terminal/src/cascadia/WindowsTerminal/AppHost.cpp

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.

#include "pch.h"
#include "AppHost.h"
#include "../types/inc/Viewport.hpp"
#include "../types/inc/utils.hpp"
#include "../types/inc/User32Utils.hpp"
#include "resource.h"

#include <winrt/Microsoft.Terminal.TerminalControl.h>

using namespace winrt::Windows::UI;
using namespace winrt::Windows::UI::Composition;
using namespace winrt::Windows::UI::Xaml;
using namespace winrt::Windows::UI::Xaml::Hosting;
using namespace winrt::Windows::Foundation::Numerics;
using namespace ::Microsoft::Console;
using namespace ::Microsoft::Console::Types;

// This magic flag is "documented" at https://msdn.microsoft.com/en-us/library/windows/desktop/ms646301(v=vs.85).aspx
// "If the high-order bit is 1, the key is down; otherwise, it is up."
static constexpr short KeyPressed{ gsl::narrow_cast<short>(0x8000) };

AppHost::AppHost() noexcept :
    _app{},
    _logic{ nullptr }, // don't make one, we're going to take a ref on app's
    _window{ nullptr }
{
    _logic = _app.Logic(); // get a ref to app's logic

    _useNonClientArea = _logic.GetShowTabsInTitlebar();

    // If there were commandline args to our process, try and process them here.
    // Do this before AppLogic::Create, otherwise this will have no effect
    _HandleCommandlineArgs();

    if (_useNonClientArea)
    {
        _window = std::make_unique<NonClientIslandWindow>(_logic.GetRequestedTheme());
    }
    else
    {
        _window = std::make_unique<IslandWindow>();
    }

    // Tell the window to callback to us when it's about to handle a WM_CREATE
    auto pfn = std::bind(&AppHost::_HandleCreateWindow,
                         this,
                         std::placeholders::_1,
                         std::placeholders::_2,
                         std::placeholders::_3);
    _window->SetCreateCallback(pfn);

    _window->SetSnapDimensionCallback(std::bind(&winrt::TerminalApp::AppLogic::CalcSnappedDimension,
                                                _logic,
                                                std::placeholders::_1,
                                                std::placeholders::_2));
    _window->MouseScrolled({ this, &AppHost::_WindowMouseWheeled });
    _window->SetAlwaysOnTop(_logic.AlwaysOnTop());
    _window->MakeWindow();
}

AppHost::~AppHost()
{
    // destruction order is important for proper teardown here
    _window = nullptr;
    _app.Close();
    _app = nullptr;
}

bool AppHost::OnDirectKeyEvent(const uint32_t vkey, const uint8_t scanCode, const bool down)
{
    if (_logic)
    {
        return _logic.OnDirectKeyEvent(vkey, scanCode, down);
    }
    return false;
}

// Method Description:
// - Retrieve any commandline args passed on the commandline, and pass them to
//   the app logic for processing.
// - If the logic determined there's an error while processing that commandline,
//   display a message box to the user with the text of the error, and exit.
//    * We display a message box because we're a Win32 application (not a
//      console app), and the shell has undoubtedly returned to the foreground
//      of the console. Text emitted here might mix unexpectedly with output
//      from the shell process.
// Arguments:
// - <none>
// Return Value:
// - <none>
void AppHost::_HandleCommandlineArgs()
{
    if (auto commandline{ GetCommandLineW() })
    {
        int argc = 0;

        // Get the argv, and turn them into a hstring array to pass to the app.
        wil::unique_any<LPWSTR*, decltype(&::LocalFree), ::LocalFree> argv{ CommandLineToArgvW(commandline, &argc) };
        if (argv)
        {
            std::vector<winrt::hstring> args;
            for (auto& elem : wil::make_range(argv.get(), argc))
            {
                args.emplace_back(elem);
            }

            const auto result = _logic.SetStartupCommandline({ args });
            const auto message = _logic.ParseCommandlineMessage();
            if (!message.empty())
            {
                const auto displayHelp = result == 0;
                const auto messageTitle = displayHelp ? IDS_HELP_DIALOG_TITLE : IDS_ERROR_DIALOG_TITLE;
                const auto messageIcon = displayHelp ? MB_ICONWARNING : MB_ICONERROR;
                // TODO:GH#4134: polish this dialog more, to make the text more
                // like msiexec /?
                MessageBoxW(nullptr,
                            message.data(),
                            GetStringResource(messageTitle).data(),
                            MB_OK | messageIcon);

                if (_logic.ShouldExitEarly())
                {
                    ExitProcess(result);
                }
            }
        }
    }
}

