draw: tool to draw via lua

Author: frioux

README.mdwn

@@ -97,6 +97,7 @@ echo "---\nfoo: 1" | leatherman yaml2json
 ### misc
 
  * `backlight`: Modifies screen brightness. ([internal/tool/misc/backlight/backlight.md](https://github.com/frioux/leatherman/blob/main/internal/tool/misc/backlight/backlight.md))
+ * `draw`: Draws images with lua. ([internal/tool/misc/img/draw.md](https://github.com/frioux/leatherman/blob/main/internal/tool/misc/img/draw.md))
  * `export-bamboohr`: Exports company directory as JSON. ([internal/tool/misc/bamboo/export-bamboohr.md](https://github.com/frioux/leatherman/blob/main/internal/tool/misc/bamboo/export-bamboohr.md))
  * `export-bamboohr-tree`: Exports company org chart as JSON. ([internal/tool/misc/bamboo/export-bamboohr-tree.md](https://github.com/frioux/leatherman/blob/main/internal/tool/misc/bamboo/export-bamboohr-tree.md))
  * `prepend-hist`: Combines a history file and stdin. ([internal/tool/misc/prependhist/prepend-hist.md](https://github.com/frioux/leatherman/blob/main/internal/tool/misc/prependhist/prepend-hist.md))

dispatch.go

@@ -30,6 +30,7 @@ import "embed"
 //go:embed internal/tool/mail/email/email2json.md
 //go:embed internal/tool/mail/email/render-mail.md
 //go:embed internal/tool/misc/backlight/backlight.md
+//go:embed internal/tool/misc/img/draw.md
 //go:embed internal/tool/misc/bamboo/export-bamboohr.md
 //go:embed internal/tool/misc/bamboo/export-bamboohr-tree.md
 //go:embed internal/tool/misc/prependhist/prepend-hist.md
@@ -101,6 +102,8 @@ var helpPaths = map[string]string{
 
 	"backlight": "internal/tool/misc/backlight/backlight.md",
 
+	"draw": "internal/tool/misc/img/draw.md",
+
 	"export-bamboohr": "internal/tool/misc/bamboo/export-bamboohr.md",
 
