[feat] add OpenGL NV12 underlay rendering for Slint on Windows

src/gui/application/gui_application.cpp

@@ -35,6 +35,7 @@
 #include <GL/gl.h>
 
 #include "platform/tray/win_tray.h"
+#include "platform/windows_opengl_video_renderer.h"
 #elif defined(__APPLE__)
 #include "platform/metal_video_renderer.h"
 #include "platform/tray/mac_tray.h"
@@ -1043,7 +1044,10 @@ void GuiApplication::InitializeModules() {
   if (modules_inited_) {
     return;
   }
-#if defined(__APPLE__)
+#if defined(_WIN32)
+  windows_opengl_video_renderer_ =
+      std::make_unique<WindowsOpenGlVideoRenderer>();
+#elif defined(__APPLE__)
   // Metal setup can log device, shader, or pipeline failures. Initialize it
   // here, after Run() has selected the application's log directory, rather
   // than from GuiRuntime's constructor before InitializeLogger().
@@ -2277,6 +2281,11 @@ void GuiApplication::SyncStreamWindow() {
   }
   if (!has_sessions) {
     SetStreamKeyboardFocus(false);
+#if defined(_WIN32)
+    if (windows_opengl_video_renderer_) {
+      windows_opengl_video_renderer_->SetSelectedStream({});
+    }
+#endif
 #if defined(__APPLE__)
     void* stream_view = (*ui_->stream)->window().appkit_view();
     SetStreamWindowFullscreen(false);
@@ -2564,6 +2573,44 @@ void GuiApplication::SyncStreamVideoFrame() {
   }
 #endif
 
+#if defined(_WIN32)
+  if (windows_opengl_video_renderer_ &&
+      windows_opengl_video_renderer_->IsReady()) {
+    windows_opengl_video_renderer_->SetSelectedStream(props->remote_id_);
+    SubmitCachedFrameToOpenGl(props);
+    if (!(*ui_->stream)->get_native_video_enabled()) {
+      (*ui_->stream)->set_native_video_enabled(true);
+    }
+
+    int width = 0;
+    int height = 0;
+    uint64_t sequence = 0;
+    {
+      std::lock_guard lock(props->video_frame_mutex_);
+      width = props->video_width_;
+      height = props->video_height_;
+      sequence = props->video_frame_sequence_;
+    }
+    const bool has_frame = width > 0 && height > 0 && sequence > 0;
+    (*ui_->stream)->set_has_frame(has_frame);
+    if (has_frame) {
+      (*ui_->stream)->set_receiving_text("");
+      (*ui_->stream)
+          ->set_stats_resolution(UiText(std::to_string(width) + "x" +
+                                        std::to_string(height)));
+      if (ui_->displayed_frame_sequence[props->remote_id_] != sequence) {
+        ui_->displayed_frame_sequence[props->remote_id_] = sequence;
+        ++props->frame_count_;
+      }
+    }
+    (*ui_->stream)->window().request_redraw();
+    return;
+  }
+  if ((*ui_->stream)->get_native_video_enabled()) {
+    (*ui_->stream)->set_native_video_enabled(false);
+  }
+#endif
+
   std::shared_ptr<std::vector<unsigned char>> frame;
   int width = 0;
   int height = 0;
@@ -2736,9 +2783,36 @@ void GuiApplication::ConfigureStreamVideoRenderer() {
           glBindTexture(GL_TEXTURE_2D,
                         static_cast<GLuint>(previous_texture));
           ui_->video_gl_texture = texture;
+#if defined(_WIN32)
+          if (windows_opengl_video_renderer_ &&
+              windows_opengl_video_renderer_->Setup()) {
+            windows_opengl_video_renderer_->SetSelectedStream(
+                focused_remote_id_);
+            video_frame_dirty_.store(true, std::memory_order_release);
+          }
+#endif
           return;
         }
 
+#if defined(_WIN32)
+        if (state == slint::RenderingState::BeforeRendering &&
+            windows_opengl_video_renderer_ &&
+            windows_opengl_video_renderer_->IsReady() && ui_->stream &&
+            (*ui_->stream)->get_native_video_enabled()) {
+          const auto window_size = (*ui_->stream)->window().size();
+          const float scale_factor =
+              std::max(1.0f, (*ui_->stream)->window().scale_factor());
+          const int top_inset =
+              !fullscreen_button_pressed_ && ui_->tab_ids.size() > 1
+                  ? static_cast<int>(std::lround(30.0f * scale_factor))
+                  : 0;
+          windows_opengl_video_renderer_->RenderLatest(
+              focused_remote_id_, static_cast<int>(window_size.width),
+              static_cast<int>(window_size.height), top_inset);
+          return;
+        }
+#endif
+
         if (state == slint::RenderingState::BeforeRendering &&
             ui_->video_gl_texture != 0 && ui_->video_gl_pending_dirty &&
             !ui_->video_gl_pending_frame.empty()) {
@@ -2769,6 +2843,11 @@ void GuiApplication::ConfigureStreamVideoRenderer() {
         }
 
         if (state == slint::RenderingState::RenderingTeardown) {
+#if defined(_WIN32)
+          if (windows_opengl_video_renderer_) {
+            windows_opengl_video_renderer_->Teardown();
+          }
+#endif
           if (ui_->video_gl_texture != 0) {
             const GLuint texture = ui_->video_gl_texture;
             glDeleteTextures(1, &texture);
@@ -2783,10 +2862,50 @@ void GuiApplication::ConfigureStreamVideoRenderer() {
       });
   if (error.has_value()) {
     LOG_WARN("Slint OpenGL video renderer unavailable, using pixel buffers");
+#if defined(_WIN32)
+  } else if (windows_opengl_video_renderer_) {
+    windows_opengl_video_renderer_->SetSelectedStream(focused_remote_id_);
+#endif
   }
 #endif
 }
 
