deargui-vpl/examples/application/source/platform_win32.cpp

# include "platform.h"
# include "setup.h"

# if BACKEND(IMGUI_WIN32)

# include "application.h"
# include "renderer.h"

# define NOMINMAX
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
# include <tchar.h>
# include <string>

# include <imgui.h>
# include "imgui_impl_win32.h"

# if defined(_UNICODE)
std::wstring Utf8ToNative(const std::string& str)
{
    int size = MultiByteToWideChar(CP_UTF8, 0, &str[0], (int)str.size(), nullptr, 0);
    std::wstring result(size, 0);
    MultiByteToWideChar(CP_UTF8, 0, str.data(), (int)str.size(), (wchar_t*)result.data(), size);
    return result;
}
# else
std::string Utf8ToNative(const std::string& str)
{
    return str;
}
# endif

IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

struct PlatformWin32 final
    : Platform
{
    static PlatformWin32* s_Instance;

    PlatformWin32(Application& application);

    bool ApplicationStart(int argc, char** argv) override;
    void ApplicationStop() override;
    bool OpenMainWindow(const char* title, int width, int height) override;
    bool CloseMainWindow() override;
    void* GetMainWindowHandle() const override;
    void SetMainWindowTitle(const char* title) override;
    void ShowMainWindow() override;
    bool ProcessMainWindowEvents() override;
    bool IsMainWindowVisible() const override;
    void SetRenderer(Renderer* renderer) override;
    void NewFrame() override;
    void FinishFrame() override;
    void Quit() override;

    WindowState GetWindowState() const override;
    bool SetWindowState(const WindowState& state) override;

    void SetDpiScale(float dpiScale);

    LRESULT WinProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);

    Application&    m_Application;
    WNDCLASSEX      m_WindowClass = {};
    HWND            m_MainWindowHandle = nullptr;
    bool            m_IsMinimized = false;
    bool            m_WasMinimized = false;
    bool            m_CanCloseResult = false;
    Renderer*       m_Renderer = nullptr;
};

std::unique_ptr<Platform> CreatePlatform(Application& application)
{
    return std::make_unique<PlatformWin32>(application);
}

PlatformWin32* PlatformWin32::s_Instance = nullptr;

PlatformWin32::PlatformWin32(Application& application)
    : m_Application(application)
{
}

bool PlatformWin32::ApplicationStart(int argc, char** argv)
{
    if (s_Instance)
        return false;

    s_Instance = this;

    auto winProc = [](HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) -> LRESULT
    {
        return s_Instance->WinProc(hWnd, msg, wParam, lParam);
    };

    m_WindowClass =
    {
        sizeof(WNDCLASSEX),
        CS_CLASSDC,
        winProc,
        0L,
        0L,
        GetModuleHandle(nullptr),
        LoadIcon(GetModuleHandle(nullptr),
        IDI_APPLICATION),
        LoadCursor(nullptr, IDC_ARROW),
        nullptr,
        nullptr,
        _T("imgui-node-editor-application"),
        LoadIcon(GetModuleHandle(nullptr),
        IDI_APPLICATION)
    };

    if (!RegisterClassEx(&m_WindowClass))
    {
        s_Instance = nullptr;
        return false;
    }

    ImGui_ImplWin32_EnableDpiAwareness();

    return true;
}

void PlatformWin32::ApplicationStop()
{
    if (!s_Instance)
        return;

    UnregisterClass(m_WindowClass.lpszClassName, m_WindowClass.hInstance);

    s_Instance = nullptr;
}


bool PlatformWin32::OpenMainWindow(const char* title, int width, int height)
{
    if (m_MainWindowHandle)
        return false;

    m_MainWindowHandle = CreateWindow(
        m_WindowClass.lpszClassName,
        Utf8ToNative(title).c_str(),
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT,
        width < 0 ? CW_USEDEFAULT : width,
        height < 0 ? CW_USEDEFAULT : height,
        nullptr, nullptr, m_WindowClass.hInstance, nullptr);

    if (!m_MainWindowHandle)
        return false;

    if (!ImGui_ImplWin32_Init(m_MainWindowHandle))
    {
        DestroyWindow(m_MainWindowHandle);
        m_MainWindowHandle = nullptr;
        return false;
    }

