Merge GLFW library implementations (#194)

Merges the GLFW-based embedding implementations for Windows and
Linux into a single shared implementation. At this point the implementations
are largely identical, and having two copies is increasingly a maintenance
burden.

Originally they were separate since they were intended to be throw-away,
and their development proceeded at different speeds. Now that they have
reached parity, and there's a possibility that the GLFW implementation
will be longer-lived than initially expected, having one copy that's testable
on several platforms should simplify development.

Author: stuartmorgan

example/linux/flutter_embedder_example.cc

@@ -26,7 +26,7 @@
 #ifdef USE_FLATTENED_INCLUDES
 #include <flutter_desktop_embedding/embedder.h>
 #else
-#include <flutter_desktop_embedding/linux/embedder.h>
+#include <flutter_desktop_embedding/glfw/embedder.h>
 #endif
 
 namespace {
@@ -53,7 +53,7 @@ std::string GetExecutableDirectory() {
 }  // namespace
 
 int main(int argc, char **argv) {
-  if (!glfwInit()) {
+  if (!flutter_desktop_embedding::FlutterInit()) {
     std::cerr << "Couldn't init GLFW" << std::endl;
   }
 
@@ -78,7 +78,7 @@ int main(int argc, char **argv) {
   auto window = flutter_desktop_embedding::CreateFlutterWindowInSnapshotMode(
       640, 480, assets_path, icu_data_path, arguments);
   if (window == nullptr) {
-    glfwTerminate();
+    flutter_desktop_embedding::FlutterTerminate();
     return EXIT_FAILURE;
   }
 

example/windows/GLFW Example.vcxproj

@@ -72,7 +72,7 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug Dynamic Library|x64'">
     <OutDir>$(SolutionDir)bin\$(Platform)\$(Configuration)\$(ProjectName)\</OutDir>
     <IntDir>$(SolutionDir)bin\intermediates\$(Platform)\$(Configuration)\$(ProjectName)\</IntDir>
-    <IncludePath>$(ProjectDir)..\..\library\windows\dependencies\;$(ProjectDir)..\..\;$(IncludePath);$(ProjectDir)..\..\library\windows\</IncludePath>
+    <IncludePath>$(ProjectDir)..\..\library\windows\dependencies\;$(ProjectDir)..\..\;$(IncludePath);$(ProjectDir)..\..\library\windows\;$(ProjectDir)..\..\library\include\</IncludePath>
     <LibraryPath>$(ProjectDir)..\..\library\windows\dependencies\GLFW\;$(SolutionDir)bin\$(Platform)\$(Configuration)\GLFW Library\;$(LibraryPath)</LibraryPath>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug Static Library|x64'">

example/windows/flutter_embedder_example.cpp

@@ -15,7 +15,7 @@
 #include <iostream>
 #include <vector>
 
-#include "embedder.h"
+#include "flutter_desktop_embedding/glfw/embedder.h"
 
 int main(int argc, char **argv) {
   if (!flutter_desktop_embedding::FlutterInit()) {

library/BUILD.gn

@@ -17,14 +17,22 @@ import("//build/packaging.gni")
 import("//library/engine.gni")
 
 published_shared_library("flutter_embedder") {
-  if (is_linux) {
-    sources = [
-      "linux/src/embedder.cc",
-    ]
+  # GLFW embedding implementation.
+  if (is_linux || is_win) {
     public = [
-      "include/flutter_desktop_embedding/linux/embedder.h",
+      "include/flutter_desktop_embedding/glfw/embedder.h",
+    ]
+    sources = [
+      "common/glfw/embedder.cc",
+      "common/glfw/key_event_handler.cc",
+      "common/glfw/key_event_handler.h",
+      "common/glfw/keyboard_hook_handler.h",
+      "common/glfw/text_input_plugin.cc",
+      "common/glfw/text_input_plugin.h",
     ]
   }
+
+  # Embedding-agnostic shared C++.
   if (is_linux || is_win) {
     sources += [
       "common/internal/engine_method_result.cc",
@@ -56,16 +64,6 @@ published_shared_library("flutter_embedder") {
       "include/flutter_desktop_embedding/plugin.h",
     ]
   }
-  # GLFW-specific code.
-  if (is_linux || is_win) {
-    sources += [
-      "common/glfw/key_event_handler.cc",
-      "common/glfw/key_event_handler.h",
-      "common/glfw/keyboard_hook_handler.h",
-      "common/glfw/text_input_plugin.cc",
-      "common/glfw/text_input_plugin.h",
-    ]
-  }
 
   deps = [
     ":fetch_flutter_engine",

library/README.md

@@ -49,7 +49,7 @@ $ sudo apt-get install libglfw3-dev libepoxy-dev libjsoncpp-dev libgtk-3-dev \
 #### Using the Library
 
 Run `make` under `linux/`, then link `libflutter_embedder.so` into your
-binary. See [embedder.h](linux/include/flutter_desktop_embedding/embedder.h)
+binary. See [embedder.h](include/flutter_desktop_embedding/glfw/embedder.h)
 for details on calling into the library.
 
