snapshot of https://github.com/shadcn-ui/ui.git (main, 2026-09-15; blobs > 131072B omitted)

apps/v4/app/(app)/(create)/components/preview.tsx

@@ -0,0 +1,197 @@
+"use client"
+
+import * as React from "react"
+
+import { CMD_K_FORWARD_TYPE } from "@/app/(app)/(create)/components/action-menu"
+import { CreateDevtools } from "@/app/(app)/(create)/components/create-devtools"
+import {
+  REDO_FORWARD_TYPE,
+  UNDO_FORWARD_TYPE,
+} from "@/app/(app)/(create)/components/history-buttons"
+import { DARK_MODE_FORWARD_TYPE } from "@/app/(app)/(create)/components/mode-switcher"
+import { usePreviewOverrideValue } from "@/app/(app)/(create)/components/preview-override"
+import { PreviewSwitcher } from "@/app/(app)/(create)/components/preview-switcher"
+import { RANDOMIZE_FORWARD_TYPE } from "@/app/(app)/(create)/components/random-button"
+import { sendToIframe } from "@/app/(app)/(create)/hooks/use-iframe-sync"
+import { OPEN_PRESET_FORWARD_TYPE } from "@/app/(app)/(create)/hooks/use-open-preset"
+import { RESET_FORWARD_TYPE } from "@/app/(app)/(create)/hooks/use-reset"
+import {
+  serializeDesignSystemSearchParams,
+  useDesignSystemSearchParams,
+} from "@/app/(app)/(create)/lib/search-params"
+
+// Hoisted — avoids recreating on every message event. (js-hoist-regexp)
+const MAC_REGEX = /Mac|iPhone|iPad|iPod/
+
+function isSameParams(
+  a: ReturnType<typeof useDesignSystemSearchParams>[0] | null,
+  b: ReturnType<typeof useDesignSystemSearchParams>[0]
+) {
+  if (!a) {
+    return false
+  }
+
+  return Object.keys(b).every(
+    (key) => a[key as keyof typeof b] === b[key as keyof typeof b]
+  )
+}
+
+export function Preview() {
+  const [params] = useDesignSystemSearchParams()
+  const override = usePreviewOverrideValue()
+  const iframeRef = React.useRef<HTMLIFrameElement>(null)
+  const lastSentParamsRef = React.useRef<typeof params | null>(null)
+
+  // Hover previews overlay the committed params without touching the URL —
+  // clearing the override re-sends the committed params, reverting the preview.
+  const mergedParams = React.useMemo(
+    () => (override ? { ...params, ...override } : params),
+    [params, override]
+  )
+
+  React.useEffect(() => {
+    const iframe = iframeRef.current
+    if (!iframe) {
+      return
+    }
+
+    const sendParams = () => {
+      sendToIframe(iframe, "design-system-params", mergedParams)
+      lastSentParamsRef.current = mergedParams
+    }
+
+    // Skip content-identical re-sends (e.g. an override matching the committed
+    // params) — each message triggers a full param sync in the iframe.
+    if (
+      iframe.contentWindow &&
+      !isSameParams(lastSentParamsRef.current, mergedParams)
+    ) {
+      sendParams()
+    }
+
+    iframe.addEventListener("load", sendParams)
+    return () => {
+      iframe.removeEventListener("load", sendParams)
+    }
+  }, [mergedParams])
+
+  React.useEffect(() => {
+    const handleMessage = (event: MessageEvent) => {
+      const iframeWindow = iframeRef.current?.contentWindow
+      if (
+        !iframeWindow ||
+        event.origin !== window.location.origin ||
+        event.source !== iframeWindow ||
+        !event.data ||
+        typeof event.data !== "object"
+      ) {
+        return
+      }
+
+      const type = event.data.type
+      if (type === CMD_K_FORWARD_TYPE) {
+        const isMac = MAC_REGEX.test(navigator.userAgent)
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: event.data.key || "k",
+            metaKey: isMac,
+            ctrlKey: !isMac,
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      } else if (type === RANDOMIZE_FORWARD_TYPE) {
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: event.data.key || "r",
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      } else if (type === OPEN_PRESET_FORWARD_TYPE) {
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: event.data.key || "o",
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      } else if (type === UNDO_FORWARD_TYPE) {
+        const isMac = MAC_REGEX.test(navigator.userAgent)
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: "z",
+            metaKey: isMac,
+            ctrlKey: !isMac,
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      } else if (type === REDO_FORWARD_TYPE) {
+        const isMac = MAC_REGEX.test(navigator.userAgent)
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: "z",
+            shiftKey: true,
+            metaKey: isMac,
+            ctrlKey: !isMac,
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      } else if (type === RESET_FORWARD_TYPE) {
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: "R",
+            shiftKey: true,
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      } else if (type === DARK_MODE_FORWARD_TYPE) {
+        document.dispatchEvent(
+          new KeyboardEvent("keydown", {
+            key: event.data.key || "d",
+            bubbles: true,
+            cancelable: true,
+          })
+        )
+      }
+    }
+
+    window.addEventListener("message", handleMessage)
+    return () => {
+      window.removeEventListener("message", handleMessage)
+    }
+  }, [])
+
+  const iframeSrc = React.useMemo(() => {
+    // The iframe src needs to include the serialized design system params
+    // for the initial load, but not be reactive to them as it would cause
+    // full-iframe reloads on every param change (flashes & loss of state).
+    // Further updates of the search params will be sent to the iframe
+    // via a postMessage channel, for it to sync its own history onto the host's.
+    return serializeDesignSystemSearchParams(
+      `/preview/${params.base}/${params.item}`,
+      params
+    )
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [params.base, params.item])
+
+  return (
+    <div className="relative flex flex-1 flex-col justify-center overflow-hidden rounded-2xl ring ring-foreground/10 md:ring-muted dark:ring-foreground/10">
+      <div className="relative z-0 mx-auto flex w-full flex-1 flex-col overflow-hidden">
+        <div className="absolute inset-0 bg-muted dark:bg-muted/30" />
+        <iframe
+          key={params.base + params.item}
+          ref={iframeRef}
+          src={iframeSrc}
+          className="z-10 size-full flex-1"
+          title="Preview"
+        />
+      </div>
+      <CreateDevtools />
+      <PreviewSwitcher />
+    </div>
+  )
+}