+#if defined(_WIN32)
+void GuiApplication::SubmitCachedFrameToOpenGl(
+    const std::shared_ptr<RemoteSession>& session) {
+  if (!session || !windows_opengl_video_renderer_ ||
+      !windows_opengl_video_renderer_->IsReady() ||
+      session->connection_status_.load() != ConnectionStatus::Connected) {
+    return;
+  }
+
+  std::shared_ptr<std::vector<unsigned char>> cached_frame;
+  int cached_width = 0;
+  int cached_height = 0;
+  {
+    std::lock_guard lock(session->video_frame_mutex_);
+    if (session->front_frame_ && !session->front_frame_->empty()) {
+      cached_frame = session->front_frame_;
+      cached_width = session->video_width_;
+      cached_height = session->video_height_;
+    } else if (session->thumbnail_frame_ &&
+               !session->thumbnail_frame_->empty()) {
+      cached_frame = session->thumbnail_frame_;
+      cached_width = session->thumbnail_width_;
+      cached_height = session->thumbnail_height_;
+    }
+  }
+
+  if (cached_frame && cached_width > 0 && cached_height > 0 &&
+      windows_opengl_video_renderer_->SubmitCachedNv12(
+          session->remote_id_, cached_frame->data(), cached_frame->size(),
+          cached_width, cached_height) ==
+          WindowsOpenGlVideoRenderer::SubmitResult::submitted) {
+    video_frame_dirty_.store(true, std::memory_order_release);
+  }
+}
+#endif
+
 #if defined(__APPLE__)
 void GuiApplication::SubmitCachedFrameToMetal(
     const std::shared_ptr<RemoteSession>& session) {
@@ -3124,7 +3243,7 @@ void GuiApplication::SelectStreamTab(int index) {
     return;
   }
   const std::string selected_remote_id = ui_->tab_ids[index];
-#if defined(__APPLE__)
+#if defined(__APPLE__) || defined(_WIN32)
   const bool selection_changed = focused_remote_id_ != selected_remote_id;
   bool renderer_selection_changed = false;
 #endif
@@ -3134,7 +3253,18 @@ void GuiApplication::SelectStreamTab(int index) {
   }
   focused_remote_id_ = selected_remote_id;
   controlled_remote_id_ = selected_remote_id;
-#if defined(__APPLE__)
+#if defined(_WIN32)
+  if (windows_opengl_video_renderer_) {
+    renderer_selection_changed =
+        windows_opengl_video_renderer_->SetSelectedStream(selected_remote_id);
+  }
+  if (renderer_selection_changed) {
+    video_frame_dirty_.store(true, std::memory_order_release);
+  }
+  if (selection_changed && ui_->stream) {
+    (*ui_->stream)->set_has_frame(false);
+  }
+#elif defined(__APPLE__)
   if (mac_metal_video_renderer_) {
     renderer_selection_changed =
         mac_metal_video_renderer_->SetSelectedStream(selected_remote_id);
@@ -3163,7 +3293,11 @@ void GuiApplication::SelectStreamTab(int index) {
         selected_session->connection_status_.load() ==
             ConnectionStatus::Connected;
   }
-#if defined(__APPLE__)
+#if defined(_WIN32)
+  if (renderer_selection_changed) {
+    SubmitCachedFrameToOpenGl(selected_session);
+  }
+#elif defined(__APPLE__)
   if (renderer_selection_changed) {
     SubmitCachedFrameToMetal(selected_session);
   }
@@ -3215,7 +3349,12 @@ void GuiApplication::CloseStreamTab(const std::string& remote_id) {
   if (focused_remote_id_ == remote_id) {
     focused_remote_id_.clear();
     controlled_remote_id_.clear();
-#if defined(__APPLE__)
+#if defined(_WIN32)
+    if (windows_opengl_video_renderer_ &&
+        windows_opengl_video_renderer_->SetSelectedStream({})) {
+      video_frame_dirty_.store(true, std::memory_order_release);
+    }
+#elif defined(__APPLE__)
     if (mac_metal_video_renderer_ &&
         mac_metal_video_renderer_->SetSelectedStream({})) {
       video_frame_dirty_.store(true, std::memory_order_release);
@@ -3414,6 +3553,11 @@ void GuiApplication::Cleanup() {
   WaitForThumbnailSaveTasks();
   devices_.DestroyAudioOutput();
   if (ui_->stream) {
+#if defined(_WIN32)
+    if (windows_opengl_video_renderer_) {
+      windows_opengl_video_renderer_->SetSelectedStream({});
+    }
+#endif
 #if defined(__APPLE__)
     void* stream_view = (*ui_->stream)->window().appkit_view();
     SetStreamWindowFullscreen(false);

src/gui/application/gui_application.h

@@ -41,6 +41,10 @@ private:
   void SyncStreamVideoFrame();
   void ScheduleNextVideoFrame();
   void ConfigureStreamVideoRenderer();
+#if defined(_WIN32)
+  void SubmitCachedFrameToOpenGl(
+      const std::shared_ptr<RemoteSession>& session);
+#endif
 #if defined(__APPLE__)
   void SubmitCachedFrameToMetal(
       const std::shared_ptr<RemoteSession>& session);

