juce中真正的窗口过程

    static LRESULT CALLBACK windowProc (HWND h, UINT message, WPARAM wParam, LPARAM lParam)
    {
        if (HWNDComponentPeer* const peer = getOwnerOfWindow (h))
        {
            jassert (isValidPeer (peer));
            return peer->peerWindowProc (h, message, wParam, lParam);
        }
        return DefWindowProcW (h, message, wParam, lParam);
    }

    class WindowClassHolder    : private DeletedAtShutdown
    {
    public:
        WindowClassHolder()
        {
            // this name has to be different for each app/dll instance because otherwise poor old Windows can
            // get a bit confused (even despite it not being a process-global window class).
            String windowClassName ("JUCE_");
            windowClassName << String::toHexString (Time::currentTimeMillis());
            HINSTANCE moduleHandle = (HINSTANCE) Process::getCurrentModuleInstanceHandle();
            TCHAR moduleFile [1024] = { 0 };
            GetModuleFileName (moduleHandle, moduleFile, 1024);
            WORD iconNum = 0;
            WNDCLASSEX wcex = { 0 };
            wcex.cbSize         = sizeof (wcex);
            wcex.style          = CS_OWNDC;
            wcex.lpfnWndProc    = (WNDPROC) windowProc;
            wcex.lpszClassName  = windowClassName.toWideCharPointer();
            wcex.cbWndExtra     = 32;
            wcex.hInstance      = moduleHandle;
            wcex.hIcon          = ExtractAssociatedIcon (moduleHandle, moduleFile, &iconNum);
            iconNum = 1;
            wcex.hIconSm        = ExtractAssociatedIcon (moduleHandle, moduleFile, &iconNum);
            atom = RegisterClassEx (&wcex);
            jassert (atom != 0);
            isEventBlockedByModalComps = checkEventBlockedByModalComps;
        }

        hwnd = CreateWindowEx (exstyle, WindowClassHolder::getInstance()->getWindowClassName(),
                               L"", type, 0, 0, 0, 0, parentToAddTo, 0,
                               (HINSTANCE) Process::getCurrentModuleInstanceHandle(), 0);

    static void* createWindowCallback (void* userData)
    {
        static_cast<HWNDComponentPeer*> (userData)->createWindow();
        return nullptr;
    }

    //==============================================================================
    HWNDComponentPeer (Component& comp, const int windowStyleFlags, HWND parent, bool nonRepainting)
        : ComponentPeer (comp, windowStyleFlags),
          dontRepaint (nonRepainting),
          parentToAddTo (parent),
          currentRenderingEngine (softwareRenderingEngine),
          lastPaintTime (0),
          lastMagnifySize (0),
          fullScreen (false),
          isDragging (false),
          isMouseOver (false),
          hasCreatedCaret (false),
          constrainerIsResizing (false),
          currentWindowIcon (0),
          dropTarget (nullptr),
          updateLayeredWindowAlpha (255)
    {
        callFunctionIfNotLocked (&createWindowCallback, this);
        setTitle (component.getName());
        if ((windowStyleFlags & windowHasDropShadow) != 0
             && Desktop::canUseSemiTransparentWindows()
             && ((! hasTitleBar()) || SystemStats::getOperatingSystemType() < SystemStats::WinVista))
        {
            shadower = component.getLookAndFeel().createDropShadowerForComponent (&component);
            if (shadower != nullptr)
                shadower->setOwner (&component);
        }
    }

ModifierKeys HWNDComponentPeer::currentModifiers;
ModifierKeys HWNDComponentPeer::modifiersAtLastCallback;
 
ComponentPeer* Component::createNewPeer (int styleFlags, void* parentHWND)
{
    return new HWNDComponentPeer (*this, styleFlags, (HWND) parentHWND, false);
}
 
ComponentPeer* createNonRepaintingEmbeddedWindowsPeer (Component& component, void* parentHWND)
{
    return new HWNDComponentPeer (component, ComponentPeer::windowIgnoresMouseClicks,
                                  (HWND) parentHWND, true);
}

//==============================================================================
void Component::addToDesktop (int styleWanted, void* nativeWindowToAttachTo)
{
    // if component methods are being called from threads other than the message
    // thread, you‘ll need to use a MessageManagerLock object to make sure it‘s thread-safe.
    ASSERT_MESSAGE_MANAGER_IS_LOCKED
    if (isOpaque())
        styleWanted &= ~ComponentPeer::windowIsSemiTransparent;
    else
        styleWanted |= ComponentPeer::windowIsSemiTransparent;
    // don‘t use getPeer(), so that we only get the peer that‘s specifically
    // for this comp, and not for one of its parents.
    ComponentPeer* peer = ComponentPeer::getPeerFor (this);
    if (peer == nullptr || styleWanted != peer->getStyleFlags())
    {
        const WeakReference<Component> safePointer (this);
       #if JUCE_LINUX
        // it‘s wise to give the component a non-zero size before
        // putting it on the desktop, as X windows get confused by this, and
        // a (1, 1) minimum size is enforced here.
        setSize (jmax (1, getWidth()),
                 jmax (1, getHeight()));
       #endif
        const Point<int> topLeft (getScreenPosition());
        bool wasFullscreen = false;
        bool wasMinimised = false;
        ComponentBoundsConstrainer* currentConstrainer = nullptr;
        Rectangle<int> oldNonFullScreenBounds;
        int oldRenderingEngine = -1;
        if (peer != nullptr)
        {
            ScopedPointer<ComponentPeer> oldPeerToDelete (peer);
            wasFullscreen = peer->isFullScreen();
            wasMinimised = peer->isMinimised();
            currentConstrainer = peer->getConstrainer();
            oldNonFullScreenBounds = peer->getNonFullScreenBounds();
            oldRenderingEngine = peer->getCurrentRenderingEngine();
            flags.hasHeavyweightPeerFlag = false;
            Desktop::getInstance().removeDesktopComponent (this);
            internalHierarchyChanged(); // give comps a chance to react to the peer change before the old peer is deleted.
            if (safePointer == nullptr)
                return;
            setTopLeftPosition (topLeft);
        }
        if (parentComponent != nullptr)
            parentComponent->removeChildComponent (this);
        if (safePointer != nullptr)
        {
            flags.hasHeavyweightPeerFlag = true;
            peer = createNewPeer (styleWanted, nativeWindowToAttachTo);
            Desktop::getInstance().addDesktopComponent (this);
            bounds.setPosition (topLeft);
            peer->updateBounds();
            if (oldRenderingEngine >= 0)
                peer->setCurrentRenderingEngine (oldRenderingEngine);
            peer->setVisible (isVisible());
            peer = ComponentPeer::getPeerFor (this);
            if (peer == nullptr)
                return;
            if (wasFullscreen)
            {
                peer->setFullScreen (true);
                peer->setNonFullScreenBounds (oldNonFullScreenBounds);
            }
            if (wasMinimised)
                peer->setMinimised (true);
           #if JUCE_WINDOWS
            if (isAlwaysOnTop())
                peer->setAlwaysOnTop (true);
           #endif
            peer->setConstrainer (currentConstrainer);
            repaint();
            internalHierarchyChanged();
        }
    }
}