Fixing diagrams/svg in blog post

Author: heeckhau

blog/2026-01-01-do-not-pass-go/access-control.svg

@@ -0,0 +1,66 @@
+#!/bin/bash
+
+FORMAT="svg"
+
+SOURCE_DIR=$(dirname "$0")
+TARGET_DIR=$(realpath "$(dirname "$0")/")
+
+OS=$(uname)
+case "$OS" in
+"Darwin") # Mac
+    DRAW_IO="/Applications/draw.io.app/Contents/MacOS/draw.io"
+    ;;
+"Linux") # Linux
+    DRAW_IO="drawio"
+    ;;
+esac
+
+# Unset Electron env vars that interfere with draw.io when running from VSCode
+unset ELECTRON_RUN_AS_NODE ELECTRON_NO_ATTACH_CONSOLE
+
+if ! command -v "$DRAW_IO" &>/dev/null; then
+    echo "Error: draw.io executable not found. Please install draw.io and make sure it's in your PATH."
+    exit 1
+fi
+
+SOURCE="$SOURCE_DIR/diagrams.drawio"
+
+# Extract page names from uncompressed XML
+TMPFILE=$(mktemp)
+"$DRAW_IO" --export --format xml --no-sandbox --uncompressed -o "$TMPFILE" "$SOURCE" 2>/dev/null
+
+# Read page names into an array
+mapfile -t PAGES < <(grep -oP '<diagram[^>]*name="\K[^"]*' "$TMPFILE")
+rm "$TMPFILE"
+
+for i in "${!PAGES[@]}"; do
+    name="${PAGES[$i]}"
+    page_num=$((i + 1))
+    for theme in "dark" "light"; do
+        TARGET="${TARGET_DIR}/${theme}/${name}.${FORMAT}"
+        # Only convert if the source is more recent than the target
+        if [[ "$SOURCE" -nt "${TARGET}" ]]; then
+            echo "Exporting page $page_num ($name) -> $theme/$name.$FORMAT"
+            "$DRAW_IO" --export --format ${FORMAT} --scale 2.5 --svg-theme "${theme}" --no-sandbox --page-index "$page_num" -o "${TARGET}" "$SOURCE"
+            # Remove DOCTYPE to prevent SVGO entity count errors during build
+            sed -i '/<!DOCTYPE/d' "${TARGET}"
+            # Fix embedded SVG icons for dark theme: draw.io can't resolve
+            # currentColor inside base64-encoded SVG images, so we replace
+            # it with an explicit color after export.
+            if [[ "$theme" == "dark" ]]; then
+                node -e '
+                    const fs = require("fs");
+                    const file = process.argv[1];
+                    let svg = fs.readFileSync(file, "utf8");
+                    svg = svg.replace(/xlink:href="data:image\/svg\+xml;base64,([^"]+)"/g, (m, b64) => {
+                        const dec = Buffer.from(b64, "base64").toString("utf8");
+                        let fixed = dec.replace(/currentColor/g, "#ffffff");
+                        if (fixed === dec) return m;
+                        return "xlink:href=\"data:image/svg+xml;base64," + Buffer.from(fixed).toString("base64") + "\"";
+                    });
+                    fs.writeFileSync(file, svg);
+                ' "${TARGET}"
+            fi
+        fi
+    done
+done