เมื่อโหลดเว็บแอป แอปนั้นจะบันทึกการเรียกกลับด้วย Interactive Canvas API
หากการตอบกลับของ Canvas มีช่อง data ระบบจะส่งค่าออบเจ็กต์ของช่อง data ไปยังการเรียกกลับ onUpdate ที่ลงทะเบียนไว้ของเว็บแอป
ในตัวอย่างนี้ ตรรกะแบบบทสนทนาจะส่งการตอบกลับ Canvas พร้อมช่องข้อมูลที่มีตัวแปรที่มีค่า blue
หลังจากได้รับค่า data ของการตอบสนอง Canvas การเรียกกลับ onUpdate จะใช้ตรรกะที่กําหนดเองสําหรับเว็บแอปและทําการเปลี่ยนแปลงที่กําหนดได้ ในตัวอย่างนี้ โค้ดเรียกกลับ onUpdate จะอ่านค่าสีจาก data และเปลี่ยนหน้าจอเป็นสีน้ําเงิน
การดําเนินการในฝั่งไคลเอ็นต์และฝั่งเซิร์ฟเวอร์
เมื่อสร้างการดําเนินการของ Canvas แบบอินเทอร์แอกทีฟ คุณจะเลือกเส้นทางการใช้งานตามการดําเนินการได้ 2 แบบ ได้แก่ การดําเนินการตามเซิร์ฟเวอร์หรือการดําเนินการตามไคลเอ็นต์ การใช้เซิร์ฟเวอร์
เป็น API ที่ต้องใช้เว็บฮุคเป็นหลัก การดําเนินการตามไคลเอ็นต์ช่วยให้คุณใช้ API ฝั่งไคลเอ็นต์และ API ที่ต้องใช้เว็บฮุคสําหรับฟีเจอร์ที่ไม่ใช่ Canvas ได้ (เช่น การลิงก์บัญชี) หากจําเป็น
[null,null,["อัปเดตล่าสุด 2023-05-16 UTC"],[[["\u003cp\u003eInteractive Canvas is a framework by Google Assistant to build interactive, full-screen web apps for visual experiences within Conversational Actions.\u003c/p\u003e\n"],["\u003cp\u003eIt is currently supported on smart displays and Android mobile devices and is primarily used for gaming, storytelling, and educational experiences.\u003c/p\u003e\n"],["\u003cp\u003eInteractive Canvas Actions utilize a conversational interface paired with a web app, communicating using the Interactive Canvas API for dynamic updates.\u003c/p\u003e\n"],["\u003cp\u003eYou can implement your Action's logic using either server fulfillment (webhooks) or client fulfillment (client-side APIs).\u003c/p\u003e\n"],["\u003cp\u003eFor detailed guidance and a sample project, refer to the web apps documentation and the GitHub sample.\u003c/p\u003e\n"]]],[],null,["# Interactive Canvas\n\n**Figure 1.** An interactive game built using Interactive Canvas.\n\nInteractive Canvas is a framework built on Google Assistant that allows\ndevelopers to add visual, immersive experiences to Conversational Actions. This visual\nexperience is an interactive web app that Assistant sends as a response to the\nuser in conversation. Unlike [rich responses](/assistant/conversational/prompts-rich) that exist in-line in an\nAssistant conversation, the Interactive Canvas web app renders as a full-screen\nweb view.\n\nUse Interactive Canvas if you want to do any of the following in your Action:\n\n- Create full-screen visuals\n- Create custom animations and transitions\n- Do data visualization\n- Create custom layouts and GUIs\n\n| **Note:** At this time, Google is only approving Actions that use Interactive Canvas for gaming, storytelling, and educational experiences. Actions that use Interactive Canvas also take slightly longer for Google's review team to test and approve. Allow extra time in your release process to account for this.\n\nSupported devices\n-----------------\n\nInteractive Canvas is currently available on the following devices:\n\n- Smart displays\n- Android mobile devices\n\n| **Note:** For Canvas to work on Android mobile devices, your Android Google Search App (AGSA) must be version 9.86 or later.\n\nHow it works\n------------\n\nAn Action that uses Interactive Canvas consists of two main components:\n\n- **Conversational Action:** An Action that uses a conversational interface to fulfill user requests. You can use either [Actions Builder](/assistant/conversational/build#actions_builder) or the [Actions SDK](/assistant/conversational/build#actions_sdk) to build your conversation.\n- **Web app:** A front-end web app with customized visuals that your Action sends as a response to users during a conversation. You build the web app with web technologies like HTML, JavaScript, and CSS.\n\nUsers interacting with an Interactive Canvas Action have a back-and-forth\nconversation with Google Assistant to fulfill their goal. However, for\nInteractive Canvas, the bulk of this conversation occurs within the context of\nyour web app. When connecting your Conversational Action to your web app, you must include\nthe **Interactive Canvas API** in your web app code.