// Method Description:
// - Initializes the XAML island, creates the terminal app, and sets the
//   island's content to that of the terminal app's content. Also registers some
//   callbacks with TermApp.
// !!! IMPORTANT!!!
// This must be called *AFTER* WindowsXamlManager::InitializeForCurrentThread.
// If it isn't, then we won't be able to create the XAML island.
// Arguments:
// - <none>
// Return Value:
// - <none>
void AppHost::Initialize()
{
    _window->Initialize();

    if (_useNonClientArea)
    {
        // Register our callback for when the app's non-client content changes.
        // This has to be done _before_ App::Create, as the app might set the
        // content in Create.
        _logic.SetTitleBarContent({ this, &AppHost::_UpdateTitleBarContent });
    }

    // Register the 'X' button of the window for a warning experience of multiple
    // tabs opened, this is consistent with Alt+F4 closing
    _window->WindowCloseButtonClicked([this]() { _logic.WindowCloseButtonClicked(); });

    // Add an event handler to plumb clicks in the titlebar area down to the
    // application layer.
    _window->DragRegionClicked([this]() { _logic.TitlebarClicked(); });

    _logic.RequestedThemeChanged({ this, &AppHost::_UpdateTheme });
    _logic.FullscreenChanged({ this, &AppHost::_FullscreenChanged });
    _logic.FocusModeChanged({ this, &AppHost::_FocusModeChanged });
    _logic.AlwaysOnTopChanged({ this, &AppHost::_AlwaysOnTopChanged });

    _logic.Create();

    _logic.TitleChanged({ this, &AppHost::AppTitleChanged });
    _logic.LastTabClosed({ this, &AppHost::LastTabClosed });

    _window->UpdateTitle(_logic.Title());

    // Set up the content of the application. If the app has a custom titlebar,
    // set that content as well.
    _window->SetContent(_logic.GetRoot());
    _window->OnAppInitialized();

    // THIS IS A HACK
    //
    // We've got a weird crash that happens terribly inconsistently, but pretty
    // readily on migrie's laptop, only in Debug mode. Apparently, there's some
    // weird ref-counting magic that goes on during teardown, and our
    // Application doesn't get closed quite right, which can cause us to crash
    // into the debugger. This of course, only happens on exit, and happens
    // somewhere in the XamlHost.dll code.
    //
    // Crazily, if we _manually leak the Application_ here, then the crash
    // doesn't happen. This doesn't matter, because we really want the
    // Application to live for _the entire lifetime of the process_, so the only
    // time when this object would actually need to get cleaned up is _during
    // exit_. So we can safely leak this Application object, and have it just
    // get cleaned up normally when our process exits.
    ::winrt::TerminalApp::App a{ _app };
    ::winrt::detach_abi(a);
}

// Method Description:
// - Called when the app's title changes. Fires off a window message so we can
//   update the window's title on the main thread.
// Arguments:
// - sender: unused
// - newTitle: the string to use as the new window title
// Return Value:
// - <none>
void AppHost::AppTitleChanged(const winrt::Windows::Foundation::IInspectable& /*sender*/, winrt::hstring newTitle)
{
    _window->UpdateTitle(newTitle);
}

// Method Description:
// - Called when no tab is remaining to close the window.
// Arguments:
// - sender: unused
// - LastTabClosedEventArgs: unused
// Return Value:
// - <none>
void AppHost::LastTabClosed(const winrt::Windows::Foundation::IInspectable& /*sender*/, const winrt::TerminalApp::LastTabClosedEventArgs& /*args*/)
{
    _window->Close();
}

