v0.1.5 — export graph as PNG (closes #4)

Adds a download button to the bottom-left React Flow controls that
exports the current canvas view as a PNG with the dot grid preserved.

- New util src/client/utils/exportPng.ts: html-to-image capture +
  manual canvas composition (solid bg + dot grid + captured layer).
  Works around html-to-image's SVG <pattern> limitations and produces
  a deterministic 3x retina PNG.
- During capture, temporary CSS disables ring-shadow halos and forces
  service node bodies to a solid dark fill so the dot grid doesn't
  bleed through. State is still indicated by border colors and the
  inner state dot. Group node headers are excluded so their outlines
  stay intact.
- New component src/client/components/ExportPngButton.tsx integrated
  as a custom ControlButton inside <Controls> (bottom-left).
- App.tsx: id="dashboard-canvas" + data-no-export on project filter.
- i18n: 4 keys (EN + ES) for the button and 3 error states.
- New dependency: html-to-image@1.11.13

bun.lock

@@ -8,6 +8,7 @@
         "@modelcontextprotocol/sdk": "^1.27.1",
         "dockerode": "^4",
         "hono": "^4",
+        "html-to-image": "^1.11.13",
         "lucide-react": "^0.577.0",
         "yaml": "^2",
         "zod": "^3",
@@ -494,6 +495,8 @@
 
     "hono": ["hono@4.12.8", "", {}, "sha512-VJCEvtrezO1IAR+kqEYnxUOoStaQPGrCmX3j4wDTNOcD1uRPFpGlwQUIW8niPuvHXaTUxeOUl5MMDGrl+tmO9A=="],
 
+    "html-to-image": ["html-to-image@1.11.13", "", {}, "sha512-cuOPoI7WApyhBElTTb9oqsawRvZ0rHhaHwghRLlTuffoD1B2aDemlCruLeZrUIIdvG7gs9xeELEPm6PhuASqrg=="],
+
     "http-errors": ["http-errors@2.0.1", "", { "dependencies": { "depd": "~2.0.0", "inherits": "~2.0.4", "setprototypeof": "~1.2.0", "statuses": "~2.0.2", "toidentifier": "~1.0.1" } }, "sha512-4FbRdAX+bSdmo4AUFuS0WNiPz8NgFt+r8ThgNWmlrjQjt1Q7ZR9+zTlce2859x4KSXrwIsaeTqDoKQmtP8pLmQ=="],
 
     "iconv-lite": ["iconv-lite@0.7.2", "", { "dependencies": { "safer-buffer": ">= 2.1.2 < 3.0.0" } }, "sha512-im9DjEDQ55s9fL4EYzOAv0yMqmMBSZp6G0VvFyTMPKWxiSBHUj9NW/qqLmXUwXrrM7AvqSlTCfvqRb0cM8yYqw=="],

package.json

@@ -1,6 +1,6 @@
 {
   "name": "containerflow",
-  "version": "0.1.4",
+  "version": "0.1.5",
   "license": "AGPL-3.0-or-later",
   "author": "Jorge Gonzalez D. (RGJorge)",
   "type": "module",
@@ -21,6 +21,7 @@
     "@modelcontextprotocol/sdk": "^1.27.1",
     "dockerode": "^4",
     "hono": "^4",
+    "html-to-image": "^1.11.13",
     "lucide-react": "^0.577.0",
     "yaml": "^2",
     "zod": "^3"

src/client/App.tsx

@@ -24,6 +24,7 @@ import { NodeContextMenu } from "./components/NodeContextMenu";
 import { LoginScreen } from "./components/LoginScreen";
 import { OffsetEdge } from "./components/OffsetEdge";
 import { HeaderBar, type Page } from "./components/HeaderBar";
+import { ExportPngButton } from "./components/ExportPngButton";
 import { EdgeLegend } from "./components/EdgeLegend";
 import { ActionErrorToast } from "./components/ActionErrorToast";
 import { Wifi, WifiOff, ChevronDown, Check } from "lucide-react";
@@ -570,7 +571,7 @@ function Dashboard({ token }: { token: string }) {
       {activePage === "settings" && <SettingsPage projects={projects} servicesCount={services.length} token={token} />}
 