 You will also need to link `libflutter_engine.so` into your binary.

library/linux/src/embedder.cc renamed to library/common/glfw/embedder.cc

@@ -11,18 +11,14 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-#include <flutter_desktop_embedding/linux/embedder.h>
 
-#include <X11/Xlib.h>
-#include <assert.h>
-#include <gtk/gtk.h>
+#include "library/include/flutter_desktop_embedding/glfw/embedder.h"
 
+#include <assert.h>
 #include <algorithm>
 #include <chrono>
 #include <cstdlib>
 #include <iostream>
-#include <memory>
-#include <string>
 
 #include <flutter_embedder.h>
 
@@ -31,6 +27,12 @@
 #include "library/common/glfw/text_input_plugin.h"
 #include "library/common/internal/plugin_handler.h"
 
+#ifdef __linux__
+// For plugin-compatible event handling (e.g., modal windows).
+#include <X11/Xlib.h>
+#include <gtk/gtk.h>
+#endif
+
 // GLFW_TRUE & GLFW_FALSE are introduced since libglfw-3.3,
 // add definitions here to compile under the old versions.
 #ifndef GLFW_TRUE
@@ -51,67 +53,22 @@ struct FlutterEmbedderState {
   // deleted from the heap.
   std::vector<flutter_desktop_embedding::KeyboardHookHandler *>
       keyboard_hook_handlers;
+
   // Handles raw key interactions from GLFW.
-  // TODO: Move key_event_handler once
-  // https://github.com/google/flutter-desktop-embedding/issues/102 is resolved.
+  // TODO: Revisit ownership model once Issue #102 is resolved.
   std::unique_ptr<flutter_desktop_embedding::KeyEventHandler> key_event_handler;
 };
 
 static constexpr char kDefaultWindowTitle[] = "Flutter";
 
-// Callback forward declarations.
-static void GLFWKeyCallback(GLFWwindow *window, int key, int scancode,
-                            int action, int mods);
-static void GLFWCharCallback(GLFWwindow *window, unsigned int code_point);
-static void GLFWmouseButtonCallback(GLFWwindow *window, int key, int action,
-                                    int mods);
-
+// Retrieves state bag for the window in question from the GLFWWindow.
 static FlutterEmbedderState *GetSavedEmbedderState(GLFWwindow *window) {
   return reinterpret_cast<FlutterEmbedderState *>(
       glfwGetWindowUserPointer(window));
 }
 
-// Flushes event queue and then assigns default window callbacks.
-static void GLFWAssignEventCallbacks(GLFWwindow *window) {
-  glfwPollEvents();
-  glfwSetKeyCallback(window, GLFWKeyCallback);
-  glfwSetCharCallback(window, GLFWCharCallback);
-  glfwSetMouseButtonCallback(window, GLFWmouseButtonCallback);
-}
-
-// Clears default window events.
-static void GLFWClearEventCallbacks(GLFWwindow *window) {
-  glfwSetKeyCallback(window, nullptr);
-  glfwSetCharCallback(window, nullptr);
-  glfwSetMouseButtonCallback(window, nullptr);
-}
-
-static void GLFWwindowSizeCallback(GLFWwindow *window, int width, int height) {
-  FlutterWindowMetricsEvent event = {};
-  event.struct_size = sizeof(event);
-  event.width = width;
-  event.height = height;
-  event.pixel_ratio = 1.0;
-  auto state = GetSavedEmbedderState(window);
-  FlutterEngineSendWindowMetricsEvent(state->engine, &event);
-}
-
-static void GLFWOnFlutterPlatformMessage(const FlutterPlatformMessage *message,
-                                         void *user_data) {
-  if (message->struct_size != sizeof(FlutterPlatformMessage)) {
-    std::cerr << "Invalid message size received. Expected: "
-              << sizeof(FlutterPlatformMessage) << " but received "
-              << message->struct_size << std::endl;
-    return;
-  }
-
-  GLFWwindow *window = reinterpret_cast<GLFWwindow *>(user_data);
-  auto state = GetSavedEmbedderState(window);
-  state->plugin_handler->HandleMethodCallMessage(
-      message, [window] { GLFWClearEventCallbacks(window); },
-      [window] { GLFWAssignEventCallbacks(window); });
-}
-
+// When GLFW calls back to the window with a cursor position move, forwards to
+// FlutterEngine as a pointer event with appropriate phase.
 static void GLFWcursorPositionCallbackAtPhase(GLFWwindow *window,
                                               FlutterPointerPhase phase,
                                               double x, double y) {
@@ -124,14 +81,16 @@ static void GLFWcursorPositionCallbackAtPhase(GLFWwindow *window,
       std::chrono::duration_cast<std::chrono::microseconds>(
           std::chrono::high_resolution_clock::now().time_since_epoch())
           .count();
-  auto state = GetSavedEmbedderState(window);
-  FlutterEngineSendPointerEvent(state->engine, &event, 1);
+  FlutterEngineSendPointerEvent(GetSavedEmbedderState(window)->engine, &event,
+                                1);
 }
 
