pulsar/windows/runner/flutter_window.cpp

#include "flutter_window.h"

#include <optional>
#include <string>

#include <flutter/method_channel.h>
#include <flutter/standard_method_codec.h>
#include <flutter/encodable_value.h>
#include <windows.h>

#include "flutter/generated_plugin_registrant.h"

FlutterWindow::FlutterWindow(const flutter::DartProject& project)
    : project_(project) {}

FlutterWindow::~FlutterWindow() {}

static void HandleInjectInput(const flutter::EncodableMap& args) {
  auto typeIt = args.find(flutter::EncodableValue("type"));
  if (typeIt == args.end()) return;

  std::string type = std::get<std::string>(typeIt->second);

  int screenW = GetSystemMetrics(SM_CXSCREEN);
  int screenH = GetSystemMetrics(SM_CYSCREEN);

  if (type == "move") {
    double nx = std::get<double>(args.at(flutter::EncodableValue("x")));
    double ny = std::get<double>(args.at(flutter::EncodableValue("y")));

    INPUT input = {};
    input.type = INPUT_MOUSE;
    input.mi.dx = (LONG)(nx * 65535);
    input.mi.dy = (LONG)(ny * 65535);
    input.mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE;
    SendInput(1, &input, sizeof(INPUT));

  } else if (type == "click") {
    double nx = std::get<double>(args.at(flutter::EncodableValue("x")));
    double ny = std::get<double>(args.at(flutter::EncodableValue("y")));
    int btn = 0;
    auto btnIt = args.find(flutter::EncodableValue("button"));
    if (btnIt != args.end()) btn = std::get<int>(btnIt->second);

    // move first
    INPUT moveInput = {};
    moveInput.type = INPUT_MOUSE;
    moveInput.mi.dx = (LONG)(nx * 65535);
    moveInput.mi.dy = (LONG)(ny * 65535);
    moveInput.mi.dwFlags = MOUSEEVENTF_MOVE | MOUSEEVENTF_ABSOLUTE;
    SendInput(1, &moveInput, sizeof(INPUT));

    INPUT clickInput[2] = {};
    clickInput[0].type = INPUT_MOUSE;
    clickInput[1].type = INPUT_MOUSE;

    if (btn == 1) {
      clickInput[0].mi.dwFlags = MOUSEEVENTF_RIGHTDOWN;
      clickInput[1].mi.dwFlags = MOUSEEVENTF_RIGHTUP;
    } else {
      clickInput[0].mi.dwFlags = MOUSEEVENTF_LEFTDOWN;
      clickInput[1].mi.dwFlags = MOUSEEVENTF_LEFTUP;
    }
    SendInput(2, clickInput, sizeof(INPUT));

  } else if (type == "keydown" || type == "keyup") {
    auto keyIt = args.find(flutter::EncodableValue("keyCode"));
    if (keyIt == args.end()) return;

    // Flutter logical key IDs dont map 1:1 to VKs — use low byte as rough VK
    int logicalKey = std::get<int>(keyIt->second);
    WORD vk = (WORD)(logicalKey & 0xFF);

    INPUT keyInput = {};
    keyInput.type = INPUT_KEYBOARD;
    keyInput.ki.wVk = vk;
    if (type == "keyup") keyInput.ki.dwFlags = KEYEVENTF_KEYUP;

    SendInput(1, &keyInput, sizeof(INPUT));
  }
}

bool FlutterWindow::OnCreate() {
  if (!Win32Window::OnCreate()) {
    return false;
  }

  RECT frame = GetClientArea();

  flutter_controller_ = std::make_unique<flutter::FlutterViewController>(
      frame.right - frame.left, frame.bottom - frame.top, project_);

  if (!flutter_controller_->engine() || !flutter_controller_->view()) {
    return false;
  }
  RegisterPlugins(flutter_controller_->engine());

  // register input injection channel
  auto channel = std::make_shared<flutter::MethodChannel<flutter::EncodableValue>>(
      flutter_controller_->engine()->messenger(),
      "com.pulsar/input",
      &flutter::StandardMethodCodec::GetInstance()
  );

  channel->SetMethodCallHandler(
      [](const flutter::MethodCall<flutter::EncodableValue>& call,
         std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
        if (call.method_name() == "injectInput") {
          if (const auto* args = std::get_if<flutter::EncodableMap>(call.arguments())) {
            HandleInjectInput(*args);
          }
          result->Success();
        } else {
          result->NotImplemented();
        }
      });

  SetChildContent(flutter_controller_->view()->GetNativeWindow());

  flutter_controller_->engine()->SetNextFrameCallback([&]() {
    this->Show();
  });
  flutter_controller_->ForceRedraw();

  return true;
}

void FlutterWindow::OnDestroy() {
  if (flutter_controller_) {
    flutter_controller_ = nullptr;
  }
  Win32Window::OnDestroy();
}

LRESULT FlutterWindow::MessageHandler(HWND hwnd, UINT const message,
                                      WPARAM const wparam,
                                      LPARAM const lparam) noexcept {
  if (flutter_controller_) {
    std::optional<LRESULT> result =
        flutter_controller_->HandleTopLevelWindowProc(hwnd, message, wparam, lparam);
    if (result) return *result;
  }

  switch (message) {
    case WM_FONTCHANGE:
      flutter_controller_->engine()->ReloadSystemFonts();
      break;
  }

  return Win32Window::MessageHandler(hwnd, message, wparam, lparam);
}