PowerToys/src/modules/fancyzones/lib/Zone.cpp

#include "pch.h"


#include <Shellscalingapi.h>

#include <common/dpi_aware.h>
#include <common/monitors.h>
#include "Zone.h"
#include "Settings.h"
#include "util.h"

namespace
{
    bool ValidateZoneRect(const RECT& rect)
    {
        int width  = rect.right - rect.left;
        int height = rect.bottom - rect.top;
        return rect.left >= 0 && rect.right >= 0 && rect.top >= 0 && rect.bottom >= 0 && width >= 0 && height >= 0;
    }

    BOOL CALLBACK saveDisplayToVector(HMONITOR monitor, HDC hdc, LPRECT rect, LPARAM data)
    {
        reinterpret_cast<std::vector<HMONITOR>*>(data)->emplace_back(monitor);
        return true;
    }

    bool allMonitorsHaveSameDpiScaling()
    {
        std::vector<HMONITOR> monitors;
        EnumDisplayMonitors(NULL, NULL, saveDisplayToVector, reinterpret_cast<LPARAM>(&monitors));

        if (monitors.size() < 2)
        {
            return true;
        }

        UINT firstMonitorDpiX;
        UINT firstMonitorDpiY;

        if (S_OK != GetDpiForMonitor(monitors[0], MDT_EFFECTIVE_DPI, &firstMonitorDpiX, &firstMonitorDpiY))
        {
            return false;
        }

        for (int i = 1; i < monitors.size(); i++)
        {
            UINT iteratedMonitorDpiX;
            UINT iteratedMonitorDpiY;

            if (S_OK != GetDpiForMonitor(monitors[i], MDT_EFFECTIVE_DPI, &iteratedMonitorDpiX, &iteratedMonitorDpiY) ||
                iteratedMonitorDpiX != firstMonitorDpiX)
            {
                return false;
            }
        }

        return true;
    }

}

struct Zone : winrt::implements<Zone, IZone>
{
public:
    Zone(RECT zoneRect, const size_t zoneId) :
        m_zoneRect(zoneRect),
        m_id(zoneId)
    {
    }

    IFACEMETHODIMP_(RECT) GetZoneRect() const noexcept { return m_zoneRect; }
    IFACEMETHODIMP_(size_t) Id() const noexcept { return m_id; }
    IFACEMETHODIMP_(RECT) ComputeActualZoneRect(HWND window, HWND zoneWindow) const noexcept;

private:
    RECT m_zoneRect{};
    const size_t m_id{};
    std::map<HWND, RECT> m_windows{};
};

RECT Zone::ComputeActualZoneRect(HWND window, HWND zoneWindow) const noexcept
{
    // Take care of 1px border
    RECT newWindowRect = m_zoneRect;

    RECT windowRect{};
    ::GetWindowRect(window, &windowRect);

    RECT frameRect{};

    const auto level = DPIAware::GetAwarenessLevel(GetWindowDpiAwarenessContext(window));
    const bool accountForUnawareness = level < DPIAware::PER_MONITOR_AWARE;

    if (SUCCEEDED(DwmGetWindowAttribute(window, DWMWA_EXTENDED_FRAME_BOUNDS, &frameRect, sizeof(frameRect))))
    {
        LONG leftMargin = frameRect.left - windowRect.left;
        LONG rightMargin = frameRect.right - windowRect.right;
        LONG bottomMargin = frameRect.bottom - windowRect.bottom;
        newWindowRect.left -= leftMargin;
        newWindowRect.right -= rightMargin;
        newWindowRect.bottom -= bottomMargin;
    }

    // Map to screen coords
    MapWindowRect(zoneWindow, nullptr, &newWindowRect);

    MONITORINFO mi{ sizeof(mi) };
    if (GetMonitorInfoW(MonitorFromWindow(zoneWindow, MONITOR_DEFAULTTONEAREST), &mi))
    {
        const auto taskbar_left_size = std::abs(mi.rcMonitor.left - mi.rcWork.left);
        const auto taskbar_top_size = std::abs(mi.rcMonitor.top - mi.rcWork.top);
        OffsetRect(&newWindowRect, -taskbar_left_size, -taskbar_top_size);

        if (accountForUnawareness && !allMonitorsHaveSameDpiScaling())
        {
            newWindowRect.left = max(mi.rcMonitor.left, newWindowRect.left);
            newWindowRect.right = min(mi.rcMonitor.right - taskbar_left_size, newWindowRect.right);
            newWindowRect.top = max(mi.rcMonitor.top, newWindowRect.top);
            newWindowRect.bottom = min(mi.rcMonitor.bottom - taskbar_top_size, newWindowRect.bottom);
        }
    }

    if ((::GetWindowLong(window, GWL_STYLE) & WS_SIZEBOX) == 0)
    {
        newWindowRect.right = newWindowRect.left + (windowRect.right - windowRect.left);
        newWindowRect.bottom = newWindowRect.top + (windowRect.bottom - windowRect.top);
    }

    return newWindowRect;
}

winrt::com_ptr<IZone> MakeZone(const RECT& zoneRect, const size_t zoneId) noexcept
{
    if (ValidateZoneRect(zoneRect) && zoneId > 0)
    {
        return winrt::make_self<Zone>(zoneRect, zoneId);
    }
    else
    {
        return nullptr;
    }
}