src/gui/platform/windows_opengl_video_renderer.cpp

@@ -0,0 +1,812 @@
+#include "platform/windows_opengl_video_renderer.h"
+
+#if !defined(_WIN32)
+#error "WindowsOpenGlVideoRenderer is only available on Windows"
+#endif
+
+#include <windows.h>
+
+#include <GL/gl.h>
+#include <GL/glext.h>
+
+#include <algorithm>
+#include <array>
+#include <atomic>
+#include <cstring>
+#include <limits>
+#include <mutex>
+#include <string>
+#include <utility>
+
+#include "rd_log.h"
+
+namespace crossdesk {
+namespace {
+
+constexpr size_t kFrameSlotCount = 3;
+
+enum class SlotUse {
+  available,
+  pending,
+  uploading,
+};
+
+struct FrameSlot {
+  std::vector<unsigned char> bytes;
+  int width = 0;
+  int height = 0;
+  std::string remote_id;
+  uint64_t sequence = 0;
+  SlotUse use = SlotUse::available;
+  bool valid = false;
+};
+
+struct SharedFrameState {
+  mutable std::mutex mutex;
+  std::array<FrameSlot, kFrameSlotCount> slots;
+  std::string selected_stream;
+  uint64_t next_sequence = 1;
+};
+
+template <typename T> bool LoadOpenGlFunction(T *function, const char *name) {
+  PROC address = wglGetProcAddress(name);
+  if (address == nullptr || address == reinterpret_cast<PROC>(1) ||
+      address == reinterpret_cast<PROC>(2) ||
+      address == reinterpret_cast<PROC>(3) ||
+      address == reinterpret_cast<PROC>(-1)) {
+    HMODULE module = GetModuleHandleW(L"opengl32.dll");
+    address = module ? GetProcAddress(module, name) : nullptr;
+  }
+  *function = reinterpret_cast<T>(address);
+  return *function != nullptr;
+}
+
+struct OpenGlFunctions {
+  PFNGLACTIVETEXTUREPROC active_texture = nullptr;
+  PFNGLATTACHSHADERPROC attach_shader = nullptr;
+  PFNGLBINDBUFFERPROC bind_buffer = nullptr;
+  PFNGLBUFFERDATAPROC buffer_data = nullptr;
+  PFNGLCOMPILESHADERPROC compile_shader = nullptr;
+  PFNGLCREATEPROGRAMPROC create_program = nullptr;
+  PFNGLCREATESHADERPROC create_shader = nullptr;
+  PFNGLDELETEBUFFERSPROC delete_buffers = nullptr;
+  PFNGLDELETEPROGRAMPROC delete_program = nullptr;
+  PFNGLDELETESHADERPROC delete_shader = nullptr;
+  PFNGLDISABLEVERTEXATTRIBARRAYPROC disable_vertex_attrib_array = nullptr;
+  PFNGLENABLEVERTEXATTRIBARRAYPROC enable_vertex_attrib_array = nullptr;
+  PFNGLGENBUFFERSPROC gen_buffers = nullptr;
+  PFNGLGETATTRIBLOCATIONPROC get_attrib_location = nullptr;
+  PFNGLGETPROGRAMINFOLOGPROC get_program_info_log = nullptr;
+  PFNGLGETPROGRAMIVPROC get_program_iv = nullptr;
+  PFNGLGETSHADERINFOLOGPROC get_shader_info_log = nullptr;
+  PFNGLGETSHADERIVPROC get_shader_iv = nullptr;
+  PFNGLGETUNIFORMLOCATIONPROC get_uniform_location = nullptr;
+  PFNGLGETVERTEXATTRIBIVPROC get_vertex_attrib_iv = nullptr;
+  PFNGLGETVERTEXATTRIBPOINTERVPROC get_vertex_attrib_pointer_v = nullptr;
+  PFNGLLINKPROGRAMPROC link_program = nullptr;
+  PFNGLSHADERSOURCEPROC shader_source = nullptr;
+  PFNGLUNIFORM1IPROC uniform_1i = nullptr;
+  PFNGLUSEPROGRAMPROC use_program = nullptr;
+  PFNGLVERTEXATTRIBPOINTERPROC vertex_attrib_pointer = nullptr;
+
+  bool Load() {
+    return LoadOpenGlFunction(&active_texture, "glActiveTexture") &&
+           LoadOpenGlFunction(&attach_shader, "glAttachShader") &&
+           LoadOpenGlFunction(&bind_buffer, "glBindBuffer") &&
+           LoadOpenGlFunction(&buffer_data, "glBufferData") &&
+           LoadOpenGlFunction(&compile_shader, "glCompileShader") &&
+           LoadOpenGlFunction(&create_program, "glCreateProgram") &&
+           LoadOpenGlFunction(&create_shader, "glCreateShader") &&
+           LoadOpenGlFunction(&delete_buffers, "glDeleteBuffers") &&
+           LoadOpenGlFunction(&delete_program, "glDeleteProgram") &&
+           LoadOpenGlFunction(&delete_shader, "glDeleteShader") &&
+           LoadOpenGlFunction(&disable_vertex_attrib_array,
+                              "glDisableVertexAttribArray") &&
+           LoadOpenGlFunction(&enable_vertex_attrib_array,
+                              "glEnableVertexAttribArray") &&
+           LoadOpenGlFunction(&gen_buffers, "glGenBuffers") &&
+           LoadOpenGlFunction(&get_attrib_location, "glGetAttribLocation") &&
+           LoadOpenGlFunction(&get_program_info_log, "glGetProgramInfoLog") &&
+           LoadOpenGlFunction(&get_program_iv, "glGetProgramiv") &&
+           LoadOpenGlFunction(&get_shader_info_log, "glGetShaderInfoLog") &&
+           LoadOpenGlFunction(&get_shader_iv, "glGetShaderiv") &&
+           LoadOpenGlFunction(&get_uniform_location, "glGetUniformLocation") &&
+           LoadOpenGlFunction(&get_vertex_attrib_iv, "glGetVertexAttribiv") &&
+           LoadOpenGlFunction(&get_vertex_attrib_pointer_v,
+                              "glGetVertexAttribPointerv") &&
+           LoadOpenGlFunction(&link_program, "glLinkProgram") &&
+           LoadOpenGlFunction(&shader_source, "glShaderSource") &&
+           LoadOpenGlFunction(&uniform_1i, "glUniform1i") &&
+           LoadOpenGlFunction(&use_program, "glUseProgram") &&
+           LoadOpenGlFunction(&vertex_attrib_pointer, "glVertexAttribPointer");
+  }
+};
+
+GLuint CompileShader(const OpenGlFunctions &gl, GLenum type,
+                     const char *source) {
+  const GLuint shader = gl.create_shader(type);
+  if (shader == 0) {
+    return 0;
+  }
+  gl.shader_source(shader, 1, &source, nullptr);
+  gl.compile_shader(shader);
+
+  GLint compiled = GL_FALSE;
+  gl.get_shader_iv(shader, GL_COMPILE_STATUS, &compiled);
+  if (compiled == GL_TRUE) {
+    return shader;
+  }
+
+  GLint log_length = 0;
+  gl.get_shader_iv(shader, GL_INFO_LOG_LENGTH, &log_length);
+  std::string log(static_cast<size_t>(std::max(log_length, 1)), '\0');
+  GLsizei written = 0;
+  gl.get_shader_info_log(shader, static_cast<GLsizei>(log.size()), &written,
+                         log.data());
+  if (written >= 0 && static_cast<size_t>(written) < log.size()) {
+    log.resize(static_cast<size_t>(written));
+  }
+  LOG_ERROR("OpenGL NV12 {} shader compilation failed: {}",
+            type == GL_VERTEX_SHADER ? "vertex" : "fragment", log);
+  gl.delete_shader(shader);
+  return 0;
+}
+
+bool IsEnabled(GLenum capability) { return glIsEnabled(capability) == GL_TRUE; }
+
+void RestoreCapability(GLenum capability, bool enabled) {
+  if (enabled) {
+    glEnable(capability);
+  } else {
+    glDisable(capability);
+  }
+}
+
+struct VertexAttribState {
+  GLint enabled = GL_FALSE;
+  GLint size = 4;
+  GLint stride = 0;
+  GLint type = GL_FLOAT;
+  GLint normalized = GL_FALSE;
+  GLint buffer = 0;
+  void *pointer = nullptr;
+};
+
+VertexAttribState CaptureVertexAttrib(const OpenGlFunctions &gl, GLuint index) {
+  VertexAttribState state;
+  gl.get_vertex_attrib_iv(index, GL_VERTEX_ATTRIB_ARRAY_ENABLED,
+                          &state.enabled);
+  gl.get_vertex_attrib_iv(index, GL_VERTEX_ATTRIB_ARRAY_SIZE, &state.size);
+  gl.get_vertex_attrib_iv(index, GL_VERTEX_ATTRIB_ARRAY_STRIDE, &state.stride);
+  gl.get_vertex_attrib_iv(index, GL_VERTEX_ATTRIB_ARRAY_TYPE, &state.type);
+  gl.get_vertex_attrib_iv(index, GL_VERTEX_ATTRIB_ARRAY_NORMALIZED,
+                          &state.normalized);
+  gl.get_vertex_attrib_iv(index, GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING,
+                          &state.buffer);
+  gl.get_vertex_attrib_pointer_v(index, GL_VERTEX_ATTRIB_ARRAY_POINTER,
+                                 &state.pointer);
+  return state;
+}
+
+void RestoreVertexAttrib(const OpenGlFunctions &gl, GLuint index,
+                         const VertexAttribState &state) {
+  if (state.buffer != 0 || state.pointer != nullptr) {
+    gl.bind_buffer(GL_ARRAY_BUFFER, static_cast<GLuint>(state.buffer));
+    gl.vertex_attrib_pointer(index, state.size, static_cast<GLenum>(state.type),
+                             static_cast<GLboolean>(state.normalized),