 	"export-bamboohr-tree": "internal/tool/misc/bamboo/export-bamboohr-tree.md",

help_generated.go

@@ -0,0 +1,237 @@
+package img
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"io"
+	"math"
+	"os"
+
+	lua "github.com/yuin/gopher-lua"
+)
+
+func Draw(args []string, _ io.Reader) error {
+	if len(args) == 1 {
+		args = append(args, "")
+	}
+
+	img := image.NewNRGBA(image.Rect(0, 0, 128, 128))
+	for x := 0; x < 128; x++ {
+		for y := 0; y < 128; y++ {
+			img.Set(x, y, color.Black)
+		}
+	}
+
+	if err := luaEval(img, args[1:]); err != nil {
+		return err
+	}
+
+	return png.Encode(os.Stdout, img)
+}
+
+func luaEval(img *image.NRGBA, code []string) error {
+	L := lua.NewState()
+	defer L.Close()
+
+	registerImageFunctions(L, img)
+
+	for _, c := range code {
+		if err := L.DoString(c); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func checkColor(L *lua.LState, w int) color.Color {
+	ud := L.CheckUserData(w)
+	if v, ok := ud.Value.(color.Color); ok {
+		return v
+	}
+	L.ArgError(w, "image.Color expected")
+	return nil
+}
+
+func registerImageFunctions(L *lua.LState, img *image.NRGBA) {
+	L.SetGlobal("set", L.NewFunction(func(L *lua.LState) int {
+		x := L.CheckNumber(1)
+		y := L.CheckNumber(2)
+		c := checkColor(L, 3)
+
+		img.Set(int(x), int(y), c)
+
+		return 0
+	}))
+
+	L.SetGlobal("rgb", L.NewFunction(func(L *lua.LState) int {
+		r := L.CheckNumber(1)
+		g := L.CheckNumber(2)
+		b := L.CheckNumber(3)
+
+		ud := L.NewUserData()
+		ud.Value = color.RGBA{uint8(r), uint8(g), uint8(b), 255}
+
+		L.Push(ud)
+		return 1
+	}))
+
+	{
+		black := L.NewUserData()
+		black.Value = color.Black
+		L.SetGlobal("black", black)
+
+		white := L.NewUserData()
+		white.Value = color.RGBA{0, 0, 0, 255}
+		L.SetGlobal("white", white)
+
+		red := L.NewUserData()
+		red.Value = color.RGBA{255, 0, 0, 255}
+		L.SetGlobal("red", red)
+
+		blue := L.NewUserData()
+		blue.Value = color.RGBA{0, 0, 255, 255}
+		L.SetGlobal("blue", blue)
+
+		yellow := L.NewUserData()
+		yellow.Value = color.RGBA{255, 255, 0, 255}
+		L.SetGlobal("yellow", yellow)
+
+		green := L.NewUserData()
+		green.Value = color.RGBA{0, 255, 0, 255}
+		L.SetGlobal("green", green)
+
+		orange := L.NewUserData()
+		orange.Value = color.RGBA{255, 165, 0, 255}
+		L.SetGlobal("orange", orange)
+
+		purple := L.NewUserData()
+		purple.Value = color.RGBA{128, 0, 128, 255}
+		L.SetGlobal("purple", purple)
+
+		cyan := L.NewUserData()
+		cyan.Value = color.RGBA{0, 255, 255, 255}
+		L.SetGlobal("cyan", cyan)
+
+		magenta := L.NewUserData()
+		magenta.Value = color.RGBA{255, 0, 255, 255}
+		L.SetGlobal("magenta", magenta)
+	}
+
+	L.SetGlobal("sin", L.NewFunction(func(L *lua.LState) int {
+		t := L.CheckNumber(1)
+
+		L.Push(lua.LNumber(math.Sin(float64(t))))
+		return 1
+	}))
+
+	L.SetGlobal("cos", L.NewFunction(func(L *lua.LState) int {
+		t := L.CheckNumber(1)
+
+		L.Push(lua.LNumber(math.Cos(float64(t))))
+		return 1
+	}))
+
+	L.SetGlobal("tan", L.NewFunction(func(L *lua.LState) int {
+		t := L.CheckNumber(1)
+
+		L.Push(lua.LNumber(math.Tan(float64(t))))
+		return 1
+	}))
+
+	L.SetGlobal("PI", lua.LNumber(math.Pi))
+
+	L.SetGlobal("rect", L.NewFunction(func(L *lua.LState) int {
+		x1 := int(L.CheckNumber(1))
+		y1 := int(L.CheckNumber(2))
+		x2 := int(L.CheckNumber(3))
+		y2 := int(L.CheckNumber(4))
+		border := checkColor(L, 5)
+		fill := checkColor(L, 6)
+
+		// draw borders
+		for x := x1; x <= x2; x++ {
+			img.Set(x, y1, border)
+			img.Set(x, y2, border)
+		}
+		for y := y1 + 1; y < y2; y++ {
+			img.Set(x1, y, border)
+			img.Set(x2, y, border)
+		}
+
+		// draw fill
+		for x := x1 + 1; x < x2; x++ {
+			for y := y1 + 1; y < y2; y++ {
+				img.Set(x, y, fill)
+			}
+		}
+
+		return 0
+	}))
+
+	line := func(x1, y1, x2, y2 float64, c color.Color) {
+		m := (y2 - y1) / (x2 - x1)
+		// y = m*x + b
+		// y - m*x = b
+		// b = y - m*x
+		b := y1 - m*x1
+		l := math.Sqrt(math.Pow(x2-x1, 2) + math.Pow(y2-y1, 2))
+
+		if m == math.Inf(1) || m == math.Inf(-1) {
+			start, end := y1, y2
+			if start > end {
+				start, end = end, start
+			}
+			for y := start; y <= end; y += l / 1000 {
+				img.Set(int(math.Round(x1)), int(math.Round(y)), c)
+			}
+		} else {
+			start, end := x1, x2
+			if start > end {
+				start, end = end, start
+			}
+
+			for x := start; x <= end; x += l / 1000 {
+				y := m*x + b
+				img.Set(int(math.Round(x)), int(math.Round(y)), c)
+			}
+		}
+	}
+
+	L.SetGlobal("circ", L.NewFunction(func(L *lua.LState) int {
+		x := int(L.CheckNumber(1))
+		y := int(L.CheckNumber(2))
+		r := float64(L.CheckNumber(3))
+		border := checkColor(L, 4)
+		fill := checkColor(L, 5)
+
+		// draw borders
+		for t := 0.0; t < 2*math.Pi; t += 0.001 /* uhh */ {
+			xt := r*math.Cos(t) + float64(x)
+			yt := r*math.Sin(t) + float64(y)
+
+			line(float64(x), float64(y), xt, yt, fill)
+		}
+		for t := 0.0; t < 2*math.Pi; t += 0.001 /* uhh */ {
+			xt := r*math.Cos(t) + float64(x)
+			yt := r*math.Sin(t) + float64(y)
+
+			img.Set(int(math.Round(xt)), int(math.Round(yt)), border)
+		}
+
+		return 0
+	}))
+
+	L.SetGlobal("line", L.NewFunction(func(L *lua.LState) int {
+		x1 := float64(L.CheckNumber(1))
+		y1 := float64(L.CheckNumber(2))
+		x2 := float64(L.CheckNumber(3))
+		y2 := float64(L.CheckNumber(4))
+		c := checkColor(L, 5)
+
+		line(x1, y1, x2, y2, c)
+
+		return 0
+	}))
+}