// Method Description:
// - Resize the window we're about to create to the appropriate dimensions, as
//   specified in the settings. This will be called during the handling of
//   WM_CREATE. We'll load the settings for the app, then get the proposed size
//   of the terminal from the app. Using that proposed size, we'll resize the
//   window we're creating, so that it'll match the values in the settings.
// Arguments:
// - hwnd: The HWND of the window we're about to create.
// - proposedRect: The location and size of the window that we're about to
//   create. We'll use this rect to determine which monitor the window is about
//   to appear on.
// - launchMode: A LaunchMode enum reference that indicates the launch mode
// Return Value:
// - None
void AppHost::_HandleCreateWindow(const HWND hwnd, RECT proposedRect, winrt::TerminalApp::LaunchMode& launchMode)
{
    launchMode = _logic.GetLaunchMode();

    // Acquire the actual initial position
    auto initialPos = _logic.GetInitialPosition(proposedRect.left, proposedRect.top);
    proposedRect.left = static_cast<long>(initialPos.X);
    proposedRect.top = static_cast<long>(initialPos.Y);

    long adjustedHeight = 0;
    long adjustedWidth = 0;

    // Find nearest monitor.
    HMONITOR hmon = MonitorFromRect(&proposedRect, MONITOR_DEFAULTTONEAREST);

    // Get nearest monitor information
    MONITORINFO monitorInfo;
    monitorInfo.cbSize = sizeof(MONITORINFO);
    GetMonitorInfo(hmon, &monitorInfo);

    // This API guarantees that dpix and dpiy will be equal, but neither is an
    // optional parameter so give two UINTs.
    UINT dpix = USER_DEFAULT_SCREEN_DPI;
    UINT dpiy = USER_DEFAULT_SCREEN_DPI;
    // If this fails, we'll use the default of 96.
    GetDpiForMonitor(hmon, MDT_EFFECTIVE_DPI, &dpix, &dpiy);

    // We need to check if the top left point of the titlebar of the window is within any screen
    RECT offScreenTestRect;
    offScreenTestRect.left = proposedRect.left;
    offScreenTestRect.top = proposedRect.top;
    offScreenTestRect.right = offScreenTestRect.left + 1;
    offScreenTestRect.bottom = offScreenTestRect.top + 1;

    bool isTitlebarIntersectWithMonitors = false;
    EnumDisplayMonitors(
        nullptr, &offScreenTestRect, [](HMONITOR, HDC, LPRECT, LPARAM lParam) -> BOOL {
            auto intersectWithMonitor = reinterpret_cast<bool*>(lParam);
            *intersectWithMonitor = true;
            // Continue the enumeration
            return FALSE;
        },
        reinterpret_cast<LPARAM>(&isTitlebarIntersectWithMonitors));

    if (!isTitlebarIntersectWithMonitors)
    {
        // If the title bar is out-of-screen, we set the initial position to
        // the top left corner of the nearest monitor
        proposedRect.left = monitorInfo.rcWork.left;
        proposedRect.top = monitorInfo.rcWork.top;
    }

    auto initialSize = _logic.GetLaunchDimensions(dpix);

    const short islandWidth = Utils::ClampToShortMax(
        static_cast<long>(ceil(initialSize.Width)), 1);
    const short islandHeight = Utils::ClampToShortMax(
        static_cast<long>(ceil(initialSize.Height)), 1);

    // Get the size of a window we'd need to host that client rect. This will
    // add the titlebar space.
    const auto nonClientSize = _window->GetTotalNonClientExclusiveSize(dpix);
    adjustedWidth = islandWidth + nonClientSize.cx;
    adjustedHeight = islandHeight + nonClientSize.cy;

    const COORD origin{ gsl::narrow<short>(proposedRect.left),
                        gsl::narrow<short>(proposedRect.top) };
    const COORD dimensions{ Utils::ClampToShortMax(adjustedWidth, 1),
                            Utils::ClampToShortMax(adjustedHeight, 1) };

    const auto newPos = Viewport::FromDimensions(origin, dimensions);
    bool succeeded = SetWindowPos(hwnd,
                                  nullptr,
                                  newPos.Left(),
                                  newPos.Top(),
                                  newPos.Width(),
                                  newPos.Height(),
                                  SWP_NOACTIVATE | SWP_NOZORDER);

    // Refresh the dpi of HWND because the dpi where the window will launch may be different
    // at this time
    _window->RefreshCurrentDPI();

    // If we can't resize the window, that's really okay. We can just go on with
    // the originally proposed window size.
    LOG_LAST_ERROR_IF(!succeeded);