+                             state.stride, state.pointer);
+  }
+  if (state.enabled == GL_TRUE) {
+    gl.enable_vertex_attrib_array(index);
+  } else {
+    gl.disable_vertex_attrib_array(index);
+  }
+}
+
+} // namespace
+
+struct WindowsOpenGlVideoRenderer::Impl {
+  OpenGlFunctions gl;
+  std::shared_ptr<SharedFrameState> frames =
+      std::make_shared<SharedFrameState>();
+  std::atomic<bool> ready{false};
+  GLuint program = 0;
+  GLuint vertex_buffer = 0;
+  GLuint y_texture = 0;
+  GLuint uv_texture = 0;
+  GLint position_location = -1;
+  GLint texcoord_location = -1;
+  GLint y_texture_location = -1;
+  GLint uv_texture_location = -1;
+  int texture_width = 0;
+  int texture_height = 0;
+  std::string uploaded_stream;
+  uint64_t uploaded_sequence = 0;
+
+  void ResetGlHandles() {
+    program = 0;
+    vertex_buffer = 0;
+    y_texture = 0;
+    uv_texture = 0;
+    position_location = -1;
+    texcoord_location = -1;
+    y_texture_location = -1;
+    uv_texture_location = -1;
+    texture_width = 0;
+    texture_height = 0;
+    uploaded_stream.clear();
+    uploaded_sequence = 0;
+  }
+};
+
+WindowsOpenGlVideoRenderer::WindowsOpenGlVideoRenderer()
+    : impl_(std::make_unique<Impl>()) {}
+
+WindowsOpenGlVideoRenderer::~WindowsOpenGlVideoRenderer() = default;
+
+bool WindowsOpenGlVideoRenderer::Setup() {
+  if (IsReady()) {
+    return true;
+  }
+  impl_->ready.store(false, std::memory_order_release);
+  impl_->ResetGlHandles();
+  if (!impl_->gl.Load()) {
+    LOG_WARN("OpenGL NV12 underlay unavailable: required functions missing");
+    return false;
+  }
+
+  static constexpr char kGlesVertexShader[] = R"glsl(
+#version 100
+attribute vec2 position;
+attribute vec2 texcoord;
+varying vec2 video_texcoord;
+void main() {
+  video_texcoord = texcoord;
+  gl_Position = vec4(position, 0.0, 1.0);
+}
+)glsl";
+  static constexpr char kGlesFragmentShader[] = R"glsl(
+#version 100
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+uniform sampler2D y_texture;
+uniform sampler2D uv_texture;
+varying vec2 video_texcoord;
+void main() {
+  float y = 1.16438356 *
+            (texture2D(y_texture, video_texcoord).r - 16.0 / 255.0);
+  vec2 uv = texture2D(uv_texture, video_texcoord).ra - vec2(0.5, 0.5);
+  vec3 rgb = vec3(y + 1.59602678 * uv.y,
+                  y - 0.39176229 * uv.x - 0.81296764 * uv.y,
+                  y + 2.01723214 * uv.x);
+  gl_FragColor = vec4(clamp(rgb, 0.0, 1.0), 1.0);
+}
+)glsl";
+  static constexpr char kDesktopVertexShader[] = R"glsl(
+#version 110
+attribute vec2 position;
+attribute vec2 texcoord;
+varying vec2 video_texcoord;
+void main() {
+  video_texcoord = texcoord;
+  gl_Position = vec4(position, 0.0, 1.0);
+}
+)glsl";
+  static constexpr char kDesktopFragmentShader[] = R"glsl(
+#version 110
+uniform sampler2D y_texture;
+uniform sampler2D uv_texture;
+varying vec2 video_texcoord;
+void main() {
+  float y = 1.16438356 *
+            (texture2D(y_texture, video_texcoord).r - 16.0 / 255.0);
+  vec2 uv = texture2D(uv_texture, video_texcoord).ra - vec2(0.5, 0.5);
+  vec3 rgb = vec3(y + 1.59602678 * uv.y,
+                  y - 0.39176229 * uv.x - 0.81296764 * uv.y,
+                  y + 2.01723214 * uv.x);
+  gl_FragColor = vec4(clamp(rgb, 0.0, 1.0), 1.0);
+}
+)glsl";
+
+  const auto *version = reinterpret_cast<const char *>(glGetString(GL_VERSION));
+  const bool is_gles = version && std::strstr(version, "OpenGL ES") != nullptr;
+  const char *vertex_source =
+      is_gles ? kGlesVertexShader : kDesktopVertexShader;
+  const char *fragment_source =
+      is_gles ? kGlesFragmentShader : kDesktopFragmentShader;
+
+  const GLuint vertex_shader =
+      CompileShader(impl_->gl, GL_VERTEX_SHADER, vertex_source);
+  const GLuint fragment_shader =
+      CompileShader(impl_->gl, GL_FRAGMENT_SHADER, fragment_source);
+  if (vertex_shader == 0 || fragment_shader == 0) {
+    if (vertex_shader != 0)
+      impl_->gl.delete_shader(vertex_shader);
+    if (fragment_shader != 0)
+      impl_->gl.delete_shader(fragment_shader);
+    return false;
+  }
+
+  impl_->program = impl_->gl.create_program();
+  impl_->gl.attach_shader(impl_->program, vertex_shader);
+  impl_->gl.attach_shader(impl_->program, fragment_shader);
+  impl_->gl.link_program(impl_->program);
+  impl_->gl.delete_shader(vertex_shader);
+  impl_->gl.delete_shader(fragment_shader);
+
+  GLint linked = GL_FALSE;
+  impl_->gl.get_program_iv(impl_->program, GL_LINK_STATUS, &linked);
+  if (linked != GL_TRUE) {
+    GLint log_length = 0;
+    impl_->gl.get_program_iv(impl_->program, GL_INFO_LOG_LENGTH, &log_length);
+    std::string log(static_cast<size_t>(std::max(log_length, 1)), '\0');
+    GLsizei written = 0;
+    impl_->gl.get_program_info_log(
+        impl_->program, static_cast<GLsizei>(log.size()), &written, log.data());
+    if (written >= 0 && static_cast<size_t>(written) < log.size()) {
+      log.resize(static_cast<size_t>(written));
+    }
+    LOG_ERROR("OpenGL NV12 program link failed: {}", log);
+    impl_->gl.delete_program(impl_->program);
+    impl_->ResetGlHandles();
+    return false;
+  }
+
+  impl_->position_location =
+      impl_->gl.get_attrib_location(impl_->program, "position");
+  impl_->texcoord_location =
+      impl_->gl.get_attrib_location(impl_->program, "texcoord");
+  impl_->y_texture_location =
+      impl_->gl.get_uniform_location(impl_->program, "y_texture");
+  impl_->uv_texture_location =
+      impl_->gl.get_uniform_location(impl_->program, "uv_texture");
+  if (impl_->position_location < 0 || impl_->texcoord_location < 0 ||
+      impl_->y_texture_location < 0 || impl_->uv_texture_location < 0) {
+    LOG_ERROR("OpenGL NV12 program is missing required shader bindings");
+    impl_->gl.delete_program(impl_->program);
+    impl_->ResetGlHandles();
+    return false;
+  }
+
+  static constexpr GLfloat kVertices[] = {
+      -1.0f, 1.0f,  0.0f, 0.0f, // top-left
+      -1.0f, -1.0f, 0.0f, 1.0f, // bottom-left
+      1.0f,  1.0f,  1.0f, 0.0f, // top-right
+      1.0f,  -1.0f, 1.0f, 1.0f, // bottom-right
+  };
+  GLint previous_array_buffer = 0;
+  glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &previous_array_buffer);
+  impl_->gl.gen_buffers(1, &impl_->vertex_buffer);
+  impl_->gl.bind_buffer(GL_ARRAY_BUFFER, impl_->vertex_buffer);
+  impl_->gl.buffer_data(GL_ARRAY_BUFFER, sizeof(kVertices), kVertices,
+                        GL_STATIC_DRAW);
+  impl_->gl.bind_buffer(GL_ARRAY_BUFFER,
+                        static_cast<GLuint>(previous_array_buffer));
+
+  GLint previous_active_texture = GL_TEXTURE0;
+  glGetIntegerv(GL_ACTIVE_TEXTURE, &previous_active_texture);
+  impl_->gl.active_texture(GL_TEXTURE0);
+  GLint previous_texture_0 = 0;
+  glGetIntegerv(GL_TEXTURE_BINDING_2D, &previous_texture_0);
+  impl_->gl.active_texture(GL_TEXTURE1);
+  GLint previous_texture_1 = 0;
+  glGetIntegerv(GL_TEXTURE_BINDING_2D, &previous_texture_1);
+  while (glGetError() != GL_NO_ERROR) {
+  }
+  glGenTextures(1, &impl_->y_texture);
+  glGenTextures(1, &impl_->uv_texture);
+  for (const auto [unit, texture] :
+       {std::pair{GL_TEXTURE0, impl_->y_texture},
+        std::pair{GL_TEXTURE1, impl_->uv_texture}}) {
+    impl_->gl.active_texture(unit);
+    glBindTexture(GL_TEXTURE_2D, texture);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  }
+  impl_->gl.active_texture(GL_TEXTURE0);
+  glBindTexture(GL_TEXTURE_2D, static_cast<GLuint>(previous_texture_0));
+  impl_->gl.active_texture(GL_TEXTURE1);
+  glBindTexture(GL_TEXTURE_2D, static_cast<GLuint>(previous_texture_1));
+  impl_->gl.active_texture(static_cast<GLenum>(previous_active_texture));
+
+  const GLenum setup_error = glGetError();
+  if (impl_->program == 0 || impl_->vertex_buffer == 0 ||
+      impl_->y_texture == 0 || impl_->uv_texture == 0 ||
+      setup_error != GL_NO_ERROR) {
