getting this up

.devcontainer/Dockerfile

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+# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.241.1/containers/go/.devcontainer/base.Dockerfile
+
+# [Choice] Go version (use -bullseye variants on local arm64/Apple Silicon): 1, 1.18, 1.17, 1-bullseye, 1.18-bullseye, 1.17-bullseye, 1-buster, 1.18-buster, 1.17-buster
+ARG VARIANT="1.18-bullseye"
+FROM mcr.microsoft.com/vscode/devcontainers/go:0-${VARIANT}
+
+# [Choice] Node.js version: none, lts/*, 16, 14, 12, 10
+ARG NODE_VERSION="none"
+RUN if [ "${NODE_VERSION}" != "none" ]; then su vscode -c "umask 0002 && . /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSION} 2>&1"; fi
+
+# [Optional] Uncomment this section to install additional OS packages.
+# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+#     && apt-get -y install --no-install-recommends <your-package-list-here>
+
+# [Optional] Uncomment the next lines to use go get to install anything else you need
+# USER vscode
+# RUN go get -x <your-dependency-or-tool>
+
+# [Optional] Uncomment this line to install global node packages.
+# RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && npm install -g <your-package-here>" 2>&1

.devcontainer/devcontainer.json

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+// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
+// https://github.com/microsoft/vscode-dev-containers/tree/v0.241.1/containers/go
+{
+	"name": "Go",
+	"build": {
+		"dockerfile": "Dockerfile",
+		"args": {
+			// Update the VARIANT arg to pick a version of Go: 1, 1.18, 1.17
+			// Append -bullseye or -buster to pin to an OS version.
+			// Use -bullseye variants on local arm64/Apple Silicon.
+			"VARIANT": "1.18-bullseye",
+			// Options
+			"NODE_VERSION": "none"
+		}
+	},
+	"runArgs": [ "--cap-add=SYS_PTRACE", "--security-opt", "seccomp=unconfined" ],
+
+	// Configure tool-specific properties.
+	"customizations": {
+		// Configure properties specific to VS Code.
+		"vscode": {
+			// Set *default* container specific settings.json values on container create.
+			"settings": { 
+				"go.toolsManagement.checkForUpdates": "local",
+				"go.useLanguageServer": true,
+				"go.gopath": "/go"
+			},
+			
+			// Add the IDs of extensions you want installed when the container is created.
+			"extensions": [
+				"golang.Go"
+			]
+		}
+	},
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	// "postCreateCommand": "go version",
+
+	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	"remoteUser": "vscode",
+	"features": {
+		"docker-in-docker": "latest",
+		"kubectl-helm-minikube": "latest",
+		"git": "latest"
+	}
+}

Dockerfile

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+from registry.local/rgbarm64lib:latest
+
+workdir /usr/src/app/work
+COPY . .
+RUN go mod tidy
+
+RUN go build .

go.mod

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+module rgb
+
+go 1.18
+
+require (
+        gitea.wagshome.duckdns.org/publicWagsHome/go-rpi-rgb-led-matrix v0.0.0-20220709235716-bf87ebdb3e55
+        github.com/fogleman/gg v1.3.0
+)
+
+require (
+        dmitri.shuralyov.com/gpu/mtl v0.0.0-20201218220906-28db891af037 // indirect
+        github.com/go-gl/glfw/v3.3/glfw v0.0.0-20200222043503-6f7a984d4dc4 // indirect
+        github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 // indirect
+        github.com/jezek/xgb v1.0.0 // indirect
+        golang.org/x/exp/shiny v0.0.0-20220713135740-79cabaa25d75 // indirect
+        golang.org/x/image v0.0.0-20220617043117-41969df76e82 // indirect
+        golang.org/x/mobile v0.0.0-20220518205345-8578da9835fd // indirect
+        golang.org/x/sys v0.0.0-20211019181941-9d821ace8654 // indirect
+        gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
+)
+
+replace gitea.wagshome.duckdns.org/publicWagsHome/go-rpi-rgb-led-matrix v0.0.0-20220709235716-bf87ebdb3e55 => /usr/src/app

main.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"image/color"
+
+	rgbmatrix "gitea.wagshome.duckdns.org/publicWagsHome/go-rpi-rgb-led-matrix"
+)
+
+var (
+	rows                     = flag.Int("led-rows", 32, "number of rows supported")
+	cols                     = flag.Int("led-cols", 32, "number of columns supported")
+	parallel                 = flag.Int("led-parallel", 1, "number of daisy-chained panels")
+	chain                    = flag.Int("led-chain", 2, "number of displays daisy-chained")
+	brightness               = flag.Int("brightness", 100, "brightness (0-100)")
+	hardware_mapping         = flag.String("led-gpio-mapping", "regular", "Name of GPIO mapping used.")
+	show_refresh             = flag.Bool("led-show-refresh", false, "Show refresh rate.")
+	inverse_colors           = flag.Bool("led-inverse", false, "Switch if your matrix has inverse colors on.")
+	disable_hardware_pulsing = flag.Bool("led-no-hardware-pulse", false, "Don't use hardware pin-pulse generation.")
+)
+
+func main() {
+	config := &rgbmatrix.DefaultConfig
+	config.Rows = *rows
+	config.Cols = *cols
+	config.Parallel = *parallel
+	config.ChainLength = *chain
+	config.Brightness = *brightness
+	config.HardwareMapping = *hardware_mapping
+	config.ShowRefreshRate = *show_refresh
+	config.InverseColors = *inverse_colors
+	config.DisableHardwarePulsing = *disable_hardware_pulsing
+
+	m, err := rgbmatrix.NewRGBLedMatrix(config)
+	fatal(err)
+
+	c := rgbmatrix.NewCanvas(m)
+	defer c.Close()
+
+	bounds := c.Bounds()
+	for x := bounds.Min.X; x < bounds.Max.X; x++ {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			fmt.Println("x", x, "y", y)
+			c.Set(x, y, color.RGBA{255, 0, 0, 255})
+			c.Render()
+		}
+	}
+}
+
+func init() {
+	flag.Parse()
+}
+
+func fatal(err error) {
+	if err != nil {
+		panic(err)
+	}
+}