+// Reports cursor move to the Flutter engine.
 static void GLFWcursorPositionCallback(GLFWwindow *window, double x, double y) {
   GLFWcursorPositionCallbackAtPhase(window, FlutterPointerPhase::kMove, x, y);
 }
 
+// Reports mouse button press to the Flutter engine.
 static void GLFWmouseButtonCallback(GLFWwindow *window, int key, int action,
                                     int mods) {
   double x, y;
@@ -147,13 +106,15 @@ static void GLFWmouseButtonCallback(GLFWwindow *window, int key, int action,
   }
 }
 
+// Passes character input events to registered handlers.
 static void GLFWCharCallback(GLFWwindow *window, unsigned int code_point) {
   for (flutter_desktop_embedding::KeyboardHookHandler *handler :
        GetSavedEmbedderState(window)->keyboard_hook_handlers) {
     handler->CharHook(window, code_point);
   }
 }
 
+// Passes raw key events to registered handlers.
 static void GLFWKeyCallback(GLFWwindow *window, int key, int scancode,
                             int action, int mods) {
   for (flutter_desktop_embedding::KeyboardHookHandler *handler :
@@ -162,6 +123,51 @@ static void GLFWKeyCallback(GLFWwindow *window, int key, int scancode,
   }
 }
 
+// Reports window size changes to the Flutter engine.
+static void GLFWwindowSizeCallback(GLFWwindow *window, int width, int height) {
+  FlutterWindowMetricsEvent event = {};
+  event.struct_size = sizeof(event);
+  event.width = width;
+  event.height = height;
+  // TODO: Handle pixel ratio for different DPI monitors.
+  event.pixel_ratio = 1.0;
+  FlutterEngineSendWindowMetricsEvent(GetSavedEmbedderState(window)->engine,
+                                      &event);
+}
+
+// Flushes event queue and then assigns default window callbacks.
+static void GLFWAssignEventCallbacks(GLFWwindow *window) {
+  glfwPollEvents();
+  glfwSetKeyCallback(window, GLFWKeyCallback);
+  glfwSetCharCallback(window, GLFWCharCallback);
+  glfwSetMouseButtonCallback(window, GLFWmouseButtonCallback);
+}
+
+// Clears default window events.
+static void GLFWClearEventCallbacks(GLFWwindow *window) {
+  glfwSetKeyCallback(window, nullptr);
+  glfwSetCharCallback(window, nullptr);
+  glfwSetMouseButtonCallback(window, nullptr);
+}
+
+// The Flutter Engine calls out to this function when new platform messages are
+// available
+static void GLFWOnFlutterPlatformMessage(const FlutterPlatformMessage *message,
+                                         void *user_data) {
+  if (message->struct_size != sizeof(FlutterPlatformMessage)) {
+    std::cerr << "Invalid message size received. Expected: "
+              << sizeof(FlutterPlatformMessage) << " but received "
+              << message->struct_size << std::endl;
+    return;
+  }
+
+  GLFWwindow *window = reinterpret_cast<GLFWwindow *>(user_data);
+  auto state = GetSavedEmbedderState(window);
+  state->plugin_handler->HandleMethodCallMessage(
+      message, [window] { GLFWClearEventCallbacks(window); },
+      [window] { GLFWAssignEventCallbacks(window); });
+}
+
 static bool GLFWMakeContextCurrent(void *user_data) {
   GLFWwindow *window = reinterpret_cast<GLFWwindow *>(user_data);
   glfwMakeContextCurrent(window);
@@ -192,7 +198,7 @@ static uint32_t GLFWGetActiveFbo(void *user_data) { return 0; }
 static void GLFWClearCanvas(GLFWwindow *window) {
   glfwMakeContextCurrent(window);
   // This color is Material Blue Grey.
-  glClearColor(0.92549, 0.93725, 0.9451, 0);
+  glClearColor(236.0 / 255.0, 239.0 / 255.0, 241.0 / 255.0, 0);
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
   glFlush();
   glfwSwapBuffers(window);
@@ -242,6 +248,13 @@ static FlutterEngine RunFlutterEngine(
 