+    LOG_ERROR("OpenGL NV12 resource setup failed, error={}", setup_error);
+    Teardown();
+    return false;
+  }
+
+  impl_->ready.store(true, std::memory_order_release);
+  LOG_INFO("OpenGL NV12 underlay initialized ({})",
+           version ? version : "unknown OpenGL version");
+  return true;
+}
+
+void WindowsOpenGlVideoRenderer::Teardown() {
+  impl_->ready.store(false, std::memory_order_release);
+  if (impl_->y_texture != 0)
+    glDeleteTextures(1, &impl_->y_texture);
+  if (impl_->uv_texture != 0)
+    glDeleteTextures(1, &impl_->uv_texture);
+  if (impl_->vertex_buffer != 0 && impl_->gl.delete_buffers) {
+    impl_->gl.delete_buffers(1, &impl_->vertex_buffer);
+  }
+  if (impl_->program != 0 && impl_->gl.delete_program) {
+    impl_->gl.delete_program(impl_->program);
+  }
+  impl_->ResetGlHandles();
+}
+
+bool WindowsOpenGlVideoRenderer::IsReady() const {
+  return impl_->ready.load(std::memory_order_acquire);
+}
+
+bool WindowsOpenGlVideoRenderer::SetSelectedStream(std::string remote_id) {
+  std::lock_guard lock(impl_->frames->mutex);
+  if (impl_->frames->selected_stream == remote_id) {
+    return false;
+  }
+  impl_->frames->selected_stream = std::move(remote_id);
+  for (auto &slot : impl_->frames->slots) {
+    if (slot.use == SlotUse::pending &&
+        slot.remote_id != impl_->frames->selected_stream) {
+      slot.use = SlotUse::available;
+    }
+  }
+  return true;
+}
+
+void WindowsOpenGlVideoRenderer::DiscardStream(std::string_view remote_id) {
+  std::lock_guard lock(impl_->frames->mutex);
+  for (auto &slot : impl_->frames->slots) {
+    if (slot.remote_id == remote_id && slot.use != SlotUse::uploading) {
+      slot.valid = false;
+      slot.use = SlotUse::available;
+      slot.remote_id.clear();
+    }
+  }
+  if (impl_->frames->selected_stream == remote_id) {
+    impl_->frames->selected_stream.clear();
+  }
+}
+
+WindowsOpenGlVideoRenderer::SubmitResult
+WindowsOpenGlVideoRenderer::SubmitNv12(std::string_view remote_id,
+                                       const uint8_t *data, size_t size,
+                                       int width, int height) {
+  return SubmitNv12Internal(remote_id, data, size, width, height, true);
+}
+
+WindowsOpenGlVideoRenderer::SubmitResult
+WindowsOpenGlVideoRenderer::SubmitCachedNv12(std::string_view remote_id,
+                                             const uint8_t *data, size_t size,
+                                             int width, int height) {
+  return SubmitNv12Internal(remote_id, data, size, width, height, false);
+}
+
+WindowsOpenGlVideoRenderer::SubmitResult
+WindowsOpenGlVideoRenderer::SubmitNv12Internal(std::string_view remote_id,
+                                               const uint8_t *data, size_t size,
+                                               int width, int height,
+                                               bool replace_pending) {
+  if (!IsReady()) {
+    return SubmitResult::failed;
+  }
+  if (data == nullptr || width <= 0 || height <= 0 || (width & 1) != 0 ||
+      (height & 1) != 0) {
+    return SubmitResult::failed;
+  }
+  const size_t y_size = static_cast<size_t>(width) * height;
+  const size_t required_size = y_size + y_size / 2;
+  if (size < required_size) {
+    return SubmitResult::failed;
+  }
+
+  auto &frames = *impl_->frames;
+  std::lock_guard lock(frames.mutex);
+  if (frames.selected_stream != remote_id) {
+    return SubmitResult::not_selected;
+  }
+
+  FrameSlot *target = nullptr;
+  if (replace_pending) {
+    for (auto &slot : frames.slots) {
+      if (slot.use == SlotUse::pending) {
+        target = &slot;
+        break;
+      }
+    }
+  } else {
+    for (const auto &slot : frames.slots) {
+      if (slot.valid && slot.remote_id == remote_id &&
+          (slot.use == SlotUse::pending || slot.use == SlotUse::uploading)) {
+        return SubmitResult::dropped;
+      }
+    }
+  }
+  if (target == nullptr) {
+    uint64_t oldest_sequence = std::numeric_limits<uint64_t>::max();
+    for (auto &slot : frames.slots) {
+      if (slot.use != SlotUse::available) {
+        continue;
+      }
+      if (!slot.valid) {
+        target = &slot;
+        break;
+      }
+      if (slot.sequence < oldest_sequence) {
+        oldest_sequence = slot.sequence;
+        target = &slot;
+      }
+    }
+  }
+  if (target == nullptr) {
+    return SubmitResult::dropped;
+  }
+
+  target->bytes.resize(required_size);
+  std::memcpy(target->bytes.data(), data, required_size);
+  target->width = width;
+  target->height = height;
+  target->remote_id.assign(remote_id);
+  target->sequence = frames.next_sequence++;
+  target->use = SlotUse::pending;
+  target->valid = true;
+  return SubmitResult::submitted;
+}
+
+WindowsOpenGlVideoRenderer::RenderOutcome
+WindowsOpenGlVideoRenderer::RenderLatest(std::string_view remote_id,
+                                         int target_width, int target_height,
+                                         int top_inset_pixels) {
+  if (!IsReady() || target_width <= 0 || target_height <= 0) {
+    return {RenderResult::failed};
+  }
+
+  size_t slot_index = kFrameSlotCount;
+  uint64_t sequence = 0;
+  int source_width = 0;
+  int source_height = 0;
+  const unsigned char *frame_data = nullptr;
+  {
+    std::lock_guard lock(impl_->frames->mutex);
+    for (size_t index = 0; index < impl_->frames->slots.size(); ++index) {
+      const auto &slot = impl_->frames->slots[index];
+      if (slot.valid && slot.use == SlotUse::pending &&
+          slot.remote_id == remote_id &&
+          (slot_index == kFrameSlotCount || slot.sequence > sequence)) {
+        slot_index = index;
+        sequence = slot.sequence;
+      }
+    }
+    if (slot_index != kFrameSlotCount) {
+      auto &selected = impl_->frames->slots[slot_index];
+      selected.use = SlotUse::uploading;
+      source_width = selected.width;
+      source_height = selected.height;
+      frame_data = selected.bytes.data();
+      for (size_t index = 0; index < impl_->frames->slots.size(); ++index) {
+        auto &slot = impl_->frames->slots[index];
+        if (index != slot_index && slot.use == SlotUse::pending &&
+            slot.remote_id == remote_id) {
+          slot.use = SlotUse::available;
+        }
+      }
+    }
+  }
+
+  GLint previous_program = 0;
+  GLint previous_active_texture = GL_TEXTURE0;
+  GLint previous_array_buffer = 0;
+  GLint previous_unpack_alignment = 4;
+  GLint previous_viewport[4] = {};
+  GLint previous_scissor_box[4] = {};
+  GLfloat previous_clear_color[4] = {};
+  GLboolean previous_color_mask[4] = {};
+  glGetIntegerv(GL_CURRENT_PROGRAM, &previous_program);
+  glGetIntegerv(GL_ACTIVE_TEXTURE, &previous_active_texture);
+  glGetIntegerv(GL_ARRAY_BUFFER_BINDING, &previous_array_buffer);
+  glGetIntegerv(GL_UNPACK_ALIGNMENT, &previous_unpack_alignment);
+  glGetIntegerv(GL_VIEWPORT, previous_viewport);
+  glGetIntegerv(GL_SCISSOR_BOX, previous_scissor_box);
+  glGetFloatv(GL_COLOR_CLEAR_VALUE, previous_clear_color);
+  glGetBooleanv(GL_COLOR_WRITEMASK, previous_color_mask);
+  const bool blend_enabled = IsEnabled(GL_BLEND);
+  const bool cull_enabled = IsEnabled(GL_CULL_FACE);
+  const bool depth_enabled = IsEnabled(GL_DEPTH_TEST);
+  const bool scissor_enabled = IsEnabled(GL_SCISSOR_TEST);
+  const bool stencil_enabled = IsEnabled(GL_STENCIL_TEST);
+
+  impl_->gl.active_texture(GL_TEXTURE0);
+  GLint previous_texture_0 = 0;
+  glGetIntegerv(GL_TEXTURE_BINDING_2D, &previous_texture_0);
+  impl_->gl.active_texture(GL_TEXTURE1);
+  GLint previous_texture_1 = 0;
+  glGetIntegerv(GL_TEXTURE_BINDING_2D, &previous_texture_1);
+
+  const auto position_state = CaptureVertexAttrib(
+      impl_->gl, static_cast<GLuint>(impl_->position_location));
+  const auto texcoord_state = CaptureVertexAttrib(
