espanso/native/libwinbridge/bridge.cpp

#include "bridge.h"
#include <iostream>
#include <string>
#include <vector>
#include <array>

#define UNICODE

#include <Windows.h>

// How many milliseconds must pass between keystrokes to refresh the keyboard layout
const long refreshKeyboardLayoutInterval = 2000;

DWORD lastKeyboardPressTick = 0;
HKL currentKeyboardLayout;
HWND window;

const wchar_t* const winclass = L"Espanso";

KeypressCallback keypress_callback;
void * interceptor_instance;

void register_keypress_callback(void * self, KeypressCallback callback) {
    keypress_callback = callback;
    interceptor_instance = self;
}

/*
 * Message handler procedure for the Worker window
 */
LRESULT CALLBACK window_worker_procedure(HWND window, unsigned int msg, WPARAM wp, LPARAM lp)
{
    switch (msg)
    {
        case WM_DESTROY:
            std::cout << "\ndestroying window\n";
            PostQuitMessage(0);
            return 0L;
        case WM_INPUT:  // Message relative to the RAW INPUT events
        {
            // Get the input size
            UINT dwSize;
            GetRawInputData(
                    (HRAWINPUT)lp,
                    RID_INPUT,
                    NULL,
                    &dwSize,
                    sizeof(RAWINPUTHEADER)
            );

            // Create a proper sized structure to hold the data
            std::vector<BYTE> lpb(dwSize);

            // Request the Raw input data
            if (GetRawInputData((HRAWINPUT)lp, RID_INPUT, lpb.data(), &dwSize,
                                sizeof(RAWINPUTHEADER)) != dwSize) {
                return 0;
            }

            // Convert the input data
            RAWINPUT* raw = reinterpret_cast<RAWINPUT*>(lpb.data());

            // Make sure it's a keyboard type event, relative to a key release.
            if (raw->header.dwType == RIM_TYPEKEYBOARD && raw->data.keyboard.Message == WM_KEYUP)
            {
                DWORD currentTick = GetTickCount();

                // If enough time has passed between the last keypress and now, refresh the keyboard layout
                if ((currentTick - lastKeyboardPressTick) > refreshKeyboardLayoutInterval) {

                    // Because keyboard layouts on windows are Window-specific, to get the current
                    // layout we need to get the foreground window and get its layout.

                    HWND hwnd = GetForegroundWindow();
                    if (hwnd) {
                        DWORD threadID = GetWindowThreadProcessId(hwnd, NULL);
                        HKL newKeyboardLayout = GetKeyboardLayout(threadID);

                        // It's not always valid, so update the current value only if available.
                        if (newKeyboardLayout != 0) {
                            currentKeyboardLayout = newKeyboardLayout;
                        }
                    }

                    lastKeyboardPressTick = currentTick;
                }

                // Get keyboard state ( necessary to decode the associated Unicode char )
                std::vector<BYTE> lpKeyState(256);
                if (GetKeyboardState(lpKeyState.data())) {
                    // Convert the virtual key to an unicode char
                    std::array<WCHAR, 4> buffer;
                    int result = ToUnicodeEx(raw->data.keyboard.VKey, raw->data.keyboard.MakeCode, lpKeyState.data(), buffer.data(), buffer.size(), 0, currentKeyboardLayout);

                    //std::cout << result << " " << buffer[0] << " " << raw->data.keyboard.VKey << std::endl;

                    // We need to call the callback in two different ways based on the type of key
                    // The only modifier we use that has a result > 0 is the BACKSPACE, so we have to consider it.
                    if (result >= 1 && raw->data.keyboard.VKey != VK_BACK) {
                        keypress_callback(interceptor_instance, reinterpret_cast<int32_t*>(buffer.data()), buffer.size(), 0, raw->data.keyboard.VKey);
                    }else{
                        keypress_callback(interceptor_instance, nullptr, 0, 1, raw->data.keyboard.VKey);
                    }
                }
            }

            return 0;
        }
        default:
            return DefWindowProc(window, msg, wp, lp);
    }
}

int32_t initialize_window() {
    // Initialize the default keyboard layout
    currentKeyboardLayout = GetKeyboardLayout(0);