       {/* Canvas — inset (only visible on dashboard) */}
-      <div className={`flex-1 min-h-0 relative mx-2 mt-1 rounded-xl overflow-hidden ring-1 ring-slate-700/60 shadow-[inset_0_2px_12px_rgba(0,0,0,0.5)] ${activePage !== "dashboard" ? "hidden" : ""}`}>
+      <div id="dashboard-canvas" className={`flex-1 min-h-0 relative mx-2 mt-1 rounded-xl overflow-hidden ring-1 ring-slate-700/60 shadow-[inset_0_2px_12px_rgba(0,0,0,0.5)] ${activePage !== "dashboard" ? "hidden" : ""}`}>
         <ReactFlow
           onInit={(instance) => { reactFlowRef.current = instance; }}
           nodes={dimmedNodes}
@@ -641,7 +642,9 @@ function Dashboard({ token }: { token: string }) {
           proOptions={{ hideAttribution: true }}
         >
           <Background color="#374151" gap={30} size={2} />
-          <Controls position="bottom-left" />
+          <Controls position="bottom-left">
+            <ExportPngButton onError={(msg) => pushActionError("dashboard", "export", msg)} />
+          </Controls>
           <EdgeLegend />
           <MiniMap
             position="bottom-right"
@@ -659,7 +662,7 @@ function Dashboard({ token }: { token: string }) {
 
         {/* Project filter */}
         {projects.length > 1 && (
-          <div className="absolute top-3 right-3 z-10" ref={filterRef}>
+          <div data-no-export="true" className="absolute top-3 right-3 z-10" ref={filterRef}>
             <button
               onClick={() => setFilterOpen((v) => !v)}
               className="flex items-center gap-2 text-sm text-slate-400 bg-slate-800/80 backdrop-blur-sm hover:bg-slate-700/80 border border-slate-700/50 px-3 py-1.5 rounded-md transition-colors"

src/client/components/ExportPngButton.tsx

@@ -0,0 +1,40 @@
+import { useState } from "react";
+import { ControlButton } from "@xyflow/react";
+import { Download, Loader2 } from "lucide-react";
+import { useT } from "../i18n";
+import { exportGraphAsPng, downloadPng } from "../utils/exportPng";
+
+interface Props {
+  onError?: (message: string) => void;
+}
+
+export function ExportPngButton({ onError }: Props) {
+  const { t } = useT();
+  const [busy, setBusy] = useState(false);
+
+  const handleClick = async () => {
+    if (busy) return;
+    setBusy(true);
+    try {
+      const { dataUrl } = await exportGraphAsPng();
+      downloadPng(dataUrl, window.location.hostname);
+    } catch (err) {
+      const code = err instanceof Error ? err.message : "UNKNOWN";
+      const message =
+        code === "EMPTY_GRAPH"
+          ? t("controls.exportPng.empty")
+          : code === "GRAPH_TOO_LARGE"
+            ? t("controls.exportPng.tooLarge")
+            : t("controls.exportPng.failed");
+      onError?.(message);
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <ControlButton onClick={handleClick} title={t("controls.exportPng")} disabled={busy}>
+      {busy ? <Loader2 className="animate-spin" /> : <Download />}
+    </ControlButton>
+  );
+}

src/client/i18n.tsx

@@ -20,6 +20,12 @@ const en = {
   "filter.projects": "Projects",
   "filter.all": "All",
 