+      impl_->gl, static_cast<GLuint>(impl_->texcoord_location));
+
+  glDisable(GL_BLEND);
+  glDisable(GL_CULL_FACE);
+  glDisable(GL_DEPTH_TEST);
+  glDisable(GL_SCISSOR_TEST);
+  glDisable(GL_STENCIL_TEST);
+  glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
+  glViewport(0, 0, target_width, target_height);
+  glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  bool upload_succeeded = true;
+  if (slot_index != kFrameSlotCount) {
+    while (glGetError() != GL_NO_ERROR) {
+    }
+    const size_t y_size = static_cast<size_t>(source_width) * source_height;
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    impl_->gl.active_texture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, impl_->y_texture);
+    impl_->gl.active_texture(GL_TEXTURE1);
+    glBindTexture(GL_TEXTURE_2D, impl_->uv_texture);
+    if (impl_->texture_width != source_width ||
+        impl_->texture_height != source_height) {
+      impl_->gl.active_texture(GL_TEXTURE0);
+      glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, source_width, source_height,
+                   0, GL_LUMINANCE, GL_UNSIGNED_BYTE, frame_data);
+      impl_->gl.active_texture(GL_TEXTURE1);
+      glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE_ALPHA, source_width / 2,
+                   source_height / 2, 0, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE,
+                   frame_data + y_size);
+    } else {
+      impl_->gl.active_texture(GL_TEXTURE0);
+      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, source_width, source_height,
+                      GL_LUMINANCE, GL_UNSIGNED_BYTE, frame_data);
+      impl_->gl.active_texture(GL_TEXTURE1);
+      glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, source_width / 2,
+                      source_height / 2, GL_LUMINANCE_ALPHA, GL_UNSIGNED_BYTE,
+                      frame_data + y_size);
+    }
+    const GLenum upload_error = glGetError();
+    upload_succeeded = upload_error == GL_NO_ERROR;
+    if (upload_succeeded) {
+      impl_->texture_width = source_width;
+      impl_->texture_height = source_height;
+      impl_->uploaded_stream.assign(remote_id);
+      impl_->uploaded_sequence = sequence;
+    } else {
+      LOG_WARN("OpenGL NV12 texture upload failed, error={}", upload_error);
+    }
+  }
+
+  {
+    std::lock_guard lock(impl_->frames->mutex);
+    if (slot_index != kFrameSlotCount) {
+      auto &slot = impl_->frames->slots[slot_index];
+      if (slot.sequence == sequence && slot.use == SlotUse::uploading) {
+        slot.use = SlotUse::available;
+      }
+    }
+  }
+
+  RenderOutcome outcome{RenderResult::empty};
+  if (upload_succeeded && impl_->uploaded_stream == remote_id &&
+      impl_->texture_width > 0 && impl_->texture_height > 0) {
+    source_width = impl_->texture_width;
+    source_height = impl_->texture_height;
+    sequence = impl_->uploaded_sequence;
+    const int video_height = std::max(
+        0, target_height - std::clamp(top_inset_pixels, 0, target_height));
+    if (video_height > 0) {
+      const double source_aspect =
+          static_cast<double>(source_width) / source_height;
+      const double target_aspect =
+          static_cast<double>(target_width) / video_height;
+      int viewport_width = target_width;
+      int viewport_height = video_height;
+      int viewport_x = 0;
+      int viewport_y = 0;
+      if (source_aspect > target_aspect) {
+        viewport_height =
+            std::max(1, static_cast<int>(target_width / source_aspect + 0.5));
+        viewport_y = (video_height - viewport_height) / 2;
+      } else {
+        viewport_width =
+            std::max(1, static_cast<int>(video_height * source_aspect + 0.5));
+        viewport_x = (target_width - viewport_width) / 2;
+      }
+
+      glViewport(viewport_x, viewport_y, viewport_width, viewport_height);
+      impl_->gl.use_program(impl_->program);
+      impl_->gl.active_texture(GL_TEXTURE0);
+      glBindTexture(GL_TEXTURE_2D, impl_->y_texture);
+      impl_->gl.uniform_1i(impl_->y_texture_location, 0);
+      impl_->gl.active_texture(GL_TEXTURE1);
+      glBindTexture(GL_TEXTURE_2D, impl_->uv_texture);
+      impl_->gl.uniform_1i(impl_->uv_texture_location, 1);
+      impl_->gl.bind_buffer(GL_ARRAY_BUFFER, impl_->vertex_buffer);
+      impl_->gl.vertex_attrib_pointer(
+          static_cast<GLuint>(impl_->position_location), 2, GL_FLOAT, GL_FALSE,
+          4 * static_cast<GLsizei>(sizeof(GLfloat)), nullptr);
+      impl_->gl.vertex_attrib_pointer(
+          static_cast<GLuint>(impl_->texcoord_location), 2, GL_FLOAT, GL_FALSE,
+          4 * static_cast<GLsizei>(sizeof(GLfloat)),
+          reinterpret_cast<const void *>(2 * sizeof(GLfloat)));
+      impl_->gl.enable_vertex_attrib_array(
+          static_cast<GLuint>(impl_->position_location));
+      impl_->gl.enable_vertex_attrib_array(
+          static_cast<GLuint>(impl_->texcoord_location));
+      glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+      outcome = {glGetError() == GL_NO_ERROR ? RenderResult::rendered
+                                             : RenderResult::failed,
+                 source_width, source_height, sequence};
+    }
+  }
+
+  RestoreVertexAttrib(impl_->gl, static_cast<GLuint>(impl_->position_location),
+                      position_state);
+  RestoreVertexAttrib(impl_->gl, static_cast<GLuint>(impl_->texcoord_location),
+                      texcoord_state);
+  impl_->gl.bind_buffer(GL_ARRAY_BUFFER,
+                        static_cast<GLuint>(previous_array_buffer));
+  impl_->gl.active_texture(GL_TEXTURE0);
+  glBindTexture(GL_TEXTURE_2D, static_cast<GLuint>(previous_texture_0));
+  impl_->gl.active_texture(GL_TEXTURE1);
+  glBindTexture(GL_TEXTURE_2D, static_cast<GLuint>(previous_texture_1));
+  impl_->gl.active_texture(static_cast<GLenum>(previous_active_texture));
+  impl_->gl.use_program(static_cast<GLuint>(previous_program));
+  glPixelStorei(GL_UNPACK_ALIGNMENT, previous_unpack_alignment);
+  glViewport(previous_viewport[0], previous_viewport[1], previous_viewport[2],
+             previous_viewport[3]);
+  glScissor(previous_scissor_box[0], previous_scissor_box[1],
+            previous_scissor_box[2], previous_scissor_box[3]);
+  glClearColor(previous_clear_color[0], previous_clear_color[1],
+               previous_clear_color[2], previous_clear_color[3]);
+  glColorMask(previous_color_mask[0], previous_color_mask[1],
+              previous_color_mask[2], previous_color_mask[3]);
+  RestoreCapability(GL_BLEND, blend_enabled);
+  RestoreCapability(GL_CULL_FACE, cull_enabled);
+  RestoreCapability(GL_DEPTH_TEST, depth_enabled);
+  RestoreCapability(GL_SCISSOR_TEST, scissor_enabled);
+  RestoreCapability(GL_STENCIL_TEST, stencil_enabled);
+  const GLenum restore_error = glGetError();
+  if (restore_error != GL_NO_ERROR) {
+    LOG_WARN("OpenGL NV12 state restoration failed, error={}", restore_error);
+    if (outcome.result == RenderResult::rendered) {
+      outcome.result = RenderResult::failed;
+    }
+  }
+  return outcome;
+}
+
+bool WindowsOpenGlVideoRenderer::CopyLatestNv12(
+    std::string_view remote_id, std::vector<unsigned char> *output, int *width,
+    int *height) const {
+  if (!output || !width || !height) {
+    return false;
+  }
+  std::lock_guard lock(impl_->frames->mutex);
+  const FrameSlot *newest = nullptr;
+  for (const auto &slot : impl_->frames->slots) {
+    if (slot.valid && slot.remote_id == remote_id &&
+        (!newest || slot.sequence > newest->sequence)) {
+      newest = &slot;
+    }
+  }
+  if (!newest || newest->bytes.empty()) {
+    return false;
+  }
+  *output = newest->bytes;
+  *width = newest->width;
+  *height = newest->height;
+  return true;
+}
+
+} // namespace crossdesk