\n\n- **Interactive Canvas library:** A JavaScript library that you include in the web app to enable communication between the web app and your Conversational Action using an API. For more information, see the [Interactive Canvas API documentation](/assistant/interactivecanvas/reference).\n\nIn addition to including the Interactive Canvas library, you must return the\n[`Canvas`](/assistant/conversational/reference/rest/v1/TopLevel/fulfill#canvas) response type in your conversation to open your web app on the\nuser's device. You can also use a `Canvas` response to update your web app based\non the user's input.\n\n- **`Canvas`:** A response that contains a URL of the web app and data to pass it. Actions Builder can automatically populate the `Canvas` response with the matched intent and current scene data to update the web app. Alternatively, you can send a `Canvas` response from a webhook using the [Node.js fulfillment library](https://actions-on-google.github.io/assistant-conversation-nodejs/3.0.0/classes/_conversation_prompt_canvas_.canvas.html). For more information, see [Canvas prompts](/assistant/interactivecanvas/prompts).\n\nTo illustrate how Interactive Canvas works, imagine a hypothetical Action\ncalled *Cool Colors* that changes the device screen color to a color the user\nspecifies. After the user invokes the Action, the following flow happens:\n\n1. The user says, *\"Turn the screen blue.\"* to the Assistant device.\n2. The Actions on Google platform routes the user's request to your conversational logic to match an intent.\n3. The platform matches the intent with the Action's scene, which triggers an event and sends a `Canvas` response to the device. The device loads a web app using a URL provided in the response (if it has not yet been loaded).\n4. When the web app loads, it registers callbacks with the Interactive Canvas API. If the Canvas response contains a `data` field, the object value of the `data` field is passed into the registered `onUpdate` callback of the web app. In this example, the conversational logic sends a `Canvas` response with a data field that includes a variable with the value of `blue`.\n5. Upon receiving the `data` value of the `Canvas` response, the `onUpdate` callback can execute custom logic for your web app and make the defined changes. In this example, the `onUpdate` callback reads the color from `data` and turns the screen blue.\n\nClient-side and server-side fulfillment\n---------------------------------------\n\n| **Warning:** Some client-side APIs listed in this documentation are in Developer Preview. You can test these APIs in the simulator, but do not deploy an Action that uses this feature to alpha, beta, or production channels. Actions deployed using these features will not function on end-user devices.\n\nWhen building an Interactive Canvas Action, you can choose between two fulfillment\nimplementation paths: server fulfillment or client fulfillment. With server\nfulfillment, you primarily use APIs that require a webhook. With client fulfillment,\nyou can use client-side APIs and, if needed, APIs that require a webhook for\nnon-Canvas features (such as account linking).\n\nIf you choose to build with [**server webhook fulfillment**](/assistant/interactivecanvas/prompts#enable_interactive_canvas) in\nthe project creation stage, you must deploy a webhook to handle the conversational\nlogic and client-side JavaScript to update the web app and manage communication\nbetween the two.\n\nIf you choose to build with [**client fulfillment**](/assistant/interactivecanvas/prompts#enable_interactive_canvas)\n(currently available in Developer Preview), you can use new client-side APIs to\nbuild your Action's logic exclusively in the web app, which simplifies the\ndevelopment experience, reduces latency between conversational turns, and\nenables you to use on-device capabilities. If needed, you can also switch to\nserver-side logic from the client.\n\nFor more information about client-side capabilities, see\n[Build with client-side fulfillment](/assistant/interactivecanvas/fulfillment#build_with_client-side_fulfillment).\n\nNext steps\n----------\n\nTo learn how to build a web app for Interactive Canvas, see [Web apps](/assistant/interactivecanvas/web-apps).\n\nTo see the code for a complete Interactive Canvas Action, see the\n[sample on GitHub](https://github.com/actions-on-google/actions-builder-canvas-nodejs)."]]