+  // Canvas controls
+  "controls.exportPng": "Export graph as PNG",
+  "controls.exportPng.empty": "No containers to export",
+  "controls.exportPng.tooLarge": "Graph is too large to export at full quality",
+  "controls.exportPng.failed": "Failed to export graph",
+
   // Login
   "login.connecting": "Connecting...",
   "login.connect": "Connect",
@@ -279,6 +285,12 @@ const es: Record<TranslationKey, string> = {
   "filter.projects": "Proyectos",
   "filter.all": "Todos",
 
+  // Canvas controls
+  "controls.exportPng": "Exportar grafo como PNG",
+  "controls.exportPng.empty": "No hay containers para exportar",
+  "controls.exportPng.tooLarge": "El grafo es muy grande para exportar en alta calidad",
+  "controls.exportPng.failed": "Error al exportar el grafo",
+
   // Login
   "login.connecting": "Conectando...",
   "login.connect": "Conectar",

src/client/utils/exportPng.ts

@@ -0,0 +1,165 @@
+import { toPng } from "html-to-image";
+
+const PIXEL_RATIO = 3;
+const BACKGROUND = "#0f172a"; // slate-900 (matches dashboard)
+const DOT_COLOR = "rgba(55, 65, 81, 0.7)"; // slate-700 at 70% — matches the perceptual softness of the SVG pattern
+const DOT_GAP = 30;
+const DOT_SIZE = 2;
+// Hard cap to avoid browser canvas memory issues. 100M pixels ≈ 800 MB RAM.
+const MAX_PIXELS = 100_000_000;
+
+export interface ExportPngOptions {
+  pixelRatio?: number;
+  backgroundColor?: string;
+}
+
+export interface ExportPngResult {
+  dataUrl: string;
+  width: number;
+  height: number;
+}
+
+/**
+ * Captures the dashboard canvas (React Flow area) as a PNG data URL.
+ *
+ * The React Flow `<Background>` component renders dots as an SVG `<pattern>`,
+ * which html-to-image does not rasterize reliably across browsers. To get a
+ * deterministic output we:
+ *   1. Capture the React Flow area with transparent background (nodes/edges
+ *      only) and skip the buggy SVG pattern via `filter`.
+ *   2. Paint our own background + dot grid onto a canvas at the correct
+ *      pixel ratio.
+ *   3. Draw the captured layer on top.
+ *
+ * Overlay UI (Controls, MiniMap, EdgeLegend, anything with `data-no-export`)
+ * is excluded so the export is just the graph itself.
+ */
+export async function exportGraphAsPng(opts: ExportPngOptions = {}): Promise<ExportPngResult> {
+  const pixelRatio = opts.pixelRatio ?? PIXEL_RATIO;
+  const backgroundColor = opts.backgroundColor ?? BACKGROUND;
+
+  const target = document.querySelector(".react-flow") as HTMLElement | null;
+  if (!target) {
+    throw new Error("CANVAS_NOT_FOUND");
+  }
+
+  const rect = target.getBoundingClientRect();
+  const width = Math.ceil(rect.width);
+  const height = Math.ceil(rect.height);
+
+  if (width === 0 || height === 0) {
+    throw new Error("EMPTY_GRAPH");
+  }
+  if (width * height * pixelRatio * pixelRatio > MAX_PIXELS) {
+    throw new Error("GRAPH_TOO_LARGE");
+  }
+
+  // 1. Temporarily disable CSS effects that don't translate well to a
+  // rasterized PNG: Tailwind's `ring-*` (box-shadow halo around rounded
+  // corners shows as harsh edges without backdrop-blur underneath) and
+  // `backdrop-filter` (browsers don't capture it at all). Restored in
+  // the `finally` block.
+  const tempStyle = document.createElement("style");
+  tempStyle.dataset.exportPngOverride = "true";
+  tempStyle.textContent = `
+    /* Only target service (container) nodes — group headers stay transparent
+       so the group's outline / border remains visible at the top. */
+    .react-flow__node:not(.react-flow__node-group) > * {