src/gui/platform/windows_opengl_video_renderer.h

@@ -0,0 +1,86 @@
+#ifndef CROSSDESK_GUI_PLATFORM_WINDOWS_OPENGL_VIDEO_RENDERER_H_
+#define CROSSDESK_GUI_PLATFORM_WINDOWS_OPENGL_VIDEO_RENDERER_H_
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace crossdesk {
+
+// Windows NV12 underlay for Slint's FemtoVG OpenGL renderer. MiniRTC submits
+// tightly packed CPU NV12 frames from its decode callback thread. The Slint UI
+// thread uploads the newest frame as Y and UV textures and performs color
+// conversion and scaling in a fragment shader before Slint draws its overlay.
+class WindowsOpenGlVideoRenderer {
+public:
+  enum class SubmitResult {
+    submitted,
+    not_selected,
+    dropped,
+    failed,
+  };
+
+  enum class RenderResult {
+    rendered,
+    idle,
+    empty,
+    failed,
+  };
+
+  struct RenderOutcome {
+    RenderResult result = RenderResult::failed;
+    int width = 0;
+    int height = 0;
+    uint64_t sequence = 0;
+  };
+
+  WindowsOpenGlVideoRenderer();
+  ~WindowsOpenGlVideoRenderer();
+
+  WindowsOpenGlVideoRenderer(const WindowsOpenGlVideoRenderer &) = delete;
+  WindowsOpenGlVideoRenderer &
+  operator=(const WindowsOpenGlVideoRenderer &) = delete;
+
+  // These methods must run while Slint's OpenGL context is current, from the
+  // RenderingSetup and RenderingTeardown notifier states respectively.
+  bool Setup();
+  void Teardown();
+  bool IsReady() const;
+
+  // Only the selected stream is queued for upload. Frames for other tabs are
+  // retained by GuiRuntime at a throttled rate for thumbnail/tab restoration.
+  bool SetSelectedStream(std::string remote_id);
+  void DiscardStream(std::string_view remote_id);
+
+  // Thread-safe; called from MiniRTC's decode callback thread.
+  SubmitResult SubmitNv12(std::string_view remote_id, const uint8_t *data,
+                          size_t size, int width, int height);
+  SubmitResult SubmitCachedNv12(std::string_view remote_id, const uint8_t *data,
+                                size_t size, int width, int height);
+
+  // Draws below Slint while its OpenGL context is current. target dimensions
+  // and top_inset_pixels are physical pixels in the window client area.
+  RenderOutcome RenderLatest(std::string_view remote_id, int target_width,
+                             int target_height, int top_inset_pixels);
+
+  // Used during disconnect cleanup so thumbnail generation does not require a
+  // second per-frame CPU copy during normal playback.
+  bool CopyLatestNv12(std::string_view remote_id,
+                      std::vector<unsigned char> *output, int *width,
+                      int *height) const;
+
+private:
+  SubmitResult SubmitNv12Internal(std::string_view remote_id,
+                                  const uint8_t *data, size_t size, int width,
+                                  int height, bool replace_pending);
+
+  struct Impl;
+  std::unique_ptr<Impl> impl_;
+};
+
+} // namespace crossdesk
+
+#endif // CROSSDESK_GUI_PLATFORM_WINDOWS_OPENGL_VIDEO_RENDERER_H_

src/gui/runtime/connection_runtime.cpp

@@ -11,6 +11,9 @@
 #include "display_stream_id.h"
 #include "localization.h"
 #include "platform.h"
+#if defined(_WIN32)
+#include "platform/windows_opengl_video_renderer.h"
+#endif
 #ifdef __APPLE__
 #include "platform/metal_video_renderer.h"
 #endif
@@ -226,7 +229,7 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
     frame_snapshot = props->front_frame_;
     video_width = props->video_width_;
     video_height = props->video_height_;
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
     if ((!frame_snapshot || frame_snapshot->empty()) &&
         props->thumbnail_frame_ && !props->thumbnail_frame_->empty()) {
       frame_snapshot = props->thumbnail_frame_;
@@ -235,15 +238,18 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
     }
 #endif
   }
-#ifdef __APPLE__
-  if ((!frame_snapshot || frame_snapshot->empty()) &&
-      mac_metal_video_renderer_) {
-    auto metal_snapshot =
-        std::make_shared<std::vector<unsigned char>>();
-    if (mac_metal_video_renderer_->CopyLatestNv12(
-            props->remote_id_, metal_snapshot.get(), &video_width,
-            &video_height)) {
-      frame_snapshot = std::move(metal_snapshot);
+#if defined(__APPLE__) || defined(_WIN32)
+#if defined(_WIN32)
+  auto* native_renderer = windows_opengl_video_renderer_.get();
+#else
+  auto* native_renderer = mac_metal_video_renderer_.get();
+#endif
+  if ((!frame_snapshot || frame_snapshot->empty()) && native_renderer) {
+    auto native_snapshot = std::make_shared<std::vector<unsigned char>>();
+    if (native_renderer->CopyLatestNv12(props->remote_id_,
+                                        native_snapshot.get(), &video_width,
+                                        &video_height)) {
+      frame_snapshot = std::move(native_snapshot);
     }
   }
 #endif
@@ -270,9 +276,9 @@ void GuiRuntime::CloseRemoteSession(std::shared_ptr<RemoteSession> props) {
     }
   }
 
-#ifdef __APPLE__
-  if (mac_metal_video_renderer_) {
-    mac_metal_video_renderer_->DiscardStream(props->remote_id_);
+#if defined(__APPLE__) || defined(_WIN32)
+  if (native_renderer) {
+    native_renderer->DiscardStream(props->remote_id_);
     video_frame_dirty_.store(true, std::memory_order_release);
   }
 #endif
@@ -337,7 +343,7 @@ void GuiRuntime::ResetRemoteSessionResources(
     std::lock_guard<std::mutex> lock(props->video_frame_mutex_);
     props->front_frame_.reset();
     props->back_frame_.reset();
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
     props->thumbnail_frame_.reset();
     props->thumbnail_width_ = 0;
     props->thumbnail_height_ = 0;

src/gui/runtime/gui_runtime.cpp

@@ -12,6 +12,9 @@
 
 #include "display_stream_id.h"
 #include "localization.h"
+#if defined(_WIN32)
+#include "platform/windows_opengl_video_renderer.h"
+#endif
 #ifdef __APPLE__
 #include "platform/metal_video_renderer.h"
 #endif

src/gui/runtime/gui_runtime.h

@@ -15,6 +15,9 @@
 
 namespace crossdesk {
 
+#if defined(_WIN32)
+class WindowsOpenGlVideoRenderer;
+#endif
 #ifdef __APPLE__
 class MacMetalVideoRenderer;
 #endif
@@ -87,6 +90,9 @@ class GuiRuntime : protected gui_detail::GuiState {
   KeyboardController keyboard_;
   PeerEventHandler peer_events_;
   std::atomic<bool> video_frame_dirty_{false};
+#if defined(_WIN32)
+  std::unique_ptr<WindowsOpenGlVideoRenderer> windows_opengl_video_renderer_;
+#endif
 #ifdef __APPLE__
   std::unique_ptr<MacMetalVideoRenderer> mac_metal_video_renderer_;
 #endif

src/gui/runtime/peer_event_handler.cpp

@@ -16,6 +16,9 @@
 #include "file_transfer.h"
 #include "localization.h"
 #include "platform.h"
+#if defined(_WIN32)
+#include "platform/windows_opengl_video_renderer.h"
+#endif
 #ifdef __APPLE__
 #include "platform/metal_video_renderer.h"
 #endif
@@ -316,22 +319,29 @@ void PeerEventHandler::OnConnectionStatus(ConnectionStatus status,
         props->enable_mouse_control_ = false;
         runtime->ResetRemoteServiceStatus(*props);
 