internal/tool/misc/img/draw.go

@@ -0,0 +1,71 @@
+Draws images with lua.
+
+```bash
+$ draw 'rect(10, 10, 118, 118, red, yellow)' > x.png
+```
+
+Inspired by pico-8.  This tool takes lua scripts as strings and writes a png to
+standard out.
+
+Consider this tool unstable, I'll likely make it read scripts from either
+standard in, or files, or both, and make arguments no longer the default.
+
+## Lua API
+
+### `set(x, y, c)`
+
+Takes an x, y coordinate and sets it to a color.
+
+### `rgb(r, g, b)`
+
+Takes a red, green, and blue value (from 0 to 255), returns a color value.
+
+The following colors are defined as globals for you:
+
+ * black
+ * white
+ * red
+ * blue
+ * yellow
+ * green
+ * orange
+ * purple
+ * cyan
+ * magenta
+
+### `sin(t)`
+
+Returns sine of t, in terms of pi, not degrees.
+
+### `cos(t)`
+
+Returns cosine of t, in terms of pi, not degrees.
+
+### `tan(t)`
+
+Returns tangent of t, in terms of pi, not degrees.
+
+### `PI`
+
+Constant for pi.
+
+### `rect(x1, y1, x2, y2, bordercolor, fillcolor)`
+
+Draws a rectangle from (x1, y1) to (x2, y2) with a border of bordercolor and
+filled with fillcolor.
+
+### `circ(x, y, r, bordercolor, fillcolor)`
+
+Draws a circle around (x, y) with radius r with a border of bordercolor and
+filled with fillcolor.
+
+### `line(x1, y1, x2, y2, color)`
+
+Draws a line from (x1, y1) to (x2, y2) in color.
+
+## BUGS
+
+Something is wrong with `line` in certain situations (I'm assuming infinity or
+NaN or something is causing the issue.)  `line` is used when drawing `circle`s,
+so you can see the bug by drawing a circle and there will be weird gaps in the
+top and bottom of them.