    SetDpiScale(ImGui_ImplWin32_GetDpiScaleForHwnd(m_MainWindowHandle));

    return true;
}

bool PlatformWin32::CloseMainWindow()
{
    if (m_MainWindowHandle == nullptr)
        return true;

    SendMessage(m_MainWindowHandle, WM_CLOSE, 0, 0);

    return m_CanCloseResult;
}

void* PlatformWin32::GetMainWindowHandle() const
{
    return m_MainWindowHandle;
}

void PlatformWin32::SetMainWindowTitle(const char* title)
{
    SetWindowText(m_MainWindowHandle, Utf8ToNative(title).c_str());
}

void PlatformWin32::ShowMainWindow()
{
    if (m_MainWindowHandle == nullptr)
        return;

    //ShowWindow(m_MainWindowHandle, SW_SHOWMAXIMIZED);
    ShowWindow(m_MainWindowHandle, SW_SHOW);
    UpdateWindow(m_MainWindowHandle);
}

bool PlatformWin32::ProcessMainWindowEvents()
{
    if (m_MainWindowHandle == nullptr)
        return false;

    auto fetchMessage = [this](MSG* msg) -> bool
    {
        if (!m_IsMinimized)
            return PeekMessage(msg, nullptr, 0U, 0U, PM_REMOVE) != 0;
        else
            return GetMessage(msg, nullptr, 0U, 0U) != 0;
    };

    MSG msg = {};
    while (fetchMessage(&msg))
    {
        if (msg.message == WM_KEYDOWN && (msg.wParam == VK_ESCAPE))
            PostQuitMessage(0);

        if (msg.message == WM_QUIT)
            return false;

        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return true;
}

bool PlatformWin32::IsMainWindowVisible() const
{
    if (m_MainWindowHandle == nullptr)
        return false;

    if (m_IsMinimized)
        return false;

    return true;
}

void PlatformWin32::SetRenderer(Renderer* renderer)
{
    m_Renderer = renderer;
}

void PlatformWin32::NewFrame()
{
    ImGui_ImplWin32_NewFrame();

    if (m_WasMinimized)
    {
        ImGui::GetIO().DeltaTime = 0.1e-6f;
        m_WasMinimized = false;
    }
}

void PlatformWin32::FinishFrame()
{
    if (m_Renderer)
        m_Renderer->Present();
}

void PlatformWin32::Quit()
{
    PostQuitMessage(0);
}

WindowState PlatformWin32::GetWindowState() const
{
    WindowState state;
    
    if (!m_MainWindowHandle)
        return state;
    
    WINDOWPLACEMENT placement = { sizeof(WINDOWPLACEMENT) };
    if (GetWindowPlacement(m_MainWindowHandle, &placement))
    {
        state.x = placement.rcNormalPosition.left;
        state.y = placement.rcNormalPosition.top;
        state.width = placement.rcNormalPosition.right - placement.rcNormalPosition.left;
        state.height = placement.rcNormalPosition.bottom - placement.rcNormalPosition.top;
        state.maximized = (placement.showCmd == SW_SHOWMAXIMIZED);
    }
    
    // Get monitor index (0-based)
    HMONITOR hMonitor = MonitorFromWindow(m_MainWindowHandle, MONITOR_DEFAULTTONEAREST);
    state.monitor = 0; // Default to primary
    
    // Enumerate monitors to find index
    struct MonitorEnumData {
        HMONITOR target;
        int index;
        int currentIndex;
    };
    
    MonitorEnumData enumData = { hMonitor, 0, 0 };
    
    EnumDisplayMonitors(nullptr, nullptr, [](HMONITOR hMon, HDC, LPRECT, LPARAM data) -> BOOL {
        auto* enumData = reinterpret_cast<MonitorEnumData*>(data);
        if (hMon == enumData->target) {
            enumData->index = enumData->currentIndex;
            return FALSE; // Stop enumeration
        }
        enumData->currentIndex++;
        return TRUE;
    }, reinterpret_cast<LPARAM>(&enumData));
    
    state.monitor = enumData.index;
    
    return state;
}

bool PlatformWin32::SetWindowState(const WindowState& state)
{
    if (!m_MainWindowHandle)
        return false;
    
