gdamore · gdamore · Aug 23, 2025 · Aug 23, 2025
@@ -0,0 +1,176 @@
+//go:build ignore
+// +build ignore
+
+// Copyright 2019 The TCell Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use file except in compliance with the License.
+// You may obtain a copy of the license at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// colors just displays a single centered rectangle that should pulse
+// through available colors.  It uses the RGB color cube, bumping at
+// predefined larger intervals (values of about 8) in order that the
+// changes happen quickly enough to be appreciable.
+//
+// Press ESC to exit the program.
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/gdamore/tcell/v2"
+	"github.com/mattn/go-runewidth"
+)
+
+var red = int32(rand.Int() % 256)
+var grn = int32(rand.Int() % 256)
+var blu = int32(rand.Int() % 256)
+var inc = int32(8) // rate of color change
+var redi = int32(inc)
+var grni = int32(inc)
+var blui = int32(inc)
+
+func emitStr(s tcell.Screen, x, y int, style tcell.Style, str string) {
+	for _, c := range str {
+		var comb []rune
+		w := runewidth.RuneWidth(c)
+		if w == 0 {
+			comb = []rune{c}
+			c = ' '
+			w = 1
+		}
+		s.SetContent(x, y, c, comb, style)
+		x += w
+	}
+}
+
+func makebox(s tcell.Screen, name string, color tcell.Color) {
+	w, h := s.Size()
+
+	if w == 0 || h == 0 {
+		return
+	}
+
+	lh := h - 3
+	lw := w
+	lx := 0
+	ly := 0
+	st := tcell.StyleDefault
+	gl := ' '
+
+	s.Fill(' ', st)
+	bg := st.Background(color)
+	for row := 0; row < lh; row++ {
+		for col := 0; col < lw; col++ {
+			s.SetCell(lx+col, ly+row, bg, gl)
+		}
+	}
+	cn := color.Name()
+	if cn == "" {
+		cn = "rgb"
+	}
+	msg := fmt.Sprintf("This is %s (#%06x, %s). Terminal supports %d colors.", name, color.Hex(), cn, s.Colors())
+	if len(msg) < w {
+		lx = (w - len(msg)) / 2
+	} else {
+		lx = 0
+	}
+	emitStr(s, lx, lh+1, st, msg)
+	s.Show()
+}
+
+func fatal(v string, args ...any) {
+	fmt.Fprintf(os.Stderr, v+"\n", args...)
+	os.Exit(1)
+}
+
+func main() {
+
+	if len(os.Args) != 2 {
+		fatal("usage: %s color", os.Args[0])
+	}
+
+	var color tcell.Color
+
+	if strings.HasPrefix(os.Args[1], "#") {
+		name := os.Args[1][1:]
+		if len(name) == 3 {
+			hex, err := strconv.ParseUint(name, 16, 12)
+			if err != nil {
+				fatal("invalid color specification")
+			}
+			// expand 12 bit color to 24 bit
+			r := int32((hex & 0xf00) >> 8)
+			g := int32((hex & 0x0f0) >> 4)
+			b := int32(hex & 0x00f)
+			r = r<<4 + r
+			g = g<<4 + g
+			b = b<<4 + b
+			color = tcell.NewRGBColor(r, g, b)
+		} else if len(name) == 6 {
+			hex, err := strconv.ParseUint(name, 16, 32)
+			if err != nil {
+				fatal("invalid color specification")
+			}
+			color = tcell.NewHexColor(int32(hex))
+		} else {
+			fatal("invalid color specification")
+		}
+	} else if val, err := strconv.Atoi(os.Args[1]); err == nil {
+		color = tcell.ColorBlack + tcell.Color(val)
+	} else if val, ok := tcell.ColorNames[strings.ToLower(os.Args[1])]; ok {
+		color = val
+	} else {
+		fatal("invalid color specification")
+	}
+
+	tcell.SetEncodingFallback(tcell.EncodingFallbackASCII)
+	s, e := tcell.NewScreen()
+	if e != nil {
+		fatal("new screen: %v", e.Error())
+	}
+	if e = s.Init(); e != nil {
+		fatal("new screen: %v", e.Error())
+	}
+
+	s.SetStyle(tcell.StyleDefault.
+		Foreground(tcell.ColorBlack).
+		Background(tcell.ColorWhite))
+	s.Clear()
+
+	quit := make(chan struct{})
+	go func() {
+		for {
+			ev := s.PollEvent()
+			switch ev := ev.(type) {
+			case *tcell.EventKey:
+				switch ev.Key() {
+				case tcell.KeyEscape, tcell.KeyEnter:
+					close(quit)
+					return
+				case tcell.KeyCtrlL:
+					s.Sync()
+				}
+			case *tcell.EventResize:
+				s.Sync()
+			}
+		}
+	}()
+
+	makebox(s, os.Args[1], color)
+	<-quit
+
+	s.Fini()
+}