+      --tw-ring-shadow: 0 0 #0000 !important;
+      backdrop-filter: none !important;
+      /* Solid dark fill so the dot grid doesn't bleed through node bodies.
+         State is still indicated by the border colors and the inner state dot. */
+      background-color: rgb(15 23 42 / 0.85) !important;
+    }
+  `;
+  document.head.appendChild(tempStyle);
+
+  let nodesDataUrl: string;
+  try {
+    // 2. Capture nodes/edges with transparent background.
+    nodesDataUrl = await toPng(target, {
+      width,
+      height,
+      pixelRatio,
+      backgroundColor: undefined,
+      filter: (node) => {
+        // node is typed as HTMLElement but at runtime can be any Element (incl. SVG).
+        // We rely on Element-level APIs which exist on both HTML and SVG.
+        const el = node as Element;
+        const cl = el.classList;
+        if (!cl) return true;
+        // Custom: anything explicitly marked
+        if ((node as HTMLElement).dataset?.noExport === "true") return false;
+        // React Flow overlays
+        if (cl.contains("react-flow__controls")) return false;
+        if (cl.contains("react-flow__minimap")) return false;
+        if (cl.contains("react-flow__attribution")) return false;
+        if (cl.contains("react-flow__panel")) return false;
+        // We re-render the dots manually below, skip React Flow's SVG pattern.
+        if (cl.contains("react-flow__background")) return false;
+        return true;
+      },
+    });
+  } finally {
+    document.head.removeChild(tempStyle);
+  }
+
+  // 2. Load the captured image so we can composite it onto a canvas.
+  const layer = await loadImage(nodesDataUrl);
+
+  // 3. Composite: solid bg + dot grid + captured layer.
+  const canvas = document.createElement("canvas");
+  canvas.width = width * pixelRatio;
+  canvas.height = height * pixelRatio;
+  const ctx = canvas.getContext("2d");
+  if (!ctx) {
+    throw new Error("CANVAS_CONTEXT_FAILED");
+  }
+
+  // Solid base
+  ctx.fillStyle = backgroundColor;
+  ctx.fillRect(0, 0, canvas.width, canvas.height);
+
+  // Dot grid (matches the React Flow <Background> config: gap 30, size 2)
+  ctx.fillStyle = DOT_COLOR;
+  const gap = DOT_GAP * pixelRatio;
+  const radius = (DOT_SIZE * pixelRatio) / 2;
+  for (let x = gap; x < canvas.width; x += gap) {
+    for (let y = gap; y < canvas.height; y += gap) {
+      ctx.beginPath();
+      ctx.arc(x, y, radius, 0, Math.PI * 2);
+      ctx.fill();
+    }
+  }
+
+  // Captured nodes/edges on top
+  ctx.drawImage(layer, 0, 0, canvas.width, canvas.height);
+
+  return { dataUrl: canvas.toDataURL("image/png"), width, height };
+}
+
+function loadImage(src: string): Promise<HTMLImageElement> {
+  return new Promise((resolve, reject) => {
+    const img = new Image();
+    img.onload = () => resolve(img);
+    img.onerror = (e) => reject(new Error(`Image load failed: ${e}`));
+    img.src = src;
+  });
+}
+
+/**
+ * Triggers a browser download of a data URL with a filename of the form
+ * `containerflow-<hostname>-<timestamp>.png`.
+ */
+export function downloadPng(dataUrl: string, hostname?: string): void {
+  const ts = new Date().toISOString().replace(/[:.]/g, "-").slice(0, 19);
+  const host = hostname?.replace(/[^a-z0-9-]/gi, "").toLowerCase() || "graph";
+  const filename = `containerflow-${host}-${ts}.png`;
+
+  const link = document.createElement("a");
+  link.href = dataUrl;
+  link.download = filename;
+  document.body.appendChild(link);
+  link.click();
+  document.body.removeChild(link);
+}