    // Validate and clamp position/size to be within monitor bounds
    HMONITOR hMonitor = nullptr;
    
    // Try to get the specified monitor
    int currentMonitor = 0;
    struct MonitorEnumData {
        int targetIndex;
        int currentIndex;
        HMONITOR result;
    };
    
    MonitorEnumData enumData = { state.monitor, 0, nullptr };
    
    EnumDisplayMonitors(nullptr, nullptr, [](HMONITOR hMon, HDC, LPRECT, LPARAM data) -> BOOL {
        auto* enumData = reinterpret_cast<MonitorEnumData*>(data);
        if (enumData->currentIndex == enumData->targetIndex) {
            enumData->result = hMon;
            return FALSE; // Stop enumeration
        }
        enumData->currentIndex++;
        return TRUE;
    }, reinterpret_cast<LPARAM>(&enumData));
    
    hMonitor = enumData.result;
    
    // Fall back to primary monitor if specified monitor doesn't exist
    if (!hMonitor)
    {
        const POINT pt = { 0, 0 };
        hMonitor = MonitorFromPoint(pt, MONITOR_DEFAULTTOPRIMARY);
    }
    
    // Get monitor info to validate position
    MONITORINFO monitorInfo = { sizeof(MONITORINFO) };
    GetMonitorInfo(hMonitor, &monitorInfo);
    
    // Build window placement structure
    WINDOWPLACEMENT placement = { sizeof(WINDOWPLACEMENT) };
    placement.flags = 0;
    placement.showCmd = state.maximized ? SW_SHOWMAXIMIZED : SW_SHOWNORMAL;
    
    // Set position (validate it's at least partially on screen)
    int x = state.x;
    int y = state.y;
    int w = state.width;
    int h = state.height;
    
    // Ensure window is at least partially visible
    const int MIN_VISIBLE = 50; // At least 50 pixels must be visible
    if (x + w < monitorInfo.rcWork.left + MIN_VISIBLE)
        x = monitorInfo.rcWork.left;
    if (y + h < monitorInfo.rcWork.top + MIN_VISIBLE)
        y = monitorInfo.rcWork.top;
    if (x > monitorInfo.rcWork.right - MIN_VISIBLE)
        x = monitorInfo.rcWork.right - w;
    if (y > monitorInfo.rcWork.bottom - MIN_VISIBLE)
        y = monitorInfo.rcWork.bottom - h;
    
    placement.rcNormalPosition.left = x;
    placement.rcNormalPosition.top = y;
    placement.rcNormalPosition.right = x + w;
    placement.rcNormalPosition.bottom = y + h;
    
    return SetWindowPlacement(m_MainWindowHandle, &placement) != 0;
}

void PlatformWin32::SetDpiScale(float dpiScale)
{
    SetWindowScale(dpiScale);
    SetFramebufferScale(dpiScale);
}

LRESULT PlatformWin32::WinProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    if (ImGui_ImplWin32_WndProcHandler(hWnd, msg, wParam, lParam))
        return 1;

    switch (msg)
    {
        case WM_CLOSE:
            m_CanCloseResult = m_Application.CanClose();
            if (m_CanCloseResult)
            {
                ImGui_ImplWin32_Shutdown();
                DestroyWindow(hWnd);
            }
            return 0;

        case WM_SIZE:
            if (wParam == SIZE_MINIMIZED)
            {
                m_IsMinimized  = true;
                m_WasMinimized = true;
            }
            else if (wParam == SIZE_RESTORED && m_IsMinimized)
            {
                m_IsMinimized = false;
            }

            if (m_Renderer != nullptr && wParam != SIZE_MINIMIZED)
                m_Renderer->Resize(static_cast<int>(LOWORD(lParam)), static_cast<int>(HIWORD(lParam)));
            return 0;

        case WM_SYSCOMMAND:
            if ((wParam & 0xfff0) == SC_KEYMENU) // Disable ALT application menu
                return 0;
            break;

        case WM_DPICHANGED:
            SetDpiScale(ImGui_ImplWin32_GetDpiScaleForHwnd(hWnd));
            return 0;

        case WM_DESTROY:
            PostQuitMessage(0);
            return 0;
    }

    return DefWindowProc(hWnd, msg, wParam, lParam);
}

# endif // BACKEND(IMGUI_WIN32)