XCEngine/new_editor/app/Platform/Win32/BorderlessWindowChromeDwm.cpp

#include "BorderlessWindowChrome.h"

#include <dwmapi.h>

namespace XCEngine::UI::Editor::Host {

namespace {

using DwmSetWindowAttributeFn = HRESULT(WINAPI*)(HWND, DWORD, LPCVOID, DWORD);
using DwmExtendFrameIntoClientAreaFn = HRESULT(WINAPI*)(HWND, const MARGINS*);

HMODULE GetDwmApiModule() {
    static HMODULE dwmapi = []() -> HMODULE {
        HMODULE module = GetModuleHandleW(L"dwmapi.dll");
        if (module == nullptr) {
            module = LoadLibraryW(L"dwmapi.dll");
        }
        return module;
    }();

    return dwmapi;
}

template <typename ProcedureType>
ProcedureType GetDwmApiProcedure(const char* name) {
    const HMODULE dwmapi = GetDwmApiModule();
    if (dwmapi == nullptr) {
        return nullptr;
    }

    return reinterpret_cast<ProcedureType>(GetProcAddress(dwmapi, name));
}

bool IsWindowAlignedToMonitorWorkArea(HWND hwnd) {
    if (hwnd == nullptr) {
        return false;
    }

    RECT windowRect = {};
    if (!GetWindowRect(hwnd, &windowRect)) {
        return false;
    }

    const HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
    if (monitor == nullptr) {
        return false;
    }

    MONITORINFO monitorInfo = {};
    monitorInfo.cbSize = sizeof(monitorInfo);
    if (!GetMonitorInfoW(monitor, &monitorInfo)) {
        return false;
    }

    const RECT& workArea = monitorInfo.rcWork;
    return windowRect.left == workArea.left &&
        windowRect.top == workArea.top &&
        windowRect.right == workArea.right &&
        windowRect.bottom == workArea.bottom;
}

template <typename ValueType>
void ApplyDwmWindowAttribute(HWND hwnd, DWORD attribute, const ValueType& value) {
    if (hwnd == nullptr) {
        return;
    }

    static const DwmSetWindowAttributeFn setWindowAttribute =
        GetDwmApiProcedure<DwmSetWindowAttributeFn>("DwmSetWindowAttribute");
    if (setWindowAttribute != nullptr) {
        setWindowAttribute(hwnd, attribute, &value, sizeof(value));
    }
}

} // namespace

void EnableBorderlessWindowShadow(HWND hwnd) {
    if (hwnd == nullptr) {
        return;
    }

    static const DwmExtendFrameIntoClientAreaFn extendFrameIntoClientArea =
        GetDwmApiProcedure<DwmExtendFrameIntoClientAreaFn>("DwmExtendFrameIntoClientArea");
    if (extendFrameIntoClientArea != nullptr) {
        const bool maximized = IsZoomed(hwnd) || IsWindowAlignedToMonitorWorkArea(hwnd);
        const MARGINS margins = maximized
            ? MARGINS{ 0, 0, 0, 0 }
            : MARGINS{ 1, 1, 1, 1 };
        extendFrameIntoClientArea(hwnd, &margins);
    }
}

void RefreshBorderlessWindowDwmDecorations(HWND hwnd) {
    if (hwnd == nullptr) {
        return;
    }

    const int ncRenderingPolicy = DWMNCRP_DISABLED;
    const BOOL allowNcPaint = FALSE;
    const BOOL disableTransitions = TRUE;
    const BOOL useImmersiveDarkMode = TRUE;
    const COLORREF captionColor = RGB(26, 26, 26);
    const COLORREF textColor = RGB(235, 235, 235);
    const COLORREF borderColor = RGB(26, 26, 26);

    ApplyDwmWindowAttribute(hwnd, DWMWA_NCRENDERING_POLICY, ncRenderingPolicy);
    ApplyDwmWindowAttribute(hwnd, DWMWA_ALLOW_NCPAINT, allowNcPaint);
    ApplyDwmWindowAttribute(hwnd, DWMWA_TRANSITIONS_FORCEDISABLED, disableTransitions);
    ApplyDwmWindowAttribute(hwnd, DWMWA_USE_IMMERSIVE_DARK_MODE, useImmersiveDarkMode);
    ApplyDwmWindowAttribute(hwnd, DWMWA_CAPTION_COLOR, captionColor);
    ApplyDwmWindowAttribute(hwnd, DWMWA_TEXT_COLOR, textColor);
    ApplyDwmWindowAttribute(hwnd, DWMWA_BORDER_COLOR, borderColor);
    EnableBorderlessWindowShadow(hwnd);
}

bool HandleBorderlessWindowGetMinMaxInfo(HWND hwnd, LPARAM lParam) {
    if (hwnd == nullptr || lParam == 0) {
        return false;
    }

    auto* minMaxInfo = reinterpret_cast<MINMAXINFO*>(lParam);
    if (minMaxInfo == nullptr) {
        return false;
    }

    const HMONITOR monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);
    if (monitor == nullptr) {
        return false;
    }

    MONITORINFO monitorInfo = {};
    monitorInfo.cbSize = sizeof(monitorInfo);
    if (!GetMonitorInfoW(monitor, &monitorInfo)) {
        return false;
    }

    const RECT& workArea = monitorInfo.rcWork;
    const RECT& monitorArea = monitorInfo.rcMonitor;
    minMaxInfo->ptMaxPosition.x = workArea.left - monitorArea.left;
    minMaxInfo->ptMaxPosition.y = workArea.top - monitorArea.top;
    minMaxInfo->ptMaxSize.x = workArea.right - workArea.left;
    minMaxInfo->ptMaxSize.y = workArea.bottom - workArea.top;
    minMaxInfo->ptMaxTrackSize = minMaxInfo->ptMaxSize;
    return true;
}

LRESULT HandleBorderlessWindowNcCalcSize(
    HWND hwnd,
    WPARAM wParam,
    LPARAM lParam,
    UINT dpi) {
    (void)hwnd;
    (void)wParam;
    (void)lParam;
    (void)dpi;
    return 0;
}

} // namespace XCEngine::UI::Editor::Host