    // Initialize the Worker window

    // Docs: https://docs.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-wndclassexa
    WNDCLASSEX wndclass = {
            sizeof(WNDCLASSEX),				// cbSize: Size of this structure
            0,								// style: Class styles
            window_worker_procedure,		// lpfnWndProc: Pointer to the window procedure
            0,								// cbClsExtra: Number of extra bytes to allocate following the window-class structure
            0,								// cbWndExtra: The number of extra bytes to allocate following the window instance.
            GetModuleHandle(0),				// hInstance: A handle to the instance that contains the window procedure for the class.
            NULL,							// hIcon: A handle to the class icon.
            LoadCursor(0,IDC_ARROW),	    // hCursor: A handle to the class cursor.
            NULL,							// hbrBackground: A handle to the class background brush.
            NULL,							// lpszMenuName: Pointer to a null-terminated character string that specifies the resource name of the class menu
            winclass,						// lpszClassName: A pointer to a null-terminated string or is an atom.
            NULL							// hIconSm: A handle to a small icon that is associated with the window class.
    };

    if (RegisterClassEx(&wndclass))
    {
        // Docs: https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-createwindowexw
        window = CreateWindowEx(
                0,										// dwExStyle: The extended window style of the window being created.
                winclass,								// lpClassName: A null-terminated string or a class atom created by a previous call to the RegisterClass
                L"Espanso Worker Window",				// lpWindowName: The window name.
                WS_OVERLAPPEDWINDOW,					// dwStyle: The style of the window being created.
                CW_USEDEFAULT,							// X: The initial horizontal position of the window.
                CW_USEDEFAULT,							// Y: The initial vertical position of the window.
                100,									// nWidth: The width, in device units, of the window.
                100,									// nHeight: The height, in device units, of the window.
                NULL,									// hWndParent:  handle to the parent or owner window of the window being created.
                NULL,									// hMenu: A handle to a menu, or specifies a child-window identifier, depending on the window style.
                GetModuleHandle(0),						// hInstance: A handle to the instance of the module to be associated with the window.
                NULL									// lpParam: Pointer to a value to be passed to the window
        );

        // Register raw inputs
        RAWINPUTDEVICE Rid[1];

        Rid[0].usUsagePage = 0x01;
        Rid[0].usUsage = 0x06;
        Rid[0].dwFlags = RIDEV_NOLEGACY | RIDEV_INPUTSINK;   // adds HID keyboard and also ignores legacy keyboard messages
        Rid[0].hwndTarget = window;

        if (RegisterRawInputDevices(Rid, 1, sizeof(Rid[0])) == FALSE) {  // Something went wrong, error.
            return -1;
        }
    }else{
        // Something went wrong, error.
        return -1;
    }

    return 1;
}

void eventloop() {
    if (window)
    {
        // Hide the window
        ShowWindow(window, SW_HIDE);

        // Enter the Event loop
        MSG msg;
        while (GetMessage(&msg, 0, 0, 0))  DispatchMessage(&msg);
    }

    // Something went wrong, this should have been an infinite loop.
}

/*
 * Type the given string simulating keyboard presses.
 */
void send_string(const wchar_t * string) {
    std::wstring msg = string;

    std::vector<INPUT> vec;
    for (auto ch : msg)
    {
    	INPUT input = { 0 };
    	input.type = INPUT_KEYBOARD;
    	input.ki.dwFlags = KEYEVENTF_UNICODE;
    	input.ki.wScan = ch;
    	vec.push_back(input);

    	input.ki.dwFlags |= KEYEVENTF_KEYUP;
    	vec.push_back(input);
    }

    SendInput(vec.size(), vec.data(), sizeof(INPUT));
}

/*
 * Send the backspace keypress, *count* times.
 */
void delete_string(int32_t count) {
    std::vector<INPUT> vec;

    for (int i = 0; i < count; i++) {
        INPUT input = { 0 };

        input.type = INPUT_KEYBOARD;
        input.ki.wScan = 0;
        input.ki.time = 0;
        input.ki.dwExtraInfo = 0;
        input.ki.wVk = VK_BACK;
        input.ki.dwFlags = 0; // 0 for key press
        vec.push_back(input);

        // Release the "A" key
        input.ki.dwFlags = KEYEVENTF_KEYUP; // KEYEVENTF_KEYUP for key release
        vec.push_back(input);
    }

    SendInput(vec.size(), vec.data(), sizeof(INPUT));
}