Video Rendering

┌─────────────────────────────────────────────────────────────────┐
│                    VIDEO SUBSCRIPTION FLOW                      │
├─────────────────────────────────────────────────────────────────┤
│  onSessionJoin       →  Subscribe to self video                 │
│  onUserVideoStatusChanged →  Subscribe to remote video (when ON)│
│  onUserLeave         →  Unsubscribe and cleanup                 │
└─────────────────────────────────────────────────────────────────┘

// WRONG - Video may not be ready yet!
void onUserJoin(IZoomVideoSDKUserHelper* helper,
                IVideoSDKVector<IZoomVideoSDKUser*>* userList) override {
    for (int i = 0; i < userList->GetCount(); i++) {
        IZoomVideoSDKUser* user = userList->GetItem(i);
        // This returns Error 2 (Internal_Error) - video not ready!
        user->GetVideoCanvas()->subscribeWithView(hwnd, aspect, resolution);
    }
}

// CORRECT - Wait for video status change
void onUserVideoStatusChanged(IZoomVideoSDKVideoHelper* helper,
                               IVideoSDKVector<IZoomVideoSDKUser*>* userList) override {
    IZoomVideoSDKUser* myself = g_sdk->getSessionInfo()->getMyself();
    
    for (int i = 0; i < userList->GetCount(); i++) {
        IZoomVideoSDKUser* user = userList->GetItem(i);
        
        // Skip self (handled separately)
        if (user == myself) continue;
        
        // Check if video is actually on
        ZoomVideoSDKVideoStatus status = user->GetVideoPipe()->getVideoStatus();
        if (status.isOn) {
            // NOW it's safe to subscribe
            SubscribeToUser(user);
        } else {
            // Video turned off - unsubscribe
            UnsubscribeFromUser(user);
        }
    }
}

#pragma once
#include <windows.h>
#include <map>
#include <vector>
#include "zoom_video_sdk_interface.h"

USING_ZOOM_VIDEO_SDK_NAMESPACE

class VideoCanvasManager {
public:
    VideoCanvasManager(HWND parentWindow, IZoomVideoSDK* sdk);
    ~VideoCanvasManager();
    
    // Subscribe to self video
    void SubscribeToSelf();
    
    // Subscribe/unsubscribe to remote user
    void SubscribeToUser(IZoomVideoSDKUser* user);
    void UnsubscribeFromUser(IZoomVideoSDKUser* user);
    
    // Cleanup
    void UnsubscribeAll();
    
    // Layout
    void UpdateLayout();
    
private:
    HWND CreateVideoWindow();
    void DestroyVideoWindow(HWND hwnd);
    
    IZoomVideoSDK* m_sdk;
    HWND m_parentWindow;
    
    // Self video
    HWND m_selfVideoWindow;
    IZoomVideoSDKCanvas* m_selfCanvas;
    
    // Remote users: user -> window mapping
    std::map<IZoomVideoSDKUser*, HWND> m_userWindows;
    std::map<IZoomVideoSDKUser*, IZoomVideoSDKCanvas*> m_userCanvases;
};

#include "VideoCanvasManager.h"
#include <iostream>

VideoCanvasManager::VideoCanvasManager(HWND parentWindow, IZoomVideoSDK* sdk)
    : m_parentWindow(parentWindow)
    , m_sdk(sdk)
    , m_selfVideoWindow(nullptr)
    , m_selfCanvas(nullptr) {
}

VideoCanvasManager::~VideoCanvasManager() {
    UnsubscribeAll();
}

class MyDelegate : public IZoomVideoSDKDelegate {
private:
    VideoCanvasManager* m_videoManager;
    
public:
    MyDelegate(HWND parentWindow, IZoomVideoSDK* sdk) {
        m_videoManager = new VideoCanvasManager(parentWindow, sdk);
    }
    
    ~MyDelegate() {
        delete m_videoManager;
    }
    
    void onSessionJoin() override {
        // Subscribe to self video
        m_videoManager->SubscribeToSelf();
    }
    
    void onUserVideoStatusChanged(IZoomVideoSDKVideoHelper* helper,
                                   IVideoSDKVector<IZoomVideoSDKUser*>* userList) override {
        IZoomVideoSDKUser* myself = g_sdk->getSessionInfo()->getMyself();
        
        for (int i = 0; i < userList->GetCount(); i++) {
            IZoomVideoSDKUser* user = userList->GetItem(i);
            if (user == myself) continue;
            
            ZoomVideoSDKVideoStatus status = user->GetVideoPipe()->getVideoStatus();
            if (status.isOn) {
                m_videoManager->SubscribeToUser(user);
            } else {
                m_videoManager->UnsubscribeFromUser(user);
            }
        }
    }
    
    void onUserLeave(IZoomVideoSDKUserHelper* helper,
                     IVideoSDKVector<IZoomVideoSDKUser*>* userList) override {
        for (int i = 0; i < userList->GetCount(); i++) {
            m_videoManager->UnsubscribeFromUser(userList->GetItem(i));
        }
    }
    
    void onSessionLeave() override {
        m_videoManager->UnsubscribeAll();
    }
    
    // ... other callbacks
};

void onVideoCanvasSubscribeFail(ZoomVideoSDKSubscribeFailReason reason,
                                 IZoomVideoSDKUser* user, void* handle) override {
    std::wcout << L"Subscribe failed for: " << user->getUserName() 
               << L" reason: " << reason << std::endl;
    
    switch (reason) {
        case ZoomVideoSDKSubscribeFailReason_HasSubscribe1080POr720P:
            std::cout << "Already have a 1080p/720p subscription" << std::endl;
            break;
        case ZoomVideoSDKSubscribeFailReason_HasSubscribeExceededLimit:
            std::cout << "Subscription limit exceeded" << std::endl;
            break;
        case ZoomVideoSDKSubscribeFailReason_TooFrequentCall:
            std::cout << "Calling too frequently - add Sleep(200)" << std::endl;
            break;
    }
}