JUCE/modules/juce_events/native/juce_win32_Messaging.cpp

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2016 - ROLI Ltd.

   Permission is granted to use this software under the terms of the ISC license
   http://www.isc.org/downloads/software-support-policy/isc-license/

   Permission to use, copy, modify, and/or distribute this software for any
   purpose with or without fee is hereby granted, provided that the above
   copyright notice and this permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
   FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT,
   OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
   USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
   TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
   OF THIS SOFTWARE.

   -----------------------------------------------------------------------------

   To release a closed-source product which uses other parts of JUCE not
   licensed under the ISC terms, commercial licenses are available: visit
   www.juce.com for more information.

  ==============================================================================
*/

extern HWND juce_messageWindowHandle;

typedef bool (*CheckEventBlockedByModalComps) (const MSG&);
CheckEventBlockedByModalComps isEventBlockedByModalComps = nullptr;

//==============================================================================
namespace WindowsMessageHelpers
{
    const unsigned int customMessageID = WM_USER + 123;
    const unsigned int broadcastMessageMagicNumber = 0xc403;

    const TCHAR messageWindowName[] = _T("JUCEWindow");
    ScopedPointer<HiddenMessageWindow> messageWindow;

    void dispatchMessageFromLParam (LPARAM lParam)
    {
        if (MessageManager::MessageBase* message = reinterpret_cast<MessageManager::MessageBase*> (lParam))
        {
            JUCE_TRY
            {
                message->messageCallback();
            }
            JUCE_CATCH_EXCEPTION

            message->decReferenceCount();
        }
    }

    BOOL CALLBACK broadcastEnumWindowProc (HWND hwnd, LPARAM lParam)
    {
        if (hwnd != juce_messageWindowHandle)
        {
            TCHAR windowName[64] = { 0 }; // no need to read longer strings than this
            GetWindowText (hwnd, windowName, 63);

            if (String (windowName) == messageWindowName)
                reinterpret_cast<Array<HWND>*> (lParam)->add (hwnd);
        }

        return TRUE;
    }

    void handleBroadcastMessage (const COPYDATASTRUCT* const data)
    {
        if (data != nullptr && data->dwData == broadcastMessageMagicNumber)
        {
            struct BroadcastMessage  : public CallbackMessage
            {
                BroadcastMessage (CharPointer_UTF32 text, size_t length) : message (text, length) {}
                void messageCallback() override { MessageManager::getInstance()->deliverBroadcastMessage (message); }

                String message;
            };

            (new BroadcastMessage (CharPointer_UTF32 ((const CharPointer_UTF32::CharType*) data->lpData),
                                   data->cbData / sizeof (CharPointer_UTF32::CharType)))
                ->post();
        }
    }

    //==============================================================================
    LRESULT CALLBACK messageWndProc (HWND h, const UINT message, const WPARAM wParam, const LPARAM lParam) noexcept
    {
        if (h == juce_messageWindowHandle)
        {
            if (message == customMessageID)
            {
                // (These are trapped early in our dispatch loop, but must also be checked
                // here in case some 3rd-party code is running the dispatch loop).
                dispatchMessageFromLParam (lParam);
                return 0;
            }

            if (message == WM_COPYDATA)
            {
                handleBroadcastMessage (reinterpret_cast<const COPYDATASTRUCT*> (lParam));
                return 0;
            }
        }

        return DefWindowProc (h, message, wParam, lParam);
    }
}

//==============================================================================
bool MessageManager::dispatchNextMessageOnSystemQueue (const bool returnIfNoPendingMessages)
{
    using namespace WindowsMessageHelpers;
    MSG m;

    if (returnIfNoPendingMessages && ! PeekMessage (&m, (HWND) 0, 0, 0, PM_NOREMOVE))
        return false;

    if (GetMessage (&m, (HWND) 0, 0, 0) >= 0)
    {
        if (m.message == customMessageID && m.hwnd == juce_messageWindowHandle)
        {
            dispatchMessageFromLParam (m.lParam);
        }
        else if (m.message == WM_QUIT)
        {
            if (JUCEApplicationBase* const app = JUCEApplicationBase::getInstance())
                app->systemRequestedQuit();
        }
        else if (isEventBlockedByModalComps == nullptr || ! isEventBlockedByModalComps (m))
        {
            if ((m.message == WM_LBUTTONDOWN || m.message == WM_RBUTTONDOWN)
                  && ! JuceWindowIdentifier::isJUCEWindow (m.hwnd))
            {
                // if it's someone else's window being clicked on, and the focus is
                // currently on a juce window, pass the kb focus over..
                HWND currentFocus = GetFocus();

                if (currentFocus == 0 || JuceWindowIdentifier::isJUCEWindow (currentFocus))
                    SetFocus (m.hwnd);
            }

            TranslateMessage (&m);
            DispatchMessage (&m);
        }
    }

    return true;
}

bool MessageManager::postMessageToSystemQueue (MessageManager::MessageBase* const message)
{
    message->incReferenceCount();
    return PostMessage (juce_messageWindowHandle, WindowsMessageHelpers::customMessageID, 0, (LPARAM) message) != 0;
}

void MessageManager::broadcastMessage (const String& value)
{
    const String localCopy (value);

    Array<HWND> windows;
    EnumWindows (&WindowsMessageHelpers::broadcastEnumWindowProc, (LPARAM) &windows);

    for (int i = windows.size(); --i >= 0;)
    {
        COPYDATASTRUCT data;
        data.dwData = WindowsMessageHelpers::broadcastMessageMagicNumber;
        data.cbData = (localCopy.length() + 1) * sizeof (CharPointer_UTF32::CharType);
        data.lpData = (void*) localCopy.toUTF32().getAddress();

        DWORD_PTR result;
        SendMessageTimeout (windows.getUnchecked (i), WM_COPYDATA,
                            (WPARAM) juce_messageWindowHandle,
                            (LPARAM) &data,
                            SMTO_BLOCK | SMTO_ABORTIFHUNG, 8000, &result);
    }
}

//==============================================================================
void MessageManager::doPlatformSpecificInitialisation()
{
    OleInitialize (0);

    using namespace WindowsMessageHelpers;
    messageWindow = new HiddenMessageWindow (messageWindowName, (WNDPROC) messageWndProc);
    juce_messageWindowHandle = messageWindow->getHWND();
}

void MessageManager::doPlatformSpecificShutdown()
{
    WindowsMessageHelpers::messageWindow = nullptr;

    OleUninitialize();
}

//==============================================================================
struct MountedVolumeListChangeDetector::Pimpl   : private DeviceChangeDetector
{
    Pimpl (MountedVolumeListChangeDetector& d) : DeviceChangeDetector (L"MountedVolumeList"), owner (d)
    {
        File::findFileSystemRoots (lastVolumeList);
    }

    void systemDeviceChanged() override
    {
        Array<File> newList;
        File::findFileSystemRoots (newList);

        if (lastVolumeList != newList)
        {
            lastVolumeList = newList;
            owner.mountedVolumeListChanged();
        }
    }

    MountedVolumeListChangeDetector& owner;
    Array<File> lastVolumeList;
};

MountedVolumeListChangeDetector::MountedVolumeListChangeDetector()  { pimpl = new Pimpl (*this); }
MountedVolumeListChangeDetector::~MountedVolumeListChangeDetector() {}