-#ifdef __APPLE__
-        std::shared_ptr<std::vector<unsigned char>> metal_snapshot;
-        int metal_snapshot_width = 0;
-        int metal_snapshot_height = 0;
-        bool needs_metal_snapshot = false;
+#if defined(__APPLE__) || defined(_WIN32)
+        std::shared_ptr<std::vector<unsigned char>> native_snapshot;
+        int native_snapshot_width = 0;
+        int native_snapshot_height = 0;
+        bool needs_native_snapshot = false;
         {
           std::lock_guard<std::mutex> lock(props->video_frame_mutex_);
-          needs_metal_snapshot = !props->thumbnail_frame_ ||
-                                 props->thumbnail_frame_->empty();
+          needs_native_snapshot = !props->thumbnail_frame_ ||
+                                  props->thumbnail_frame_->empty();
         }
-        if (needs_metal_snapshot && runtime->mac_metal_video_renderer_) {
+        if (needs_native_snapshot) {
+#if defined(_WIN32)
+          auto* native_renderer =
+              runtime->windows_opengl_video_renderer_.get();
+#else
+          auto* native_renderer = runtime->mac_metal_video_renderer_.get();
+#endif
           auto snapshot = std::make_shared<std::vector<unsigned char>>();
-          if (runtime->mac_metal_video_renderer_->CopyLatestNv12(
-                  remote_id, snapshot.get(), &metal_snapshot_width,
-                  &metal_snapshot_height)) {
-            metal_snapshot = std::move(snapshot);
+          if (native_renderer && native_renderer->CopyLatestNv12(
+                                     remote_id, snapshot.get(),
+                                     &native_snapshot_width,
+                                     &native_snapshot_height)) {
+            native_snapshot = std::move(snapshot);
           }
         }
 #endif
@@ -339,12 +349,12 @@ void PeerEventHandler::OnConnectionStatus(ConnectionStatus status,
           std::lock_guard<std::mutex> lock(props->video_frame_mutex_);
           props->front_frame_.reset();
           props->back_frame_.reset();
-#ifdef __APPLE__
-          if (metal_snapshot &&
+#if defined(__APPLE__) || defined(_WIN32)
+          if (native_snapshot &&
               (!props->thumbnail_frame_ || props->thumbnail_frame_->empty())) {
-            props->thumbnail_frame_ = std::move(metal_snapshot);
-            props->thumbnail_width_ = metal_snapshot_width;
-            props->thumbnail_height_ = metal_snapshot_height;
+            props->thumbnail_frame_ = std::move(native_snapshot);
+            props->thumbnail_width_ = native_snapshot_width;
+            props->thumbnail_height_ = native_snapshot_height;
           }
 #endif
           props->video_width_ = 0;
@@ -353,9 +363,14 @@ void PeerEventHandler::OnConnectionStatus(ConnectionStatus status,
           props->render_rect_dirty_ = true;
           props->stream_cleanup_pending_ = true;
         }
-#ifdef __APPLE__
-        if (runtime->mac_metal_video_renderer_) {
-          runtime->mac_metal_video_renderer_->DiscardStream(remote_id);
+#if defined(__APPLE__) || defined(_WIN32)
+#if defined(_WIN32)
+        auto* native_renderer = runtime->windows_opengl_video_renderer_.get();
+#else
+        auto* native_renderer = runtime->mac_metal_video_renderer_.get();
+#endif
+        if (native_renderer) {
+          native_renderer->DiscardStream(remote_id);
           runtime->video_frame_dirty_.store(true,
                                             std::memory_order_release);
         }

src/gui/runtime/peer_media_callbacks.cpp

@@ -7,14 +7,18 @@
 #include <vector>
 
 #include "runtime/gui_runtime.h"
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
 #include <chrono>
 
+#if defined(_WIN32)
+#include "platform/windows_opengl_video_renderer.h"
+#else
 #include "platform/metal_video_renderer.h"
 #endif
+#endif
 
 namespace crossdesk {
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
 namespace {
 
 constexpr auto kBackgroundSnapshotInterval = std::chrono::seconds(1);
@@ -41,17 +45,24 @@ void PeerEventHandler::OnReceiveVideoBuffer(
       runtime->remote_sessions_.find(remote_id)->second.get();
 
   if (props->connection_established_) {
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
     bool background_snapshot_only = false;
-    if (runtime->mac_metal_video_renderer_ &&
-        runtime->mac_metal_video_renderer_->IsReady() &&
-        runtime->mac_metal_video_renderer_->IsAttached()) {
-      const auto submit_result =
-          runtime->mac_metal_video_renderer_->SubmitNv12(
-              remote_id,
-              reinterpret_cast<const uint8_t*>(video_frame->data),
-              video_frame->size, video_frame->width, video_frame->height);
-      if (submit_result == MacMetalVideoRenderer::SubmitResult::submitted) {
+#if defined(_WIN32)
+    auto* native_renderer = runtime->windows_opengl_video_renderer_.get();
+    using NativeVideoRenderer = WindowsOpenGlVideoRenderer;
+#else
+    auto* native_renderer = runtime->mac_metal_video_renderer_.get();
+    using NativeVideoRenderer = MacMetalVideoRenderer;
+#endif
+    if (native_renderer && native_renderer->IsReady()
+#if defined(__APPLE__)
+        && native_renderer->IsAttached()
+#endif
+    ) {
+      const auto submit_result = native_renderer->SubmitNv12(
+          remote_id, reinterpret_cast<const uint8_t*>(video_frame->data),
+          video_frame->size, video_frame->width, video_frame->height);
+      if (submit_result == NativeVideoRenderer::SubmitResult::submitted) {
         std::lock_guard<std::mutex> lock(props->video_frame_mutex_);
         const bool size_changed =
             (props->video_width_ != video_frame->width) ||
@@ -63,7 +74,7 @@ void PeerEventHandler::OnReceiveVideoBuffer(
         props->video_height_ = video_frame->height;
         props->video_size_ = video_frame->size;
         // Once the native renderer owns the current stream, do not leave an
-        // older CPU frame ahead of the Metal close snapshot.
+        // older CPU frame ahead of the renderer's close snapshot.
         props->front_frame_.reset();
         props->back_frame_.reset();
         props->thumbnail_frame_.reset();
@@ -75,21 +86,22 @@ void PeerEventHandler::OnReceiveVideoBuffer(
         runtime->video_frame_dirty_.store(true, std::memory_order_release);
         return;
       }
-      if (submit_result == MacMetalVideoRenderer::SubmitResult::dropped ||
-          submit_result == MacMetalVideoRenderer::SubmitResult::failed) {
-        // Keep presenting the last Metal frame. A later decoded frame can
+      if (submit_result == NativeVideoRenderer::SubmitResult::dropped ||
+          submit_result == NativeVideoRenderer::SubmitResult::failed) {
+        // Keep presenting the last native frame. A later decoded frame can
         // reuse the renderer without changing ownership mid-window.
         props->streaming_ = true;
         return;
       }
-      if (submit_result == MacMetalVideoRenderer::SubmitResult::not_selected) {
+      if (submit_result ==
+          NativeVideoRenderer::SubmitResult::not_selected) {
         background_snapshot_only = true;
       }
     }
 #endif
     {
       std::lock_guard<std::mutex> lock(props->video_frame_mutex_);
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
       const auto now = std::chrono::steady_clock::now();
       if (background_snapshot_only && props->thumbnail_frame_ &&
           !props->thumbnail_frame_->empty() &&
@@ -125,7 +137,7 @@ void PeerEventHandler::OnReceiveVideoBuffer(
       props->video_size_ = video_frame->size;
 
       props->front_frame_.swap(props->back_frame_);
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
       props->thumbnail_frame_ = props->front_frame_;
       props->thumbnail_width_ = video_frame->width;
       props->thumbnail_height_ = video_frame->height;
@@ -137,7 +149,7 @@ void PeerEventHandler::OnReceiveVideoBuffer(
     }
 
     props->streaming_ = true;
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
     if (background_snapshot_only) {
       return;
     }

src/gui/runtime/remote_session.h

@@ -110,7 +110,7 @@ struct RemoteSession {
   std::mutex video_frame_mutex_;
   std::shared_ptr<std::vector<unsigned char>> front_frame_;
   std::shared_ptr<std::vector<unsigned char>> back_frame_;
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN32)
   // Retains the most recent background CPU frame across disconnect cleanup
   // so closing an unselected tab can still update its recent-item thumbnail.
   std::shared_ptr<std::vector<unsigned char>> thumbnail_frame_;