 namespace flutter_desktop_embedding {
 
+// Initialize glfw
+bool FlutterInit() { return glfwInit(); }
+
+// Tear down glfw
+void FlutterTerminate() { glfwTerminate(); }
+
+// set up embedder state and add the plugin to the plugin_handler
 bool AddPlugin(GLFWwindow *flutter_window, std::unique_ptr<Plugin> plugin) {
   auto state = GetSavedEmbedderState(flutter_window);
   return state->plugin_handler->AddPlugin(std::move(plugin));
@@ -261,7 +274,9 @@ GLFWwindow *CreateFlutterWindow(size_t initial_width, size_t initial_height,
                                 const std::string &packages_path,
                                 const std::string &icu_data_path,
                                 const std::vector<std::string> &arguments) {
+#ifdef __linux__
   gtk_init(0, nullptr);
+#endif
   auto window = glfwCreateWindow(initial_width, initial_height,
                                  kDefaultWindowTitle, NULL, NULL);
   if (window == nullptr) {
@@ -274,6 +289,7 @@ GLFWwindow *CreateFlutterWindow(size_t initial_width, size_t initial_height,
     glfwDestroyWindow(window);
     return nullptr;
   }
+
   FlutterEmbedderState *state = new FlutterEmbedderState();
   state->plugin_handler = std::make_unique<PluginHandler>(engine);
   state->engine = engine;
@@ -297,13 +313,19 @@ GLFWwindow *CreateFlutterWindow(size_t initial_width, size_t initial_height,
 }
 
 void FlutterWindowLoop(GLFWwindow *flutter_window) {
+#ifdef __linux__
   // Necessary for GTK thread safety.
   XInitThreads();
+#endif
   while (!glfwWindowShouldClose(flutter_window)) {
+#ifdef __linux__
     glfwPollEvents();
     if (gtk_events_pending()) {
       gtk_main_iteration();
     }
+#else
+    glfwWaitEvents();
+#endif
     // TODO(awdavies): This will be deprecated soon.
     __FlutterEngineFlushPendingTasksNow();
   }

library/windows/embedder.h renamed to library/include/flutter_desktop_embedding/glfw/embedder.h

@@ -12,15 +12,25 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#ifndef WINDOWS_LIBRARY_EMBEDDER_H_
-#define WINDOWS_LIBRARY_EMBEDDER_H_
+#ifndef LIBRARY_INCLUDE_FLUTTER_DESKTOP_EMBEDDING_GLFW_EMBEDDER_H_
+#define LIBRARY_INCLUDE_FLUTTER_DESKTOP_EMBEDDING_GLFW_EMBEDDER_H_
 
+#include <memory>
 #include <string>
 #include <vector>
 
+#ifdef __linux__
+// Epoxy must be included before any graphics-related code.
+#include <epoxy/gl.h>
+#endif
+
 #include <GLFW/glfw3.h>
 
-#include "library/include/flutter_desktop_embedding/plugin.h"
+#ifdef USE_FLATTENED_INCLUDES
+#include "plugin.h"
+#else
+#include "../plugin.h"
+#endif
 
 namespace flutter_desktop_embedding {
 
@@ -86,4 +96,4 @@ void FlutterWindowLoop(GLFWwindow *flutter_window);
 
 }  // namespace flutter_desktop_embedding
 
-#endif  // WINDOWS_LIBRARY_EMBEDDER_H_
+#endif  // LIBRARY_INCLUDE_FLUTTER_DESKTOP_EMBEDDING_GLFW_EMBEDDER_H_