max.X; x ++ { + context.dstData[x + y * context.dstStride] = context.color + }} +} + +func (context plottingContext) plotSource (center image.Point) { + square := context.square(center) + for y := square.Min.Y; y < square.Max.Y; y ++ { + for x := square.Min.X; x < square.Max.X; x ++ { + // we offset srcIndex here because we have already applied the + // offset to the square, and we need to reverse that to get the + // proper source coordinates. + srcIndex := + x + context.offset.X + + (y + context.offset.Y) * context.dstStride + dstIndex := x + y * context.dstStride + context.dstData[dstIndex] = context.srcData [srcIndex] + }} +} diff --git a/shapes/rectangle.go b/shapes/rectangle.go new file mode 100644 index 0000000..be82bf5 --- /dev/null +++ b/shapes/rectangle.go @@ -0,0 +1,130 @@ +package shapes + +import "art" +import "image" +import "art/shatter" +import "image/color" + +// TODO: return updatedRegion for all routines in this package + +func FillRectangle ( + destination art.Canvas, + source art.Canvas, + bounds image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + dstData, dstStride := destination.Buffer() + srcData, srcStride := source.Buffer() + + offset := source.Bounds().Min.Sub(destination.Bounds().Min) + drawBounds := + source.Bounds().Sub(offset). + Intersect(destination.Bounds()). + Intersect(bounds) + if drawBounds.Empty() { return } + updatedRegion = drawBounds + + point := image.Point { } + for point.Y = drawBounds.Min.Y; point.Y < drawBounds.Max.Y; point.Y ++ { + for point.X = drawBounds.Min.X; point.X < drawBounds.Max.X; point.X ++ { + offsetPoint := point.Add(offset) + dstIndex := point.X + point.Y * dstStride + srcIndex := offsetPoint.X + offsetPoint.Y * srcStride + dstData[dstIndex] = srcData[srcIndex] + }} + + return +} + +func StrokeRectangle ( + destination art.Canvas, + source art.Canvas, + bounds image.Rectangle, + weight int, +) ( + updatedRegion image.Rectangle, +) { + insetBounds := bounds.Inset(weight) + if insetBounds.Empty() { + return FillRectangle(destination, source, bounds) + } + return FillRectangleShatter(destination, source, bounds, insetBounds) +} + +// FillRectangleShatter is like FillRectangle, but it does not draw in areas +// specified in "rocks". +func FillRectangleShatter ( + destination art.Canvas, + source art.Canvas, + bounds image.Rectangle, + rocks ...image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + tiles := shatter.Shatter(bounds, rocks...) + for _, tile := range tiles { + FillRectangle ( + art.Cut(destination, tile), + source, tile) + updatedRegion = updatedRegion.Union(tile) + } + return +} + +// FillColorRectangle fills a rectangle within the destination canvas with a +// solid color. +func FillColorRectangle ( + destination art.Canvas, + color color.RGBA, + bounds image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + dstData, dstStride := destination.Buffer() + bounds = bounds.Canon().Intersect(destination.Bounds()) + if bounds.Empty() { return } + + updatedRegion = bounds + for y := bounds.Min.Y; y < bounds.Max.Y; y ++ { + for x := bounds.Min.X; x < bounds.Max.X; x ++ { + dstData[x + y * dstStride] = color + }} + + return +} + +// FillColorRectangleShatter is like FillColorRectangle, but it does not draw in +// areas specified in "rocks". +func FillColorRectangleShatter ( + destination art.Canvas, + color color.RGBA, + bounds image.Rectangle, + rocks ...image.Rectangle, +) ( + updatedRegion image.Rectangle, +) { + tiles := shatter.Shatter(bounds, rocks...) + for _, tile := range tiles { + FillColorRectangle(destination, color, tile) + updatedRegion = updatedRegion.Union(tile) + } + return +} + +// StrokeColorRectangle is similar to FillColorRectangle, but it draws an inset +// outline of the given rectangle instead. +func StrokeColorRectangle ( + destination art.Canvas, + color color.RGBA, + bounds image.Rectangle, + weight int, +) ( + updatedRegion image.Rectangle, +) { + insetBounds := bounds.Inset(weight) + if insetBounds.Empty() { + return FillColorRectangle(destination, color, bounds) + } + return FillColorRectangleShatter(destination, color, bounds, insetBounds) +} diff --git a/shatter/shatter.go b/shatter/shatter.go new file mode 100644 index 0000000..806dfda --- /dev/null +++ b/shatter/shatter.go @@ -0,0 +1,97 @@ +// Package shatter provides boolean operations for image.Rectangle. +package shatter + +import "image" + +// Shatter takes in a bounding rectangle, and several rectangles to be +// subtracted from it. It returns a slice of rectangles that tile together to +// make up the difference between them. This is intended to be used for figuring +// out which areas of a container element's background are covered by other +// elements so it doesn't waste CPU cycles drawing to those areas. +func Shatter ( + glass image.Rectangle, + rocks ...image.Rectangle, +) ( + tiles []image.Rectangle, +) { + // in this function, the metaphor of throwing several rocks at a sheet + // of glass is used to illustrate the concept. + + tiles = []image.Rectangle { glass } + for _, rock := range rocks { + + // check each tile to see if the rock has collided with it + tileLen := len(tiles) + for tileIndex := 0; tileIndex < tileLen; tileIndex ++ { + tile := tiles[tileIndex] + if !rock.Overlaps(tile) { continue } + newTiles, n := shatterOnce(tile, rock) + if n > 0 { + // the tile was shattered into one or more sub + // tiles + tiles[tileIndex] = newTiles[0] + tiles = append(tiles, newTiles[1:n]...) + } else { + // the tile was entirely obscured by the rock + // and must be wholly removed + tiles = remove(tiles, tileIndex) + tileIndex -- + tileLen -- + } + } + } + return +} + +func shatterOnce (glass, rock image.Rectangle) (tiles [4]image.Rectangle, n int) { + rock = rock.Intersect(glass) + + // |'''''''''''| + // | | + // |###|'''| | + // |###|___| | + // | | + // |___________| + if rock.Min.X > glass.Min.X { tiles[n] = image.Rect ( + glass.Min.X, rock.Min.Y, + rock.Min.X, rock.Max.Y, + ); n ++ } + + // |'''''''''''| + // | | + // | |'''|###| + // | |___|###| + // | | + // |___________| + if rock.Max.X < glass.Max.X { tiles[n] = image.Rect ( + rock.Max.X, rock.Min.Y, + glass.Max.X, rock.Max.Y, + ); n ++ } + + // |###########| + // |###########| + // | |'''| | + // | |___| | + // | | + // |___________| + if rock.Min.Y > glass.Min.Y { tiles[n] = image.Rect ( + glass.Min.X, glass.Min.Y, + glass.Max.X, rock.Min.Y, + ); n ++ } + + // |'''''''''''| + // | | + // | |'''| | + // | |___| | + // |###########| + // |###########| + if rock.Max.Y < glass.Max.Y { tiles[n] = image.Rect ( + glass.Min.X, rock.Max.Y, + glass.Max.X, glass.Max.Y, + ); n ++ } + return +} + +func remove[ELEMENT any] (slice []ELEMENT, s int) []ELEMENT { + return append(slice[:s], slice[s + 1:]...) +}