    TraceLoggingWrite(
        g_hWindowsTerminalProvider,
        "WindowCreated",
        TraceLoggingDescription("Event emitted upon creating the application window"),
        TraceLoggingKeyword(MICROSOFT_KEYWORD_MEASURES),
        TelemetryPrivacyDataTag(PDT_ProductAndServicePerformance));
}

// Method Description:
// - Called when the app wants to set its titlebar content. We'll take the
//   UIElement and set the Content property of our Titlebar that element.
// Arguments:
// - sender: unused
// - arg: the UIElement to use as the new Titlebar content.
// Return Value:
// - <none>
void AppHost::_UpdateTitleBarContent(const winrt::Windows::Foundation::IInspectable&, const winrt::Windows::UI::Xaml::UIElement& arg)
{
    if (_useNonClientArea)
    {
        (static_cast<NonClientIslandWindow*>(_window.get()))->SetTitlebarContent(arg);
    }
}

// Method Description:
// - Called when the app wants to change its theme. We'll forward this to the
//   IslandWindow, so it can update the root UI element of the entire XAML tree.
// Arguments:
// - sender: unused
// - arg: the ElementTheme to use as the new theme for the UI
// Return Value:
// - <none>
void AppHost::_UpdateTheme(const winrt::Windows::Foundation::IInspectable&, const winrt::Windows::UI::Xaml::ElementTheme& arg)
{
    _window->OnApplicationThemeChanged(arg);
}

void AppHost::_FocusModeChanged(const winrt::Windows::Foundation::IInspectable&,
                                const winrt::Windows::Foundation::IInspectable&)
{
    _window->FocusModeChanged(_logic.FocusMode());
}

void AppHost::_FullscreenChanged(const winrt::Windows::Foundation::IInspectable&,
                                 const winrt::Windows::Foundation::IInspectable&)
{
    _window->FullscreenChanged(_logic.Fullscreen());
}

void AppHost::_AlwaysOnTopChanged(const winrt::Windows::Foundation::IInspectable&,
                                  const winrt::Windows::Foundation::IInspectable&)
{
    _window->SetAlwaysOnTop(_logic.AlwaysOnTop());
}

// Method Description:
// - Called when the IslandWindow has received a WM_MOUSEWHEEL message. This can
//   happen on some laptops, where their trackpads won't scroll inactive windows
//   _ever_.
// - We're going to take that message and manually plumb it through to our
//   TermControl's, or anything else that implements IMouseWheelListener.
// - See GH#979 for more details.
// Arguments:
// - coord: The Window-relative, logical coordinates location of the mouse during this event.
// - delta: the wheel delta that triggered this event.
// Return Value:
// - <none>
void AppHost::_WindowMouseWheeled(const til::point coord, const int32_t delta)
{
    if (_logic)
    {
        // Find all the elements that are underneath the mouse
        auto elems = winrt::Windows::UI::Xaml::Media::VisualTreeHelper::FindElementsInHostCoordinates(coord, _logic.GetRoot());
        for (const auto& e : elems)
        {
            // If that element has implemented IMouseWheelListener, call OnMouseWheel on that element.
            if (auto control{ e.try_as<winrt::Microsoft::Terminal::TerminalControl::IMouseWheelListener>() })
            {
                try
                {
                    // Translate the event to the coordinate space of the control
                    // we're attempting to dispatch it to
                    const auto transform = e.TransformToVisual(nullptr);
                    const til::point controlOrigin{ til::math::flooring, transform.TransformPoint(til::point{ 0, 0 }) };

                    const til::point offsetPoint = coord - controlOrigin;

                    const auto lButtonDown = WI_IsFlagSet(GetKeyState(VK_LBUTTON), KeyPressed);
                    const auto mButtonDown = WI_IsFlagSet(GetKeyState(VK_MBUTTON), KeyPressed);
                    const auto rButtonDown = WI_IsFlagSet(GetKeyState(VK_RBUTTON), KeyPressed);

                    if (control.OnMouseWheel(offsetPoint, delta, lButtonDown, mButtonDown, rButtonDown))
                    {
                        // If the element handled the mouse wheel event, don't
                        // continue to iterate over the remaining controls.
                        break;
                    }
                }
                CATCH_LOG();
            }
        }
    }
}